bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen Uptake by Spring Wheat, Soil Distribution, and Recovery of N Fertilizer from Alternate Crop‐fallow and Recrop Field Management Systems1
Authors: Jones A. J. , Skogley E. O. , Meints V. W. , Martin J. M. 
Published: July 2010

AbstractKnowledge of N fertilizer utilization, movement, and recovery is required to attain maximum efficiency of applied N when shifting from fallow to recrop management. Field experiments involving spring wheat (Triticum aestivum) were established at two locations with different soil and climatic regimes in southwest Montana on fields which had been fallowed (fallow) or cropped (recrop) the previous year to evaluate the uptake, leaching, and recovery of 15NH415NO3 fertilizer. Ammonium nitrate fertilizer was applied to these fields at rates of 30, 60, and 90 kg N/ha under dryland conditions. The fallow and recrop fields had high (greater than 100 kg/ha/120 cm depth) and low (less than 50 kg/ha/120 cm depth) levels of nitrate‐N at seeding, respectively.The N content of grain was 48% greater on recrop than on fallow with higher N content associated with higher rates of N fertilizer. The N content of straw showed trends similar to that for grain. In addition, increased translocation of N from straw to grain was associated with recropping and increased rates of N fertilizer. The proportion of N in the plant derived from fertilizer averaged twice as great on recrop as on fallow and increased 2‐ to 20‐fold with the addition of 90 kg N/ha. These responses reflected the variation in initial NO3‐N level of each field.Residual NO3‐N and total 15N levels in the soil at harvest were low and decreased with depth to 120 cm. Soil NO3‐N levels ranged from 5 to 15 kg/ha. Maximum recovery of N fertilizer was at the soil surface with little difference between fallow and recrop. No leaching below 120 cm was indicated. Total recovery of N fertilizer ranged from 45 to 90%. Overall there was 18% more N fertilizer recovered on recrop than on fallow. For each component, grain, straw, and soil, there was 22, 8, and 20% respectively more N fertilizer recovered on recrop than on fallow. Total recovery of N fertilizer varied from 67 to 77% for the rate of N applied. Grain and straw N recovery increased significantly with increasing N rate while soil recovery was highly variable.
Grain Protein Content as an Indicator of N Sufficiency for Winter Wheat1
Authors: Goos R. J. , Westfall D. G. , Ludwick A. E. , Goris J. E. 
Published: July 2010

AbstractA great majority of the dryland winter wheat (Triticum aestivum L.) producers in the west central Great Plains currently do not use soil tests to determine N fertilizer needs although most producers have grain protein data from their fields. Field experiments with N rate as the variable were conducted throughout eastern Colorado over a 4‐year period with winter wheat grown under summer fallow cropping. The objective was to determine if grain protein content could be used as a post‐harvest indicator of sufficiency of N for maximum grain yield. The soil types were of the Paleustoll, Argiustoll, Paleargid, and Haplargid great groups. The yield and protein response data from the experimental locations were analyzed by an interaction chisquare procedure.Grain protein content was found to be an effective post‐harvest indicator of N nutrition adequacy for grain production. Both a critical level and a transitional zone of grain protein content were defined using interaction chi‐square analysis. The most critical level was determined to be 11.5% protein and the transition zone between the deficient and N sufficient populations of yield observations was between 11.1 to 12.0%. The amount of yield lost to N deficiency was not related to grain protein content. Workers in other geographic areas should be able to take existing N response data and develop similar guidelines appropriate for those areas.
Corn and Soybean Response to Allelopathic Effects of Weed and Crop Residues1
Authors: Bhowmik P. C. , Doll J. D. 
Published: July 2010

