bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water Transport Characteristics of Cotton as Affected by Drip Irrigation Layout
Authors: Moreshet Samuel , Fuchs Marcel , Cohen Yehezkel , Cohen Yefet , Langensiepen Matthias 
Published: July 2010

AbstractTo reduce drip irrigation equipment costs, dripper lines are laid in alternate interrow spaces. This study examined the effect of this practice on cotton (Gossypium hirsutum L.) water relations. Measurements of water uptake and water potential of plants grown in the field were conducted during four rainless summers at two locations. During the first summer, drippers in every interrow space delivered about 50 mm of water, the exact amount depending on estimated evapotranspiration (ET), every 10 d. The following summer, drip lines were laid in alternate interrow spaces, applying frequent (2‐4 d) and small (10‐20 mm) amounts of water, based on estimated ET. Treatments were repeated the following two summers. Measurements included water uptake (F), leaf water potential (ψ1, and soil water content. Whenever a linear relationship between diurnal ψ1 and F was found, we determined the hydraulic conductance (KT) of the plants as the line's slope reciprocal, and the intercept (ψ0) as the water potential at the root‐soil interface. A linear relation was found in the treatment with drippers in every interrow space. Water stress developed toward the end of the irrigation interval, causing KT to decrease without affecting ψ0. Irrigation restored KT to its initial value. With the alternate interrow‐space pattern, the relationship between ψ1 and F remained linear only until midday. Afternoon (ψ1, F) points were below those of the morning, suggesting a lowering of the soil water potential near the roots. It was concluded that drippers laid in alternate interrow spaces expose cotton to frequent short periods of water stress.
Sorghum Response to Saline Industrial Cooling Water Applied at Three Growth Stages
Authors: Ulery April L. , Ernst Frederick F. 
Published: July 2010

AbstractSaline wastewater from industrial or agricultural sources may be an alternative irrigation supply in arid regions if effective crop and water management strategies for their use are developed. A field experiment was conducted to determine if grain yields of sorghum [Sorghum bicolor (L.) Moench] irrigated with undiluted saline waste‐water from cooling towers of an electrical power generation plant can be significantly increased by applying nonsaline water at a critical growth stage. The wastewater had an average electrical conductivity (EC) of 0.67 S m−1 and was high in CaSO4. Plot studies were conducted for 4 yr using conventional cultural practices and sprinkler irrigation on Tujunga loamy sand—Hanford fine sandy loam soil (mixed, thermic Typic Xeropsamment—coarse‐loamy, mixed, nonacid, thermic Typic Xerorthent). Highest grain yields were obtained from the nonsaline control plots and from treatments that received nonsaline water during either the vegetative or reproductive growth stages. Plant height decreased in response to salinity, and differences between treatments were apparent by 27 d after planting. Plant height and grain yield were both negatively correlated with soil salinity by the 3rd yr of the experiment. Over an extended length of time, the best treatment for maximizing yield and utilizing saline wastewater is the application of nonsaline water early in the season to germinate and establish seedlings, followed by saline water during the grain‐filling stage.
Grass–Legume Bicultures as Winter Annual Cover Crops
Authors: Ranells Noah N. , Wagger Michael G. 
Published: July 2010

