bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recycling in situ of Legume‐Fixed and Soil Nitrogen in Tropical Lowland Rice
Authors: George Thomas , Buresh Roland J. , Ladha Jagdish K. , Punzalan Gloria 
Published: July 2010

AbstractIn tropical rice lowlands, vegetation during the dry‐to‐wet season transition (DTW) facilitates in situ recycling of N from soil or legume biological nitrogen fixation (BNF) to wet‐season flooded rice. As little is known, we examined the fates of soil N and BNF N in DTW vegetation in a 2‐yr study on a Philippine Tropudalf using 15N‐labeled residues produced and soil‐incorporated in situ. During DTW, Sesbania rostrata (Bremek. & Oberm.), mungbean [Vigna radiata (L.) R. Wilczek var. radiata], weeds, and a weed‐free fallow were subplots in dry‐season main plots of weedy, weed‐free, and frequently tilled fallows. Rice yield and N uptake were not influenced by dry‐season fallows, which did influence soil N and BNF N in DTW vegetation and, therefore, the amount of soil N lost, removed in a product or recycled. Build‐up and decline of soil NH4−N occurred within 5 wk of residue incorporation, before significant N uptake by rice. Rice yield and N uptake responded to greater recycled DTW N; N uptake averaged 103 kg ha−1 with 208 kg S. rostrata N ha−1, 79 kg ha−1 with 62 kg mungbean N ha−1, 61 kg ha−1 with 41 kg weed N ha−1, and 44 kg ha−1 with no residue N. Nitrogen‐15 estimates of N recovery by rice (20% of S. rostrata N, 27% of mungbean N, 16% of weed N) were lower than the actual increase in rice N uptake due to residues. High proportions of residue N remained in soil, but N loss of 32% was estimated for S. rostrata N. As green manure (GM) N is ineffective beyond the first few weeks of incorporation, incorporating much legume N to flooded rice wastes valuable BNF N. Unmet rice N demand beyond early crop stage is better supplied with fertilizer N synchronized with rice N demand. A mixture of native weeds and GM legume is likely to prevent build‐up of soil NO∐3−N and allow BNF while limiting total N accumulation in the DTW vegetation for use as GM.
Management Studies on Seed Production of Turf‐Type Tall Fescue: II. Seed Yield Components
Authors: Young William C. , Youngberg Harold W. , Silberstein Thomas B. 
Published: July 2010

AbstractInformation on how management affects seed yield components of turf‐type tall fescue (Festuca arundinacea Schreber) cultivars is needed to improve cultural practices for seed production. We tested factorial combinations of two post‐harvest residue managements (flailchopping or burning the stubble), two row spacing (0.3 and 0.6 m), three spring‐applied N rates (100, 145, and 190 kg ha−1), and three N application timings (double‐ridge, spikelet initiation, and equally split between the two) on seed yield components of turf‐type cultivars Falcon, Rebel, and Bonanza, and the forage cultivar Fawn. Seed yields of all cultivars were closely correlated with the number of seeds produced per unit area (m2), but yields were weakly and negatively correlated with weight per seed. Compared with flail‐chopping, burning the residue increased the numbers of fertile tillers, floret sites, and seeds per unit area in all cultivars. The number of seeds per unit area was not affected by row spacing in Fawn and Bonanza, but was increased at 0.3‐m row spacing in Falcon when the residue was burned, and was greater at 0.6‐m in Rebel when the residue was flail‐chopped. Increasing N rate above 100 kg ha‐1 decreased floret site utilization and seeds per unit area in Fawn, but did not affect these components in Falcon and Rebel. Seeds per unit area in Bonanza was the greatest at 145 kg N ha‐1. For all cultivars, N application timing had little effect on seeds per unit area. We conclude that management practices for the turf‐type cultivars should focus on maintaining a high number of fertile tillers throughout the stand life by burning post‐harvest residue. Using narrower row spacings for early‐ and mid‐maturing turf‐type cultivars also could increase the number of fertile tillers per unit area when the post‐harvest residue is burned. The optimum spring‐applied N rate for seed production is apparently greater for the late‐maturing turf types than for forage cultivars.
Cover Crop Root Distribution and Its Effects on Soil Nitrogen Cycling
Authors: Sainju Upendra M. , Singh Bharat P. , Whitehead Wayne F. 
Published: July 2010

