Patent ID: 12221395

Like elements in the various figures are denoted by like reference numerals for consistency.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the following embodiments, it will be understood that the descriptions are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents that may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be readily apparent to one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components, and circuits have not been described in detail so as not to unnecessarily obscure aspects of the present invention.

The technical proposal(s) of embodiments of the present invention will be fully and clearly described in conjunction with the drawings in the following embodiments. It will be understood that the descriptions are not intended to limit the invention to these embodiments. Based on the described embodiments of the present invention, other embodiments can be obtained by one skilled in the art without creative contribution and are in the scope of legal protection given to the present invention.

Furthermore, all characteristics, measures or processes disclosed in this document, except characteristics and/or processes that are mutually exclusive, can be combined in any manner and in any combination possible. Any characteristic disclosed in the present specification, claims, Abstract and Figures can be replaced by other equivalent characteristics or characteristics with similar objectives, purposes and/or functions, unless specified otherwise.

For the sake of convenience and simplicity, the terms “data” and “information” are generally used interchangeably herein, but are generally given their art-recognized meanings. Also, for convenience and simplicity, the terms “location” and “site” may be used interchangeably, as may the terms “connected to,” “coupled with,” “coupled to,” and “in communication with,” but these terms are also generally given their art-recognized meanings.

The invention, in its various aspects, will be explained in greater detail below with regard to exemplary embodiments.

An Exemplary Method of Applying Formic Acid or Formate Ions to Soil to Increase the Ability of Irrigation/Fertigation Water to Permeate the Soil

Illustrative embodiments recognize and take into account that irrigation water may contain ions that form insoluble salts or other compounds in soil that can accumulate over time. The buildup of these insoluble deposits can lead to decreased soil permeation, soil compaction, alkaline soil conditions, and reduced nutrient availability in the root zone of plants or crops in the soil. Conditions that can lead to decreased soil permeation include: (1) inorganic loading of the source water, (2) addition of fertilizers and/or soil amendments to the source water; and (3) efficiency of the irrigation water filtration system.

Embodiments of the present invention provide a method of increasing delivery of irrigation water and optionally a fertilizer to a predetermined depth in soil containing agricultural crops. Formic acid and/or a formate salt are introduced to irrigation water to form a formate-enhanced irrigation water having a formate concentration of from about 10 ppm to about 10,000 ppm. The formate-enhanced irrigation water is distributed to the soil in an amount sufficient to (i) increase a flow rate of the irrigation water through the soil, (ii) reduce a compaction of the soil, and/or (iii) reduce a calcium concentration in the soil.

Although irrigation water sources vary dramatically, they frequently contain inorganic ions, dissolved hydrogen sulfide and dissolved carbon dioxide. The presence of such constituents can lead to several fouling problems. High levels of calcium, magnesium and carbon dioxide at a basic pH (e.g., a pH of 7 to 8 or higher) can form insoluble or only slightly soluble calcium and magnesium carbonates. Under such pH conditions, iron and manganese, even at low levels, form insoluble or only slightly soluble iron and manganese oxides that have a propensity to precipitate from the water.

Most naturally-occurring water contains dissolved ions and minerals that can form insoluble salts when combined with ions in common NPK (nitrogen, phosphorus, and potassium) fertilizer formulations. For example, bicarbonate alkalinity concentrations in water exceeding about 2 meq/liter (e.g., 200 ppm as CaCO3) can cause calcium carbonate precipitation. Calcium concentrations exceeding 2-3 meq/liter (e.g., 100-150 ppm as CaCO3) can cause precipitates to form during the introduction of phosphate fertilizers. The solubility chart below provides an overview of inorganic anion/cation incompatibilities (that is, anions and cations that, when both are present, lead to insoluble inorganic salt formation) that can result in insoluble material accumulating in the soil, leading to compaction and decreased soil permeation.

CHART 1Solubility Chart for Common Irrigation System Anions and CationsAnionCationCl−HCO3−OH−NO3−CO3−2SO4−2S−2PO4−3Na+SSSSSSSSK+SSSSSSSSNH4+SSSSSSSSH+SSH2OSCO2SH2SSCa+2SSSVSSSIVSSXXXIMg+2SSISVSSSXXXTFe+2SSSVSSSVSSSIIFe+3SIISISXXXIMn+2SXXXISISII

In Chart 1, S means soluble (over 5,000 ppm), SS means slightly soluble (2,000 to 5,000 ppm), VSS means very slightly soluble (20-2,000 ppm), I means insoluble (<20 ppm) and XXX means does not form (is not a compound). From Kemmer, Frank N.,Water: The Universal Solvent, Basic Chemistry, p. 37, Nalco Chemical Company (1977). As seen from the solubility information in Chart 1, the addition of phosphates, such as phosphate fertilizers, to hard water (e.g., which contains calcium or magnesium ions) can lead to the formation of insoluble inorganic salts.

Fertilizers are generally defined as materials that add nutrient value to the soil that enables enhanced growth and development of a plant or crop in the soil. Soil amendments are generally defined as materials that enable the nutrients, already in the soil, to be more efficiently utilized and transported to the plant or crop being grown. Regardless of whether the material is a fertilizer or soil amendment, these additives, when added to irrigation water, can cause the accumulation of insoluble compounds, leading to soil compaction and decreased soil permeation.

These problematic fertilizer and/or soil amendment additives include inorganic materials such as: (1) various NPK (nitrogen, phosphorus, and potassium) fertilizer formulations; (2) diverse micronutrient formulations that can contain iron, zinc, or manganese, as well as other heavy metals; and (3) common inorganic soil amendments, such as calcium sulfate (e.g., gypsum) and calcium carbonate (e.g., lime). All of these additives can elevate the risk of fouling of the micro-irrigation system due to precipitation of inorganic ions. Chart 1 above provides solubility data for common cation/anion combinations to demonstrate the potential for precipitation and deposit formation. In other words, Chart 1 shows the anions and cations that, when both are present, can lead to the formation of insoluble inorganic compounds.

The compositions and methods of exemplary embodiments of the invention provide a reliable, safe, economical, and environmentally friendly approach to increasing soil permeation and delivery of irrigation water and fertilizer(s) to at least a predetermined depth into soil (e.g., a root depth of a crop or plant in the soil). The present methods and compositions may be effective for improving delivery of fertilizer(s) to soil that has been compacted due to the accumulation of one or more insoluble materials in the soil. The compositions can be formed by introducing formic acid and/or a formate salt to irrigation water to form a formate-enhanced irrigation water having a formate concentration from about 10 ppm to about 10,000 ppm. For example, the compositions may comprise formic acid or formate ion (e.g., a formate salt, such as potassium formate, ammonium formate, calcium formate or magnesium formate), which may be added (e.g., as an aqueous solution) to the irrigation water to improve soil permeation and delivery of irrigation water and fertilizers to predetermined depths into the soil.

Formic acid, which may be used alone in the practice of the invention, is commercially available. It is typically available in concentrations ranging from 20 percent to 99 percent (e.g., 30 to 95 percent) as formic acid in water. Such commercially available formic acid sources can be used as a stock solution of formic acid for use in the invention. Once formed, the formate-enhanced irrigation water may comprise an amount of formic acid and/or formate salt from about 10 parts per million (ppm) to about 10,000 ppm (e.g., by weight or by moles), or any value or range of values therein (e.g., 100-1000 ppm by weight). In some embodiments, the formate-enhanced irrigation water contains from 0.001 to 1.0 parts by weight of formic acid per 100 parts by weight of the formate-enhanced irrigation water, or any value or range of values therein.

For a typical treatment, the formic acid stock solution and/or an aqueous formate salt solution can be added to the irrigation water at a flow rate of from about 0.1 to about 10 units volume (e.g., gallons, liters, etc.) per unit time (e.g., minute, hour, etc.) for every 1000 units volume per unit time of irrigation water. For example, the formic acid stock solution and/or aqueous formate salt solution may be introduced to the irrigation water (e.g., by pumping) at a flow rate ratio of from about 0.1 to about 10 gallons/min for every 1000 gallons/min of irrigation water being distributed to the soil. The soil to which the formic acid and/or formate salt solution is distributed is typically not the entire field served by the irrigation system, but instead, a block of the field that may encompass the acreage normally under simultaneous irrigation (typically from about 5 to about 100 acres). The optimum or near optimum flow rate ratio and length of time for distributing the formate-enhanced irrigation water to the soil (e.g., the block in the agricultural field), whereby an efficient and successful, but not impractically excessive, concentration of actives (i.e., formic acid or formate ion) is fed to the irrigation water, may depend on the water quality of the irrigation water, the compaction of the soil, the depth of the root zone in the soil, the concentration, distribution and/or depth of insoluble carbonates, bicarbonates and oxides in the soil, etc. Ultimately, in a typical application, the present method distributes from about 0.1 liters of actives per acre (0.04 l/hectare of actives) to about 50 liters of actives per acre (20 l/hectare of actives), or any value or range of values therein.

