bluuebunny/crossref_metadata_2025 huggingface dataset:
Foliar Application of Selenium to Field Corn1
Authors: Cary E. E. , Rutzke M.
Published: July 2010

Much of the northeastern quarter of the USA produces feed corn (Zea mays L.) that contains too little selenium (Se) to meet animal nutritional requirements. This experiment was conducted to determine if Se concentration in corn (‘Cornell 281’) could be increased by foliar application of Se. Selenium was applied by hand sprayer to corn growing on Mardin silt loam (Typic Fragiochrept) in a field when the 4th to 6th leaves were the last fully expanded or when tassels were just emerging. Treatments were 0, 7.5, and 15 g Se/ha added as Na2SeO3 in 359 liter/ha of water containing 48 ml of surfactant. Selenium rate, stage of growth, and Se × stage of growth were highly significant (P<1%). At maturity, the concentration of Se in the whole plant minus the ear vs. grain and ear leaf blade vs. grain was linearly correlated, with r = 0.99** and r = 0.88*, respectively. The concentration of Se in grain with no added Se was 0.01 ppm Se. Doubling the Se concentration sprayed on the corn increased the Se concentration from 0.05 to 0.12 ppm Se in grain for the early treatment and from 0.14 to 0.24 ppm Se in grain from the late treatment. The increase in Se concentration in plants sprayed at early tassel stage over those sprayed at a younger age apparently was associated with the total amount of Se intercepted by the plant. Foliar application may be an efficient and safe way to increase Se in feeds and forages.
Phosphorus Uptake by Fescue from Soils Amended with Sewage Sludge Compost1
Authors: Sikora L. J. , Tester C. F. , Taylor J. M. , Parr J. F.
Published: July 2010

The value of sewage sludge compost as a source of P for plants has not been evaluated. The study reported is part of a series designed to assess benefits of amending soils with sewage sludge compost and deals specifically with P uptake by fescue grown in two soils amended with combinations of compost and N and P fertilizers. An Evesboro loamy sand (Typic Quartzipsamments) and a Fauquier silt loam (Ultic Hapludalfs) were amended with four rates of sewage sludge compost (0 to 6% equal to 0 to 134.4 metric tons/ha, dry weight), plus an additional lime control and two rates of N, (0 and 195 kg/ha) P, (0 and 390 kg/ha), or N plus P in a factorial greenhouse study. ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreb.) was grown and harvested at 40,76,120, and 167 days and the clippings were dried and weighed.

All of the clippings and one replicate of roots and crowns grown in the Evesboro soil were analyzed for total P. Similar to the data on fescue yields, the cumulative fescue P grown in compost‐amended Evesboro soil was approximately double that from compost‐amended Fauquier. Cumulative P was not linearly related to compost amendment in either soil. Fertilizer N, P, or N and P additions resulted in greater P uptake by fescue grown in both compost amended soils. However, fescue grown in compost amended soils without fertilizer contained adequate P levels to satisfy the nutritional requirements of feed for ruminants. Highly significant regression equations were derived describing total P uptake and fescue P concentration as affected by compost amendment, fertilizer addition, and time. The percentage of total P added as compost that was taken up by fescue grown in Evesboro soil equaled 4.5, 3.0, and 2.5 for the 44.8, 89.6, and 134.4 metric tons/ha amendment rates, respectively.
Wheat and Barley Responses to Rates of Seeding and Fertilizer in Southwestern Saskatchewan
Authors: Read D. W. L. , Warder F. G.
Published: July 2010

Research from 1960 to 1968 at Swift Current, Saskatchewan, on orthic brown chernozemic clay loam under semiarid conditions indicated that the seeding rate of hard red spring wheat (Triticum aestivum L.) could be reduced to half of the seeding rate most commonly used by farmers. This study in 1976 and 1977 extended the testing to orthic brown chernozemic loam and heavy clay soils and included fertilizer treatments.

Tests were conducted on stubble and fallow land at three locations in 1976 and 1977. Seeding rates were 20, 40, and 60 kg/ha with fertilizer applied at rates of 0‐0 (check), 10‐9 and 50‐22 kg/ha of N and P, respectively.

With the exception of barley (Hordeum vulgare L.) on fallow, no significant fertilizer ✕ seeding rate interactions for yield were recorded, indicating that fertilizer rates and seeding rates were factors that operated relatively independently. However, differences in yield between locations were observed. In 1977, a location ✕ seeding rate interaction was obtained on fallow while location ✕ fertilizer interactions on fallow in 1976 and on stubble in 1977 occurred.

Fertilizer increased the yield over the check yield for all crops on stubble and fallow. Reducing the seeding rate to 20 kg/ha for wheat and barley on stubble and to 40 kg/ha for barley and durum (Triticum durum Des. F.) on fallow caused no significant reduction in yield. For durum on stubble and wheat on fallow seeding rates of 60 kg/ha were required for maximum yields. The responses of barley and durum to fertilizer and seeding rates were similar to the responses of wheat for yield, N and P content, kermel and volume weight of the grain.