AbstractMany crop plants and perennial weed species have been known for their allelopathic effects. The question of whether annual weed species can be allelopathic remains unanswered. Consequently, studies were conducted in laboratory, greenhouse, and in the field to determine the allelopathic potential of weed and crop residues (above ground biomass) on corn (Zea mays L.) and soybeans [Glycine max (L.) Merr.]. Water extracts of dried residues of common lambsquarters (Chenopodium album L.), redroot pigweed (Amaranthus retroflexus L.), fall panicum (Panicum dichotomiflorum Michx.), giant foxtail (Setaria faberi Herrm.), green foxtail [Setaria viridis (L.) Beauv.], and yellow foxtail [Setaria glauca (L.) Beauv.] inhibited radicle elongation in corn; whereas, only common lambsquarters extract reduced coleoptile growth. Redroot pigweed, fall panicum, and green foxtail extracts inhibited hypocotyl elongation in soybeans. Residues of common ragweed (Ambrosia artemisifolia L.), velvetleaf (Abutilon theophrasti Medic.), and barnyardgrass [Echinochloa crus‐galli (L.) Beauv.] as well as the above species inhibited corn and soybean growth in the greenhouse. Inhibition of the receiver species (corn and soybeans) was greater with the double‐pot watering method than subsurface and surface watering methods. Corn was inhibited most in silica sand, less in a silica sand and silt loam mixture (Typic Agriudoll fine, silty, mixed mesic), and least in silt loam soil under each method of watering. In the field, residues of barnyardgrass and giant foxtail reduced corn yield. Soybean yield reductions occurred ranging from 14 to 19% with common lambsquarters, redroot pigweed, velvetleaf, soybeans, and sunflower (Helianthus annuus L.) residues. Corn and giant foxtail residues enhanced soybean yield in the field. These results demonstrate the allelopathic potential of the residues and suggest that these residues may affect crop yields due to the inhibitory or stimulatory effects of allelochemicals present in the residues.
Estimation of Nitrogen Fixation by Isotope Dilution in Field and Greenhouse Experiments1
Authors: Broadbent F. E. , Nakashima T. , Chang Grace Y. 
Published: July 2010

AbstractIsotope dilution methodology offers the advantage of an integrative technique for measuring N2 fixation in the field, but may have limitations in grass‐legume mixtures because of the possibility of transfer of fixed N from legume to grass. A study was conducted in the greenhouse and in the field utilizing two soils, Hanford sandy loam and Yolo silt loam (Typic Xerorthents) in which the organic matter was labeled by previous application of either 15N‐depleted or 15N‐enriched compounds. Contributions of atmospheric N2 to total plant N were calculated from the isotopic composition of plant tissue, using the composition of the non‐legume as a reference value.Ladino clover (Trifolium repens L.) and Wimmera ryegrass (Lolium rigidum L.) were grown alone and in mixture for purposes of comparison. In the greenhouse estimation of N2 fixation by the isotope and difference methods were in good agreement. There was essentially no transfer of fixed N2 from the clover to the ryegrass in any of the pot experiments. In the field experiment, clover obtained 85 to 100% of its N from the fixation process. In the clover‐ryegrass mixture, % total N and % 15N excess comparisons both indicated substantial transfer of N from clover to ryegrass after the stand had been established after about 6 months. Up to 79% of the N in ryegrass was calculated to be derived from such transfer. It is concluded that the isotope dilution method gives estimates of N2 fixation at least as good as those obtained by yield‐dependent methods such as the difference method, but it is not suitable for grass‐legume mixtures.
Evaluating the Crop Coefficient Using Spectral Reflectance1
Authors: Heclman J. L. , Heilman W. E. , Moore D. G. 
Published: July 2010

AbstractA field study was conducted in four differentially irrigated plots of alfalfa (Medicago sativa L.) planted in Shiprock sandy loam (coarseloamy, mixed, mesic Typic Haplargid) to assess spectral reflectance for estimating the crop coefficient (Kc), defined here as the ratio of actual to potential evapotranspiration (ET). A bidirectional reflectance factor was measured using a three‐channel (0.63 to 0.69 µm, 0.76 to 0.90 µm, and 1.55 to 1.75 µm) handheld radiometer, and was used to calculate a perpendicular vegetation index (PVI). Actual ET was determined by the water balance method in non‐weighing lysimeters, and potential ET was calculated using Penman's equation.Significant linear relationships were found between PVI and percent cover (r2 = 0.911), and between Kc and percent cover (r2 = 0.815). In addition, the position of the PVl intersection on the soil background line changed as a result of soil moisture increases following irrigation, even at high percent cover. Thus, once experimental relationships between Kc and crop growth are established, a mean Kc can be determined from spectral estimates of stage of development and the soil background component of PVI can be used to adjust the mean K, for increased evaporation following irrigation because the ratio of actual to potential evapotranspiration will approach 1 when the soil surface is wet.
Nodulation, N2 Fixation, and Seed Yield of Navy Beans as Influenced by Inoculant Rate and Inoculant Carrier1
Authors: Sparrow S. D. , Ham G. E. 
Published: July 2010