The formate-enhanced irrigation water is distributed directly to the soil, rather than through an irrigation system. The formate-enhanced irrigation water can be distributed directly to the soil by flooding the field or block with a predetermined volume of formate-enhanced irrigation water. The formic acid and/or formate salt solution may be distributed to the irrigation water at an inlet in the irrigation water supply pipe/conduit upstream from outlet in the pipe/conduit to the field or block, or at the outlet in the pipe/conduit.

To accomplish the present method, formic acid and/or a formate salt can be introduced into the irrigation system (e.g., at a manifold) just before the irrigation water conduit to the field. A typical irrigation system includes a pump that can pump water at a rate of up to approximately 1000 to 10,000 liters per minute, typically at a pressure of up to about 40 to 80 psi. The formic acid stock solution can be introduced into the water of the irrigation system via a positive displacement pump, at a rate of about 0.5 to about 40 1 per minute. Such a feed rate is from about 10 ppm to about 10,000 ppm relative to the volume of irrigation water at the rate at which it is pumped. A typical block to be irrigated is about 20-50 acres. At a flow rate of, for example, 1000 1 to about 15,000 1 per minute of the formate-enhanced irrigation water into the field or block, the formic acid and/or formate salt may be distributed to the field or block for a length of time from about 1 to about 8 hours.

The formate-enhanced irrigation water is delivered to the soil in an amount sufficient to (i) increase a flow rate of the irrigation water through the soil, (ii) reduce a compaction of the soil, and/or (iii) reduce a calcium concentration in the soil. The flow rate of the irrigation water through the soil can be measured before and after the present method to determine the change therein. For example, the flow rate of the irrigation water through the soil can be measured according to one or more of the Examples described below.

The extent and depth of subsurface compaction in the soil can be measured using a penetrometer, or soil compaction tester (e.g., to a depth of 36 to 48 inches into the soil). Dial compaction probes can measure the pressure (e.g., in pounds per square inch) that it takes to penetrate the soil (e.g., via a needle moving across a scale on the display). Digital compaction meters are similar to dial compaction probes, but they display a digital reading of pressure and can record the depth and pressure for each test. Thus, the compaction of the soil (i.e., pressure required to penetrate the soil at a certain depth) can be measured before and after the present method to determine the change in soil compaction.

The calcium concentration in the soil can also be measured before and after the present method to determine the change therein. For example, samples of dry soil can be taken (e.g., at substantially the same site and at the same depth) before and after the present method, and a predetermined volume of water (e.g., irrigation water, tap water, distilled and/or deionized water, etc.) can be passed through the sample and collected. The calcium concentration in the water passed through the soil sample can be conventionally measured. The calcium concentrations in the water passed through the soil samples collected before and after the present method can be compared to determine the change therein as a result of the present method.

In the present method, the formate-enhanced irrigation water may leach or dissolve insoluble materials (e.g., insoluble inorganic salts) above, at or below the predetermined depth in the soil, and may decrease soil salinity and/or alkalinity within the root zone of the crops in the soil. For example, formic acid may react with carbonate salts to form calcium formate, carbon dioxide and water, and the formate salt(s) in the stock solution may exchange counterions with insoluble carbonate and bicarbonate compounds in the soil to form relatively soluble formate salts from the cations in the insoluble carbonate and bicarbonate compounds and relatively soluble carbonate and bicarbonate salts from the cation in the stock formate salt solution.

For example, the overall formic acid reaction with calcium carbonate is shown in Eq. 1 below.

Calcium formate is readily soluble in water, and can be transported out of the root zone as a dissolved eluent in excess irrigation water. Thus, the presence of formate ions in the irrigation water may also help to remove some insoluble material containing calcium ions from the soil in the root zone (or within a root depth) of the soil. Therefore, further embodiments of the present method may further include introducing formate ions, such as potassium formate, ammonium formate, or even calcium formate (in a concentration in the formate-enhanced irrigation water of <4% by weight) to the irrigation water before distributing the formate-enhanced irrigation water to the soil. Additionally, the carbon dioxide released in the soil may aid in reducing soil pH, leading to a decrease in soil compaction and a further increase in soil permeability.

Examples

The following examples or provided for explanatory purposes only and are not intended to limit the scope of the invention.

Permeation tests were conducted using multiple 2-inch diameter polyvinylchloride (PVC) columns packed with 100 grams of dry farm soil ground to a fine powder having a consistent particle size. The soil was packed in each of six columns by vibration for 30 seconds, resulting in an approximately 1- to 2-inch-tall column of soil. A 1- to 2-inch-tall pad of glass beads was placed on each of the soil columns, and 100 milliliters of (1) irrigation water without formate or formic acid (i.e., water as provided to the farm by the local water bureau or irrigation organization), (2) the same water containing 22 ppm by moles of calcium formate, or (3) the same water containing 0.33% by weight of formic acid was added to each of two of the columns and passed through the respective column. In essence, the soil acts similarly to an ion exchange medium in the permeation tests. The liquid passing through the column for each of the water, water with calcium formate, and water with formic acid was collected and weighed every 10 minutes for the first hour, then every 30 minutes until substantially all of the liquid had eluted. The weights were recorded and plotted on a bar graph. After substantially all of the solution had eluted from the soil, a sample was analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) to determine the content of certain elements in the eluant. The procedure was repeated using the same soil columns until a total of four batches of 100 g of the test solutions were passed through the soil columns (i.e., each column through which irrigation water was passed on the first pass had three more 100 g samples of irrigation water passed through them; each column through which calcium formate solution was passed on the first pass had three more 100 g samples of the same calcium formate solution passed through them; and each column through which the formic acid solution was passed on the first pass had three more 100 g samples of the same formic acid solution passed through them). Results of the first two passes of the liquid through the columns are illustrated inFIGS.1-2.

The objective was to investigate the behavior of different irrigation water treatments and determine the relative amounts of water that passed through the soil columns. The column retention times reflect the rate at which the liquid passes through the soil. Understanding these retention times provides insights about the transport and movement of irrigation water (and any fertilizers dissolved therein) through the soil, which has implications for the volume of water passing into and through the root zone, nutrient availability to crops, leaching of contaminants, and overall soil health.

FIG.1shows the averages of the permeation tests for irrigation water (left bar), aqueous calcium formate (center bar), and aqueous formic acid (right bar) during a first pass through dry soil from a first farm in the central San Joaquin Valley in California. The soil samples retained on average about 36 ml of liquid from the aqueous calcium formate and aqueous formic acid solutions, and about 38 ml of tap water. Furthermore, the aqueous formic acid solution had completed passing through the soil column on average between 120 and 150 minutes; the aqueous calcium formate solution had completed passing through the soil column on average between 150 and 180 minutes; and the tap water had completed passing through the soil column on average between about 240 and 270 minutes, never quite passing as much liquid through the soil column as the aqueous calcium formate and aqueous formic acid solutions. Comparing amounts of liquid passed through the columns at the same lengths of time, greater amounts of aqueous calcium formate and aqueous formic acid solutions passed through the columns than tap water at all times after 20 minutes, and more aqueous formic acid solution passed through the columns than aqueous calcium formate solution from about 30 minutes to about 150 minutes.

FIG.2shows the averages of the permeation tests for tap water (left bar), aqueous calcium formate (center bar), and aqueous formic acid (right bar) during a second pass through the same soil columns from the first farm providing the data forFIG.1. Because the soil samples were wet in the second pass, a greater percentage of the 100 ml of liquid added to the columns passed through the columns. Similar to the results inFIG.1, the aqueous formic acid solution had completed passing through the soil column on average between 180 and 210 minutes, and the aqueous calcium formate solution had completed passing through the soil column on average between 210 and 240 minutes. However, even after 390 minutes, the tap water may not have completed passing through the soil column. Comparing amounts of liquid passed through the columns at the same lengths of time, greater amounts of aqueous calcium formate and aqueous formic acid solutions passed through the columns than tap water at all times, and more aqueous formic acid solution passed through the columns than aqueous calcium formate solution at all times up to about 240 minutes.

