bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing the Sulfur Status of Field‐Grown Wheat by Plant Analysis1
Authors: Spencer K. , Freney J. R.
Published: July 2010

Diagnostic methods developed under laboratory or greenhouse conditions require field confirmation. This paper reports the relative field performance of four indexes for the diagnosis of S deficiency in wheat (Triticum aestivum L.) which were previously assessed in the greenhouse. Sulfate S (as percent total S), sulfate S concentration (as ppm dry matter), total S concentration (as ppm dry matter), and total N: total S ratio in the aboveground parts of a soft white wheat cultivar, ‘Olympic’, were compared as diagnostic indexes in a factorial experiment with five rates of gypsum (0 to 50 kg S/ha) and three rates of ammonium nitrate (0 to 100 kg N/ha). A strong relationship was found between final grain yield and each index at the following stages of growth; fourth leaf (61 days from sowing), fully‐tillered (92 days), and jointing (134 days). However, as the critical value for sulfate S (as percent total S) was least affected by the age of the plant or N supply, it is considered to be the most convenient index. The overall relationship between yield and sulfate S (as percent total S) was strong (r = 0.88) and the critical value at 90% of maximum yield was 13%. This compares with r values of 0.87, 0.96, and 0.91 and critical values of 14, 12, and 11% for the plant tissue at the individual growth stages examined. Where the adequacy of the S supply to a wheat crop is in question, the proportion of total S as sulfate S in the plants is indicated as a useful guide to the need for S fertilizer in securing optimal grain yield.
Survival of Rhizobium phaseoli in Contact with Chemical Seed Protectants1
Authors: Graham P. H. , Ocampo G. , Ruiz L. D. , Duque A.
Published: July 2010

abstract

In the multiple cropping systems used for bean (Phaseolus vulgaris L.) production in Latin America, seed treatment is often needed for control of soil pathogens and pests, but can be incompatible with Rhizobium inoculation. This study looks at the interaction between Rhizobium and seed protectant. One laboratory and three field studies are reported. The survival of R. phaseoli on bean seeds treated with PCNB, thiram, or captan was measured under laboratory conditions using standard serial dilution and plate count techniques. At Popayan, Colombia (typic dristandept, pH 4.8) the nodulation and nodule development of bean seeds treated with PCNB, thiram, captan, and furadan was evaluated, and different inoculation methods, including a granular soil applied inoculant, compared. Nodulation of beans protected with PCNB or thiram, and inoculated with seed or soil‐applied rhizobia was also studied at La Selva, Colombia (typic dristandept, pH 5.1).

While contact with PCNB, thiram or captan on seeds reduced Rhizobium survival, with captan most toxic, PCNB‐treated seeds maintained counts of l03 rhizobia/g seed until almost 48 hours after inoculation. Field results demonstrated the delicate balance between inoculant and seed protectant. At Popayan, nodule number/plant was not affected when thiram, furadan, or PCNB‐treated seeds were inoculated and promptly planted, but delay between inoculation and planting did reduce the nodulation of seeds protected with PCNB or thiram. At La Selva, all fungcide treatments lowered nodule number/plant. Seed protection with PCNB enhanced nodule development at Popayan and reduced root rot incidence at La Selva. Despite the somewhat acid soil conditions the best nodulation at both Popayan and La Selva was attained with granular soil‐applied inoculants. Further studies on this method of inoculation for beans are warranted.
Soil Water Effects on No‐till Corn Production in Strip and Completely Killed Mulches1
Authors: Box J. E. , Wilkinson S. R. , Dawson R. N. , Kozachyn J.
Published: July 2010

No‐till row cropping in plant residue mulches can effectively eliminate the high erosion rates of clean tilled, rolling soils in the Southern Piedmont. This study was conducted to evaluate corn (Zea mays L.) production on two mulches with five soil water treatments and a uniform high fertility level. The statistical design was a randomized block with mulches as main plots and irrigation levels on the split plots. Each treatment was replicated three times. The mulch treatments were viable fescue sod with corn planted in the same 20‐cm strips of sod killed annually prior to planting (SK); and a completely killed mulch (CK) of fescue, or winter rye on the same plot area and in the sequence of fescue‐corn (1973) followed by winter rye‐corn (1974 and 1975). Soil water treatments were: rainfall only (M1), rainfall plus sprinkler irrigation when soil water potential in the 0‐30 cm soil depth averaged −10 (M2), −5 (M3), or −2 (M4) bars, and 5 cm/wk (M5). Corn received annually about 450 kg/ha N; P, K, and Mg additions were based on soil analysis. Both fescue and winter rye received 45 kg/ha each N, P, and K in the fall.

Corn grain and stalk yields on the CK mulch were significantly higher than those on the SK mulch. Maximum grain yields occurred for both mulches on the M4 water treatment; stalk yields were largest on M2 M3, and M4, and depressed on M5. Winter and summer fescue forage yields were influenced by corn water treatments, but rye forage yields were not. Fescue stand count seemed to reach an equilibrium after the first full year, ranging from 30% after corn harvest to 60 percent before corn planting.

Corn ear leaf nutrients which were within the sufficiency range for all treatments were N, P, Ca, Mg, Fe, Cu, Mn, and Zn. Potassium was marginal for SK treatments M1, M2, M3, and M4; however, although no visual plant deficiency symptoms were observed. Boron tissue concentrations were marginal for SK treatments M1, M2 and M3.

