bluuebunny/crossref_metadata_2025 huggingface dataset:
Water‐repellent Soil Clods and Pellets as Mulch1
Authors: Fairbourn Merle L. , Gardner H. R.
Published: July 2010

Water‐repellent clods and pellets of a Mollisol soil, Nunn clay loam, were tested in laboratory and field experiments to determine the potential for use in place of gravel as a mulch for reducing soil water evaporation. Solutions of two hydrophobic compounds, dialkyl quaternary ammonium chloride (Arquad), and sodium methyl silanolate (R‐20), were used either as a dip for soil clods and pellets or for mixing with the soil to form pellets. Seven treatments were tested for endurance in the laboratory by the wet sieve, alternate freezing and thawing, and alternate wetting and drying methods. The treatments were also exposed to the ambient climate. The most stable treatments, R‐20 dipped clods, R‐20 mixed pellets, and Arquad mixed pellets, were compared with treatments of gravel and bare soil in evaporation tests to determine the efficiency in reducing soil water loss. The three soil clod and pellet treatments were durable for over 1 year, and each reduced cumulative evaporation with time compared with a bare soil. First‐day evaporation rates after a 5.0‐cm water application showed bare soil was higher than gravel by 79%, R‐20 mixed pellets by 73%, R‐20 dipped clods by 63%, and Arquad mixed pellets by 36%. The R‐20 mixed‐pellet, mulch‐reduced soil water evaporation rate with nearly the same efficiency as gravel and could save about 30% more precipitation for plant use than a bare soil.
Germination of Italian Ryegrass Seeds1
Authors: Young James A. , Evans Raymond A. , Kay Burgess L.
Published: July 2010

Italian ryegrass (Lolium multiflorum Lam.) is widely planted on western California and Oregon rangelands, but it does not persist or spread. Understanding seed germination characteristics may help to explain its rather poor competitive ability as compared to other naturalized annual grasses. We studied the germination of seeds (caryopses) of Italian ryegrass under constant and alternating temperatures, and we studied simulated litter as a germination substrate. Constant and alternating temperature regimes were used from −6, −4, −2, 0, 2, and 5 C and 5 degree increments to 30 and 40 C, with 16 hours at the lower temperatures and 8 hours at the higher temperatures. Seeds used were from a naturalized population and two commercial seed sources. Italian ryegrass germinated over a wider range of temperatures and at more extreme diurnal fluctuations than did other annual grasses from the same environment. Germination of the naturalized population was highest at both relatively cool (5 C) nights and warmer (10 to 25 C) days and at a second peak of 10 C nights and high (30 to 40 C) days. Commercial seed lots had maximum germination over a wider range of temperatures than the naturalized seed lot. Litter‐germinated seedlings were very susceptible to drying and had virtually no root regeneration in comparison to other annual grasses. The limited temperature range at which Italian ryegrass germinates and the inability of roots to resist drying or to regenerate after drying may limit it ecologically.
Differential Effect of Bermuda and Bahiagrasses on Soil Chemical Characteristics1
Authors: Tan K. H. , Beaty E. R. , McCreery R. A. , Jones J. B.
Published: July 2010

The use of bermudagrass (Cynodon dactylon (L.) Pers.) and bahiagrass (Paspalum notatum Flugge) has attracted considerable research attention with respect to forage production. Little information is available on the influence of these grasses on soil properties and a direct comparison to effectively estimate the differential effect of bermudagrass and bahiagrass on major soil chemical properties is still lacking. This research was conducted to observe the effect of these grasses on selected soil properties following 4 years of clipping and N fertilizers treatments. A randomized split plot experiment was carried out in three replicates using a Montevallo soil planted with several bermudagrass and bahiagrass varieties, receiving annual application of 0, 224, and 672 kg N per ha from 1967 to 1970. In 1971 herbage and soil samples were collected for yield and chemical analysis.

The results indicated the absence of differences in the effects of the grasses on soil pH, N, P, K, and Ca, but there were differences in organic matter contents. The amount of organic matter accumulated in the soil under bermudagrass varied considerably with increased N fertilization, but showed a definite increase under bahiagrass. The lower root/herbage ratio of bahiagrass may explain the differences in soil organic matter under the two grasses. Base content and pH declined similarly in the soils under both bermudagrass and bahiagrass. The reduction in soil pH was related to decreasing amounts of K and Ca present in the soil. A negative correlation was also found between soil pH and N content of bermuda‐grass. In conclusion, over a period of time bahiagrass can be as effective as bermudagrass in its effect on soil properties.
Effects of Soil‐Moisture Regimes on the Growth of Barley1
Authors: Day A. D. , Thompson R. K.
Published: July 2010

Effects of soil‐moisture stress at three different stages of growth (jointing, flowering, and dough) on grain yield, grain quality, and plant growth of Spring barley (Hordeum vulgare L. emend Lam.) planted in November were studied under the field conditions at Mesa, Ariz. The experiment was conducted to determine the limitations to irragation water conservation in a semi arid environment. Four by four Latin square designs were used to compare four irrigation treatments. Effects of soil‐moisture stress for 7 days at the jointing, flowering, and dough stages of growth and/or until 100% of available water in the first 3 feet of soil was depleted were compared with plants not stressed. Withholding irrigation water during the jointing stage of growth did not reduce and in some cases increased grain yields. Moisture stress at the flowering and dough stages of growth decreased grain yield. Moisture stress at the dough lowered grain bushel‐weight. Stressing barley for water at jointing resulted in shorter plants, less lodging, more tillering, and more heads per unit area. Moisture stress at flowering and the dough stage decreased seeds per head and seed weight, respectively. Cultivars differed in response to soil‐moisture stress. Adequate soil‐moisture must be provided throughout the growing season for maximum yields of high quality grain from Spring barley grown as a Winter‐annual under irrigation.
Oat Agronomic and Grain Quality Responses to Growth Regulators1
Authors: Oplinger E. S. , Veith W. A. , Youngs V. L.
Published: July 2010