Increased rates of fertilizer produced some increases in the N content of the grain, particularly at the highest rates, but both rates reduced the P content. Higher fertilizer rates tended to reduce the kernel and volume weights for all crops. The higher seeding rates reduced the N and P content of the grain, and the kernel weight, but increased the volume weight.
Dinoseb and Triacontanol as Growth Regulators in Irrigated and Nonirrigated Field Corn1
Authors: Regehr D. L.
Published: July 2010

The growth regulators dinoseb (2‐sec‐butyl‐4,6‐dinitrophenol) and triacontanol [CH3(CH2)28CH2OH] have previously been applied to several crops, including corn (Zea mays L.), in efforts to stimulate yields. Field performance has been erratic with both yield increases and yield decreases reported. It was hypothesized that crop response to dinoseb and triacontanol may be influenced by environmental stress on the growing crop to which they are applied. This is a report of two field experiments (1978 and 1979) in which dinoseb and triacontanol were applied to irrigated and water‐deficient field corn to test this hypothesis.

Two corn hybrids (Pioneer 3369A and Funks G4646) were planted in irrigated and nonirrigated split blocks. Dinoseb (17.4 g/ha) and triacontanol (4.0 g/ha) were applied as foliar sprays, 2 weeks before tasseling. Corn grain yields were significantly reduced in 11 of 12 dinoseb‐treated vs. untreated comparisons. Yield reductions averaged 18.0% in irrigated corn and 18.4% in nonirrigated corn. A significant irrigation ✕ dinoseb interaction occurred in only one of six comparisons. Some of the grain yield reduction in dinoseb‐treated plots could be attributed to reduced harvest index and reduced percentage ear fill.

Triacontanol did not affect grain yield in six of eight comparisons of triacontanol‐treated vs. untreated plots. One of the four irrigation ✕ triacontanol interactions was significant, showing a yield increase due to triacontanol under irrigation, and a yield decrease in waterdeficient corn. Harvest index and percentage ear fill were not affected by triacontanol.

The hypothesized interaction of environmental stress with the growth regulators dinoseb and triacontanol was not substantiated in these experiments. Triacontanol had minimal effect on corn performance, and dinoseb had very detrimental effects on both irrigated and water‐deficient corn. It is suggested that the inconsistent performance of these compounds, as reported in the literature, should not be attributed to environmental conditions of the growing crops.
Comparison of Water Stress of Cotton from Measurements with the Hydraulic Press and the Pressure Chamber1
Authors: Radulovich R. A. , Phene C. J. , Davis K. R. , Brownell J. R.
Published: July 2010

The Hydraulic Press (HP) is gaining some acceptance as a tool for estimating plant water status and some large cotton growers in the Central California area are already using this instrument for irrigation scheduling. Since no published data validating the use of the HP with cotton have been found, the objective of this research was to develop a data set to support or reject the use of the HP for estimating cotton water status, as compared to the widely accepted Pressure Chamber (PC).

Measurements of water status of cotton (Gossypium hirsutum L., Acala SJ2 Var.) obtained with the HP and the PC were compared and correlated hi replicated experiments under greenhouse and field conditions. Results indicate that 1) the HP does not measure low water potential accurately below −940 kPa as determined by the PC, and 2) the most representative endpoint to use with the HP is the pressure at which water exudes from the cut edge of a tip of an uppermost fully expanded leaf.

The HP can be used advantageously for irrigation scheduling of cotton if the threshold value is −940 kPa or higher, as determined when the highest water potential values for a day are found (i.e., predawn). However, this inability of the HP to estimate low water potentials of cotton leaves, under the conditions herein described, seems to be a serious limitation of the instrument.
Forage Cell Wall Degradation and ρ‐Coumaric, Ferulic, and Sinapic Acids1
Authors: Akin Danny E.
Published: July 2010

Phenolic acids are associated with carbohydrates in forage cell walls. Since phenolic compounds are often toxic to microorganisms, the objective was to test ρ‐coumaric, ferulic, and sinapic acids for their effect on rumen bacterial growth (turbidity and roll tubes), rumen protozoal motility, cellulose (filter paper) degradation, and cell wall digestion using light microscopy. The addition of 0.1% ρ‐coumaric acid to the media inhibited the growth of cellobiose‐utilizing bacteria and increased the days required for cellulose degradation by two to three times. This acid also inhibited the growth of xylan‐utilizing rumen bacteria, and caused a reduction of about 50% of the colonies appearing on xylan roll tubes. The percent motility of the entodiniomorph protozoa, but not the holotrichs, decreased more rapidly with time in the medium with ρ‐coumaric acid than in control medium. Sinapic acid was not toxic in any of the tests. Ferulic acid slowed the growth rate of rumen microorganisms on a habitat‐simulating broth medium, but had little or no effect on cellulose‐utilizing microorganisms. Ferulic acid did reduce slightly the growth of xylan‐utilizing microbes in some tests. At the 0.2% level, ρ‐coumaric but not ferulic acid prevented the degradation of mesophyll and epidermis that were normally easily digested in orchardgrass (Dactylis glomerata L.) leaf blades. The results showed that ρ‐coumaric acid was toxic to certain rumen protozoa and the rumen bacteria expected to play a dominant role in the digestion of forage cell walls.
Root Initiation and Root and Leaf Elongation of Dependent Little Bluestem Tillers Following Defoliation1
Authors: Carman J. G. , Briske D. D.
Published: July 2010

Newly initiated tillers must survive for a period of time without an established root system and, therefore, are dependent on the parent‐ shoot for water and nutrients. Little is known about the influence of defoliation on subsequent root initiation and root and leaf elongation in dependent tillers. This investigation, conducted in a controlled environment, was designed to 1) determine the leaf stage at which dependent little bluestem [Schizachyrium scoparium (Michx.) Nash var. frequens R. T. Hubb.] tillers are capable of initiating adventitious roots and 2) compare the influence of two intensities of differential defoliation on root initiation and root and leaf elongation of dependent little bluestem tillers. Treatments included defoliation of the dependent tiller, defoliation of the parent‐shoot and defoliation of all plant shoots except for the dependent tiller, to a 3 or 5 cm stubble height.