AbstractPeat is the most commonly used carrier of Rhizobium sp. (rhizobia) in inoculants. The lack of suitable local peat in many areas of the world leads to interest in other materials as carriers of rhizobia. The purposes of these studies were 1) to compare potential carriers of Rhizobium phaseoli for their ability, under field conditions, to supply viable rhizobia to promote nodulation, N2 fixation, and increased seed yield of navy beans (Phaseolus vulgaris L.), and 2) to determine the optimum rate of inoculation with Rhizobium phaseoli to promote nodulation, N2 fixation, and increased seed yield of navy beans in two soils in Minnesota, a loamy sand (sandy, mixed, Udorthentic Haploborall) and a silt loam (fine‐silty over sandy, mixed, mesic Typic Hapludoll).In 1978, five inoculation rates (ranging from 1 to 108 cells/ cm of row) of liquid suspensions of R. phaseoli inoculants were applied at planting. In 1979, R. phaseoli in six inoculant carriers, peat, charcoal, vermiculite, corn (Zea mays L.) cobs, peanut (Arachis hypogaea L.) hulls, and liquid medium, was used to inoculate navy beans at rates of 2.5 ✕ 104 and 5 ✕ 106 cells/cm of row. Nodule numbers and weight, acetylene reduction rates, seed yield, and seed N percentage were determined.In 1978, in most parameters measured, inoculation rates of 105—106 cells/ cm were required for a statistically significant increase over the lowest inoculation rate. In 1979 there was no effect of inoculation on a soil with a relatively high population of soil R. phaseoli (104 cells/g soil) and relatively high mineral N content (30 ppm). On a soil with an indigenous population of <10 cells/g soil and mineral N content of 8 ppm, peat and charcoal inoculants resulted in the highest seed yield, nodule numbers and weight, and acetylene reduction rates. Peanut hulls and corn cobs gave the poorest responses. These results indicate that peat, charcoal, and vermiculite can be successfully used as carriers of R. phaseoli but peanut hulls and corn cobs are unsatisfactory.
Fertilizer‐N Effects on N2 Fixation by Cowpea and Soybean1
Authors: Eaglesham A. R. J. , Hassouna S. , Seegers R. 
Published: July 2010

AbstractWhile it is established that high levels of combined N inhibit the development and function of legume root nodules, the application of low‐level “starter” doses of fertilizer‐N is sometimes recommended to improve nodulation and N2 fixation in the long term. The amounts of combined N which are required to optimize legume symbiosis are poorly defined. Before screening a number of rhizobial isolates for effectiveness with cowpea [Vigna unguiculata (L.) Walp.] we set out to determine what levels of fertilizer‐N are optimal for symbiosis in pot conditions.We examined the effects of fertilizer‐N applied at or soon after sowing, on nodulation, N, fixation and growth of two cultivars of cowpea and, for comparison one of soybean [Glycine mar (L.) Merr.] in the greenhouse. Two experiments were done to examine (a) the effects of fertilizer N before flowering and (b) the effects of fertilizer‐N throughout the growth cycle and on final yield. The levels of N found to stimulate symbiosis during the pre‐flowering period were an order of magnitude higher than those previously reported. Applications of 36 and 72 mg N/plant increased nodule weights and acetylene reduction activities up to fourfold and sixfold, respectively, but trends varied with legume host and time of harvest. When 30, 90, 180, or 360 mg N/plant were applied as NH4NO3, KNO3, or urea, symbiotic responses again varied and no single N treatment was optimal for all three legumes. Synergistic effects of applied N on total amounts of N fixed were observed with each host with various N treatments. The strongest synergism occurred in soybean with urea at 30 mg N/plant; for every milligram of urea‐N absorbed, an additional 15 mg of N were fixed symbiotically.
Chloride Toxicity of Soybeans Grown on Atlantic Coast Flatwoods Soils1
Authors: Parker Myron B. , Gascho G. J. , Gaines T. P. 
Published: July 2010

AbstractLeaf scorch, caused by CI toxicity, affected over 20,000 ha of soybeans (Glycine max (L.) Merr.) in 1980 in the poorly‐drained Flatwoods soils of Georgia. This new disorder, compounded by the extended drought of 1980, resulted in Severe yield reductions of ‘Bragg’ soybeans. Field studies involving fertilizer treatments in two experiments and 15 cultivars in one experiment were conducted in 1981 to determine the cause of the problem. Phosphorus, Mg, and Cl treatments were evaluated on two problem areas—a Leefield sand (arenic Plinthaquic Paleudults) and an Alapaha sand (arenic Plinthic Paleaquults). Cultivars also were evaluated on the Alapaba sand. Leaf scorch developed on plants receiving Cl containing fertilizer and on 5 of 15 cultivars. Symptoms observed were the same as those described for Cl toxicity. Leaf and seed Cl levels averaged 0.12% and 75 µg/g, respectively, for plants receiving no KCl fertilizer compared to 0.94% and 166 µg/g for plants receiving KCl. Leaf and seed Cl levels averaged 1.67% and 682 µg/g, respectively, for five susceptible cultivars compared to 0.09% and 111 µg/g for 10 tolerant cultivars. The parent seed of each cultivar contained relatively low levels of Cl, indicating that susceptible cultivars are not high Cl accumulators when grown under low Cl soil conditions. Leaf scorch ratings were positively correlated with leaf and seed Cl and negatively correlated with seed weight and yield. The leaf scorch problem on susceptible cultivars apparently is caused by a Cl buildup in poorly‐drained Flatwoods soils. The major source of Cl appears to be KCl fertilizer.
Mower Blade Sharpness Effects on Turf1
Authors: Steinegger D. H. , Shearman R. C. , Riordan T. P. , Kinbacher E. J. 
Published: July 2010