Lodging often limits oat (Avena sativa L.) yields and retards or prevents establishment of forage legumes seeded with it. We tried to determine whether growth regulators might be used to prevent oat lodging and to learn their effects on grain yield and quality. Ten chemical growth regulators were applied to foliage of two cultivars at two stages of development. Studies were conducted over a 3‐year period (1971–1973) at Arlington, Wis. on ‘Froker,’ a stiff‐strawed cultivar, and ‘Ajax,’ a weak‐strawed cultivar. Agronomic characteristics evaluated included grain yield, test weight, plant height, and lodging. Quality aspects evaluated included groat protein yield, weight, percent, oil concentration, fatty acid composition, and protein and mineral concentrations of both groats and hulls.

Several chemical treatments reduced plant height and lodging; however, these were often accompanied by lower test weights and lower yields. Low rates of application which were ineffective in reducing lodging also resulted in few beneficial effects on yield. With a few exceptions the treatments had little effect on grain quality.
Population Density and Sampling Location Effects on Net Radiation Measurements over Corn1
Authors: Linvill D. E. , Dale R. F.
Published: July 2010

Little information is available on the amounts of net radiation utilized by different populations of corn (Zea mays L.). To increase the range in corn microenvironments for a weather and corn growth study, we used two planting dates and two populations in 1970 at West Lafayette, Ind.

The soil was Chalmers silt loam. Soil moisture in the top meter remained above 60% available throughout the season. Net radiation was measured 1 m above two corn populations of 42,000 (42K) and 62,000 (62K) plants/ha within an early and a late planting. Pairs of Fritschen‐type net radiometers were exposed from a permanent mast within each of the four microenvironments. Replication was with two portable masts moved every week to alternate temporary locations in each population. Differences between net radiation measured within the same population at the permanent and temporary mast locations generally were larger than those between the permanent mast locations in the 42K and 62K populations. For the incompletely replicated experiment, we used a difference of differences t‐test to determine that there were no significant differences (α level 0.20) between net radiation measured over the 62K and 42K populations. Sources of experimental error discussed are instrumental calibration, field measurements of net radiation, possible canopy wear associated with the temporary mast movement, and nonhomogeneous crop canopies, especially with the net radiometers exposed ≤ 1 m above the crop. Without adequate replication interpreting environmental measurements risky, especially in row crops.
Techniques for Vegetatively Establishing Kentucky Bluegrass Turf1
Authors: Solon E. G. , Turgeon A. J.
Published: July 2010

Field studies were undertaken to investigate establishment of ‘A‐20’ Kentucky bluegrass (Poa pratensis L.) from plugs and shredded sod planted in prepared soil in early summer. Plug spacing was more critical than plug size in determining the rate of turfgrass establishment. Where companion grasses were seeded in conjunction with plugging, faster ground cover resulted, but the lateral growth of the A‐20 plugs was retarded. Planting of shredded sod resulted in poor turfgrass cover due to desiccation of the plants and annual weed development initially; however, good turfs were developed within 2 years with heavier planting rates resulting in faster establishment.
Vernalization of Winter Field Pea1
Authors: Trevino I. C. , Murray G. A.
Published: July 2010

Understanding the response of winter field peas (Pisum sativum spp. arvense L.) to vernalization is essential for cultural and breeding programs designed to improve seed yield and quality. The objective of this study was to determine the influence of vernalization on flower position, earliness of flowering, yield, and protein content of ‘Fenn’ winter field pea.

Seedlings, 2‐days‐old, were vernalized at 2 to 4 C for 0 to 4 and 0 to 5 weeks in two consecutive experiments. Vernalization significantly accelerated flowering by reducing the number of nodes and days after treatment to the first flower. Progressive acceleration of flowering was observed as duration of exposure to cold treatment increased. Maximum acceleration of flowering was attained by exposure to 4 weeks of cold temperature.

Vernalization slightly inhibited vegetative dry matter production and seed yield. Percent protein in the seed was slightly increased by vernalization because equal amounts of N were translocated to smaller sinks induced by the cold treatment. Total seed protein/plant was not affected by the cold treatment.
Storage Duration and Temperature, and Wheat Genotype Effect on Sedimentation Value1
Authors: Ephrat J. , Sinmena Bebi
Published: July 2010

The sedimentation test is a valuable tool in screening wheat selections for baking quality in early breeding stages. Its shortcoming is the decline in the sedimentation values (SV) during storage, A series of experiments were conducted to study the dynamics of the sedimentation values as a function of genotype, storage temperature, and storage duration. Grains of various common wheat, Triticum aestivum L., cultivars and selections were stored for 7 to 11 months at 3, 11, 20, and 30 C, and at room temperature; they were periodically milled and tested for SV and protein content of the flour.

Entries with high initial SV generally showed a steep decrease in SV, especially during the first two to three months after harvest. Genotypical differences in the SV dynamics were found within the high‐quality group of cultivars. No decrease in SV was observed in cultivars showing low initial values.