Corn can be grown successfully either in annually strip‐killed fescue, or in completely killed mulch. Corn grain and stalk yields and total biomass production were consistently higher at all soil water levels for the CK mulch.
Crude Protein, IVOMD, and Yield of Stockpiled Limpograsses1
Authors: Quesenberry K. H. , Ocumpaugh W. R.
Published: July 2010

Most tropical grasses show a marked decline in digestibility with age, thus a system of field stockpiling is not suitable. The purpose of this research was to investigate the use of three limpograss (Hemarthria altissima [Poir] Stapf. et C. E. Hubb) cultivars as autumn‐winter conserved forage. In 1976, plots of each cultivar were clipped and allowed to regrow from 1 July, 29 July, and 26 August. Six yield and quality harvests were taken at 6 week intervals beginning on 23 Sept. 1976. In 1977 all plots were clipped and allowed to regrow from 1 August with five harvest for yield and quality taken at 4‐week intervals beginning on 26 Sept. 1977. The yield results from 1976 suggest that stockpiling should begin by 1 August to allow for adequate dry matter accumulation by first freeze. ‘Redalta’ had higher yields than either ‘Greenalta’ or ‘Bigalta’ in both years, but dry matter accumulation patterns were similar for all grasses. In vitro organic matter digestion (IVOMD) of Bigalta was higher than Redalta or Greenalta at all sampling dates in both years. Regression analysis indicated a higher intercept and lower rate of decline in IVOMD of Bigalta than either Redalta or Greenalta.

Log transformation of crude protein (CP) increased (P > 0.05) the fit over the linear model for all grasses. The decay in CP occurred rapidly in all grasses and by the time the grasses would be consumed as a stockpiled forage it had dropped below the level necessary to maintain zero N balance in the grazing animal. No meaningful differences in CP among grasses were observed. Our results suggest that Bigalta Limpograss has potential fot autumn‐winter stockpiling, but Redalta and Greenalta are probably not acceptable.
Effect of Leaf Age and Position on Photosynthesis and Stomatal Conductance of Forage Grasses1
Authors: Frank A. B.
Published: July 2010

Information on photosynthesis and stomatal conductance of different position leaves is needed to determine which leaf to sample for comparing rates of different grass species and genotypes. Photosynthesis and stomatal conductance were measured on the top three or four leaves on several dates after leaf collar formation on field‐grown accessions of pubescent wheatgrass [Agropyron intermedium var. trichophorum (Link) Halac.], crested wheatgrass [A. desertorum (Fisch. ex Link) Schult.], and reed canarygrass (Phalaris arundinacea L.). The study was conducted during 1976 and 1977 at Mandan, ND. Stomatal conductance was a primary factor affecting photosynthesis throughout the growing period. Leaf‐age effects were difficult to evaluate, but the data suggested a negligible effect of leaf age on photosynthesis for the three species studied. Leaf‐position effects were more evident for pubescent and crested wheatgrass than for reed canarygrass. There was no interaction between leaf position and genotypes within species. The uppermost leaves of each species studied had higher rates of photosynthesis at a given conductance when compared with lower position leaves.

The study showed that, to compare genotypes within a species, relative photosynthetic rates of single leaves, can be determined from different leaf positions and from the time of leaf collar formation until leaf senescence, provided that these comparisons are made within each leaf position.
Water Consumption and Growth Rate of 11 Turfgrasses as Affected by Mowing Height, Irrigation Frequency, and Soil Moisture1
Authors: Biran I. , Bravdo B. , Bushkin‐Harav I. , Rawitz E.
Published: July 2010

Water availability and cost is a limiting factor in the growth of turfgrass under warm semi‐arid zone conditions. Methods of reducing water consumption of turfgrasses in these zones are of major importance.

Water consumption and dry matter yield of clippings were determined for 11 turfgrass species or cultivars, 2 of which were cool season and 9 warm‐season types. The former belong to the C‐3 and the latter to the C‐4 group. The plants were grown in containers under typical summer conditions of the warm, semi‐arid zone. The growth rate of plants in the C‐3 groups was similar to that of those in the C4 group but their water consumption was higher. Amongst the C‐4 group, those plants with a sparse, vertical, growth habit, typical of forage crops, had a higher growth rate and water consumption than the dense, low growing ones. A significant correlation coefficient (r = 0.71 at p<0.05), was found between water consump tion and growth rate for the C‐4 plants.

Delaying irrigation until the onset of temporary wilting, caused a significant decrease in water consumption and growth (up to 35%) in most gasses. Raising the clipping height from 3 cm to 6 cm for a period of 6 weeks led to increased vigor in all grasses as evidenced by growth rate, chlorophyll content and water consumption. This effect was continuous throughout the measurement period for the C‐3 types, but was temporary for the C‐4 types, declining again after 6 weeks.

In experiments carried out under constant 34.5 C temperature, net photosynthesis of tall fescue (Festuca arundinacea Schreb. ‘Alta’) (C‐3) was only about one‐third that of C4 grasses although the evapotranspiration rate was equally high. The water uptake of the C4 type Zoysia matrella (L.) Merr. ceased at a much higher soil water potential than that observed for the C‐3 tall fescue and other C‐4 types. The decline of the rate of photosynthesis preceded the decrease in transpiration rate caused by the decreasing soil water potential.