Adventitious root intiation of dependent little bluestem tillers seldom occurred prior to the fourth leaf stage. Defoliation of only the dependent tiller did not significantly (P ≤ 0.05) decrease the number of adventitious roots initiated or suppress mean root length of dependent tillers in comparison with untreated plants. Defoliation of either the parent‐shoot or all plant shoots suppressed root initiation and root elongation of dependent tillers to a much greater extent than did dependent tiller defoliation. Mean root and leaf length of dependent tillers differed between treatments where all plant shoots were defoliated, and where only the parent‐shoot was defoliated. Mean root length of dependent tillers in the former treatments were 62 and 57% of the corresponding length in the latter treatments for the moderate and severe defoliation intensities, respectively. Mean leaf length of dependent tillers in the former treatments were 135 and 147% of the corresponding length in the latter treatments for the moderate and severe defoliation intensities, respectively.

Following defoliation of all plant shoots, mean leaf length of dependent tillers was greater than in untreated plants while mean root length was less than in untreated plants. When only parent‐shoots were defoliated, mean root length of dependent tillers was shorter than in untreated plants, while mean leaf length was unaffected. Reduced rates of dependent tiller root elongation following plant defoliation may reduce forage production by preventing successful establishment of newly initiated tillers.
Economic and Agronomic Impacts of Varied Philosophies of Soil Testing1
Authors: Olson R. A. , Frank K. D. , Grabouski P. H. , Rehm G. W.
Published: July 2010

Philosophical differences exist in the interpretation and recommendations made from soil test values acquired by different organizations that provide advice to farmers on fertilizer use. It was the objective of this study to evaluate the economic and agronomic impacts of these varied philosophies with particular reference to concepts of cation ratio, nutrient maintenance, and nutrient sufficiency level. Field experiments were conducted during 1973–1980 on four major soils of Nebraska comparing yields of corn (Zea mays L.) grown with fertilizer treatments as recommended by five soil testing laboratories operating in the state. The 29 field comparisons revealed no real yield differences despite wide variation in number, rate, and cost of nutrients applied. Since soil test levels are increasing or at least holding steady with the “nutrient sufficiency” approach to soil testing, we find no economic or agronomic basis for the “balance” or “maintenance” concepts on these representative soils of the western Corn Belt. Not to be overlooked are environmental implications nor the waste of energy and resources from any approach responsible for excessive fertilizer use. It is recognized that reserves of available nutrients in the deep subsoils and underlying soil‐forming materials in this region have a substantial bearing on soil test calibration and that different calibrations may exist with less favorable subsoil rooting conditions.
Effect of Temperature and Fertilizer N on Apex Development in Spring Wheat1
Authors: Frank A. B. , Bauer A.
Published: July 2010

Development of crop growth simulation models has indicated a lack of information on effects of specific environmental factors on growth and yield of hard red spring wheat, Triticum aestivum L. em Thell. One environmentally sensitive yield component is the number of kernels per ear. The objective of this research was to determine effects of temperature and fertilizer N on early plant growth, apex development, and number of spikelets and kernels per ear. ‘Sinton’ spring wheat was grown in a controlled environment chamber at 10, 18, and 26 C with 0, 78, and 224 kg N/ha. Irradiance was 1,000 µEm−2 sec−1 and 16‐hour photoperiod. Duration of the vegetative phase of the apexes was determined for the main stem (M) and the first (T1), second (T2), and third (T3) tillers and duration of the spikelet development phase was measured for M. Tillers and leaves were tagged as they appeared and their development related to apex development. Spikelets and kernels per ear were determined for each stem at maturity.

Duration of M apex vegetative phase was influenced by temperature but not by N level; the spikelet development phase was influenced by both temperature and N level. Duration of the vegetative phase was 24, 22, and 17 days at 10, 18, and 26 C, respectively. Duration of the spikelet development phase was significantly shorter at 26 C (4.8 days) than at 10 C (6.5 days) and 18 C (7.4 days). Development of tiller apexes appeared to be strongly synchronized to development of the M apex. Inflorescence initiation on M occurred at the 5.1 leaf stage at 18 C and at 4.4 leaf stage for both the 10 and 26 C treatment.

Kernels per ear for the main stem and tillers decreased significantly from 27.2 and 24.8, to 18.5 as temperature increased from 10 to 18 to 26 C, respectively. Fertilizer N levels of 0, 78, and 224 kg N/ha produced kernel numbers of 20.8, 23.5, and 26.2, respectively. Tillers originating at the coleoptile node produced fewer kernels per ear at 10 C than leaf tillers, but not at 18 or 26 C. The percentage of first tillers elongating from the coleoptile node was 62, 47, and 30 at 10, 18, and 26 C, respectively.