High storage temperature (30 C and RT), had a much more pronounced effect on the SV dynamics than did lower temperatures. Protein content was not involved in the SV decline.

Reliability of the sedimentation test for breeding purposes can be increased by storing material at low temperatures, preferably not higher than 5 C, or by carrying out at short intervals recurrent sedimentation tests of a check cultivar.
A Carbon‐14 Technique for Measuring Photosynthate Distribution in Field Grown Turf1
Authors: Hull Richard J.
Published: July 2010

The effect of management or environmental factors on the short‐term distribution of current photosynthate within field grown turf has received little study. However, variation in the initial energy flow within turfgrasses certainly influences the longer term energy levels and ultimate survival of turf. A technique is described by which photoassimilated carbon was followed within ‘Merion’ Kentucky bluegrass (Poa pratensis L.) grown as a closely mowed turf under field conditions. A 189 cm2 area of grass was covered with a glass bell jar into which introduced 15 μCi of 14CO2. Depending on climatic conditions, between 19 and 69% of the 14C applied was recovered from a 10.5‐cm plug of turf harvested within 2 hours of treatment. During the 15 min exposure period, the temperature within the bell jar increased, however, 14CO2 sufficient for tracer analysis was assimilated presumably via a normal carbon reduction pathway.

The utility of this technique is illustrated in a fertility experiment which showed that high fertility turf (24‐4‐8 or 48‐8‐16 g/m2 N‐P‐K) often fixed more 14CO2 than did low fertility grass (12‐2‐4 g/m2). Photoassimilated 14C translocated to roots at a greater velocity in September than in December but the quantity translocated was greater in December. During late summer, photosynthate moved more rapidly to roots of low fertility turf and accumulated in deep roots more than it did in heavily fertilized turf.

This technique appears to provide an effective method for measuring the short term energy distribution within turfgrass sod grown under natural conditions.
Yield‐Nutrient Absorption Relationships as Affected by Environmental Growth Factors1
Authors: Terman G. L. , Khasawneh F. E. , Allen S. E. , Engelstad O. P.
Published: July 2010

Widely varying results and conclusions are reported in the literature concerning the effects of environmental growth factors, especially temperature, on yields of dry matter and nutrient absorption by plants. The purpose of this paper is thus to evaluate the effects of temperature in three greenhouse pot experiments and as reported in the literature on yield‐nutrient uptake relationships. Several rates of applied N and P were compared in Exp. 1 for oats (Avena sativa L.) grown for 7 weeks at three combinations of day length and temperature. Several rates of N and P in factorial combination were compared in Exp. 2 for corn (Zea mays L.) grown for 4 weeks at water bath temperatures of 16 and 27 C. Corn was also grown in Exp. 3 for 3 and 6 weeks to compare P rates and temperatures of 16 and 21 C and at ambient temperatures (25 to 35 C). Dry matter yields and uptake of N and P (also of cations in Exp. 3) were determined. Plant nutrient concentrations, especially of P, increase with higher soil temperatures in experiments of short duration and with little yield response to temperature. However, with marked yield response, dilution of plant nutrient concentrations but higher uptake are the dominant trends with increase in temperature up to the optimum for each crop species. The reverse usually occurs at temperatures above the optimum. Release of nutrients from the substrate with higher temperatures varies greatly with soil fertility level and amounts of applied nutrients. Rate of root growth is also very likely a predominant factor in plant uptake of nutrients, especially those having limited mobility in the soil.
Yield and Quality of Midland and Two New F1 Hybrid Bermudagrasses1
Authors: Horn F. P. , Taliaferro C. M. , Morrison R. D.
Published: July 2010

This study was conducted during the 1974 growing season to compare ‘Midland’ bermudagrass (Cynodon dactylon (L.) Pers.), and two newly developed F1 hybrids. The new hybrids appeared, on the basis of mass screening experiments, to be superior to Midland in both yield and quality. A split‐plot design was used with the three grasses as main plots (strain S‐15 and ‘Oklan’ and Midland bermudagrass), N‐fertilizer levels as subplots (17, 50, and 150 kg N/ha) and harvest interval as sub‐subplots (3, 5, 7, 9, and 11‐week intervals). The experimental site was a Canadian fine sandy loam belonging to the Udic Haplustolls. Oklan yielded significantly more dry matter (DM)/ha than did S‐15 or Midland (P<0.05). Oklan was also more digestible than S‐15 or Midland (P<0.05). S‐15 and Midland were not significantly different in either yield or digestibility (P>0.05). Oklan and Midland were not significantly different in crude protein (CP) content (P>0.05), but both were higher in CP than S‐15. It was concluded that Oklan bermudagrass is superior to Midland in terms of both yield and quality, but that the S‐15 strain is inferior to Midland bermudagrass and consequently should not be released.

Increasing levels of N fertilizer brought about a linear increase in DM yield and a linear increase in CP percentage of all grasses and, those grasses in plots receiving the high level of N were higher in digestibility (IVDMD) than were those receiving the low level of N (P<0.05).

Rate of increase in DM production declined when more than five weeks between harvests were allowed. Thus, the 5‐week harvest interval was the nearest to optimum for maximum digestible nutrient production of the harvest intervals studied.
Reduction in Sugarcane Trash by Desiccation with Paraquat1
Authors: Samuels G. , Beale A.
Published: July 2010

Incomplete preharvest burning, due to a high moisture content of green tops, has increased the trash content of sugarcane in Puerto Rico, thus raising field harvest costs and decreasing sugar recovery in the factory. The present investigation was made to study the possible use of a chemical desiccant to obtain better preharvest burning in order to decrease the trash content of the cane.