The most important single factor affecting water use was the carbon fixation pathway to which the grasses belonged. Whilst the choice of a species or cultivar of turfgrass is generally made on the basis of temperature adaptation, should the criterion be water consumption in relation to availability and cost, then C‐3 varieties should not be chosen for warm semi‐arid zones to the extent that is practiced now.
The Effects of Different Soil Tillage and Management Practices on the Physical and Chemical Properties of Soil and Maize Yield in a Rainforest Zone of Western Nigeria
Authors: Agboola Akinola A.
Published: July 2010

After World War I (1914–1918) a search for a permanent form of cultivation in Nigeria began. Among the methods tried were replacement of natural fallow with leguminous covercrops, planted grass fallow, and late minimum or zero tillage. With zero tillage, weed control and fertilizer application methods are problems that need immediate attention. An experiment conducted for 4 years employed the following eight treatments: (1) no tillage, no fertilizer; (ii) no tillage, fertilizer surface applied, herbicide applied; (iii) conventional tillage, fertilizer worked into the soil with implements; (iv) no tillage, fertilizer banded with hoe; (v) conventional tillage, fertilizer banded with hoe; (vi) herbicide, fertilizer banded with hoe; (vii) herbicide, no fertilizer; and (viii) herbicide, fertilizer mixed in a groove and maize (Zea mays L.) planted in the groove (partial tillage).

Post harvest soil analysis indicated that the treatments did not appreciably affect the nutrient elements in the soil except for K which recorded a 19% increase in the last year. Tillage and fertilizer application reduced the organic matter content of the soil by 19 and 33% over the 4‐year period.

The bulk density did not change much but tilled plots recorded slight increases with a range of 1.29 to 1.36 g/cm3. No‐tilled plots retained more water than tilled plots.

Treatments with fertilizer gave much greater average yields than those without fertilizer. The decline in yield was related to the level of soil organic matter, method of fertilizer application, and tillage operations. Banded fertilizer had an edge over other methods. Tillage operations constituted an important factor of yield reduction, although the effect was masked by fertilizer treatment. The herbicide effect was probably on the organic matter level but this was masked by fertilizer treatments as well.

In developing a more permanent form of agriculture in the tropics, soil management practices especially under a zero‐tillage system, should recognize weed control methods, and fertilizers that minimize reduction in soil organic matter and maintain high yield under continuous land use.
Development of a Wheat Yield Prediction Model1
Authors: Feyerherm A. M. , Paulsen G. M.
Published: July 2010

This research was motivated by a need to predict crop yields on a large‐area basis without benefit of direct measurement of plant characteristics. Mathematical models were developed that require only a modest amount of historical data for application on a real‐time basis to geographical regions other than the one where the models were developed. The models, one for winter wheat (Triticum aestivum L.) and one for spring wheat (Triticum aestivum L. and Triticum durum Desf.), predict wheat grain yields from observation of meterological and agronomic variables.

Use of standardized yields, simulated water budgets, and measurement of weather events over simulated phenological stages helped to create a broad data base for model development. Weather scenarios for low and high yields can be deduced from the models as can the contribution of applied N, improved cultivars, and increased irrigation to long‐term yield increases. The models include soil factors to help explain regional differences in yield. The models also allow for reduced yield estimates due to episodic events (diseases, freezes, etc.).

Root‐mean‐square errors of differences between the model and USDA estimates of yield for the U.S. Great Plains for 1955 through 1976 were 1.2 and 1.3 quintals/ha for winter and spring wheat, respectively
Wheat and Barley Growth and N Fertilizer Utilization Under Sprinkler Irrigation1
Authors: Christensen N. W. , Killorn R. J.
Published: July 2010

Information on the effectiveness of N fertilizer applied through sprinkler irrigation systems for springsown wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) is limited. Objectives were to determine grain yield and quality responses and N‐use efficiency when N fertilizer was applied at irrigation to wheat and barley grown on a fine‐silty, mixed Typic Haploboroll. Nitrogen fertilizer was applied to sprinkler irrigated ‘Newana’ hard red spring wheat and ‘Shabet’ malting barley at seeding or split between seeding and heading, flowering, or watery kernel growth stages. Treatments included N rates of 0, 50, 100, and 150 kg N/ha at seediig, 75 kg N/ha at seeding plus 25 kg N/ha at heading or flowering, and 50 kg N/ha at seeding plus 50 kg N/ha at heading or 25 kg N/ha at heading and 25 kg N/ha at flowering. Additionally, 25, 50, and 25 kg N/ha were applied to barley at seeding, heading, and flowering, respectively; and 100 and 25 kg N/ha were applied to wheat at seeding and watery kernel stage, respectively. Nitrogen at seeding was broadcast as NH4No3‐, Subsequent N applications were broadcast as NH4NO3, several, hours prior to an irrigation to simulate application through the sprinkler system. Wheat plots contained subplots fertilized with 15NH415NO3 containing 1.31 atom percent 15N to determine the fate and utilization efficiency of applied N. Grain yield increased from 1,100 to 4,850 and from 1,240 to 4,570 kg/ha for wheat and barley, respectively, as N rates were increased from 0 to 150 kg N/ha at seeding. When 100 kg N/ha was split between seeding and at irrigation, wheat yields decreased from 3,890 to 3,540 and 2,975 kg/ha as the amount of N applied at seeding was decreased from 100 to 75 and 50 kg N/ha, respectively. Barley yields averaged 4,130 kg/ha for treatments totaling 100 kg N/ha and were generally not affected by shifting N applications from seeding to at irrigation. Differential response to split applications of N was related to differences in number of spikes per unit area at harvest. The number of spikes/m2 decreased for wheat and increased for barley as the proportion of the N fertilizer applied at seeding decreased. Nitrogen fertilizer recovery in the straw and grain of wheat plants at harvest was 52.5 and 50.8% where 100 kg N/ha was applied at seeding or split between seediig and at irrigation, respectively. Percentage recovery of N fertilizer was lower in straw and higher in grain when N was applied at imgation as compared to seeding time application. Failure to obtain positive grain yield responses or increases in overall N fertilizer efficiency indicate no advantage to splitting N fertilizer applications between seeding and Irrigation for spring seeded wheat and barley on deep, medium‐fine textured soils
Yield of Alfalfa and Cotton as Influenced by Irrigation1
Authors: Sammis Theodore W.
Published: July 2010