AbstractGrass‐legume bicultures as winter annual cover crops may combine the N scavenging ability of grasses and the biological N2 fixation capacity of legumes to improve N management in crop production systems of the southeastern USA. A 3‐yr field experiment was conducted on a Norfolk loamy sand (fine‐loamy, kaolinitic, thermic Typic Kandiudults). The focus of this research was to examine the differences among legume monocultures and grass‐legume bicultures with regard to early spring dry matter (DM) and N accumulation, and related effects on soil inorganic N levels and subsequent corn (Zea mays L.) yield. Austrian winter pea [Pisum sativum L. subsp, sativum var. arvense (L.) Poir.], crimson clover (Trifolium incarnatum L.), commonve tch (Vicla saava L.), and hairy vetch (Vicla villosa Roth) were grown in monoculture and in bicultures with rye (Secale cereale L.), oat (Arena satira L.), and wheat (Triacum aestivum L.). Aboveground plant material was harvested in early March, late March, and mid‐April. Biomass was separated into component species and analyzed for total N and C concentrations. Averaged over 3 yr, legume component DM accumulation in monoculture and biculture ranged from 0.87 to 2.53 Mg ha−1, with a ranking of Austrian winter pea < hairy vetch < commonv etch < crimson clover. For the same period, the grass component DM accumulation ranged from 1.31 to 2.28 Mg ha−1, in the order rye = oat < wheat. Three‐year mean N accumulation values for the legume component followed the same relative ranking and ranged from 24 to 93 kg N ha−1. Grass factor N content ranged from 18 to 39 kg N ha−1 in the order rye < oat < wheat. For all bicultures, the average C:N ratio over the 3‐yr experiment was >30, suggesting that net N mineralization would occur from the decomposing cover crop residues. Profile soil inorganic N (0 to 90 cm) was greater in legume monoculture than in grass‐legume biculture treatments, indicating the ability of grasses to capture soil N. Corn yield was affected by the treatments in 1 of 3 yr, with greater yields following a legume monoculture than a grass‐legume biculture. Collectively, these results suggest that grass‐legume bicultures as winter annual cover crops have the potential to utilize residual soil NO3 and thereby minimize leaching while adding fixed N to cropping systems in the southeastern USA.
Deep and Shallow Banding of Phosphorus and Potassium as Alternatives to Broadcast Fertilization for No‐Till Corn
Authors: Bordoli José M. , Mallarino Antonio P. 
Published: July 2010

AbstractProper P and K management for no‐till crops is uncertain. Potential problems include inappropriate extrapolation of soil test interpretations and fertilizer recommendations from conventional tillage, inappropriate soil sampling techniques, and inefficient fertilizer placement. This study compared broadcast, deep‐band, and planter‐band P and K placements for no‐till corn (Zea mays L.). Long‐term P and K trials were established in 1994 at five Iowa research centers and were evaluated for 3 yr. Eleven short‐term P‐K trials were established in farmers' fields during the same period. Treatments were various P (0 to 56 kg P ha−1) and K (0 to 132 kg K ha−1) rates broadcast, banded with the planter 5 cm beside and below the seeds, and deep‐banded at the 15‐ to 20‐cm depth before planting. Soil samples were collected from the 0‐ to 7.5‐cm and 7.5‐ to 15‐cm depths prior to planting. Soiltest P (PST) at the 0‐ to 15‐cm depth ranged from very low to very high across sites; soil‐test K (KST) ranged from optimum to very high. There were grain yield responses to fertilization at several sites, but no significant differences between the P or K rates and no interactions between rates and placements. Phosphorus increased yields only in soils testing very low or low, and there was no response to P placement at any site. Potassium increased yields in several soils that tested optimum or higher in KST, and yields were higher when K was deepbanded. High rates of broadcast or planter‐banded K did not offset the advantage of deep‐banded K. Responses were better related with deficient rainfall in late spring and early summer than with KST. Current soil‐test P interpretations and P fertilizer recommendations based on chisel‐plow tillage are appropriate for most Iowa soils managed with no‐tillage. Further work is needed to better characterize and predict responses to deep‐banded K. Because yield response was small, the cost‐effectiveness of deep‐band K will be determined largely by application costs.
A Canopied Sprayer for Accurate Application of Herbicides
Authors: Ginn Lawrence H. , Adams E. Ray , Heatherly Larry G. , Wesley Richard A. 
Published: July 2010

AbstractPreemergent and postemergent herbicides applied to research plots must be confined to the target area and crop. Our objective was to develop an apparatus that could be used to apply herbicides effectively for weed control in randomized field plots of multiple crops with no injury to nontarget crops in adjacent plots. A canopied sprayer that attaches to a row‐crop tractor having a standard Category I or II three‐point hitch and a PTO was designed and constructed. This sprayer delivered broadcast‐ and band‐applied herbicides to small plots without causing drift‐related injury to nontarget crops planted in adjacent plots. Use of this sprayer eliminated wind‐blown drift, and ensured the confinement of herbicides to target plots, alleys, and borders.
Nitrogen Dynamics of Various Green Manure Species and the Relationship to Lowland Rice Production
Authors: Clément Alain , Ladha Jagdish K. , Chalifour François‐P. 
Published: July 2010