Results show that early vegetative growth and apex development is more sensitive to temperature than to N fertilization. Kernels per ear for tillers is controlled in part by their synchronization to the development of the M apex.
Analysis and Interpretation of Factors Which Contribute to Efficiency of Nitrogen Utilization1
Authors: Moll R. H. , Kamprath E. J. , Jackson W. A.
Published: July 2010

Differences in N response among corn (Zea mays L.) genotypes reflect variation in numerous processes involved in N use efficiency. In order to facilitate the study of such variation, we develop and demonstrate a concept for evaluating the contribution of N uptake and utilization processes to variation in N use efficiency. Eight hybrids were grown in a replicated field experiment at two levels of N fertilizer on a Dothan loamy sand (Typic Plinthic Paleudult). Differences among the hybrids for components of N use efficiency were evaluated from measurements of grain yield, N accumulation in the plant at silking, and N accumulation in the grain and stover at harvest. Significant differences were found among hybrids and between N levels for all traits. Interactions among hybrids and N levels were significant for all traits except grain yield. At low N supply, differences among hybrids for N use efficiency were due largely to variation in utilization of accumulated N, but with high N they were due largely to variation in uptake efficiency. Variation in proportion of N translocated to grain was also important at the low N supply. Variation in N accumulated after silking was not important at either level of N supply. Variation in N remobilization from vegetative tissue to grain was moderately important at the low N supply. Hybrids with similar levels of N use efficiency showed marked differences in component traits which contribute to efficiency.
Remedial Postemergence Legume Inoculation with Rhizobium1
Authors: Rogers D. D. , Warren R. D. , Chamblee D. S.
Published: July 2010

Legume inoculation failures often result in severe stand losses and yield reductions. The objective of this study was to determine the possibility of salvaging poorly nodulated stands of fall‐seeded ‘Arc’ alfalfa (Medicago sativa L.) (fine‐loamy, siliceous, thermic Typic Paleudult soil type) and ‘Viking’ birdsfoot trefoil (Lotus corniculatus L.) (clayey, kaolinitic, thermic Typic Hapludult soil type). Three postemergence soil inoculation techniques were evaluated in the field: a) Subsurface application of inoculum‐coated sand, b) subsurface application of a peat‐base granular inoculant, and c) application of a water‐inoculum suspension as a surface spray. Varying rates of the appropriate Rhizobium strains (Rhizobium meliloti Dang., or Rhizobium sp. of Lotus subgroup) were applied approximately 2, 4, or 8 weeks after seedling emergence. Measurements of nodulation, N concentration, and yield were made.

Satisfactory nodulation and plant growth were generally obtained from inoculation treatments made 2 and 4 weeks after plant emergence with all three techniques. Remedial inoculation treatments made in late fall approximately 8 weeks after plant emergence were unsuccessful. Except under low moisture conditions, inoculum application rates ranging from 1.4 to 1.9 kg/ha were sufficient for effective nodulation for techniques a and c. The lowest rates tested for technique b ranged from 4.5 to 6.8 kg/ha and were also satisfactory. Average first alfalfa harvest yields (two experiments) following subsurface application of 1.6 kg/ha of inoculum with a sand carrier were 2,900, 2,750, 970, and 360 kg/ha for the 2, 4, 8‐week, and noninoculated treatments, respectively. With sufficient moisture availability, higher yields resulted from seed inoculation than from postemergence inoculation; however, those differences had largely disappeared by the third harvest. When applied as a surface spray under favorable environmental conditions, application of 1.4 kg/ha of peat‐base inoculum in 187 liters/ha of water produced first harvest alfalfa yields of 4,305, 3,985, 520, and 200 kg/ha for the 2, 4, 8‐week, and noninoculated treatments, respectively.
Forage Corn Response to Several Trickle Irrigation and Fertilization Regimes1
Authors: Yanuka M. , Leshem Y. , Dovrat A.
Published: July 2010

The main technical advantages of trickle irrigation are better water and nutrient control (frequent supply as needed by the plant) and less outside disturbance that may cause lower water and nutrient use efficiencies (wind, loss of pressure in irrigation pipes). The purpose of this investigation was to determine the yield level of forage corn (Zea mays L.), cv. Newe Ya'ar 170 at a density of 110,000 plants per hectare, and its nutrient and moisture uptake as affected by the application of different amounts of irrigation water when plant nutrients in the soil were sufficient for maximum growth.

Crop water requirement (WR) was based on estimates of ET/Eo (ET = crop evapotranspiration and Eo = Class A pan evaporation) multiplied by Em (measured Class A pan evaporation). In order to derive the different irrigation treatments, WR was multiplied by a variable K, i.e., 1.5, 1.0, or 0.5, giving the total amounts of water applied by trickles of 693, 459, or 230 mm, respectively over an experimental period of approximately 100 days. The averages of daily water tension in several soil profiles, daily dry matter production rates, cumulative dry matter yield, and daily nutrient (N,P,K) uptake by the plant were measured.

It was found that the ratio between dry matter yield and ET/Eo was approximately 290 kg ha−1day−1 for all treatments. This value is high in comparison with those reported in the literature. The response curve of dry matter yield vs. evapotranspiration began near the origin and was linear.

The maximum dry matter yield, 32,440 kg/ha, was obtained with an average soil water tension of 4 centibars at 0 to 150 cm soil depth and average NO3‐N concentration of about 80 ppm in soil solution to a depth of 30 cm during the period of most active N uptake. Average P and K concentrations in the upper 30 cm of soil at that time were 20 and 80 ppm, respectively. The maximum rate of dry matter production was 660 kg ha−1day−1 at the time of grain filling.

As expected, irrigation with trickles allowed efficient control of the fertilizer‐water‐soil system, maintaining high water and nutrient availability to the crop.
Tiller Development at the Coleoptilar Node in Winter Wheat1
Authors: Peterson Curt M. , Klepper Betty , Rickman R. W.
Published: July 2010

The formation of a secondary crown from a coleoptilar tiller can be important in wheat (Triticum aestivum L.) producing regions where severe frosts can destroy or limit primary crown development in winter wheat. The outgrowth of a tiller from the coleoptilar node is influenced by both seed and environmental factors. This study was conducted to determine and compare factors likely to affect the carbohydrate status of the seedling, including seed reserves, seedling leaves, irradiance, and planting density.