Ten fields of sugarcane (Saccharum officinarum L.) in irrigated, normal, and high rainfall areas were divided in half, and one half of each field was sprayed with 1.8 liters of Paraquat (1,1′‐dimethyl‐4,4‐dipyridiniumbis‐dimethyl sulfate, commercially known as Gramoxone) in 76 liters of water/ha, 1 week before preharvest burning of the field to reduce cane trash. Burning was more thorough in Paraquat‐treated fields giving trash and cane fiber reductions of 5.08 and 0.72%, respectively. Values for sucrose percent cane, Brix, and purity were not significantly affected by desiccant action. The method of harvesting influenced response to the desiccant; the V‐cutter having a higher reduction in percent trash than did the cut and load harvester. No differences due to plant crop or ratoon were observed.
Forage Sorghum Yield Components and Their in vivo Digestibility1
Authors: Fribourg H. A. , Duck B. N. , Culvahouse E. M.
Published: July 2010

Although the influence of different defoliation management schemes on the productivity and digestibility of summer annual grasses has been studied extensively, little is known about the effects of management on the yield components of these plants. To determine the relative contribution of leaf, stem, and head components to total yield, and to ascertain the digestibility of these plant parts, ‘Sudax SX‐11’ and ‘Trudan’ forage sorghums (Sorghum bicolor (L.) Moench) were seeded in the field in May and in June and subjected to four defoliation schemes: 1) 75‐cm growth cut to a 2.5‐cm stubble and 2) to a 15‐cm stubble; 3) 50‐cm growth cut to a 15‐cm stubble; and 4) early bloom growth cut to a 10‐cm stubble. Dry matter (DM) yields of the first growth and subsequent regrowths, and estimated digestible dry matter (% EDDM) measured with an in vivo nylon‐bag technique, were estimated for leaf blades, culms and leaf sheaths, and inflorescences. Both cultivars produced more DM yields with 75 cm than with 50 cm of growth. Sudax SX‐11 produced less than Trudan when 2.5‐cm rather than when 15‐cm stubbles were used and this was more evident when seeding was delayed one month. Both 50‐ and 75‐cm vegetative growths produced mostly leaf yield of about 80% EDDM throughout the season. Plants cut at early bloom produced much larger DM yields than those cut at vegetative stages. Leaf % EDDM was slightly lower in the early bloom than in the other treatments but stem and head materials were of lower digestibility than leaf blades.
Leaf Canopy as Related to Yield in Barley1
Authors: Grafius J. E. , Barnard J.
Published: July 2010

The purpose of this paper was to examine the relationship between leaf canopy area integrated over time and yield of grain, using mean values from 15 populations of spring barley (Hordeum vulgare L. Emend. Lam.). Mean values of selfed (F7 or BC6) unselected populations were used to minimize the confounding effects of linkages.

No significant relationships was found for yield and leaf area canopy but significant relationships were demonstrated (P<0.05) between leaf canopy integrated over time and both fertile tiller number (X) and seeds/head (Y).

We have found no relationship between leaf canopy area and yield but yield (W) was associated with (P<0.05). This indicates that the differences between populations were not due to differences in leaf canopy but were in some degree (r for W vs. Y = 0.63) associated with the shape of the yield parallelepiped.

If we accept this reasoning, and there are ample data to support it, we arrive at the premise that the components of yield (X, Y, Z) are active participants in determining relative yield through the regulation of photosynthetic activities via a source‐sink relationship. Further the variation in leaf canopy experienced here resulted in part from the triggering mechanism of whether the genetic code called for high or low X, rather than the reverse of leaf canopy determining differences in X or Y.
Effect of Chloride and Potassium on Corn Lodging1
Authors: Liebhardt William C. , Munson Robert D.
Published: July 2010

Ammonium chloride treatments were included on selected plots in a corn (Zea mays L.) field laboratory fertility study to determine whether or not reductions in lodging observed in previous years were due to chloride or potassium in the KCl treatments. Sixty‐four percent of the corn lodged in plots receiving no potassium and no chloride or chloride as NH4Cl, while lodging was only 16% with comparable KCl treatments. It is concluded that the reduction in lodging was due to potassium and not chloride.
Application of Time Series Analysis to Investigate Crop and Environment Relationships1
Authors: Kuehl R. O. , Buxton D. R. , Briggs R. E.
Published: July 2010

Correlation techniques are important tools for investigating relationships between crop growth and environment. However when applied to a time series the presence of autocorrelation affects the estimates of correlations between two observed series, an effect which is sometimes overlooked in studies reported in the literature. Appropriate statistical techniques are needed to ensure that proper inferences can be made from these observations. Empirical time series modeling has the potential for removing autocorrelations in many of these cases. To test the feasibility of this technique the relationship between boll retention in cotton (Gossypium hirsutum L.) and 5‐day average minimum temperature during the growing season was investigated with 3 years of data. The best fitting autoregressive moving average models were selected for the observed time series for each of the 3 years. Residual series, observed minus predicted values, were computed from the estimated time series models for boll retention and minimum temperature and were free of autocorrelation. Negative crosscorrelations were found between the residual series for boll retention and average minimum temperature for the 5‐day periods beginning with 10 days and 1 day prior to anthesis, respectively. The negative relationship suggests that high nighttime temperatures accumulated over 5‐day periods prior to and during anthesis increase boll shedding. We conclude that time series modeling is an effective technique to aid the identification of relationships between agronomic variables measured in time sequences.
Nitrogen Fertilizer Potential of an Experimental Urea Formaldehyde1
Authors: Hagin J. , Cohen Liuba
Published: July 2010

An experimental urea formaldehyde (UFC) having less of its nitrogen in the hot water insoluble and thus a higher availability index than the commercial one (UF) was developed by Chemicals and Phosphates Ltd., Haifa, Israel. It was expected that UFC would act as a slow release fertilizer, releasing more of its nitrogen to plants and in a shorter time than UF and thus increasing the nitrogen recovery by plants.