The results of the third and fourth passes were similar to the second pass (FIG.2), except that the formic acid solution completely eluted a little earlier, and the results of the calcium formate solution and irrigation water gradually became more similar, while the results of the formic acid solution continuously improved. Table 1 below shows the elution results, in which the first column of data shows the average time taken for 50 g of the test solution to pass through the soil for each of the four passes, and the last three data columns show the average amount of liquid (in grams) eluted from each individual column after 60 minutes, 120 minutes and 240 minutes. “Water” refers to irrigation water, “Ca formate” refers to the calcium formate solution, and “HCO2H” refers to the formic acid solution; “1st” refers to the first pass, “2nd” refers to the second pass, etc.; NA indicates “not applicable” as all the water eluted before 240 minutes. The data in Table 1 is for the average of the two soil samples.

TABLE 1Time (50 g ofLiquid ElutedLiquid Eluted afterLiquid Eluted afterSampleliquid, in min)after 60 min (in g)120 min (in g)240 min (in g)Water 1st18015.935.560.4Water 2nd18021.339.972.1Water 3rd18019.136.266.3Water 4th18019.637.968.5Ca formate 1st12028.653.9NA*Ca formate 2nd12033.359.998.5Ca formate 3rd15026.448.886.7Ca formate 4th15024.144.675.0HCO2H 1st9034.159.7NA*HCO2H 2nd9043.978.9NA*HCO2H 3rd9036.068.3NA*HCO2H 4th9040.569.5NA*

The elution results show that the calcium formate solution passed through the column more quickly than the irrigation water, for all four passes. This can also be seen from the drainage rates (Table 2), where the amount of time for 50 g of the calcium formate solution to elute from the soil took 67% to 83% of the time of the irrigation water tests (i.e. 17% to 33% faster drainage rate). In terms of the amount of liquid eluted from the soil over fixed periods of time (60 mins, 120 mins and 240 mins), the calcium formate solution provides an 110-180% improvement compared to the irrigation water.

Repeated application of the calcium formate solution to the same soil column results in a significant improvement in drainage rate for the first pass relative to irrigation water, and the second pass with the calcium formate solution elutes much faster than the first pass. However, the third pass with the calcium formate solution elutes a little more slowly than the second pass (similar to the first pass), and the fourth pass elutes slowest of all, but still faster than the irrigation water. This result suggests that repeated applications of the calcium formate solution initially improves the drainage rate of the soil, then at some point it starts to decrease the drainage rate, although the drainage is still much better than when irrigation water is used alone. This may be related to a buildup of calcium in the soil during or after the third application of the calcium formate solution. This observation will be discussed further in relation to the ICP results presented below.

The formic acid solution showed the best performance. This solution passed through the soil significantly faster than the irrigation water or the calcium formate solution (FIGS.1-2and Table 1). The drainage rates presented in Table 2 below show that the formic acid solution elutes 170-210% more liquid by mass than the irrigation water in the first pass, 200-210% more in the second pass, ˜190% more in the third pass, and 180-210% more in the fourth pass.

TABLE 2Drainage Rates, showing the same results as presented in Table1 but presented as percentages relative to irrigation water.Time (50 g),60 mins120 mins240 minSamplein min(g)(g)(g)Ca formate 1st66.7%180%152%NA*Ca formate 2nd66.7%157%150%137%Ca formate 3rd83.3%138%135%131%Ca formate 4th83.3%123%118%110%HCO2H 1st50.0%214%168%NA*HCO2H 2nd50.0%206%198%NA*HCO2H 3rd50.0%189%189%NA*HCO2H 4th50.0%207%183%NA*

The results from the ICP analyses of the solutions that passed through the soil columns are presented in Table 3 below, in ppm. Results are presented from each individual test (i.e., each test solution was studied in duplicate, rather than presenting an average of the two side-by-side tests), where “Water A 1st” refers to the first pass with irrigation water for the first soil column, and “Water B 1st” refers to the first pass with irrigation water for the second (duplicate) soil column. The irrigation water was also analyzed by ICP as received (see the first row of data, labelled “Water”). The elements Al, As, Cd, Co, Cr, Cu, Fe, Mo, Ni, Pb, Se, Ti, and Zn were also analyzed by ICP, but are not reported, as they were found to be present at concentrations of less than 1.0 ppm.

TABLE 3BCaKMgMnNaPSSiWater0.2614.22.216.60.0310.1<LLD2.110.0Water A 1st5.43150.910.1659.61.9286.20.33112.125.8Water A 2nd2.9626.54.6910.10.1236.60.6127.825.8Water A 3rd1.3513.73.915.0<LLD26.10.658.424.8Water A 4th0.9816.94.296.20.0824.90.566.822.9Water B 1st4.84149.010.7156.91.8983.31.14112.725.2Water B 2nd2.8622.05.017.30.2731.71.9821.828.7Water B 3rd1.3413.94.024.60.0424.51.5811.324.8Water B 4th0.8012.23.874.10.0321.51.066.222.3Ca formate A 1st4.35135.110.8153.61.9582.30.4599.126.5Ca formate A 2nd2.4126.65.6910.40.1936.80.4021.225.2Ca formate A 3rd1.7421.16.018.20.1632.70.6813.928.4Ca formate A 4th0.6915.05.095.90.0521.60.565.322.3Ca formate B 1st4.97142.411.8256.42.0988.90.36103.027.6Ca formate B 2nd2.4025.25.739.80.2238.20.4119.626.2Ca formate B 3rd1.4819.45.417.60.0631.10.5813.026.2Ca formate B 4th0.7315.95.066.00.0422.90.565.522.7HCO2H A 1st4.34268.819.52107.64.40111.21.0683.531.3HCO2H A 2nd2.42173.715.3669.73.3253.91.0122.834.1HCO2H A 3rd2.09167.814.8166.65.0036.51.0913.446.9HCO2H A 4th0.79130.313.3450.64.4616.61.333.734.1HCO2H B 1st4.25261.218.52103.14.25109.80.5574.530.9HCO2H B 2nd2.41205.017.8279.23.9849.30.7322.140.9HCO2H B 3rd1.82176.416.4667.25.2331.20.9011.549.9HCO2H B 4th0.73140.715.6452.54.8416.41.633.635.3

FIGS.3-4show results for the same permeation tests run on soil at a second farm in the central San Joaquin Valley in California, using the same liquid sources, except that the calcium formate solution contained about 25 ppm of calcium formate by moles. The irrigation water at the second farm was from a different source than the first farm. The results inFIGS.3-4are considerably more striking than the results inFIGS.1-2. On the first pass, using dry soil (FIG.3), the soil samples retained on average about 41-42 ml of liquid from the aqueous formic acid solution, and about 43-44 ml of liquid from the aqueous calcium formate solution. The amount of irrigation water ultimately retained by the soil samples was not determined. Furthermore, the aqueous formic acid solution had completed passing through the soil column on average between 180 and 210 minutes; the aqueous calcium formate solution had completed passing through the soil column on average at about 240 minutes; and the irrigation water never completed passing through the soil column after 450 minutes. Comparing amounts of liquid passed through the columns at the same lengths of time, more than three times as much aqueous calcium formate and aqueous formic acid solutions passed through the columns than irrigation water at all times from 20-30 minutes (when liquid first appeared from the columns) up to 240 minutes, and more aqueous formic acid solution passed through the columns than aqueous calcium formate solution at all times after the first appearance of liquid from the columns. The differences in “first appearance” times is also striking. Aqueous formic acid solution first appeared from the columns on average before 20 min.; aqueous calcium formate solution first appeared from the columns on average between 20 and 30 min.; but irrigation water did not appear from the columns on average until nearly 60 min.

On the second pass (wet/damp soil from the second farm,FIG.4), the aqueous formic acid solution had completed passing through the soil column on average between 210 and 240 minutes, and the aqueous calcium formate solution had completed passing through the soil column on average by about 390 minutes. However, even after 450 minutes, only about one-fourth of the volume of irrigation water passed through the soil column as the aqueous formic acid and calcium formate solutions. Comparing amounts of liquid passed through the columns at the same lengths of time, greater amounts of aqueous calcium formate and aqueous formic acid solutions passed through the columns than irrigation water at all times, and more aqueous formic acid solution passed through the columns than aqueous calcium formate solution from 20 minutes up to about 390-420 minutes. It is not understood why the wet soil columns retained a greater volume of irrigation water than the dry columns.

During the permeation tests, formic acid routinely exhibited the shortest column retention times and the greatest flow-through volumes per unit time. This may be attributed to acidic interactions with soil particles and possibly dissolving water-insoluble salts in the soil, promoting faster movement of the liquid through the column. Irrigation water consistently displayed the longest column retention times and the smallest flow-through volumes per unit time. Movement of the irrigation water through the soil was relatively slow compared to both the formic acid and calcium formate solutions.