AbstractThis study was undertaken to determine effects of repeated mowing with a dull or sharp rotary mower blade on Kentucky bluegrass (Poa pratensis L.) turfs of ‘Park’ and ‘Baron‐Glade‐Adelphi’. Mower blade sharpness effects on turfgrass quality, leaf spot (Bipolaris sorokinianum Shoem.), thatch accumulation, water use rate, and mower fuel consumption were studied. Field experiments were conducted on a Sharpsburg, silty‐clay loam (fine, montmorillonitic, mesic Typic Argiudoll) at the Univ. of Nebraska Field Laboratory located near Mead. Turfgrass quality was reduced by dull mower treatment for both Park and the blend. Leafspot incidence increased on Park turfs mowed with the dull mower, but not on the blended turf which was leaf spot resistant. Thatch accumulation was not significantly influenced by mower blade sharpness. Water use rates under field conditions for Park and Baron‐Glade‐Adelphi turfs were 1.3 and 1.2 times greater, respectively, for turfs mowed with the sharp mower blade than the dull. The reduced water use rate associated with dull mower treatments was positively correlated to reduced shoot density (r = 0.88) and verdure (r = 0.93). Gasoline use was 22% greater with dull mower blade treatments than with sharp. This study substantiates the hypothesis that repeated mowing with a dull mower blade reduced turfgrass quality and increased disease susceptibility. However, these results refute the generally accepted premise that dull mower blade injury of turfgrass leaf tissue increases turfgrass water use.
Absorption and Translocation of Foliarly Applied 15N by Soybeans1
Authors: Morris D. R. , Weaver R. W. 
Published: July 2010

AbstractNitrogen nutrition of soybeans (Glycine max) is important in determining their yield potential. Labelling of leaves with 15N by foliar fertilization provides an effective method for determining mobilization and partitioning of N from leaves to other plant parts. The purpose of this field research was to develop a method that would be useful in measuring the efficiency of N absorption and translocation by leaves. Labelled urea was foliarly applied at V5‐V6, V7‐V8, and V10‐V12 growth stages while labelled (NH4)2SO4 was applied only at V5‐V6 growth stage. The N solutions were applied to a single trifoliolate leaf on each plant. A micropipette was used to apply droplets directly to leaves held stationary and horizontal by taping them to a stand. Average N uptake, into the plant, 15 h after application was 71% of that applied. No significant differences in translocation between N sources or growth stages was found.
N2‐Fixation in Field Beans Quantified by 15N Isotope Dilution. II. Effect of Cultivars of Beans1
Authors: Rennie R. J. , Kemp G. A. 
Published: July 2010

AbstractField beans (Phaseolus vulgaris L.) have been considered inferior in nis (nitrogen fixation supportive trait), i.e., in their ability to support and benefit from their symbiotic association with N2‐fixing Rhizobium phaseoli. This paper reports the use of N balance in phytotron studies and 15N isotope dilution in the field to determine the effect of R. phaseoli strains and mineral N levels on the expression of nis in 26 cultivars of field beans. Evaluation for nis under N‐free conditions in the phytotron forced total dependence on seed and atmospheric N and provided a useful screening technique before field experimentation. Ranking of cultivars for nis was highly dependent on R. phaseoli strain, mineral N levels, growth habit, growth stage, and temperature regime during evaluation. R. phaseoli strains 3644 and 8215 resulted in higher N2 fixation with temperate beans while strain 3605 was unique in high N2 fixation with two tropical cultivars, Cargamantn and Sangretoro. The addition, in the field, of 40 kg fertilizer N ha−1 on a Typic Haploboroll soil caused a 10% reduction in percent N derived from atmosphere (% Ndfa) in most cultivars but had no effect on ‘Redkloud’. In contrast, ‘Limelight’ suffered a 60 % reduction in % Ndfa. This indicated a host‐specific reaction in nis to mineral N and potential for breeding this resistance into other bean lines. Both in the phytotron and the field, climbing bean cultivars had higher % Ndfa and thus superior nis than bush cultivars. Some cultivars were superior when evaluated at anthesis but not at maturity, indicating a difference in the N2‐fixing span of the cultivar. In the field, % Ndfa of beans was approximately 50 %, the other 50 % being derived from fertilizer and or soil N. The actual amounts of Nz fixed varied between 40 kg ha−1 and 125 kg ha−1 depending on the cultivar. Thus, R. phaseoli may he considered as efficient as R. japonicum is with soybeans in supplying atmospheric N2 to the plant.
Dynamic Nature of the Photoperiod Response in Maize1
Authors: Kiniry J. R. , Ritchie J. T. , Musser R. L. 
Published: July 2010