AbstractNitrate N in the soil is susceptible to leaching with fall and winter precipitation and can pollute groundwater. Winter cover crops to scavenge residual NO‐3 through root extension are a possible solution. A 2‐yr field study was conducted on a Greenville fsl (fine, kaolinitic, thermic Rhodic Kandiudults) in central Georgia to determine root distribution of legume and nonlegume winter cover crops and their ability to absorb soil NO‐3 and accumulate it in aboveground biomass. Cereal rye (Secale cereale L.), hairy vetch (Vicia villosa Roth), and crimson clover (Trifolium incarnatum L.) were planted in a prepared seedbed in the fall and accumulated biomass was incorporated into the soil in the spring. Seasonal variations in root distribution were measured by minirhizotron and soil separation methods. Soil mineral N concentration and aboveground biomass yield and N uptake were determined at regular intervals during the growing season. Total minirhizotron root count (MRC; no. roots cm−2 soil profile) at the 1‐ to 50‐cm soil depth increased at the rate of 0.01 roots cm−2 d−1 in hairy vetch in the fall to 0.38 roots cm−2 d−1 in crimson clover in the spring, as temperature increased. Roots were well distributed to the 50‐cm soil depth. Compared with the other cover crops, rye had significantly greater total MRC from Dec. 1996 to Feb. 1997 and total root length density (RLD; cm root length cm−3 soil) at the 0‐ to 30‐cm depth from Nov. 1995 to Apr. 1996 and in Jan. 1997, and the subsequent NO‐3 inorganic N concentration in the soil was lower and aboveground biomass yield was greater. MRC was positively correlated with RLD in Nov. 1995, Apr. 1996, and Jan. 1997. A significant positive correlation was observed between MRC and aboveground biomass yield or N uptake (r = 0.52 to 0.68, P ≤ 0.05) and a negative correlation between MRC and soil NO‐3 concentration (r = ‐0.51 to ‐0.55, P ≤ 0.05) early in the growing season. Rye had the greatest root density and aboveground biomass, and scavenged more soil NO‐3 early in the growing season. Nonlegume cover crops, such as rye, may be more effective in reducing residual NO‐3 and potential leaching of NO‐3 from the soil early in the growing season than are legume cover crops, such as hairy vetch or crimson clover.
Rotation and Fertilization Effects on Corn and Soybean Yields and Soybean Cyst Nematode Populations in a No‐Tillage System
Authors: Howard Donald D. , Chambers A. Y. , Lessman Gary M. 
Published: July 2010

AbstractRotations have long been used to improve crop yields. No‐tillage production acreage is increasing, and production information on rotation effects on yields and soybean cyst nematode populations is needed for this system. Field experiments were initiated in 1985 and continued through 1992 to evaluate P‐K fertilization effects on yield of a corn‐soybean [Zea mays L.‐Glycine max (L.) Merr.] rotation and on populations of soybean cyst nematode (Heterodera glycines Ichinohe) (SCN). The research was conducted on a Loring silt loam soil (a fine‐silty, mixed, active, thermic Oxyaquic Fragiudalf), using no‐tillage management. The experimental design was a split‐plot for corn evaluation and split‐split‐plot for soybean evaluation. Individual treatments were replicated five times. Main plots were broadcast P‐K rates of 0–0, 15–28, 29–56, 44–84, and 59–112 kg ha−1. The split‐plots were continuous corn, continuous soybean, a corn‐soybean rotation, and a soybean‐corn rotation. The split‐split‐plots were two soybean cultivars possessing different levels of SCN resistance. Yields of both crops were increased by the fertilization. In this study, corn yields were increased 14% and soybean yields increased 11% with the rotation. Rotating the two cultivars produced similar yields and nonrotated yields of resistant TN 4‐86 were higher than susceptible Essex, indicating an effect of SCN. The primary benefit of corn in the rotation was to reduce SCN populations. However, within Essex rotations the SCN population recovery was rapid, while populations remained relatively low in the TN 4‐86 rotations. The SCN populations were greater when rotations were fertilized with the two lowest P‐K rates, compared with populations within the unfertilized check and the highest P‐K rate. Soybean producers should consider a no‐tillage system of rotating corn with SCN‐resistant soybean cultivars, fertilized at high P and K rates for yield improvement and reduced SCN populations.
Changes in Soil Chemical Properties Resulting from Organic and Low‐Input Farming Practices
Authors: Clark M. Sean , Horwath William R. , Shennan Carol , Scow Kate M. 
Published: July 2010