Comparing the first through fourth passes for each test solution, each subsequent elution of irrigation water took longer. In fact, the tests eventually took so long that a fourth pass was not run. For the calcium formate solution, the second pass eluted more quickly than the first pass, and the third and fourth passes took longer than the second pass (similar to the first pass). Taking into account uncertainty in the data, the first, third and fourth passes of the calcium formate solution show similar behavior, with the second pass showing a marked increase in drainage through the soil compared to the other passes. For the formic acid solution, the elution rate increased from the first to the third passes, with the fourth pass eluting slightly more slowly than the second and third passes, but still faster than the first pass.

A fourth experiment was run in which the formic acid and calcium formate solutions were alternated (first pass: formic acid; second pass: calcium formate; third pass: formic acid; fourth pass: calcium formate). The results were similar to the formic acid solution tests, although the fourth pass (calcium formate solution) eluted more quickly than the fourth pass for the formic acid solution only. This indicates that applying calcium formate solution to the soil between applications of formic acid solution improves the drainage through the soil, compared to using the formic acid solution alone. The improvement becomes more significant with repeated applications.

The differences in column retention times have practical implications in agricultural and environmental contexts. In agriculture, understanding the movement of water and nutrients through the soil is crucial for optimizing irrigation practices and nutrient management. Thus, adequate water and nutrient delivery to a predetermined root depth can be facilitated by introducing formic acid into irrigation water in the amounts described herein.

The results from the ICP and flow injection (FIA) analyses of the solutions that passed through the soil columns at the end of each pass are presented in Table 4 below, in ppm. FIA was used to determine the content of the listed anion (e.g., NO3, Cl, PO4, etc.). The same analyses on the irrigation water in these experiments is shown in Table 5. Results are presented from a single soil sample. The elements Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Se, Ti, and Zn were found to be present at concentrations of less than 1.0 ppm, and are therefore not reported or discussed.

TABLE 4SampleBCaKMgNaPSSiNO3−Cl−Water-1st0.438.72.89.796.31.931.645.04.6193.5Water-2nd0.439.93.110.299.22.234.234.60.05.7Water-3rd0.210.01.32.346.92.74.630.50.01.0Water-4thnanananananananananaCa formate-1st0.576.14.519.6169.01.051.426.30.0288.0Ca formate-2nd0.324.02.56.1110.41.114.826.90.092.1Ca formate-3rd0.221.72.45.596.41.010.324.30.091.9Ca formate-4th0.230.42.47.595.40.910.123.30.093.6HCO2H-1st0.6260.79.769.3345.50.743.831.80.0304.0HCO2H-2nd0.5312.79.081.3175.21.911.443.10.0102.8HCO2H-3rd0.4337.49.984.079.95.88.051.90.091.7HCO2H-4th0.3286.610.665.566.16.48.365.20.092.9Alternating-1st0.6264.99.670.4350.40.744.332.10.0327.4Alternating-2nd0.4151.45.739.1144.51.212.736.90.095.4Alternating-3rd0.3199.96.650.885.72.08.732.40.089.7Alternating4th0.2173.46.043.161.43.19.044.00.094.3

TABLE 5pHECCaMgNaClSO4(SP)NO3−NPO4−PKSO4−SZnMnFeCuB—dS/mmeq/Lppm6.70.92.91.35.03.72.5<5.023229654.411.824.51.50.21
Exemplary Irrigation or Fertigation Apparatuses and Methods

FIG.5shows an automatic fertilization and/or irrigation apparatus100comprising a power input102, a power transformer105, a wireless switch or router110, a programmable logic controller (PLC)115, a serializer/deserializer117, an expansion module120for the PLC115, first variable frequency drives125a-d, wiring terminals130, safety relays135a-b, a human-machine interface (HMI)137, a second variable frequency drive140, a recirculation input145, a recirculation filter155, a recirculation pump150, a pH probe190, a flow switch195, a recirculation output146, pumps160a-d, pump fans165a-d, an acid pump170, and a flow and/or pressure switch172. The apparatus100further comprises a container (not shown) configured to house all of the components shown inFIG.5. In use, the container may be sealed and/or locked, and may be configured to provide a substantially waterproof housing for the components enclosed therein. The container may comprise plastic and/or a metal, as described herein. When the container comprises plastic, a static electrical charge may build up on the container, introducing the risk of shock to personnel working with the apparatus and of short-circuiting or other damage to the components. Thus, the container may further comprise a powder coating on an exterior surface thereof, which may be adapted to dissipate or eliminate a static charge on the container. Independently, a different coating may be applied to an exterior surface of the container that is adapted to resist, reduce or inhibit corrosion of or UV damage to the container. The apparatus100may further comprise a system fan (not shown) configured or adapted to cool the interior environment or atmosphere of the apparatus (e.g., when in a sealed or locked container).

The power input102receives external electrical power and supplies electrical power to the apparatus100. The external electrical power received by power input102may come from an electric power grid, such as an electrical outlet, energy storage devices such as batteries or fuel cells, generators or alternators, solar power converters, etc. The voltage and/or current on the power input102may depend on the specific requirements of the apparatus (e.g., 120-480 V for AC and 12-90 V for DC).

The power transformer105converts the electrical power from the power input102to a corresponding voltage, current, and/or frequency to power the load of the apparatus100. The power transformer105may also regulate the voltage and/or current provided to the components of the apparatus100. The power transformer105may be a power supply having multiple power outputs at varying voltages (e.g., lower voltages may be supplied to the PLC115, while higher voltages may be supplied to the variable frequency drives125a-dand140, and the pumps150,160a-d, and170). The power transformer105may also limit the current drawn by a particular load (e.g., to a component) to safe levels, shut off the current to one or more components or to the entire system in the event of an electrical fault or an alarm (e.g., from a flow and/or pressure switch172in the main irrigation line175), prevent electronic noise or voltage/current surges on the input102from reaching the load(s), and optionally store energy to continue powering the load(s) in the event of a temporary interruption to the input102(e.g., provide an uninterruptible power supply). When the power transformer105shuts off the current due to an electrical fault or an alarm, the PLC115may latch or record some or all performance and (optionally) site information in an associated memory prior to or at the time of shut down. The power transformer105may include additional inputs and outputs for functions such as external monitoring and control (e.g., to connect a multimeter). In alternative embodiments, one or more of the electrical components of the apparatus100may include additional and separate power inputs102or power transformers105. Connections between the power transformer105and the electrical components of the apparatus100are omitted for clarity of the drawing.

The wireless switch or router110is a gateway for receiving and transmitting data (e.g., digital packets including a header and a body) wirelessly to and from a network (e.g., over the internet). The wireless switch or router110may be connected (e.g., by a serial wire or cable, using an ethernet protocol) to a network interface (e.g., network card) in the PLC115, and may also include or be directly connected to an antenna that transmits and receives wireless signals (e.g., to and from a cellular network, such as a 4G, 5G or 6G network).

The serializer/deserializer (SERDES)117connects the wireless switch or router110and the PLC115, and converts (i) serial data from the wireless switch or router110to parallel data for processing by the PLC115, as well as (ii) parallel data from the PLC115to serial data for transmission by the wireless switch or router110. Thus, the wireless switch or router110may have a serial data interface, and the PLC115may have a parallel interface. In alternative embodiments, the switch or router110may transmit and receive electrical signals using a ground-based network (e.g., a cable, telephone/DSL, or fiber-optic network).

The digital packets from the PLC115may include site information (e.g., nutrient delivery amounts and/or rates, a pH, irrigation on/off times, differences from target values, etc.), and may be organized into a table to be stored in a database (e.g., a SQL database) on a remote server. The table may be processed by software and displayed in summary report readable by a spreadsheet program such as Microsoft® Excel.

The PLC115may include one or more input modules, one or more output modules, and a central processing unit (CPU), and may include one or more arithmetic logic units (ALUs). The PLC115may include one or more microprocessors, microcontrollers, field programmable gate arrays (FPGAs), complex programmable logic devices (CPLDs), application specific integrated circuits (ASICs), or application specific standard products (ASSPs). The PLC115may include volatile memory (e.g., cache memory, random access memory [RAM]), nonvolatile memory (e.g., fuses, read-only memory [ROM], erasable and programmable memory [EPROM, EEPROM, or flash memory], or a solid-state drive), or both. The nonvolatile memory (or other tangible storage medium) may store basic instructions such as a basic input/output system (BIOS), identification code, and/or a program (instructions to be executed by the CPU) that controls the pumps160a-dand/or170.