In an incubation experiment in a silty clay soil the rates of nitrification of UFC and UF agreed well with the availability indices. In a greenhouse experiment on three soils (silty clay, sandy loam, and sand), with five levels of application, and five crops, [oats (Avena sativa), barley (Hordeum vulgare), rhodes grass (Chloris gayana), rhodes grass and oats], UFC was compared to UF and ammonium nitrate (AN). Accumulative N‐uptake by plants at the 1.0 g N/3 kg soil level, on the three soils, was highest in ihe AN treatment and higher in the UFC than in the UF treatments (1.26 vs. 1.16 vs. 0.83, 1.04 vs. 0.97 vs. 0.66, and 0.52 vs. 0.38 vs. 0.25 g N/pot), indicating that the UFC may be more efficient as a nitrogen source than the UF. In another similar greenhouse experiment, with a crop sequence of barley, rhodes grass, rhodes grass, rhodes grass, oats, but combined with leaching, the UFC showed the highest nitrogen recovery by plants, when compared to UF and ammonium nitrate. At the 1.0 g N/pot application level the accumulative N‐uptake on the silty clay soil was 0.80 vs. 0.57 vs. 0.59, respectively, on the sandy loam 0.55 vs. 0.35 vs. 0.44, and on the sand 0.37 vs. 0.22 vs. 0.27.

The experimental urea formaldehyde produced a higher nitrogen uptake by plants than the commercial one, indicating a higher nitrogen recovery, both under leaching and nonleaching conditions.
Effect of Leaf Shape on Response of Cotton to Plant Population, N Rate, and Irrigation1
Authors: Rao M. J. , Weaver J. B.
Published: July 2010

Leaves varying in shape have been identified in cotton, and it has been conjectured that leaf shape affects growth and other quantitative characters in Upland cotton, Gossypium hirsutum L.

The objective of these studies was to evaluate okra and normal leaf shape on boll rot, yield, earliness, boll size, and fiber properties. Near isogenic lines of okra and normal leaf shape cotton was evaluated at three plant populations (21,780, 32,670, and 65,338 plants/ha) and three N rates (100, 134, and 168 kg/ha) on an Appling coarse sandy loam (Typic Hapludults; clayey, kaolinitic, thermic family) soil over a 3‐year period 1971‐73. In 1972 irrigation treatments were also included.

No significant interactions were found between leaf characters, plant populations, N rates, and irrigation. Okra leaf shape increased earliness, boll size, and micronaire and decreased seed cotton loss due to boll rot. With increasing plant populations, lint yield and earliness tended to increase and boll size decreased. Higher boll rot loss was observed at higher levels of N. Irrigated cotton produced significantly greater lint yield, boll size, and fiber length and increased earliness.
Residual Zn Availability Related to Growth and Nutrient Gradients in Corn1
Authors: Ohki K. , Anderson O. E. , Jones L. S.
Published: July 2010

Responses to Zn application by corn (Zea mays L.) in the southeastern states have been few although Zn deficiency has been observed. This experiment was conducted to evaluate residual Zn availability related to growth and nutrient gradient and to explore reasons for the lack of Zn response.

Residual Zn levels were determined in corn tissue grown on Norfolk is (Typic Paleudult) in 1974 after Zn applications of 0 to 30.3 kg/ha in 1971. Zinc concentration in recently matured leaves sampled in 1974 at the five leaf stage was 20 μg/g for the control and 46 μg/g for the 30.3 kg/ha rate indicating that tissue Zn concentration of leaves sampled in 1974 continued to reflect Zn applied in the spring of 1971. Plant dry weight at the five‐leaf stage did not reflect Zn additions. A later sampling of the recently matured leaf at the eight‐leaf stage and ear‐leaf sampled at early silking continued to indicate residual Zn availability from added Zn. Plant dry weight at early silking and grain yield at harvest were not affected by Zn rates indicating that sufficient Zn was available in control plots for maximum plant and grain production.

At all residual Zn rates, Zn concentration was greatest in leaf 1 (top) and declined to leaf 7 and remained constant to leaf 10 (bottom). The ear‐leaf (leaf 8) was not as sensitive to residual Zn rates as the young leaves near the top. The Mn concentration gradient in leaves from top to bottom was 40, 54, and 36 for leaves 1, 4, and 10, respectively. Copper concentration was constant from leaf 1 to 10 and was not affected by Zn rates. Iron concentration increased gradually from 68 to 98 μg/g in leaf 1 and 10, respectively, and remained constant over residual Zn rates.
Nitrification Inhibitor with Fall‐applied vs. Split Nitrogen Applications for Winter Wheat1
Authors: Boswell F. C. , Nelson L. R. , Bitzer M. J.
Published: July 2010