Plants of ‘Stephens’ wheat, grown from seeds of three sizes, were maintained in a controlled environment. Before being sown, endosperm reserves were removed; after germination, the blade from one of the first three foliage leaves was excised to determine the influence of reduced endosperm and foliage leaf food sources on coleoptilar tiller development. Plants grown from largest seeds produced the most coleoptilar tillers, and these tillers appeared earlier in leaf development. The greatest number of subtillers and nodal roots were formed on coleoptilar tillers when plants from large seeds were grown under bright irradiance and a lower planting density. Treatments where a reduced number of coleoptilar tillers was obtained included: small seed sizes, blade excision from the first foliage leaf, intermediate irradiance, and high planting density. No coleoptilar tillers or nodal roots were produced at coleoptilar nodes both when endosperm reserves were excised prior to germination and when seedlings were grown under low irradiance. The length of the coleoptilar tiller and the number of its leaves at termination of the experiment were influenced both by seed size and irradiance levels during seedling development. The use of large seeds and adequate irradiance levels during early seedling growth resulted in more numerous coleoptilar tillers with more vigorous growth.
Moisture Deficits and Grain Sorghum Performance: Evapotranspiration‐Yield Relationships1
Authors: Garrity Dennis P. , Watts Darrell G. , Sullivan Charles Y. , Gilley James R.
Published: July 2010

Knowledge of evapotranspiration‐yield (ET‐Y) relationships is fundamental in evaluating strategies for managing limited irrigation. The work reported here was done to develop ET‐Y functions for grain sorghum [Sorghum bicolor (L.) Moench], to provide base data for a water management improvement study in Nebraska. A field experiment was conducted using a modified line source sprinkler system to establish treatments that resulted in several different ET levels during each growth stage. The system was installed on a Valentine very fine sand (Typic Ustipsament) in west central Nebraska.

The specific objectives of the study were: 1) to determine the crop evapotranspiration‐yield relationships for grain sorghum in this location, 2) determine how the timing and intensity of water deficits affect this relationship, 3) compare the evapotranspiration‐yield response of selected genotypes, and 4) to determine whether crop water use efficiency can be increased by judicious limited irrigation.

In two seasons the relationship between evapotranspiration (ET) and grain yield (Y) or dry matter was linear. Evapotranspiration reduction under all conditions tested incurred some yield reduction. For a given genotype the slope of the ET‐Y relationship varied greatly depending on the growth period treatment. The lowest slopes were associated with a treatment in which stress built up steadily over the entire growing season. The slope was generally much steeper when irrigation was restricted to varying degrees for only a portion of the growing season. With greater yield reductions per unit of ET deficit, the latter treatments were considered suboptimal irrigation strategies compared to a gradual stress buildup.

One hybrid had a lower slope of the ET‐Y relationship than the other genotypes for the treatment that provided water stress of gradually increasing severity. The percentage yield reductions were similar for all hybrids, however. The yield reduction ratios of the genotypes were different for the two growing seasons.

Water use efficiency consistently decreased as ET declined below the maximum. It appeared that water stress, regardless of timing, tended to reduce water use efficiency. The reductions were smallest when stress increased gradually throughout the growing season.
Cultivation Effects on the Amounts and Concentration of Carbon, Nitrogen, and Phosphorus in Grassland Soils1
Authors: Tiessen H. , Stewart J. W. B. , Bettany J. R.
Published: July 2010

Cultivation has substantially reduced the organic matter contents of many prairie soils. This study attempts to quantify the losses of C, N, and P from three prairie soils of different textures during cultivation. For this purpose cultivated and adjacent uncultivated soils (2 Cryoborolls and 1 Cryorthent) were sampled and their C, N, and P contents as well as their bulk densities and horizon depths were compared.

Reductions of about 35% in the C concentration were observed in clay and silt loam soils after 60 to 70 years of cultivation. At the same time reductions in N concentrations were greatly influenced by the presence or absence of legume [alfalfa, (Medicago sativa L.)] crops grown in the fields and losses varied between 18 and 34%. Phosphorus concentrations were reduced by 12% and all P losses were accounted for by the organic fraction. During a similar period of cultivation a lighter textured sandy loam had experienced greater reductions in C, N, and P concentrations of 46, 46, and 29%, respectively. In this soil P was lost from both the organic and inorganic fractions. Prolonged cultivation of 90 years did not result in a decrease in the rates of losses of C, N, and P on the silt loam soil.