The input modules may receive input data from the pH sensor190, the pumps160a-dand170, and sensors in or operably linked to pumps160a-dand170, and the output modules may transmit performance data for the apparatus100to the SERDES117and control signals to the variable frequency drives125a-dand140to control the pumps160a-dand170. For example, if the input data (e.g., from a flow sensor operably linked to one of the pumps160a-d) indicates that the pump is delivering too little of a fertilizer or nutrient, the program may generate performance data and/or a control signal to a corresponding one of the first variable frequency drives125a-dto increase the speed of the pump. The performance data may be stored in the memory to be later transmitted to an end user (e.g., a data analyst) using the wireless switch or router110.

The expansion module120for the PLC115may include inputs and outputs for both digital and analog signals. For example, some of the analog inputs may be connected to level sensors (e.g., optical, sonar or radar level sensors) that detect the volume of liquid in chemical tanks or vessels (not shown) that provide the fertilizer, nutrient or micronutrient to the pumps160a-dand170. If the volume of liquid in one of the tanks or vessels is too low, an alarm may be triggered, and the program may instruct one of the variable frequency drives125a-dand/or140(e.g., using one or more analog outputs of the expansion module120) to shut off the corresponding one of the pumps160a-dand/or the pump170. Some of the digital inputs of the expansion module120may receive outputs from the HMI137(e.g., via the wiring terminals130).

The program in the PLC115may organize the data into digital packets to be transmitted to a remote user (e.g., a data analyst) using the wireless switch or router110. The HMI137is configured to output various signals (via the wiring terminals130) to the expansion module120for the PLC115, thereby allowing a user such as a field technician to change settings (e.g., fertilizer or nutrient targets, irrigation cycles, etc.) in the PLC115using a graphical user interface (GUI) on the HMI137. The HMI137thereby functions as a user portal to the PLC115and the programming therein, allowing the user to make changes to the system controlled by the PLC115without directly making changes to the PLC programming. The GUI may be accessible using buttons and/or a touch screen. In alternative embodiments, the HMI137may be a smartphone, laptop, tablet or other computer application, and the PLC115may be connected wirelessly to the smartphone, laptop, tablet or other computer to change settings in the PLC115.

The variable frequency drives125a-dand140control the pumps160a-dand170, respectively, based on control signals from the PLC115. Values and/or on-off cycles of the control signals correspond to the settings in the PLC115and/or the performance data stored in the PLC115. The variable frequency drives125a-dand140may vary the voltage, frequency and/or pulse width(s)/duty cycle(s) of the control signals to the pumps160a-dand/or170. The variable frequency drives125a-dand140may be DC-AC or AC-AC systems, depending on the output of the power transformer105. The variable frequency drives125a-dand140may be pulse-width modulation (PWM) drives, current source inversion (CSI) drives or voltage source inversion (VSI) drives. If any of the pumps160a-dand/or170require pulsed signals (e.g., the pump is solenoid-driven), the PLC115may provide the pulsed signal(s) through one or more high-speed outputs wired to one or more corresponding optical (e.g., solid state) relays directly wired to the pump.

The wiring terminals130may receive wires from level sensors, power terminals, and output lines (e.g., from the HMI137), and provide signals to other components, such as the PLC115(e.g., through the expansion module120), the variable frequency drives125a-d, and the recirculation pump150. The safety relays135a-bmay include voltage regulators, varistors, and/or surge protectors. Additional safety relays (not shown) may be used as a fail-safe control and optionally as a de-bounce circuit configured to maintain power momentarily during false-negatives from the fail-safe control relay.

The recirculation input145receives sampled water to be tested and the recirculation output146returns the sampled water to the main irrigation line175. The recirculation pump150pulls a sample of the irrigation water from the main irrigation line175(see, e.g.,FIG.5) through the recirculation input145. The irrigation water sample is taken from the main irrigation line175at a location (not shown) downstream from the locations where the pumps160a-dand170and/or the apparatus100introduce the fertilizers, nutrients and/or micronutrients into the main irrigation line175. The recirculation input145may also include multiple bends, turns, and/or changes in dimensions to ensure thorough mixing prior to measurement of one or more parameters and/or characteristics (e.g., pH) of the irrigation water. The irrigation water sample passes through a recirculation filter155that may function as a flow switch to allow the water sample to flow into a monitoring system and/or as a filter to remove undissolved particles above a predetermined size (e.g., using a mesh strainer or other filtering material). The pH probe190measures the pH of the irrigation water sample with the fertilizers, nutrients and/or micronutrients added thereto, and may transmit the pH data to the PLC115. The PLC115may then transmit the pH data to a remote computer via the wireless switch or router110and, depending on the difference between the measured pH and a target pH, the variable frequency drive140to adjust (e.g., increase or decrease the speed, frequency and/or stroke of) the pump170. Alternatively, if one of the fertilizers, nutrients and/or micronutrients is an acid or base, a corresponding one of the variable frequency drives125a-dmay adjust the speed, frequency and/or stroke of a corresponding one of the pumps160a-d. The flow switch195allows the sampled water to return to the main line through the recirculation output146. In alternative embodiments, additional probes may determine or measure another parameter of the irrigation water sample, such as hardness, conductivity, total dissolved solids, temperature, etc.

The pumps160a-deach control the addition of one or more fertilizer, nutrient and/or micronutrient components to the main line. For example, each of the pumps160a-dmay control the feed rate of a fertilizer, nutrient or micronutrient to the irrigation water in the main irrigation line175. The fertilizers and/or nutrients may comprise one or more sources of nitrogen, phosphorous, potassium, carbon, and/or calcium. The micronutrients generally comprise an element or chemical provided in small or trace amounts or concentrations, such as boron, zinc, manganese, iron, copper, cobalt, magnesium, molybdenum, etc. The pumps160a-dmay also control the addition of other supporting chemicals or additives (e.g., an acid or base, etc.). The pump fans165a-dmay cool the pumps160a-dto prevent overheating.

The pump170is similar or substantially identical to the pumps160a-d. In the embodiment shown inFIG.5, the pump170is larger than the other pumps160a-dto provide a higher output than the other pumps, but in many cases, the pump170is identical to or smaller than the other pumps160a-d. In one example, the pump170controls the addition of acid to the main irrigation line175. Alternatively, the pump170may control the addition of base or a relatively high-volume fertilizer and/or nutrient, such as a nitrogen- or potassium-containing fertilizer and/or nutrient, to the main irrigation line175. Each of the pumps160a-dand170may include an AC motor electrically connected to the variable frequency drives125a-dand/or140. Each of the pumps160a-dand170may be connected to a chemical tank (e.g., the fertilizer/nutrient tanks115a-dor the acid tank120shown inFIG.5) using feed lines. Each of the pumps160a-dand170may be a positive displacement or a centrifugal pump, although the pumps160a-dand170are not limited thereto.

In the apparatus100, for example, all information can be recorded automatically and transmitted using a cellular network and may be accessed at any time (e.g., using a computer or mobile device). The automatic logging of data can occur at adjustable time intervals. Information may be transmitted automatically to field technicians, data analysts, managers, customers and other users using short message service (SMS, e.g., cellphone texts), email, etc., to inform the users of important alerts.

The apparatus100enables a user to know when a site is running. For example, the PLC115may detect a positive flow rate in the main line using a flow sensor. This ability allows a field technician to visit a site only when it is in operation. This ability is important since manual adjustments to components of the apparatus100are most effectively made when water is flowing through the main line.

All pertinent information for the site (e.g., the site name, acreage, fertilizer/nutrient targets, and irrigation hours) can be stored in both the PLC115and in a remote computer or server. This redundancy of information storage reduces errors in transferring and processing information. All such information may be accessed or changed remotely at any time.

The apparatus100can perform pH calibration using any number of points (e.g., 1, 2, 3, or any number of 1 or more; more pH calibration points providing for a more accurate pH measurement), and the calibration points may be adjustable. Calibration errors can be indicated (e.g., by an alarm), and a reason may be given for the error (e.g., a malfunctioning pH probe, improper calibration standard, etc.). For example, alarms for the connectivity of the pH probe190and inappropriate signal conditions can be indicated.