Since numerous small grain producers desire to make fall application of efficient levels of N for maximum yields, studies are needed to determine the efficiency of fall‐applied N (with and without an inhibitor) vs. split N applications. Field studies were conducted at two locations each year over a 3‐year period with the objective of evaluating the response of wheat (Triticum aestivum L.) to N rates, time of application, and effect of a nitrification inhibitor on soils of different characteristics (Typic Hapludult and Typic Paleudult). Yields, tissue concentrations of various elements, grain analyses, and soil NH4‐ and NO3‐N were evaluated. Splitting the N, 28 kg/ha in the fall and 56 kg/ha topdressed in the spring, was superior to applying all the N in the fall. The inclusion of the nitrification inhibtor, 2‐chloro‐6‐(trichloromethyl) pyridine (N‐Serve), with ammonium sulfate in the fall at the rate of 84 kg/ha did not influence yields or N levels in the tissue or grain. The inhibitor had no effect on elements other than N. Although the nitrification inhibitor influenced the retention of the NH4‐N in the soil until the January sampling, this retention was not evident for either soil at the March sampling. Therefore, we concluded that the N applied as a part of the complete fertilizer at the rate of 28 or even 84 kg/ha in the fall is inadequate for maximum wheat yield in either the coastal plain or piedmont regions of Georgia. A nitrificaton inhibitor applied with the ammonium sulfate was ineffective in preventing nitrification of the ammonium nitrogen or to increase yields.
Equipment for Application of Fertilizer at a Linear Increase Rate1
Authors: Peck N. H.
Published: July 2010

Conventional procedure for evaluating effects of different rates of fertilizer on crop response requires a series of plots, each receiving a different rate. This technique uses a lot of land and requires much time and labor. Thus an experimental planter that delivers fertilizer in continuously increasing rates ranging from zero to the maximum rate desired was designed and constructed. A previously weighed sample of fertilizer is distributed, at uniform depth, in a V‐shaped mold which is placed on top of the rubber belt of a conventional belt fertilizer applicator. The mold is removed and the plot is planted. Gears adjust the rate of travel of the belt so that there is a continuously increasing rate of application from the beginning of the plot, at the front of the belt, to the maximum rate, at the end of the belt where the fertilizer band on the belt is the widest. The equipment performed very satisfactorily for snap beans (Phaseolus vulgaris L.) and sweet corn (Zea mays L.) in 1975.
Lime and Nitrogen Influence on Timothy Yield and Composition1
Authors: Laughlin Winston M. , Martin Paul F. , Smith Glenn R.
Published: July 2010

No domestic grass has been successfully grown in the Caribou Hills area on Alaska's lower Kenai Peninsula where another forage has been needed to supplement the native bluejoint (Calamagrostis canadensis). Timothy (Phleum pratense L.), a highly desirable forage grass in many Alaska agricultural areas, was selected as a grass more adapted to acid conditions than many other grasses. This experiment was specifically designed to determine if lime applications would make possible growth and survival of domestic timothy. A 6‐year study with five lime and two N rates was conducted with ‘Engmo’ timothy planted on Kachemak silt loam (Typic Cryandepts) in an area domestic grasses had seldom survived. Lime applications were applied by hand to field plots and worked in with rototiller. Fertilizer applications were topdressed each spring with additional nitrogen applied after the first cutting each year. Each lime increment over 2,240 kg/ha increased soil reaction, forage yield, and N uptake and tended to decrease the N concentration in forage. Increasing N applications from 134 to 269 kg/ha increased yields, N percentages, and N uptake. Native bluejoint gradually replaced the timothy on plots receiving less than 4,480 kg lime/ha, responded to the high N rate, and thrived with two cuttings per growing season. This experiment demonstrates domestic grasses can be grown successfully on Kachemak silt loam with lime application and proper fertilization.
Simultaneous Deep Fumigation and Chisel Plowing1
Authors: Nixon Paul R. , Heilman Marvin D. , Lynn Ned G. , Vega Ramon
Published: July 2010

The design of a rugged, trouble‐free system for applying liquid soil fumigants is discussed. The system is built around a tractor‐mounted shank chisel plow and utilizes automotive electric fuel pumps to propel the liquid. Simple, nonclogging discharge tips are an important feature of the design.
Desiccation of Grain Sorghum by Foliar Application of Nitrogen Solution1
Authors: Donnelly K. J. , Vanderlip R. L. , Murphy L. S.
Published: July 2010

Adverse weather delaying harvest is a frequent problem of grain sorghum [Sorghum bicolor (L.) Moench] producers. This study evaluated the effects of foliar application of 32% nitrogen urea‐ammonium nitrate solution (UAN) to desiccate grain sorghum before harvest. Nitrogen solutions were applied at O, 67, and 134 kg N/ha when grain had reached physiological maturity. Two hybrids (‘RS671’ and ‘E57’) and two planting dates were compared at two locations in 1972 and 1973. Grain samples were collected weekly until harvest for moisture determination, then grain and forage yields and N contents were determined. The effects of N carryover to succeeding grain sorghum crops were also evaluated.

Grain drying was accelerated significantly only when N was applied at or before physiological maturity. However, application before physiological maturity reduced grain yields. Rainfall and high humidity resulting in poor drying conditions more than offset desiccation effects after grain moisture reached 20 to 25%.