Water resource planners need water‐producton functions, the relationship between yield and evapotranspiration,to determine the economic impact of various water allocation decisions. They also need to know the transferability of the functions within and between states.

Cotton (Gossypiurn hirsutum L.) and alfalfa (Medicago sativa L.) were irrigated at Las Cruces, New Mexico, with a range of water levels using a sprinkler‐line source to determine yield and evapotranspiration under deficit irrigation. Also, alfalfa was grown at five locations and cotton was grown at two locations in New Mexico, including Las Cruces, in nonweighing lysimeters that were flood irrigated to measure the yield and evapotranspiration under nonlimiting soil‐moisture conditions.

A linear water‐production function was observed for alfalfa. This function appeared to be transferable to any location in New Mexico, based on data from five locations within the state, and was statistically the same as alfalfa water‐production functions for Nevada, Nebraska, and North Dakota.

A linear water‐production function was also observed for cotton, but this function was applicable only for the two areas in southern New Mexico where the study was conducted. The cotton water‐production function for New Mexico was statistically different from the reported water‐production function of the similar study conducted in California. The cotton water‐production function had a lower coefficient of determination than the alfalfa water‐production function since cotton was harvested for lint and seed rather than biomass. This study indicated that biomass production may require the same amount of evapotranspiration regardless of site and management differences, as in the case of alfalfa, but that lint or seed production per unit of water will vary from place to place.
Wind‐tunnel Simulation and Assessment of Ammonia Volatilization from Ponded Water1
Authors: Bouwmeester Reinier J. B. , Vlek Paul L. G.
Published: July 2010

Several techniques for the prediction of ammonia volatilization rates from rice paddies are evaluated using experimental data obtained in a wind‐water tunnel, set up to simulate rice paddy conditions.

The wind tunnel results suggest that nonuniform surface conditions of waters with short fetch do not significantly limit the use of aerodynamic techniques for the prediction of ammonia volatilization rates. Comparison of volatilization rates predicted with a one‐dimensional aerodynamic technique as well as a two‐dimensional modification of this technique against those predicted from the longitudinal ammonia flux at the downwind section of a wind‐water tunnel yield differences on the order of 10%.

Ammonia volatilization rates and aqueous chemistry measured under small enclosures are compared with those measured in the wind‐water tunnel. The results indicate that quantitative assessment of ammonia volatilization losses in the field is possible if air exchange rates in the enclosure are selected which yield a gas phase resistance representative of average wind conditions.
Nitrogen Sources for Bean Seed Production1
Authors: Westermann D. T. , Kleinkopf G. E. , Porter L. K. , Leggett G. E.
Published: July 2010

Beans (Phaseolus vulgaris L.) often respond to N fertilization; however, N fertilization is not practiced for maximum seed production in southern Idaho. This suggests that the symbiotic relationship and/or soil N sources can provide most of the N needed by this legume. Our objective was to evaluate the relative contribution of the symbiotic‐nonsymbiotic N sources by studying the effects of N fertilization on the symbiotic N2 fixation and seed yields under field conditions. Experiments were conducted on silt loam soils belonging to the Portneuf series (Xerollic Calciortnids). An acetylene reduction (AR) method was used to determine the effect of N fertilization treatments on the relative seasonal N2 (AR) fixation. The symbiotic N2 fixation was also estimated by the equation, N2 = Nup − (Ni + Nm − Nh)−αNt, where Nup is the accumulated N uptake measured near physiological maturity, N1 and Nh are the amounts of soil NO3‐N in the root zone before planting and near physiological maturity, Nm is the N mineralized from soil organic N sources, and a is the recovery of the N fertilizer (Nf) applied. Estimates of the N fertilizer recoveries were obtained from two experiments using 15N‐depleted (NH4)2 SO4.