Set-up of acid (e.g., formic acid, H2SO4, etc., although any acid may be used) and base (e.g., KOH, although any base may be used) for neutralization (e.g., pH balancing) may be performed automatically in the apparatus100by initiating operation of the acid and base pumps (e.g., one of the pumps160a-dproviding the base and the acid pump170) at a relatively low speed or feed rate (e.g., a minimum speed or rate), then slowly increasing the speed of the acid and base pumps with the corresponding variable frequency drives (e.g., one of the VFDs125a-dand the VFD140) while monitoring the pH of the resulting irrigation water until the base (e.g., KOH) attains its target setting, unless the pH falls outside a predetermined and/or desired range, in which case the acid is adjusted (e.g., the speed of the acid pump170is increased or decreased) to bring the pH within the predetermined and/or desired pH range. All parameters are adjustable. Any subsequent automatic changes in the base feed rate (e.g., KOH pump output) may be executed slowly to allow for the control of the pH without large fluctuations.

Fertilizer, nutrient and other chemical tank levels may be measured using sonar, radar or optical sensors. The accuracy of this measurement is controlled or determined only by the sensor accuracy (e.g., the approximate accuracy of conventional and/or state-of-the-art sonar sensors is +/−0.125 inches). This measurement avoids errors related to human measurements from a baseline (e.g., the bottom of the tank, the ground, and/or the height of the liquid along the sides of the tank).

The apparatus100may include continuous tank level monitoring, which also provides the ability to detect tank leaks before a large amount of material has left the tank. Automated monitoring detects a significant change in a tank level that cannot be explained by normal usage, and can trigger an alarm that may be transmitted using SMS, email, etc., to one or more persons (e.g., a field technician, data analyst or account manager) to notify the person(s) that corrective action may be necessary. Also, when a tank level sensor determines that the chemical tank is empty (or nearly empty), the PLC115can set the corresponding variable frequency drive125a-dor140to zero, and transmit a notice to a user (e.g., the data analyst) to take corrective action (e.g., to ship or send the corresponding fertilizer[s], nutrient[s] and/or micronutrient[s] to the site). This action also prevents the corresponding pump160a-dor170from running dry, which may cause significant damage.

The outputs of the pumps160a-dand170may be frequently or continually monitored by the PLC115, which can send one or more commands to the corresponding variable frequency drive(s)125a-dand140to change the pump speed, and optionally a servo/stepper motor-type control of the stroke setting, thereby changing the pump output (e.g., to meet a defined or modified volumetric demand). Over- and under-feeds can be minimized (typically less than 2%) based on weekly targets, resulting in nearly linear feed rates (e.g., over the course of a growing schedule or crop cycle). This ability has been tested under rigorous and/or extreme conditions, such as very high feed rates, short irrigation times, and/or severely inaccurate pump performance (e.g., greater than 40% from theoretical). Overheating of the pumps160a-dis prevented by the cooling fans165a-dmounted to each of the pumps160a-d.

The output of each pump may be calculated automatically by the PLC115, based on fertilizer/nutrient targets, flow rates, concentrations of fertilizers/nutrients in the tanks, irrigation hours (e.g., irrigation water and fertilizer/nutrient pump on/off times), etc., thus reducing the possibility of human error. A theoretical pump stroke setting is calculated and recommended to the user (e.g., field technician, farm manager, customer, etc.). Pump outputs may be adjusted remotely at any time. Pump performance may be monitored periodically (e.g., every 3 minutes, 15 minutes, hour, 2 hours, 4 hours, etc.) or continuously, and alarms may be triggered for poorly performing pumps. Alarms such as pump alarms, pH alarms and irrigation flow alarms can be configured to shut down the entire system, and optionally, latch or record some or all system information in an on-board memory (e.g., in case power is shut off or disconnected).

The apparatus100enables a user to enter a pump correction factor to account for a known (e.g., empirically determined) performance deficiency in a pump. This ability allows for the system to more accurately feed a fertilizer, nutrient or micronutrient and to determine the amount of fertilizer, nutrient or micronutrient supplied to the irrigation water over a given length of time. All calculations can be performed by the PLC115and/or a remote computer to reduce errors. Summary reports can be generated and/or transmitted automatically, periodically (e.g., at adjustable time intervals) or on demand.

The apparatus100may include fail-safe controls to ensure that irrigation water is flowing when the apparatus100is operational. This can be accomplished by a flow-and-pressure switch in the irrigation water main line. Fail-safe controls to ensure functionality of the recirculation pump may be accomplished using a flow switch155(e.g., configured to allow irrigation water to flow from the main line to the recirculation pump150when water is flowing) in the recirculation line145. In the example inFIG.5, the flow switch155, the recirculation pump150and the recirculation line145draw treated water (to which the fertilizers, nutrients and micronutrients have been added) from the irrigation line175to be analyzed for pH. If the flow-and-pressure switch in the irrigation water main line of the flow switch155is not triggered, the corresponding pumps are turned off by removing power from the pumps. However, the variable frequency drives may remain on. Thus, the fail-safe controls may prevent the variable frequency drives from shutting down. A delay (e.g., of 1-60 seconds, or any value or range of values therein, such as 10 seconds) to keep components of the apparatus100operational in the temporary absence of electrical power may be accomplished by an electronic de-bounce circuit, as discussed herein. A secondary fail-safe may be triggered by the same conditions (e.g., lack of flow or pressure in the main line, or lack of flow in the recirculation line245), resulting in the speed of each pump being set to zero on the variable frequency drive after a predetermined and/or adjustable length of time.

Fail-safe control for pH is accomplished by setting the variable frequency drive to zero for either the acid pump or the base pump if the pH is too low or too high, respectively. This action prevents the drive(s) for the acid and/or base pumps from shutting down. Stopping the acid or base pumps can result in wild swings in pH. If the pH goes above or below the acceptable range more than a predetermined number of times, the apparatus100may return to a slow start mode, in which the acid and base pumps are set to their minimum settings. The speed of the acid and base pump is then either increased or kept constant to ensure that the pH stays within the desired range. When the base pump (e.g., providing KOH to the irrigation water) attains its target setting, the acid pump can then be adjusted independently to maintain the desired pH set point. All such parameters may be adjustable. This method for controlling the pH of irrigation water using the apparatus300has been proven to be very effective in maintaining the pH of the treated irrigation water in the desired range (e.g., 6.5±0.5, or any range within this range).

FIG.6shows an exemplary automatic fertilization and/or irrigation system200including the exemplary automated apparatus100shown inFIG.5, configured to controllably add a plurality of fertilizers, nutrients and/or micronutrients to irrigation water and to control the pH of the treated irrigation water. The automatic fertilization and/or irrigation system200includes, in addition to the automatic fertilization and/or irrigation apparatus200, a plurality of fertilizer, nutrient and/or micronutrient tanks215a-d, an acid tank220, a main irrigation water line210, a plurality of fertilizer, nutrient and/or micronutrient supply conduits230a-e, and a plurality of fertilizer, nutrient and/or micronutrient feed conduits240a-e.

Each of the tanks215a-dis adapted to contain and supply of an aqueous solution of one or more fertilizers and/or nutrients, and/or (optionally) one or more micronutrients. Typically, a first one of the tanks215a-dcontains and supplies a nitrogen-containing fertilizer and/or nutrient, a second one of the tanks215a-dcontains and supplies a phosphorous-containing fertilizer and/or nutrient, and a third one of the tanks215a-dcontains and supplies a potassium-containing fertilizer and/or nutrient, although other configurations are possible. In many cases, the tanks215a-dthat contain and supply the nitrogen-containing, phosphorous-containing and/or potassium-containing fertilizer and/or nutrient also contain and supply one or more additional fertilizers and/or nutrients, as described herein. In many embodiments, a fourth one of the tanks215a-dmay contain and supply a micronutrient mixture. Alternatively, one of the tanks215a-dmay contain and supply the acid(s) or base, alone (e.g., aqueous formic or sulfuric acid) or in combination with a nitrogen-containing, phosphorous-containing and/or potassium-containing fertilizer and/or nutrient (e.g., aqueous phosphoric acid or aqueous KOH).

The acid tank220in the embodiment shown inFIG.6contains and supplies a concentrated acid, for continuously adjusting untreated irrigation water having a neutral or slightly alkaline pH to a neutral or slightly acidic pH. In one example, the acid tank220contains and supplies concentrated aqueous sulfuric acid, but other acids are also acceptable (e.g., concentrated or dilute [e.g., 20-95 wt. %] aqueous formic acid, which also provides carbon and may reduce or eliminate scaling; concentrated aqueous phosphoric acid, which also provides phosphorous; concentrated aqueous nitric acid, which also provides nitrogen; etc.). Alternatively, when the tank220has a larger volume that some or all of the tanks215a-d, the tank220may contain and supply a relatively high-volume fertilizer and/or nutrient (e.g., a nitrogen- and/or potassium-containing fertilizer and/or nutrient), and one of the tanks215a-dmay contain and supply the acid or base, as described herein.