AbstractA general quantitative description of maize (Zea mays L.) response to photoperiod for use with widely different genotypes and environments is important in order to accurately evaluate stages in maize ontogeny. This paper describes a method for combining photoperiod and maturity information into a relatively simple model to estimate the interval from seedling emergence to tassel initiation and tassel emergence in maize. Twenty contrasting cultivars of maize were grown to tassel emergence in the Duke Univ. Phytotron at 25°C under photoperiods ranging from 10 to 17.5 h. Dates of tassel initiation were determined destructively and tassel emergence nondesrructively. An apparently general linear relationship was found for estimating the thermal time (degree days) between seedling emergence and tassel initiation from the thermal time between seedling emergence and tassel emergence. This implies that the timing of tassel initiation can be estimated with reasonable accuracy when the temperature and date of tassel emergence are known. The time to tassel initiation was not influenced by photoperiod for all cultivars studied. Those that were photoperiod sensitive experienced a delay in rime to tassel initiation only when the photoperiod was greater than a critical threshold value ranging from 10 to 13.5 h. Below the threshold photoperiod, plants appeared to be insensitive to photoperiod. For photoperiods above the threshold value, the delay in thermal time to tassel initiation was described as a linear function of photoperiod above the threshold value. For the cultivars studied, the photoperiod sensitivity ranged from zero for six insensitive early maturity cultivars to 36 degree days per hour increase in photoperiod for one late maturity cultivar.
Effects of Irrigation on Accumulation of Soil and Symbiotically Fixed N by Soybean Grown on a Norfolk Loamy Sand1
Authors: Matheny T. A. , Hunt P. G. 
Published: July 2010

AbstractIn the southeastern Coastal Plain, soybean [Glycine max (L.) Merr.] is normally grown on soils that are often exposed to drought and leaching rains as well as being low in available N. A field study was conducted to evaluate the impact of water management on accumulation of soil and symbiotically fixed N by soybean grown on these type soils. Nodulating and nonnodulating isolines of ‘Lee’ cultivar soybean were grown under irrigated and nonirrigated conditions in 1979 and 1980 on a Norfolk loamy sand (fine‐loamy, mixed, mesic Typic Paleudults). A period of excessive rainfall occurred in 1979, while a major drought occurred in 1980. Irrigated treatments had lower soil‐NO‐3 concentrations in the Ap horizon than nonirrigated treatments during 1979, but there was no effect of irrigation on soil NO‐3 in 1980. Dinitrogen fixation, as estimated by the difference in N accumulation between nodulating and nonnodulating isolines, accounted for 76 to 91% of total plant N in the irrigated plots and 55 to 60% in the nonirrigated plots. Estimates of total plant N fixed exceeded 1100 mg/plant for the irrigated plots in 1979 and 1980. Maximum N accumulation for the nodulating isoline occurred in the nonirrigated plots in 1979 and in the irrigated plots in 1980. However, the nonnodulating isoline had maximum accumulations of both N and dry matter in the nonirrigated treatments in both 1979 and 1980. The number of nodules/plant and the C2H2‐reducing activity were significantly higher in the irrigated plots during the pod growth stages in 1980. Irrigation did not significantly affect seed yield of nodulating Lee soybean in 1979, but did result in a twofold increase in 1980. The effects of irrigation on the Lee nonnodulating isoline resulted in a positive yield response in 1980, but a negative response in 1979. These findings show that a major portion of the N‐requirement for soybean in the southeastern Coastal Plain is met by fixation and that the relative importance of fixed N may vary substantially with rainfall patterns and irrigation.