Leaf loss reduced harvestable forage yields, as expected. Desiccant N gave little or no increase in N content of the grain or forage. Soil N and grain sorghum yields were increased slightly the next year in some plots, but no significant carryover of desiccant N was found in others. Low recovery of applied N in the treated crop at harvest and low carryover to the succeeding crop suggests that volatilization losses following treatment were high.
Nitrogen Use in Winter Wheat in Response to Systematic Pesticides1
Authors: Moyer Joseph L. , Paulsen Gary M.
Published: July 2010

Various pesticides exhibit plant growth regulating activity and have increased crop yields or altered concentrations of various constituents. Our purpose was to test the effect of commercially available pesticides on winter wheat (Triticum aestivum L.) with regard to N use, protein concentration, and dry matter production. Growth chamber‐grown wheat seedlings were supplied 2.5 or 10.0 mM nitrate‐N concentrations in nutrient solutions at each of two temperature regimes. Pesticides added to different pots were 0.5 mM concentrations of simazine [2‐chloro‐4, 6‐bis (ethylamino)‐S‐triazine] or dyrene [2,4‐dichloro‐6‐(0‐chloroanilo‐s‐triazine], and 25 mM concentrations of disulfoton [0, 0‐diethyl S‐(2‐(ethylthio) ethyl) phosphorodithioate] or guthion [0, 0‐dimethyl S‐(4‐oxo‐1,2,3‐benzotriazin‐3 (4H)‐ylmethyl phosphorodithioate]. Simazine increased nitrate reductase activity and nitrate concentration, and decreased glutamine synthetase activity. The same four materials were sprayed on field plots at 0.1 or 1.1 kg/ha at one of four growth stages. No autumn treatment affected yield or protein content of forage. Lower simazine rates applied at anthesis and higher simazine rates applied at all three spring growth stages decreased grain yields. Simazine treatments that decreased grain yields, and guthion applied during autumn increased grain protein concentration. The other treatments had no effect on protein or yield. Simazine applied during anthesis decreased grain test weights significantly. Decreased grain yields and increased grain protein concentrations probably resulted from detrimental effects of simazine on photosynthate accumulation and absence of a direct effect on N assimilation when foliar‐applied. Decreased grain test weights apparently resulted from floret sterility and undeveloped grains.
Microwave Treatment and Heat Damage Artifacts in Forages1
Authors: Darrah C. H. , Van Soest P. J. , Fick Gary W.
Published: July 2010

Microwave radiation has been suggested as a pretreatment to laboratory drying of freshly harvested forage samples because it quickly stops respiration. However, the effects of such treatment are not well understood. Fresh samples of both alfalfa (Medicago sativa L.) and a mixture of orchardgrass (Dactylis glomerata L.) and Ladino clover (Trifolium repens L.), as well as a dried Ladino clover forage reconstituted with water, were exposed to microwave radiation for zero to 15 min. To investigate the extent of heat damage associated with the microwave treatments, these samples were dried at 50 C and compared to material dried at 100 C. Increased levels of acid‐detergent insoluble N, an indicator of heat damage, were found after only 2 min exposure in two of the three forages, and heat damage was greater as exposure to microwaves increased. It took 15 min of microwave treatment to produce heat damage in alfalfa. Drying at 100 C caused the greatest amount of heat damage in all species tested. Significant decreases in in vitro true digestible organic matter were detected only in Ladlno clover with 15 min of microwave treatment or 100 C drying. Since forages differ in their responses to microwave radiation, this drying pretreatment should be used with caution.
Effect of Chemical Growth Retardants on Turfgrass Morphology1
Authors: Elkins D. M. , Vandeventer J. W. , Briskovich M. A.
Published: July 2010

Studies on chemical growth retardation of turfgrasses have often dealt with chemical effects on aerial parts with little or no attention devoted to root development, or to rhizome and tiller number. If a retardant is to be used for grass growth control, long‐term effects on subterranean as well as aerial parts must be considered.

Greenhouse experiments were conducted to determine the influence of 19 growth retardant treatments on several morphological growth parameters of tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.). Most growth retardant treatments which caused aerial growth reductions also restricted root spread, volume, and dry weight. Some retardants also reduced tall fescue and Kentucky bluegrass tiller number and bluegrass rhizome development.

The implications of these results are serious in terms of maintainance of long‐term stand of vigorous turf. Growth retardants for turf must be developed which recard top growth without detrimentally affecting root, rhizome, or tiller development.
Effects of pH and Al on the Growth and Chemical Composition of Cicer Milkvetch1
Authors: Vickers J. C. , Zak J. M. , Odurukwe S. O.
Published: July 2010

Cicer milkvetch (Astragalus cicer L.) is one of several legume species which has been used for the stabilization of Massachusetts roadsides. In this study the following treatments were combined in soil and water culture experiments: pH levels 4.2, 5.4, and 6.3, and aluminum levels of 0, 2.5, and 5.0 ppm added to soil, 0, 5, and 15 ppm Al in water. The objective was to examine the interactions among soil treatments, factors of acid soil infertility, and the chemical composition and growth of cicer milkvetch (‘Lutana’). Dry weights and root penetration doubled in response to soil pH 5.4. At soil pH 6.3 manganese in the soil and in the plant tissue rose to high levels while dry weights and root penetration declined. On the other hand, dry weight of tops and root elongation were significantly greater at pH 5.4 and 6.3 than at pH 4.2 in water culture. Soil Al treatments were positively related to water soluble soil P and soil Mn availability. Nutrient solution Al additions significantly enhanced Al in tops. Also, the 5 ppm Al level significantly stimulated root elongation, while 15 ppm Al was related to reduced elongation. Dry weights were not significantly affected by Al treatments in soil or water culture. The apparent acid tolerance of cicer milkvetch, plus the buffering capacity of this soil, and the sufficient supply of P at all treatments in water culture apparently diminished the A1 treatment effects. Cicer milkvetch growth is enhanced by CaCO3 application of at least 1,750 ppm to this soil for these reasons: percent Ca and P of tops rose above critical levels, while excess soil Mn and Al levels declined, allowing enhanced root penetration of the soil.
Preemergence Winter Weed Control in Dormant Bermudagrass Turf1
Authors: Johnson B. J.
Published: July 2010