AbstractSoil chemical properties during the transition from conventional to organic and low‐input farming practices were studied over 8 yr in California's Sacramento Valley to document changes in soil fertility status and nutrient storage. Four farming systems differing in crop rotation and external inputs were established on land previously managed conventionally. Fertility in the organic system depended on animal manure applications and winter cover crops; the two conventional systems received synthetic fertilizer inputs; the low‐input system used cover crops and animal manure during the first 3 yr and cover crops and synthetic fertilizer for the remaining 5 yr. At 4 and 8 yr after establishment, most changes in soil chemical properties were consistent with predictions based on nutrient budgets. Inputs of C, P, K, Ca, and Mg were higher in the organic and low‐input systems as a result of manure applications and cover crop incorporations. After 4 yr, soils in the organic and low‐input systems had higher soil organic C, soluble P, exchangeable K, and pH. Ceasing manure applications in the low‐input system in Year 4 resulted in declining levels of organic C, soluble P, and exchangeable K. Crop rotation (the presence or absence of corn) also had a significant effect on organic C levels. Differences in total N appeared to be related in part to inputs, but perhaps also to differing efficiency of the farming systems at storing excess N inputs: the low‐input system appeared to be most efficient, and the conventional systems were least efficient. Electrical conductivity (EC), soluble Ca, and soluble Mg levels were tightly linked but not consistently different among treatments. Relatively stable EC levels in the organic system indicate that animal manures did not increase salinity. Overall, our findings indicate that organic and lowinput farming in the Sacramento Valley result in small but important increases in soil organic C and larger pools of stored nutrients, which are critical for long‐term fertility maintenance.
Modeling Freezing Injury in Alfalfa to Calculate Forage Yield: I. Model Development and Sensitivity Analysis
Authors: Kanneganti V. Rao , Rotz C. Alan , Walgenbach Richard P. 
Published: July 2010

AbstractFreezing injury can cause extensive yield loss in alfalfa (Medicago sativa L.) exposed to severe winters in cold climates. Existing simulation models for alfalfa either do not account for freezing injury effects or do not differentiate cultivars for their varying response to freezing stress and subsequent effects on crop productivity. The objective of this project was to incorporate cultivar‐specific effects of freezing injury on forage dry matter (DM) yield into an existing alfalfa growth model to calculate annual forage yield during the life of an alfalfa crop. Numerical functions of cold tolerance, fall dormancy, and freezing injury were developed and integrated with the growth processes in the ALSIM 1 (Level 2) alfalfa model. The new model, ALFACOLD, requires input of: daily solar irradiance, maximum and minimum air temperature, and precipitation; latitude; dates of harvest; cultivar's fall growth score (FGS); initial plant density; and maximum plant‐available water in the root zone. The plant components modeled were leaf, stem, buds, and total nonstructural carbohydrates accumulated in the crown and root tissue. The model integrates the effects of soil moisture deficit, temperature, solar irradiance, and plant density on alfalfa growth, and the effects of subzero (°C) temperature on freezing injury and associated yield loss. Sensitivity of calculated forage DM yield to a ±25% change in selected model parameters was measured in cultivars of FGS 2, 3, and 4 during three production years of a 4‐yr alfalfa crop. The model did not simulate growth during a seeding year. A cultivar's rate of cold hardening and lowest temperature tolerance during autumn and winter influenced forage yield more than did the rate of dehardening in the spring. Field validation of ALFACOLD calculations of forage yield is presented in a companion paper.
Rhizoma Peanut Responses to Harvest Frequency and Nitrogen Fertilization on Louisiana Coastal Plain Soils
Authors: Venuto Brad C. , Redfearn Daren D. , Pitman W. D. 
Published: July 2010