Conversion of concentration data to area based total C, N, and P budgets resulted in a decrease in the differences seen between cultivated and uncultivated soils. This was caused by an increase of soil bulk densities under cultivation and by an increase in the standard deviations of the data due to variability of horizon depths in cultivated fields.
Evaluating N Fertilizer Sources and Timing for Winter Wheat1
Authors: Christensen N. W. , Meints V. W.
Published: July 2010

Ammonia volatilization can reduce the effectiveness of surface applied N fertilizers. Our objectives were to evaluate N source by timing interaction under field conditions conducive to NH3 volatilization and to compare the sensitivity of three approaches to assessing N source by timing interaction. Ammonium nitrate and urea fertilizers were topdressed at rates of 0, 34, 67, and 101 kg N/ha on 19 November or 23 March to ‘Winalta’ winter wheat (Triticum aestivum L.) grown on a nonirrigated Scobey silt loam (Aridic Argiboroll, fine, montmorillonitic). Plots receiving topdressed N contained sub‐plots fertilized at the appropriate rate and time with 15NH4 15NO3 or 15NH2CO15NH2 labeled fertilizers containing 1.31 atom percent 15N. Nitrogen fertilization increased straw yield, grain yield, grain protein, test weight, and N content of straw and grain. Uptake of soil N and fertilizer N in straw and grain were determined. Grain yield was fitted to a concurrent Mitscherlich regression model while total N uptake and fertilizer N uptake were fitted to multiple linear regression models to evaluate the relative effectiveness of each N source—timing combination. Comparison of regression coefficients for either grain yield or total N uptake revealed no significant differences between N source—timing combinations. Fertilizer N uptake regressed on rate of applied N was a better parameter for evaluating N source by timing interaction and showed that fall topdressed urea was only 69% as effective as fall topdressed ammonium nitrate. Spring topdressed urea, spring topdressed ammonium nitrate, and fall topdressed ammonium nitrate were equally effective in supplying N to wheat plants. Volatilization of NH3 from surface applied fertilizer probably accounts for the lower relative effectiveness of urea topdressed on 19 November.
Effect of Crop Residue Management and Tillage on Water Use Efficiency and Yield of Winter Wheat1
Authors: Cochran V. L. , Elliott L. F. , Papendick R. I.
Published: July 2010

Direct drilling of winter wheat (Triticum aestivum L.) into surface cereal residues reduces soil erosion but frequently has resulted in stunted plants and lower grain yields than conventional planting methods. Phytotoxins produced during decomposition of surface crop residues have been implicated as the cause of these reduced yields. Field plots were established on spring and winter wheat stubble to compare plant stands, water storage, grain yields, and water‐use efficiency between direct drill seeded and conventionally seeded winter wheat. Residue management treatments included: standing stubble, complete residue removal, moving the crop residue from the seed row, and residue incorporation. New sites were used each year with the spring and winter wheat stubble maintained on Naff silt loam (fine‐silty, mixed, mesic Ultic Argixerolls) and Palouse silt loam (finesilty, mixed, mesic pachic Ultic Haploxerolls), respectively. Water soluble phytotoxins from the surface crop residues were not found during the 3‐year study. Furthermore, moving the crop residues from the seed row did not affect yields, but did alleviate the high crown node set which in turn reduced visual injury from soil active herbicides. Surface crop residues significantly improved water storage during the one season with a major runoff event, which increased grain yields and water use efficiencies, but had no effect when soil profiles were filled by spring. During the 3‐year study, winter wheat yields from plots direct drilled into surface cereal residues were equal to those from plots tilled and seeded conventionally.
Effect of Shading on the Growth of Some Common Weeds of the Semi‐Arid Tropics1
Authors: Shetty S. V. R. , Sivakumar M. V. K. , Ram S. A.
Published: July 2010

Light is one of the major factors influencing crop‐weed balance. The influence of shading on the growth, leaf area, dry matter production, and seed production of some common weeds of the semiarid tropics was investigated in a field study at ICRISAT Research Center near Hyderabad, India, during the 1978 and 1979 rainy seasons. Different shade treatments were achieved by erecting rectangular bamboo frames over each plot. The weeds studied were Cyperus rotundus L., Digitaria ciliaris (Retz.) Koeler, Celosia argentea L., Acanthospermum hispidum DC., Tridax procumbens L., Dactyloctenium aegyptium (L.) P. Beauv., and Amaranthus viridis L. At 90% shading plant height was reduced to 30% of the control with Celosia and Tridax. Digitaria and Dactyloctenium showed 70 to 80% reductions in leaf area index (LAI) at 90% shading. Dry matter production in Digitaria, Dactyloctenium, and Acanthospermum was reduced up to 80% at higher shading levels. In Cyperus, the effect of decreasing light levels on plant height was not pronounced, but the LAI and dry matter production were severely affected. Photosynthetic photon flux density (PPFD) measurements showed a negative correlation between levels of shading and the seed production in these weeds.

The study indicated that by manipulating crop canopies to create desired shading, substantial weed suppression could be achieved. The agronomic significance of these results is discussed in the light of the weed‐suppressing capacity of crop canopies in different cropping systems of the semiarid tropics that may complement other control measures to obtain better weed management.
Effects of Lime, P, and Mo Application on Mo Concentration in Subclover1
Authors: Petrie S. E. , Jackson T. L.
Published: July 2010

Subterranean clover (Trifolium subterranium L.) is a winter annual legume grown in the hill pastures and hay fields of western Oregon. Soils are acid (pH 4.5 to 5.5) and yield responses to lime, P, and Mo are common. Lime, P, and Mo application can result in increased Mo concentrations in plants. Forage containing more than 10 µg Mo/g is potentially toxic to ruminants. An experiment involving subterranean clover and perennial ryegrass (Lolium perenne L.) was established in the fall of 1976 on a Typic Haploxeralf, fine, mixed, mesic soil to evaluate the effects of lime, P, and Mo applications on: (1) the Mo concentration in subterranean clover leaflets and petioles and in the clover‐grass mixture and (2) the longevity of the treatment effects on Mo concentration in the clover‐grass mixture. Lime was applied at 0, 4.5, or 9.0 metric tons/ha, P was applied as concentrated superphosphate at 0, 19, or 57 kg/ha, and Mo was applied as Na2Mo04 2H20 at 0 or 0.5 kg/ha. All treatments received adequate K, S, and B. Clover leaflet and petiole samples were analyzed to determine the Mo critical level for the clover and establish the maximum Mo concentration that would be consumed by a grazing animal. Clover grass mixture samples were analyzed to determine the average Mo and Cu concentration that would be consumed. The Mo concentration in clover leaflet and petiole samples collected 18 Mar. and 12 Apr. 1977 was increased from 1.5 to over 25 µg Mo/g by application of lime, P, and Mo. The Mo concentration decreased to less than 15 µg/g by 12 May 1977. Application of lime, P, and Mo increased the Mo concentration in the clover‐grass mixture from 1 to over 5 µg Mo/g and decreased the Cu:Mo ratio to below 2, which is potentially toxic to livestock.