Each of the fertilizer, nutrient and/or micronutrient supply conduits230a-eincludes a corresponding first valve232a-econfigured to control (e.g., open, close, and optionally restrict) a flow of the corresponding fertilizer, nutrient and/or micronutrient from the corresponding tank215a-dor220to a unique or corresponding one of the pumps160a-dand170. Each of the fertilizer, nutrient and/or micronutrient feed conduits240a-band240d-eincludes a corresponding second valve242a-dconfigured to control the addition of the corresponding fertilizer, nutrient and/or micronutrient by the corresponding pump160a-dor170to the main irrigation line210. The fertilizer, nutrient and/or micronutrient feed conduit240cmay have two valves244a-bconfigured to control the addition of the acid (or, alternatively, a relatively high-volume fertilizer and/or nutrient) to the main irrigation line210.

As shown inFIG.6, the recirculation input145can include a sampling conduit147, configured to withdraw a sample of the treated irrigation water a predetermined distance (e.g., 3-40 feet, 1-10 m, or any distance or range of distances therein) along the main irrigation water line210. The recirculation output146returns the sampled treated irrigation water to the main irrigation water line210in the same or a similar manner as the feed conduits240a-e.

Modes of Operation

The apparatuses100and/or200may be operated in one of a plurality of different modes: continuous mode, intermittent mode, and slug mode. In continuous mode, the water in the main irrigation line is continuously treated with small amounts of one or more fertilizers, nutrients and/or micronutrients. Thus, all of the water that reaches the crops from the main irrigation line can include fertilizer(s), nutrient(s) and/or micronutrient(s). In intermittent (e.g., semi-continuous) mode, the water in the main irrigation line is treated intermittently with one or more fertilizers, nutrients and/or micronutrients (e.g., twice a day, once a day, once a week, once every two weeks, etc.). Thus, some of the water that reaches the crops from the main irrigation line is treated with fertilizer(s), nutrient(s) and/or micronutrient(s), and some is not. In slug mode, the water in the main irrigation line is treated with a very large amount of fertilizer(s), nutrient(s) and/or micronutrient(s) a predetermined number of times (e.g., once, twice, 3 times, 4 times, etc.) during a growing season. At the same or a later time, one or more of the same and/or different fertilizers, nutrients and/or micronutrients may be added to the water in the main irrigation line. In the present method, formic acid and/or a formate salt solution may be added to the irrigation water using the apparatus100or200, but the resulting formate-enhanced irrigation water is not applied or distributed to the soil using the emitters. Instead, formate-enhanced irrigation water is applied or distributed to the soil by opening a bypass valve in the irrigation water conduits to the field(s) or block(s), which effectively bypasses the emitters and floods the field(s) or block(s).

The apparatus(es) may combine the continuous, intermittent, and/or slug modes. For example, the water in the main irrigation line may be treated with one or more fertilizers, nutrients, micronutrients or soil additives (e.g., formic acid and/or a formate salt) in slug mode at the start of the irrigation cycle, and then treated with one or more of the same or different fertilizers, nutrients and/or micronutrients in continuous mode at a later point in the irrigation cycle.

Continuous mode uses the fertilizers, nutrients and/or micronutrients most efficiently since crops generally have a fixed requirement rate (e.g., 50 grams per day for a single plant) for the fertilizers, nutrients and/or micronutrients. Continuous mode treats the irrigation water with an optimal and/or optimized amount of fertilizer for the crop (e.g., the amount of fertilizer used by that crop in a day, week, month, etc.), and thus minimizes or avoids overfeeding or underfeeding the crop. By comparison, in a manual system, fertilizer is generally fed at a much faster rate. As a result, the crop may not be able to metabolize the relatively large level of fertilizer, nutrient and/or micronutrient. If a rain event occurs, the excess fertilizer(s), nutrient(s) and/or micronutrient(s) may be washed away from the soil. Subsequent irrigations without fertilizer, nutrient or micronutrient may also wash excess fertilizer(s), nutrient(s) and/or micronutrient(s) away from the soil.

Before the fertigation system is operated, the storage tanks are installed and filled with fertilizers, nutrients, micronutrients and/or soil additives in known concentrations and amounts. In some embodiments, site information (e.g., nutrient targets, irrigation cycles and/or times, etc.) may be entered into the programmable logic controller (PLC).

Initiation and/or startup of the system may comprise the following steps. First, the irrigation water pump is turned on, and the irrigation water begins to flow through the main irrigation line. Next, the PLC senses water flow and pressure in the main irrigation line, as described herein. Once the required flow and pressure is achieved in the main irrigation line, the PLC may begin to control a first pump that adds acid or base (e.g., formic acid, potassium bisulfate, sulfuric acid or aqueous KOH) to the main irrigation line to bring the pH of the irrigation water to a target pH, while monitoring the pH of the irrigation water, continuously or periodically. The addition of acid or base may be controlled (e.g., adjusted, increased or decreased slowly) until a stable pH at the target value, plus or minus a predetermined margin (e.g., ≤±0.5) is achieved.

Although any target pH may be achieved, crops in a particular region tend to metabolize most fertilizers, nutrients and micronutrients most efficiently at a particular pH. For example, in California, irrigation water may have a pH in the range of 7.5-8.5, but many crops metabolize most or all fertilizers, nutrients and micronutrients most efficiently at a pH of about 6.5 (e.g., 6.5±0.5, 6.5±0.3, 6.5±0.2, or any other range within the target pH±0.5). Thus, in California, the target pH may be about 6.5, and the PLC controls the rate of addition of formic acid, potassium bisulfate or sulfuric acid to the irrigation water until the irrigation water is at the target pH or in the target pH range for a predetermined minimum period of time (e.g., 1 minute, 5 minutes, 15 minutes, 1 hour, or any other minimum length of time of at least 1 minute). Alternatively, the PLC may control the addition of acid to the irrigation water until the irrigation water is at a target pH in the range of 4.0-5.5, 2.0-4.0, etc., as described herein.

Once the target pH is achieved (or when the required flow and pressure is achieved in the main irrigation line), the PLC begins adding, then controlling the rate of addition of, one or more fertilizers, nutrients and/or micronutrients using one or more additional pumps. The fertilizer(s), nutrient(s) and/or micronutrient(s) may be as described herein. For example, the PLC may add, then control the rate of addition of, first, second, third and fourth fertilizers, nutrients and/or micronutrients by first, second, third and fourth pumps. When one of the fertilizers, nutrients and/or micronutrients is or comprises phosphoric acid, the pH of the irrigation water may decrease, so the PLC may adjust the rate of base using the corresponding pump to bring the pH back to the target pH or pH range. When treating the soil to increase the permeation depth and/or rate of the irrigation water into the soil, the PLC may increase the rate of addition of formic acid (as described herein), but precautions can be taken not to overfeed a corresponding fertilizer and/or nutrient at any time or underfeed a corresponding fertilizer and/or nutrient over a prolonged period of time.

Once the target levels of potassium-, nitrogen- and phosphorus-containing fertilizers and/or nutrients are achieved, the PLC may determine that a target rate or amount of calcium, carbon, sulfur, or micronutrients (e.g., a mixture of magnesium, boron, iron, cobalt, copper, manganese, molybdenum and/or zinc) may not yet be met. The PLC may then begin adding, then controlling the rate of addition of, a calcium-containing fertilizer and/or nutrient, a carbon-containing fertilizer or nutrient, a sulfur-containing fertilizer or nutrient, and/or the micronutrients using one or more corresponding pumps, and adjusting the rate of addition with the corresponding pump(s) until the target level(s) of fertilizer(s), nutrient(s) or micronutrients are achieved in the irrigation water. Throughout this process, the irrigation water is maintained at the target pH or in the target pH range, as described herein.

When the main irrigation water pump shuts off, the PLC may sense a decrease in pressure in the main irrigation water line, and may consequently shut down all of the pumps. In some embodiments, the PLC shuts down the pumps slowly (e.g., in accordance with predetermined decreases, or a predetermined rate of decrease, in the pressure or flow rate in the main irrigation water line). The system (including the PLC) may do so while maintaining the pH of the irrigation water at the target pH. When the PLC determines a no-flow condition, the pumps are turned off, and the irrigation system is shut down.