AbstractDespite limitations in stand establishment, rhizoma peanut (Arachis glabrata Benth.) is the only sustainable, productive, high‐quality, perennial, warm‐season legume available for the Coastal Plain of the lower Gulf Coast Region. Management to enhance productivity could increase acceptance of this relatively unexploited forage. Yield responses of rhizoma peanut to harvest frequency and N fertilization on Louisiana Coastal Plain soils were evaluated. Nitrogen rates of 0, 85, and 170 kg ha−1 were applied to a Dexter loam soil (Ultic Hapludalfs) in a greenhouse experiment. At three field locations, N rates were 0, 110, and 220 kg ha−1 and harvest frequencies were 30 and 60 d. Soils were the Dexter loam, Tangi silt loam (Typic Fragiudults), and Bowie fine sandy loam (Plinthic Paleudults). In the greenhouse, N accumulated in herbage (30 g kg−1 with 170 kg N ha−1 vs. 20 g kg−1 for the control) with a subsequent linear yield increase. In the field, the only responses to N fertilizer were small increases in N concentration of rhizomes plus stubble. Interactions of harvest frequency and location on herbage yield indicated effects of weather. This effect is illustrated by the 790 kg ha−1 advantage of the 30‐d harvest frequency on the Tangi silt loam in May–June vs. the 1930 kg ha−1 advantage of the 60‐d harvest frequency on the Bowie fine sandy loam in July–August. Thus, on the Louisiana Coastal Plain, yield of rhizoma peanut is not likely to be increased by N fertilization, and harvest frequency or length of regrowth period is not a reliable determinant of yield.
Soil Nitrate Accumulation and Corn Response to Preceding Small‐Grain Fertilization and Cover Crops
Authors: Vyn Tony J. , Janovicek Ken J. , Miller Murray H. , Beauchamp Eric G. 
Published: July 2010

AbstractPotential benefits associated with establishing cover crops, such as reduced NO3 leaching risk and lower fertilizer N requirements for succeeding crops, will be fully realized only when the cover crop N contribution is accurately accounted for and availability is synchronous with succeeding crop N demands. The objectives of this study were to evaluate spring soil NO3−N accumulation patterns and N availability to corn (Zea mays L.) following annual ryegrass (Lolium multiflorum L.), oilseed radish [Raphanus sativus (L.) var. oleiferus (Stokes) Metzg.], red clover (Trifolium pratense L.), and no cover crop established after either winter wheat (Triticum aestivum L.) or barley (Hordeum vulgare L.). The wheat and barley were produced with 0.5, 1.0, and 2.0 times the amount of recommended N fertilizer. Six field trials were conducted on well‐drained Typic Hapludalf soils in southwestern Ontario intermittently from 1989 to 1995. Corn was produced using a spring mulch‐till system with only 10 kg ha−1 of fertilizer N, which was applied as part of the P starter fertilizer. Applying more fertilizer N to the previous year's small‐grain crop rarely increased spring soil NO3−N concentrations or corn yields. Soil NO3−N concentration increases between the May and June sample dates following annual ryegrass and oilseed radish did not differ substantially from where a cover crop had not been established; following red clover, however, NO3−N increases were always at least 2.8 times greater than after no cover crop. Average aboveground corn biomass N at anthesis following annual ryegrass was 25.6 kg ha−1 less than when no cover crop was grown, whereas following red clover it was 40.4 kg ha−1 greater than with no cover crop. Corn yields were consistently the highest following red clover and often the lowest following annual ryegrass; yield response was positively correlated with June soil NO3−N concentrations (r = 0.61‐0.93). These results suggest that N availability to succeeding corn differs among the cover crop treatments evaluated in the order red clover > oilseed radish ≥ no cover crop > annual ryegrass.
Ammoniacal Nutrition of Transplanted Rice Fertilized with Large Urea Granules
Authors: Gaudin Remi , Dupuy Jacques 
Published: July 2010

AbstractWith deep placement of large urea granules in wetland rice (Oryza sativa L.) cultivation, N is protected from various loss mechanisms and quite well recovered by plants. The objective of this study, which was based on soil solution measurements, was to examine the relation between the localized NH3−rich area deriving from one granule and the surrounding plants. The influence of rice on the ammoniacal N was examined in terms of a model of diffusion describing the time course of the ammoniacal N concentration. Treatments were granule mass (1, 2, 3, and 4 g). Since greater amounts of NH3 are expected for larger granules, we asked whether this would hinder N consumption by the plant, and thus delay disappearance of the ammoniacal N from the soil. The soil solution was sampled with probes buried close to the granules. Urea was quickly hydrolyzed in the soil: 78 to 91% of the reaction was performed within 4 d and 95 to 98% within 13 d. As early as 4 d, the ammoniacal N generated was 0.313 mol dm−3 for 2‐g granules, with a diffusion coefficient for NH3 of 0.998 cm2 d−1 (equivalent to an instantaneous point source of NH3). In the field, diffusion drove the time course of NH3 until 10 mmol dm−3, a level attained earlier in the lower‐mass treatments (1 and 2 g) than in the 3‐ and 4‐g treatments. Thereafter, the patterns of NH3 disappearance changed: the lower‐mass treatments displayed a faster evolution than the larger treatments. This change indicates a different speed in the consumption of ammoniacal N, possibly in relation with the vegetative or reproductive stage of the plant, throughout the carbon investment into NH3 assimilation. The granule‐rice system is proposed as a model for research on source‐sink relationship at the whole‐plant level.
Performance of Sweet and Forage Sorghum Grown Continuously, Double‐Cropped with Winter Rye, or in Rotation with Soybean and Maize
Authors: Buxton Dwayne R. , Anderson Irvin C. , Hallam Arne 
Published: July 2010