The highest Mo concentration was less than 10 µg Mo/g in clover leaflet and petiole samples collected the second growing season and the Mo concentration in the clover‐grass mixture was less than 5 µg Mo/g for all treatments except one. The Mo concentration was below 2 µg Mo/g in all samples collected the third growing season. Although the Mo concentration was as low as 0.1 µg/g, yield responses from Mo application were not evident.
Response of Basin Wildrye and Tall Wheatgrass Seedlings to Salination1
Authors: Roundy Bruce A.
Published: July 2010

Tall wheatgrass [Agropyron elongatum (Host) Beau. ‘Jose’] and basin wildrye (Elymus cinereus Scribn. & Merr. ‘Magnar’) may have high potential for increasing forage production on degraded, saline/alkaline rangelands in the arid west. To compare their tolerance to salinity and decreasing soil osmotic potentials seedlings of each species were grown in salinized sand cultures in the greenhouse with isosmotic solutions of CaCI2, NaCI, Na2SO4, and equimolar CaCI2 plus NaCl and Na2SO4 plus NaCI. Calcium inhibited growth of both cultivars more than the other salts and was especially toxic to basin wildrye seedlings at osmotic pontentials below − 15 bars. Since Na2SO4, and NaCl are the predominant salts on Great Basin saline rangelands, Ca toxicity should not be a problem in field plantings, but high tolerance to Na should have adaptive value for both cultivars. Absolute yield of Jose shoots and roots exceeded that of Magnar at all soil osmotic potentials, but salination reduced root growth of Jose more than Magnar and reduced shoot growth of Magnar more than Jose. Even though both cultivars maintained relatively high turgor at low leaf water potentials small initial losses in turgor were associated with greatly reduced growth. Either the threshold turgor necessary for growth of these cultivars was very high under these experimental conditions or ionic imbalances or energy expenditures associated with osmotic adjustment limited growth despite high turgor pressure. Gradually salinized plants maintained positive turgor at average leaf water potentials of 12 bars lower than did control plants in which water stress developed rapidly due to decreasing soil matric potentials when water was withheld. Both species survived soil osmotic potentials down to ‐35 bars but grew very little below − 10 bars.
Forage Yield, Quality, and Persistence of Switchgrass and Caucasian Bluestem1
Authors: Anderson Bruce , Matches A. G.
Published: July 2010

Switchgrass (Panicum virgatum L.) and Caucasian bluestem [Bothriochloa caucasica (Trin.) C.E. Hubbard] provide forage during summer when cool‐season grasses in the southern Corn Belt are unproductive. Information is limited on the response of these grasses to defoliation, especially the effect of harvest management on regrowth. Field studies on a Creldon silt loam soil (fine, mixed, mesic Mollic Fragiudalf) were conducted to determine forage yield and quality trends and persistence of Switchgrass and Caucasian bluestem as influenced by date of first harvest and stubble height. Five dates of first harvest and two cutting heights (8 and 23 cm) were imposed factorially on established stands of Switchgrass and Caucasian bluestem for 3 years. The first harvests were taken consecutively at 1 week intervals with the initial first harvest made when plants were in a vegetative to early jointing growth stage. When cut at an 8 cm stubble height, first harvest yields of Switchgrass and Caucasian bluestem averaged over 3 years increased 763 and 1,010 kg/ha per week, respectively, with each week delay of first harvest. However, corresponding total regrowth yields/ha declined 424 kg for Switchgrass and 632 kg for Caucasian bluestem. Trends were similar for cutting at a stubble height of 23 cm, but yields were usually less than at 8 cm. Forage in vitro dry matter disappearance declined 2.0 percentage units per week for both Switchgrass and Caucasian bluestem while crude protein declined 1.6 and 1.0 percentage units per week, respectively, with each week delay in first harvest. Neutral detergent fiber (NDF) increased 1.4 percentage units per week for Caucasian bluestem at both stubble heights and for Switchgrass at 8 cm; the NDF of Switchgrass at 23 cm increased 0.4 percentage units per week. Our results indicated that Switchgrass and Caucasian bluestem should be harvested when plants begin to joint. Early harvest results in forage of higher quality and regrowth potential than harvest at later growth stages.
Leaf and Canopy Temperatures of Pearl Millet Genotypes under Irrigated and Nonirrigated Conditions1
Authors: Singh Piara , Kanemasu E. T.
Published: July 2010