The symbiotic N2 relationship contributed up to 90 kg N/ha, which was 40 to 50% of the total N found in bean plants near physiological maturity. The amount of symbiotic N2 fixed decreased as the available soil N or fertilizer N increased, and increased as the N required by the individual cultivars increased. The response to N fertilization depended upon the cultivar, as well as on the N available from soil sources. Measured fertilizer N recoveries ranged from 7 to 33%. An average of 52% of the total N uptake near physiological maturity was taken up after the maximum symbiotic N2(AR) rate occurred; while the seed contained an average of 60% of the total N uptake. A low N fertilization rate (< 50 kg N/ha) when the soil N1 was low (<50 kg N/ha) ensured an early vigorous plant growth but did not always increase seed yields. Higher N fertilization rates may be required on soils with lower amounts of mineralizable N.
Short‐Term Soil Chemical and Crop Yield Responses to Limestone Applications1
Authors: Alley M. M.
Published: July 2010

Limestone applications ranging from 0 to 17.92 metric tons/ha were applied to three acid soils for the purpose of measuring soil chemical and crop yield responses to increased levels of soil pH during the initial growing season following limestone application. Corn (Zea mays L.), barley (Hordeum vulgare L.), and alfalfa (Medicago sativa L.) were planted in a Goldsboro sandy loam (Aquic Paleudult), Pacolet sandy clay loam (Typic Hapludult), and Frederick silt loam (Typic Paleudult), respectively. Sixteen weeks after treatment, soil pH and exchangeable Ca and Mg increased, while exchangeable Al decreased with increasing lime rate. Initial crop yields increased with lime applications on all soils. Exchangeable Al saturations of 18, 8, and 11% of the effective CEC decreased corn, barley, and alfalfa yields. Regression analysis indicated that reduction in exchangeable Al was responsible for increases in corn yields (R2=0.59) and that increases in exchangeable Ca along with decreases in exchangeable Al accounted for increased alfalfa yields (R2=0.80).
Accumulation and Translocation of Zinc by Two Corn Cultivars1
Authors: Peaslee D. E. , Isarangkura Rungruang , Leggett J. E.
Published: July 2010

Differences have been observed among corn (Zea mays L.) cultivars for the accumulation and utilization of nutrients in dry matter production. ‘Pioneer Hybrid 3369A’ and ‘Conico Composite’, which have shown differences in Zn utilization, were evaluated for Zn absorption capabilities of leaves and roots and for tendencies to translocate absorbed Zn from these tissues. Plants were grown in greenhouse sand cultures with varying Zn levels in the nutrient solutions, and then were given 65Zn either in the nutrient solution or hi a foliar application to leaves at different locations on the stalks. Dry weights, total Zn, and 65Zn distribution were determined after 31 days of growth.

Shoot dry weights of Conico under Zn deficiency were 58% greater than those of 3369A, although when supplies were adequate, yields were 5% greater for 3369A than for Conico. Roots of Zn deficient Conico weighed 28% more than those of 3369A, but with adequate Zn, 3369A roots weighed 48% more than those of Conico. Concentrations of Zn in the various plant parts of the two cultivars were similar when Zn was limiting growth.

Plants grown at inadequate Zn levels accumulated lower concentrations of 65Zn in their tissues from solution cultures during 24 hours than plants grown at adequate Zn levels. Absorption and translocation of 65Zn applied to leaves was greater for 3369A than for Conico, and was greater when applied to young leaves than when applied to old leaves.

There were no indications of either cultivar being superior in Zn absorption by root systems or in translocation of absorbed Zn to shoots. Compared to 3369A, Conico produced more dry matter per unit of Zn concentration in shoot tissue (1.95 vs. 1.29 g2/µg> respectively) and thereby appeared to be more efficient when Zn supply was low.
Osmoconditioning of Carrot Seeds to Improve Seedling Establishment and Yield in Cold Soil1
Authors: Szafirowska Anna , Khan Anwar A. , Peck Nathan H.
Published: July 2010

Cold soil interferes with early establishment of uniform, vigorous seedlings in vegetables and other crops. The aim of this work was to determine if the changes induced in carrot (Daucus carota L.) seeds during partial hydration by low osmotic potential polyethylene glycol 6000 (PEG) solution would allow early planting in cold soil and thereby improve germination, growth, and yield. Seeds of two carrot cultivars, ‘Nantes’ and ‘Perfekcja’, were treated in —8.6 bars PEG solution for 6 days at 15 C. The effects of the seed treatment were evaluated by germinating the seeds on filter paper at 10 C, in Cornell Soil Mix (peat‐lite Mix A) in a growth chamber at an alternating temperature regime of 5 and 10 C and in the field (Glossoboric Hapludalf, fine loamy, mixed mesic soil) where the average soil temperature during the first 2 weeks after field planting was 10.5 C and during the first 5 weeks 12.6 C. Seed osmoconditioning improved the emergence time, stand size, and uniformity of stand in the field and increased the total yield. The increase in fresh weight of roots in Nantes and Perfekcja from PEG treated seeds were 32 and 93% and in number of roots 37 and 100%, respectively, compared to the untreated seeds
A Method to Determine the Appropriate Mathematical Form for Incorporating Soil Test Levels in Fertilizer Response Models for Recommendation Purposes1
Authors: Mombiela F. , Nicholaides J. J. , Nelson L. A.
Published: July 2010