AbstractDouble‐cropping sorghum [Sorghum bicolor (L.) Moench] with winter rye (Secale cereale L.) could increase annual dry matter production in the North‐Central region of the USA and reduce soil erosion and other environmental concerns. We conducted this study to compare yield, chemical composition, erosion potential, and economics of sorghum grown continuously (sole crop), in a 3‐yr rotation with maize (Zea mays L.) and soybean [Glycine max (L.) Merr.], or double‐cropped with winter rye (rye‐sorghum). The experiment was on a Typic Calciaquoll soil in central Iowa with a slope of less than 1% and on mixed Vertic Argiaquoll, Typic Hapludoll, and Aquertic Argiudoll soils in southern Iowa with 2 to 7% slope. Applied N moderately affected sole‐cropped sorghum, with yields of 13.5, 16.1, 16.9, and 15.9 t ha−1 when fertilized with 0, 70, 140, and 280 kg ha−1 N, respectively. Rye‐sorghum was highly responsive to N, with combined yields at 72, 84, 95, and 110% of sole‐cropped sorghum fertilized with the same annual rate of N. Drought dramatically reduced rye‐sorghum yields. Sole‐cropped sweet sorghum had yields similar to sweet sorghum grown in the 3‐yr rotation. Environmental conditions associated with years and locations affected fiber components, N, and total nonstructural carbohydrate concentrations of sorghum. Use of the Universal Soil Loss Equation revealed that planting rye before sorghum would reduce estimated soil loss at both locations, but the loss was still unacceptably high on the sloping soil in southern Iowa (22 t ha−1). An economic partial budget showed that ryesorghum cost $147 ha−1 more to produce than sole‐cropped sorghum. We conclude that, if winter rye is to be grown as a double crop with sorghum in the North‐Central region, it will likely be because of its positive influence on the environment and not because of potential for improved yield.
Midseason Stalk Breakage in Corn As Affected by Crop Rotation, Hybrid, and Nitrogen Fertilizer Rate
Authors: Wilhelm Wallace W. , Liebig Mark A. , Varvel Gary E. , Blackmer Tracy M. 
Published: July 2010

AbstractIn July of 1993 and 1994, southern Nebraska experienced devastating windstorms, with winds estimated to exceed 45 m s−1. These storms resulted in severe brittle‐snap of corn (Zea mays L.), with stalks breaking near the primary ear node in the basal portion of an elongating internode. In the storm path were several experiments established on a Hord silt loam (Cumulic Haplustolls) to determine the effect of selected management practices (crop rotation, hybrid selection, planting date, and N fertilization) on nitrate leaching to ground water from irrigated cropland. After the storms, the number of broken plants was determined in these experiments to evaluate how management practices influenced severity of the damage. In 1993, crop rotation, hybrid, planting date, and N fertilization, and their interactions, all affected the amount of brittle‐snap. Treatments that resulted in more rapid growth (optimum to excess N rates, corn rotated with soybean [Glycine max (L.) Merr.], and early planting) increased the severity of damage. In continuous corn, 7% of the plants broke, compared with 33% for rotated corn; damage ranged from 4 to 33% among hybrids; and percent broken plants increased quadratically, from 8% for the 0 kg N ha−1 treatment to 24% at N rates equal to or greater than 80 kg N ha−1. Only the hybrid factor was significant in 1994. Amount of brittle‐snap was related to stage of development (r = 0.55, n = 160, P < 0.001). The great difference in severity of damage among hybrids indicates that the current best management strategy to limit brittle‐snap losses is to plant hybrids less prone to breakage. Alternative management strategies, such as late planting, suboptimal N rates, and continuous cropping of corn, all are known to limit yield regardless of windstorms. There is a need for greater knowledge of cell and tissue characteristics that render hybrids susceptible or resistant to brittle‐snap. Also, methods for simulating brittlesnap are needed to foster effective selection for resistant lines in breeding programs.