The PLC may send a report to an email account (using the wireless switch or router) specifying the levels or amounts of potassium bisulfate and other fertilizer(s), nutrient(s) and/or micronutrient(s) added to the irrigation water. For example, the levels (or amounts per unit area) of the potassium bisulfate and other fertilizers, nutrients and micronutrients may be calculated and reported in units of lbs./acre (e.g., to the nearest 0.1 lb./acre), kg/km2, mg/m2, etc. When the email is received by a remote computer adapted to receive and process such reports, if the report contains no errors (e.g., errors that are detectable by the remote computer having a software program or app thereon configured to receive and process such reports), then the report may be automatically forwarded to one or more further recipients (e.g., a customer, an account manager, a field technician, etc.).

In some cases, the irrigation water pump may be turned on or off (e.g., manually) for a period of time different from that specified in the programming or data entered into the PLC. In such cases, the system has no control or advance knowledge of the time interval during which the irrigation pump is run or operated, but can respond adjustably to underfeeds and overfeeds resulting from a difference between the expected and actual time intervals of operation.

For example, the PLC may be programmed to calculate feed rates of the fertilizers, nutrients, micronutrients or soil additives for a given day based on an expected 8-hour irrigation schedule. However, for example, a grower, field manager or field technician may actually run the irrigation water pump for 7 hours or 9 hours on the given day. In this event, the PLC tracks the time interval(s) during which the pump is run or operated, and adjusts the feed rate of the fertilizer, nutrient and micronutrient pumps proportionally for the next scheduled irrigation day. In the example where the irrigation water pump is run for 7 hours, the feed rate of the fertilizer, nutrient and micronutrient pumps is increased to 114-115% (8/7ths) of the programmed rate on the next scheduled irrigation day, and the example where the irrigation water pump is run for 9 hours on the given day, the feed rate of the fertilizer, nutrient and micronutrient pumps is decreased to 88-90% (8/9ths) of the programmed rate on the next scheduled irrigation day. As a result, on the next irrigation day (or other period of time during which such adjustments and/or corrections are made), the PLC may correct for variations in the irrigation schedule in order to achieve the target rates over a longer period of time. If further changes occur, the PLC can maintain the desired profile by slowly making the appropriate changes or adjustments. In general, the longer the time period for such changes or adjustments, the greater the likelihood of avoiding any undesired spikes in the potassium bisulfate or other fertilizer/nutrient feed rate.

The system can turn on and off any fertilizer, nutrient, micronutrient or soil additive in accordance with predetermined and/or calculated targets and schedules (e.g., the fertigation profile). For example, the system may keep the pump for supplying phosphorous-based fertilizers and/or nutrients off until a predetermined starting time in the growing season arrives. The user (e.g., a data analyst or other user of the remote computer) typically makes a change to a target or schedule only when conditions such as weather or crop growth necessitate such a change (e.g., to the fertigation profile). Otherwise, the system (and thus, the present method) can control the addition of fertilizers, nutrients, micronutrients and soil additives according to the initial (or modified) fertigation profile for the growing season.

Slug feeding dilute formic acid or formate salt solution to agricultural crops in a field using any of the systems and methods described herein may comprise adding the formic acid or formate salt solution to the irrigation water such that the concentration of formic acid or formate salt solution in the irrigation water (by weight) is from on the order of 10 ppm to about 10,000 ppm. When using formic acid, the concentration is generally 1000 ppm by weight or volume or less to avoid risks associated with water having a low pH. Thereafter, the method further comprises providing or delivering the resulting formate-enhanced irrigation water to the soil, as described herein.

Exemplary Fertilizers, Nutrients and Micronutrients

The present method may further comprise adding to the formate-enhanced irrigation water any water-soluble fertilizer, nutrient, micronutrient, or combination thereof. Typical fertilizers and nutrients may include sources of elements such as nitrogen and phosphorus, optional sources of elements such as calcium, sulfur, magnesium and carbon, soluble organic materials, soluble soil amendments, microbiologicals, etc.

Sources of nitrogen may include water-soluble compounds such as ammonia (which can also be a base), ammonium nitrate and ammonium chloride; urea, formamide, acetamide and ammonium carbonate (each of which can also be a source of carbon); ammonium phosphate (which can also be a source of phosphorous), ammonium sulfate (which can also be a source of sulfur), and alkaline earth ammonium halides such as calcium ammonium chloride and calcium ammonium nitrate (which can also be a source of calcium), magnesium ammonium chloride and magnesium ammonium nitrate (which can also be a source of magnesium), etc. Sources of phosphorus may include phosphoric acid and phosphonic acid (each of which can also be an acid), ammonium phosphate, ammonium phosphonate, alkali metal mono-, di- and tribasic phosphates and phosphonates such as lithium mono-, di- and tribasic phosphates, sodium mono-, di- and tribasic phosphates, and potassium mono-, di- and tribasic phosphates and phosphonates (which can also be a source of potassium), etc. Additional sources of potassium may include potassium carbonate and potassium bicarbonate (each of which can also be a base and/or a source of carbon), potash, potassium chloride, potassium nitrate (which can also be a source of nitrogen), potassium phosphate, and potassium thiosulfate (which can also be a source of sulfur), etc.

Potassium bisulfate is a source of sulfur. However, if needed, additional sources of sulfur may include ammonium sulfate and ammonium sulfite (each of which can also be a source of nitrogen), alkali metal sulfites (such as potassium sulfite, which is also a source of potassium), alkaline earth sulfates and sulfites (which, in the cases of calcium and magnesium, can also provide a source of calcium and magnesium, respectively), etc.

Sources of calcium may include calcium nitrate, calcium ammonium nitrate and calcium ammonium chloride (each of which can also be a source of nitrogen), calcium chloride, dibasic calcium phosphate (which can also be a source of phosphorous), calcium formate and calcium acetate (each of which can also be a source of carbon), and calcium thiosulfate (which can also be a source of sulfur), etc. Sources of magnesium may include magnesium chloride, magnesium formate and magnesium acetate (each of which can also be a source of carbon), magnesium sulfate and magnesium thiosulfate (each of which can also be a source of sulfur), etc. Sources of carbon may include, in addition to those listed herein, carbon dioxide (carbonic acid), formic acid, acetic acid, oxalic acid, malonic acid, acetoacetic acid (3-oxobutyric acid), etc., alkali metal and alkaline earth metal salts thereof, soluble carbohydrates, etc.

Micronutrients include sources of certain minerals and elements that are applied in relatively low concentrations (e.g., at molar ratios of 1:20 or less, 1:50 or less, 1:100 or less, 1:200 or less, etc., relative to each fertilizer and/or nutrient), and may include sources of elements such as boron, iron, cobalt, copper, manganese, molybdenum and zinc, and, to the extent not included in the fertilizers and nutrients, sources of calcium, sulfur, magnesium and carbon. Micronutrients such as boron, iron, cobalt, copper, manganese, molybdenum and zinc may be present as a nitrate salt, a water-soluble complex or chelate (e.g., using ammonia, EDTA, NTA, oxalic acid, malonic acid or a dialkyl ester thereof, etc.) of an oxide or hydroxide thereof, and in the cases of the metals, a corresponding halide salt (alone or as a complex with, e.g., ammonia, water, etc., and/or chelated with EDTA, NTA, oxalic acid, malonic acid or a dialkyl ester thereof, etc.), sulfate, formate, acetate, oxalate, etc.

Other components that may be included in the water-soluble fertilizer, nutrient, micronutrient, or combination thereof are water-soluble pesticides, herbicides (e.g., that are selective for weeds and relatively less toxic or non-toxic to the crop[s]), antifungal agents, antimicrobial agents and/or other biocides (e.g., ammonium phosphite), antiviral agents, antiscaling agents, etc.

As mentioned above, any fertilizer, nutrient or micronutrient may be added to the irrigation water. Thus, any commercial, water-soluble fertilizer may be fed alone or in combination with other water-soluble fertilizers, nutrients and additives, by fertigation (as described herein) or by slug feeding. As a result, standard fertilizers such as CAN-17, UAN-32, CN-9, N-pHuric, AN-20, Thiocal, potassium thiosulfate, urea, potash, phosphoric acid, and other commodity/commercially available fertilizers and additives may be applied simultaneously with the formic acid in the irrigation water.

CONCLUSION/SUMMARY

By providing formic acid or other sources of formate ions to soil at a concentration of 10-10,000 ppm, the present invention advantageously improves water permeation through soil in which plants or crops are growing or are to be grown. The present method may also increase uptake of nutrients and micronutrients by the plants or crops, decrease compaction of the soil, and/or increase aeration of the soil.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.