A method is proposed for developing fertilizer recommendations based upon a statistical estimate of the amount of “plant‐available” nutrient in the soil (d), and determining the appropriate mathematical form of the relationship of this estimate to soil test values (T). A function of soil test is then substituted into the fertilizer response model for d. Some comparisons of the effects of three different models (Mitscherlich, quadratic and square root) upon d estimates and on the form of their relationships to soil test values were made. Regressions of d estimates obtained using the three models upon soil test P values were carried out to determine empirically the appropriate mathematical form [called f(T)] for a set of Irish potato data from Maine and North Carolina. The f(T) was found to be linear for that particular set of data for all three models, i.e., d = b0 + b1T. From these data, it was concluded that environmental conditions between states did not affect f(T) but did affect the level of maximum response (A, in the Mitscherlich model) and a factor related to curve shape (c, in the Mitscherlich model). Once f(T) is known for a model, it may be substituted into the model for d and this equation then used for fertilizer recommendations based upon site‐specific soil test information. Equations for estimating optimal P fertilizer rates assuming different cost‐price ratios (p) and marginal rates of return (R) were given for this data set. Similar equations may be derived for other specific crop‐soil conditions using the techniques described in this paper.
Effect of Environmental Stress on the Growth and Amounts and Forms of Phosphorus in Plants1
Authors: Sharpley A. N. , Reed L. W.
Published: July 2010

The effects of applied fertilizer P and soil‐water stress on the growth and amounts and forms of plant P were investigated to provide further information on the potential of plant material to contribute P to runoff. Cotton [Gossypium hirsutum (L.)], little bluestem (Andropogon scorparius Michx.), sorghum [sorghum sudanense (Piper) Stapf.], and soybean [Glycine max (L.) Merr.], plants were grown in the field on Durant loam, a member of the fine, montmorillonitic, thermic Vertic Argiustolls. Fertilizer P additions of 0, 50, 100, and 200 kg/ha were made and a water‐stress treatment initiated by applying only one‐third the amount of water lost as evapotranspiration. Plant growth and P content were determined at weekly intervals following plant emergence. Growth and total P content increased with an increase in applied fertilizer P for all plants except little bluestem. The total P and inorganic P content of the plants decreased gradually with growth. Inorganic P constituted the major proportion of plant P (approximately 80, 70, 70, and 80% for cotton, little bluestem, sorghum, and soybean, respectively), and remained constant during plant growth. A three‐fold reduction in soil‐water content (60‐fold increase in soil‐water suction) resulted in a decrease in plant growth and total and inorganic P content. The effect of the soil‐water stress was reduced by increases in applied fertilizer P. It was calculated, however, that the addition of fertilizer P was not a viable economic method of increasing crop yields to negate any drop in yield due to drought conditions.
Pod and Seed Development in Soybean Cultivars with Differences in Seed Size1
Authors: Fraser Joanna , Egli D. B. , Leggett J. E.
Published: July 2010

The accumulation of dry weight by the pod is an important process during reproductive growth in soybeans [Glycine max (L.) Merr.]. Thus, field experiments on Maury silt loam (Typic Paleudalfs) and Egam silt loam (Cumulic Hapludolls) with soybean cultivars differing in seed size were conducted for 2 years to investigate pod and seed development characteristics and associated changes in seed moisture content. Pods were tagged and random samples from different plants were taken at weekly intervals. Measurements included: pod length and width (1979 experiment only), pod wall and seed dry weight, seed moisture percentage, and water content (mg . seed‐1). Cultivars differed in maturity and final seed size which ranged from 92 to 262 mg . seed‐1.

Pod length and width in all cultivars in 1979 were at a maximum when the seeds averaged 4% of their maximum dry weight. Length and width were positively correlated with final seed size. In most cultivars sampled in both 1975 and 1979 there appeared to be little redistribution of dry matter from pod walls prior to seed physiological maturity. However, some redistribution was apparent in ‘Emerald’ and ‘Essex’ in 1979 and ‘Cutler 71’ in 1975. Seed of all cultivars showed rapid water uptake during early seed development and water content (mg . seed‐1) reached a maximum before seed physiological maturity. Moisture percentage of the seed was greater than 80% when the seed started rapid accumulation of dry matter and declined progressively during seed development, reaching less than 60% as the seed approached physiological maturity. These changes in percentage moisture during seed development were consistent across cultivars in both years, regardless of seed size. Water uptake and moisture content seemed to be directly related to the stage of seed development and were not affected by genetic differences in seed size.
Growth, P Uptake, and Quality of Warm and Cool‐Season Grasses on a Low Available P Soil1
Authors: Morris R. J. , Fox R. H. , Jung G. A.
Published: July 2010