Spur weed (Soliva sessilis P. & K.) is becoming a severe winter weed problem in the Southeast and information is needed on herbicides that will give satisfactory control of winter weed mixtures which includes spur weed. Field experiments were conducted for 2 years on Cecil loam (Typic Hapludult) and Cecil sandy loam at Griffin, Davidson sandy clay loam (Rhodic Paleudult) at Lawrenceville and 1 year on Cecil loam at Macon, Ga., to determine the effects of preemergence herbicide treatments on control of spur weed and other winter annuals in bermudagrass [Cynodon dactylon (L.) Pers. ‘Common’] turf. Herbicides as preemergence treatments were made in the fall and weed control and turfgrass tolerance ratings were made the following spring.

Napropamide [2‐(α‐naphthoxy)‐N,N‐diethylpropionamide] was the only herbicide that controlled spur weed almost completely. The control was acceptable with terbutol (2,6‐di‐tert‐butyl‐p‐tolyl methylcarbamate) at 11.2 kg/ha and profluralin [N‐(cyclopropylmethyl)‐α,α,α‐trifluoro‐2,6‐dinitro‐N‐propyl‐p‐toluidine] at 6.7 kg/ha. Combination treatments of bensulide [0,0‐diisopropyl phosphorodithioate S‐ester with N‐(2‐mercaptoethyl) benzene sulfonamide] with either benefin (N‐butyl‐N‐ethyl‐α,α,α‐trifluoro‐2,6‐dinitro‐p‐toluidine), terbutol, or pronamide [3,5‐dichloro‐(N,,1,1‐dimethyl‐2‐propynyl)benzamide) controlled more different weed species than when each was applied alone. All herbicides except oxadiazon [2‐tert‐butyl‐4‐(2,4‐dichloro‐5‐isoproxyphenyl)‐Δ2‐l,3,4‐oxadiazolin‐5‐one], butralin [4‐(l,l‐dimethylethyl)‐N‐(l‐methylpropyl)‐2,6‐ditrobenzenamine], and selected bensulide plus benefin combinations affected the green‐up of bermudagrass at one location in March and April. However, turf greenup was as good or better in all treated plots when final ratings were made in May.
Calibration of Leaf Resistance Porometers1
Authors: McCree K. J. , van Bavel C. H. M.
Published: July 2010

Leaf resistance porometers are normally calibrated by placing the humidity sensor over a wet surface, which is at a known temperature. A perforated plate of known diffusive resistance is placed between the surface and the sensor. The results are subject to systematic errors due to wetting of the calibration plate from below, condensation on the plate, and evaporative cooling of the wet surface. The possibilities for error were investigated, using commercially available equipment, and it was found that they could be greatly reduced by taking such simple precautions as placing a spacer between the wet surface and the plate, avoiding conditions in which the temperature of the plate might be less than that of the surface, and maintaining a humid atmosphere throughout the calibration.
Visual, Tissue, and Soil Factors Associated with Zn Toxicity of Peanuts1
Authors: Keisling T. C. , Lauer D. A. , Walker M. E. , Henning R. J.
Published: July 2010

Zinc (Zn) deficiency of peanuts (Arachis hypogaea L.) has not been a production problem, but many areas show possible Zn toxicity where large amounts of Zn have been applied. Field and greenhouse studies and a survey were conducted to obtain data concerning visual symptoms, tissue concentrations, and soil test information about Zn toxicity of peanuts. The greenhouse experiment had treatments ranging from 0 to 50 mg Zn per kg of soil (Plinthitic Paleudult; fine loamy, siliceous, thermic). Zinc content of field soil (Arenic Paleudult; loamy, siliceous, thermic) to a depth of 90 cm, resulting from Zn fertilizer applications 5 years previously, were determined. Data concerning soil and tissue Zn concentrations were gathered, and visual toxicity symptoms were noted. The survey was undertaken to characterize soil and tissue Zn concentrations at locations where the problem is now occurring. Appearance of acute Zn toxicity occurred 14 to 120 days after emergence. Acutely affected plants exhibited chlorosis, stunting, purple coloration of the main stem and petioles, usually a lesion at the base of the plant, and premature necrosis in severe cases. Affected areas usually were only a fraction of a hectare, with necrotic or severely stunted plants in the center, and distinct borders. Tissue Zn concentration, in both the greenhouse and field, increased 15 mg/kg for each mg/kg increase in acid‐extractable soil Zn. Tentative Zn toxicity critical values were 12 and 220 mg/kg for soil (acid‐extractable) and tissue, respectively. Liming was effective in reducing the concentration of Zn in tissue and overcoming reduction in dry matter yield due to excessive uptake of Zn but lime did not change the acid‐extractable level of Zn in soil. Zn uptake was reduced by increasing soil pH without changing extractable soil Zn. These data show that predicting Zn toxicity from values of soil Zn alone could give erroneous results. Also, an adequate liming program should reduce the problem. Acid Southeastern soils were found to retain appreciable Zn in the plow layer. Thus Zn should be cautiously applied to crops in rotation with peanuts or when planting peanuts in areas where large quantities of Zn may have been applied in the past.