It has been reported from previous research that leaf and canopy temperatures correlate with the level of water stress in a plant. If genotypes of a given species differ in their response to water stress, then leaf and canopy temperatures could serve as indices of their drought resistance. To test this hypothesis, 10 pearl millet (Penniserum americanum (L.) Leeke) genotypes differing in plant morphology were grown on a Eudora silt loam soil (fine silty, mixed, mesic, Pachic Haplustoll) under both irrigated and nonirrigated conditions. Leaf temperature (Tl), canopy temperature (Tc), canopy minus air temperature (Tc – Ta), leaf‐water potential (Ψl), leaf‐diffusion resistance (LDR), water use (WU), and crop yields were observed in both irrigated and nonirrigated treatments. Significant differences (P<0.05) were found in the grain yield, Tc, and Tc – Ta of genotypes, only in the irrigated treatment. Grain yield was negatively and significantly correlated with average afternoon Tc(r = −0.81) and average afternoon Tc – Ta(r = −0.78). Grain yield ratio (nonirrigated grain yield/irrigated grain yield) was positively and significantly correlated with average afternoon Tl(r = 0.64), average afternoon Tc(r = 0.64), and average afternoon Tc – Ta(r = 0.75). In the nonirrigated treatment, however, correlations of grain yield and grain yield ratio with various stress indices were nonsignificant. Average afternoon Tc and Tc – Ta was significantly correlated with average afternoon LDR only in the irrigated treatment. This study suggests that average afternoon Tc and Tc – Ta as observed in a nonstressed environment with an infrared thermometer could effectively be used as a technique to screen millet genotypes for their grain yield and grain‐yield stability (nonirrigated grain yield/irrigated grain yield).
Spectral Estimates of Solar Radiation Intercepted by Corn Canopies1
Authors: Daughtry C. S. T. , Gallo K. P. , Bauer M. E.
Published: July 2010

As the need for timely information on worldwide crop production intensifies the role of remote sensing is becoming more prominent. If agronomic variables related to yield could be reliably estimated from multispectral satellite data, then crop growth and yield models could be implemented for large areas. The objective of this experiment was to develop methods for combining spectral and meteorological data in crop yield models that are capable of providing accurate estimates of crop condition and yields. Initial tests of this concept using data acquired in field experiments at the Purdue Agronomy Farm, West Lafayette, Ind., are presented. Reflectance factor data were acquired with a Landsat band radiometer throughout two growing seasons for corn (Zea mays L.) canopies differing in planting dates, populations, and soil types (Typic Argiaquoll and Udollic Ochraqualf). Agronomic data collected to coincide with the spectral data included leaf area index (LAI), biomass, development stage, and final grain yields. The spectral variable greenness was associated with 76% of the variation in LAI over all treatments. Single observations of LAI or greenness were found to have limited value in predicting corn yields. The proportions of solar radiation intercepted (SRI) by these canopies were estimated using either measured LAI or greenness. Both estimates, when accumulated over the growing season, accounted for approximately 65% of the variation in yields. The Energy Crop Growth (ECG) variable was used to evaluate the daily effects of solar radiation, temperature, and moisture stress on corn yields. Coefficients of determination for grain yields were 0.67 for the ECG model using measured LAI to estimate SRI, and 0.68 for the ECG model using greenness to estimate SRI. We conclude that this concept of estimating intercepted solar radiation using spectral data represents a viable approach for merging spectral and meteorological data in crop yield models. The concept appears to be extendable to large areas by using Landsat MSS data along with daily meteorological data and could form the basis for a future crop production forecasting system.
Leaf and Stem Forage Quality of Big Bluestem and Switchgrass1
Authors: Griffin J. L. , Jung G. A.
Published: July 2010

A balanced forage program should include species that provide the highest yields of quality forage throughout the grazing period. In the Northeast, where cool‐season grasses predominate, the short supply of forage during summer limits beef cow‐calf herd size. Warm‐season (C4) perennial grasses are productive in midsummer and may supplement temperate species for grazing and hay. ‘NY 1145’ big bluestem (Andropogon gerardi Vitman) and ‘Blackwell’ switchgrass (Panicum virgatum L.) were grown on soils (Aeric Fragiaquualt and Aquic Hapludalf) low in available P at two locations in Pennsylvania to characterize changes in quality of leaf and stem tissue associated with maturation. Forage was harvested at 10‐day intervals beginning at the 3‐ to 4‐leaf stage in late June and continuing until seed set in early August. Percentage leaf tissue declined similarly with maturation for the two grasses. Leaf dry matter yields were approximately twice those of stems in June but the opposite was true in August. At early head emergence, percentage leaf tissue for big bluestem and switchgrass averaged 34 and 44%, respectively. Averaged over grasses, leaf and stem forage quality estimates at early head emergence, respectively, were: crude protein (CP), 9.7, 4.3% in vitro dry matter disappearance (IVDMD), 60.4, 50.0%; neutral detergent fiber (NDF), 66.0, 75.3%; lignin, 4.7, 7.2%; and phosphorus (P), 0.20, 0.16%. Big bluestem leaves were higher in CP but lower in NDF than switchgrass leaves. Stem tissue of big bluestem was lower in NDF but higher in lignin than that of switchgrass. The decline in leaf and stem CP, IVDMD, and P with maturation was less pronounced in leaf tissue. The increase in NDF and lignin with maturity was greater in stems than in leaves. Fiber accumulation in stem tissue continued after seedheads emerged and was accompanied by decreases in CP and IVDMD. At early vegetative stages, the high percentage of good quality leaf tissue suggest the potential use of big bluestem and switchgrass for ruminants with above maintenance energy requirements. However, at later growth stages (late joint early head), the increase in stem tissue and associated decline in nutritive value suggest using these grasses either for grazing or hay by ruminants to meet only maintenance energy needs.