Millions of hectares of pasture in the Northeast have low available soil P levels. Introducing forage species that produce well on these soils could increase forage production with minimum economic input. The objective of this study was to compare the performance of warm and cool‐season grasses under low or high available P. Several warm and cool‐season forage grasses were grown on a Berks shaly silt loam soil (Typic Dystrochrept; fine, loamy, skeletal, mesic), low in native available P (5 ppm Bray and Kurtz #1 extractable P), with and without added P. The warm‐season grasses included two Old World bluestems, ‘Caucasian’ Bothriochloa caucasica (Trin.), C. E. Hubb. and “B”‐strain, B. intermedia (R. Br.) A. Camus; three big bluestem cultivars, Andropogon gerardi Vitman; three little bluestem cultivars, Schizachyrium scoparium, Michx.; six switchgrass cultivars, Panicum virgatum L.; and two indiangrass cultivars, Sorghastrum nutans (L.) Nash. The cool‐season grasses were Ky 31 tall fescue, Festuca arundinacea Schreb., ‘Pennlate’ orchardgrass, Dactylis glomerata L., and ‘Tioga’ deertongue grass, Dichanthelium clandestinum (L.) Gould. Yields of most warm‐season grasses nearly doubled from 1977 to 1978, whereas yields of the cool‐season grasses decreased. Forage yields and P concentrations of all cultivars generally were greater with applied P both years. At the low P level, warm‐season grass yields in the second year were up to three times higher than yields of cool‐season grasses, whereas P concentrations in forage of cool‐season grasses were twice those of warm‐season grasses: The warmseason grasses, Ky 729 and ‘Blackwell’ switchgrass, Ky 2 Caucasian and B‐strain Old World bluestems, and NJ 1617‐72 indiangrass absorbed more total P than all other cultivars. Warm‐season grasses had relatively low crude protein and IVDMD levels, ranging from 4.7 to 8.5% and 34.0 to 52.3%, respectively. Of the warm‐season grasses, Old World bluestems, Caucasian and B‐strain, had the highest IVDMD values, 52.2 and 51.2%. The cool‐season grasses had an average crude protein level of 14.6% and IVDMD value of 59.4%, respectively. The two Old World bluestems, Ky 729 and Blackwell switchgrasses, and NJ 1617‐72 indiangrass appear to have the highest potential to produce forage on soils with low levels of available P.
Seeding Rates and Grass Suppression for Sod‐seeded Red Clover and Alfalfa1
Authors: Sheaffer C. C. , Swanson D. R.
Published: July 2010

Seeding rates needed for establishment of alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) in perennial grass sod may differ from those needed for conventional establishment. The objective of this research was to determine the effect of seeding rate on alfalfa and red clover establishment and yield in the establishment year and in the spring after establishment when the legumes were sod‐seeded into perennial grass sods that received variable levels of herbicidal suppression.

Field experiments were conducted at three locations on a Typic Hapludoll soil vegetated with smooth bromegrass (Bromus inermis Leyss.) at locations one (L1) and three (L3) and with smooth bromegrass, quackgrass (Agropyron repens L.), and Kentucky bluegrass (Poa pratensis L.) at location two (L2) Red clover and alfalfa were seeded at 4.4, 8.8, 13.2, and 17.6 kg/ha into grass sod sprayed with glyphosate [N‐(phos‐phonomethyl)glycine] at 1.7 or 0.6 kg/ha for high and low grass suppression levels, respectively.

At L2, greater grass suppression occurred at each herbicide rate than at L1 and L3. At L1, where moisture was limited compared to L2 and L3, increasing the seeding rate resulted in significantly greater establishment year yields of both legumes at both grass suppression levels.

Red clover yields were not affected by seeding rate at either grass suppression level at L2 or for the high suppression level at L3, but at L3, yield was significantly greater at either the 13.2 or 17.6 kg/ha rates than the 4.4 kg/ha rate for the low grass suppression treatment where high levels of grass competition existed. Total alfalfa yield was significantly greater for the 17.6 than the 4.4 kg/ha rate at the low grass suppression level at L2 and at the high grass suppression level at L3, both instances of high grass competition.

For sod‐seeding, increasing legume seeding rate beyond that usually recommended for conventional establishment procedures appears to be beneficial to establishment only when grass competition is high.
Comparison of the Nodal Distribution of Yield Components of Indeterminate Soybeans under Irrigated and Rain‐fed Condition1
Authors: Carlson R. E. , Karimi‐Abadchi M. , Shaw R. H.
Published: July 2010

Although the response of soybeans (Glycine max. L. Merr.) to soil‐moisture stress has been studied extensively, information on the vertical distribution of yield and yield component responses is limited. Therefore, an experiment was conducted in 1978 which included two soil‐moisture treatments and seven cultivars with differing maturity growing in a cumulic hapludoll. In 1978, early soil‐moisture levels were near normal, and much of the growing season received adequate rainfall. Periods of warm, dry weather in August and September, however, reduced seed yield.

The response of these soybeans under these conditions varied considerably in their expression of seed yield and the vertical display of yield components. Soil‐moisture levels, atmospheric demand, and physiological stage of development differences among cultivars led to significant yield and yield component interactions. Seed yield reductions due to soil‐moisture stress varied from 20% to 50%, depending on cultivar. The reductions for individual components of yield (ie., 100‐seed wt, seeds/pods, pods/node, and nodes/plant) varied considerably over all cultivars. These decrements ranged from 0% to 30%.
Nitrogen Sources and Methods of Application for No‐Tillage Corn Production1
Authors: Touchton J. T. , Hargrove W. L.
Published: July 2010

The efficiency of properly applied urea N fertilizers is generally equal to the efficiency of ammonium nitrate. Proper applications, however, most often include incorporation soon after application. In no‐tillage systems where cultivation is not a common practice, these fertilizers are often applied as surface sidedress applications and are sometimes used as carriers for contact herbicides. These field studies which were conducted for 3 years on a Cecil sandy loam soil (Typic hapludult) were designed to compare the efficiency of prilled urea, urea‐ammonium nitrate solution (UAN), and prilled ammonium nitrate (AN) as affected by methods of application in no‐tillage corn (Zea mays L.) production. Treatments included shallow incorporated and unincorporated band applications of all N sources plus a broadcast spray application of UAN. Nitrogen rates were 90, 180, and 270 kg/ha.

The results for corn grain yield showed that, in comparing the three N sources, the order of efficiency is generally urea < UAN solution ≤ ammonium nitrate. However, in comparing the three methods of application (surface band, incorporated band, and surface broadcast spray) for the UAN solution, little difference was observed between the surface or incorporated band applications. The surface broadcast spray treatment, on the other hand, resulted in considerably less grain yield and N uptake as judged from the ear leaf N concentrations. These results indicate that, at least for the conditions of this study, urea is not an efficient N source for no‐tillage production systems and is especially inefficient when applied in solution as a broadcast spray.
Physical Factors Influencing Soil Strength and Root Growth1
Authors: Gerard C. J. , Sexton P. , Shaw G.
Published: July 2010

Soil compaction is a major factor which influences root growth and crop yields. Studies were conducted to determine the influence of different factors on mechanical impedance and to determine the influence of mechanical impedance and other soil factors on root growth. Regression models for dependent variables, soil strength and root growth, vs. the independent variables, soil type, soil depth, clay content, bulk density, voids, and water content were computed using the maximum R2 improvement by stepwise regression. The models for soil strength and root growth varied with soil type, soil depth, and/or clay content. The soils used were a Miles fine sandy loam, Udic Paleustalf and an Abilene clay loam, Pachic Argiustoll. Soil strength for both soils studied and at all depths was influenced by bulk density, voids, and clay content. The overall equational models accounted for 75% of the variability in soil strength and 76% of the variability in root growth. Root growth in both soils and at all depths was significantly influenced by soil strength, volumetric water content, voids, and clay content. The critical strength in bars, defined as the probe pressure at which root elongation stopped, was a function of % clay. The critical strength ranged from 60 to 70 bars in coarsetextured to 25 bars in clay soils. These data provide a better understanding of the influence of mechanical impedance on root growth, and a basis for determining the need for use of deep tillage to minimize the adverse effects of excessive soil strength or compaction.
Nitrogen Utilization Efficiency by Drip Irrigated Celery Receiving Preplant or Water Applied N Fertilizer1
Authors: Feigin A. , Letey J. , Jarrell W. M.
Published: July 2010

Optimizing N‐fertilization is important from both economical and environmental quality points of view. An experiment was conducted to evaluate N utilization efficiency by celery (Apium graveolens L.) in response to type, amount, and method of N‐fertilizer application under drip irrigation. This study was conducted on San Emigdio sandy loam (coarse‐loamy, mixed (calcareous), thermic Typic Xerofluvent). Fertilizer types included ammonium sulfate (AS) and a slow release (SR) fertilizer applied to the soil before planting and urea ammonium nitrate (UAN) applied with the irrigation water during the growing season. Ammonium sulfate and SR were applied at 314 kg N/ha and UAN was applied at rates of 168, 336, and 504 kg N/ ha. Two irrigation variables were 400 and 500 mm of water application. Barley (Hordeum vulgare) was grown to determine the effect of residual soil N following the celery crop. Nitrogen uptake increased with increasing rates of UAN application with relatively little effects of irrigation treatment. Lower N uptake resulted from 500 as compared to the 400 mm irrigation treatment for the soil applied SR and AS fertilizers. There was less N uptake for SR and AS treatments than the UAN treatment of comparable N application. Nitrogen uptake results are consistent with N distributions in the soil which indicated greater leaching of SR and AS fertilizer below the root zone than UAN and higher leaching with higher irrigation treatment. Growth and N uptake by the barley crop were consistent with measured residual N for the various treatments applied to celery.
Soil Available Water as Influenced by Landscape Position and Aspect1
Authors: Hanna A. Y. , Harlan P. W. , Lewis D. T.
Published: July 2010

In dryland farming, stored soil water is an essential source of water for crop production. The amount of water available for storage and crop use in a particular soil in hillslope topography is affected by its position on the landscape. The effect of slope aspect and position on soil water and its changes throughout the year in dryland farming were studied in southeast Nebraska. North, south, and east‐facing slopes of Wymore silty clay loam (Aquic Argiudolls fine, montmorillonitic mesic) were selected for study. Four positions on each slope including summit, shoulder, backslope, and footslope were identified. Water content of the soil from 0 to 150 cm depth in 30 cm increments was measured weekly by neutron scattering for 2 years. Daily precipitation was recorded. Twenty percent more water was available in soils on the north‐facing slope than in soils on the south‐facing slope at planting and throughout the year. Soils on the east‐facing slope were the driest. They contained 50% less available water than did those on the north‐facing slope. Within slope positions, soils on the footslopes and backslopes contained an average of 4 cm more available water than soils on the summits and shoulders. Soil water sampling at planting time for crop management and yield prediction models should be done according to slope position.