AbstractGreen manure (GM) is an alternative to mineral fertilizers, particularly for subsistence farmers whose resource base is small. Published information on the influence of the chemical composition of GM on N dynamics in lowland rice (Oryza sativa L.) is scarce. A field experiment was conducted in the 1992 wet season (WS), the 1993 dry season (DS) and the 1993 wet season to compare GM species and urea as sources of N for rice, to monitor N release and uptake during the season, and to verify the effect of the chemical composition of GM on rice yield (including the residual effect on dry season rice). Ten species were compared, with two controls (with and without deep‐placed urea supergranules). Nitrogen from urea or GM crops was applied at the rate of 80 kg N ha−1. Most GM species performed as well as urea supergranules. Cowpea [Vigna unguiculata (L.) Walp.], soybean [Glycine max (L.) Merr.], and sorghum [Sorghum bicolor (L.) Moench] outyielded the urea control in the 1992 wet season. Residual effects of GM incorporation on rice grain yield during the 1993 dry season were generally modest. Rice grain yield response to GM application was comparable for both the 1992 and 1993 wet seasons (r2 = 0.83**). In microplots without rice plants, there was limited GM‐N mineralization past 30 days after transplanting (DAT). Soil NH+4‐N with rice increased until about 20 DAT, and then decreased sharply, because of rice N uptake. At 50 DAT, soil NH+4‐N reached very low levels in all treatments. Rice N uptake between 31 and 52 DAT was explained by the size of early‐season soil NH+4‐N pool (r2 = 0.83**). Higher N uptake rates by rice with GM than with urea from 52 to 69 DAT indicate a better synchrony between GM‐N availability and rice N uptake. The C/N ratio of GM species influenced rice N uptake, but only early in the season.
Are Simulation Models Ready for Agricultural Research in Developing Countries?
Authors: Mutsaers H. J. W. , Wang Zaoqian 
Published: July 2010

AbstractAs an example of the application of simulation modeling in developing countries, the SARP (Simulation and Systems Analysis for Rice Production) project is reviewed. SARP promoted the ORYZA models for paddy rice (Oryza sativa L.) research in Southeast Asia. The models successfully simulated crop growth as affected by canopy photosynthesis, sink capacity, and N nutrition. The rather crude plant physiology in these and similar models limits their usefulness in simulating the effect of morphological modifications and the response to various stress factors. Modeling skills developed by SARP in Asian research institutes cannot be maintained without continued coordination from advanced institutes. More basic knowledge on the plant's morphogenesis and feedback mechanisms is required for effective simulation of plant adaptation to complex growth environments, including intercropping, as found in many developing countries. A more rigorous modular approach to modeling is advocated, as well as standardization of modules for well‐understood processes, as part of a toolkit for applied research for use in combination with other techniques, including statistical techniques.
Insect Defoliation and Population Dynamics in Blends of Resistant and Susceptible Soybean Cultivars
Authors: Sij John W. , Bowers Glenn R. , Way M. O. , Boykin D. L. 
Published: July 2010

AbstractPhytophagous insects can cause significant economic yield loss in soybean [Glycine max (L.) Merr.] production areas of the southern United States. Although breeding efforts have resulted in developing insect‐resistant cultivars, the yield potential of these cultivars is generally lower than conventional cultivars under conditions of light insect pressure. The objective of this study was to determine if a blend of insect resistant and insect susceptible cultivars affords some degree of insect control while maintaining high yields under high insect pressure environments. Experiments were conducted on a Labelle soil (Oxyaquic Vertic Argiaquolls) near Beaumont, TX, in 1990 to 1992. The 3‐yr field study included five population ratios of Maturity Group VIII cultivars Dowling (insect susceptible, S) and Crockett (insect resistant, R): 100 S:0 R, 75 S:25 R, 50 S:50 R, 25 S:75 R, and 0 S:100 R. Plots were sampled weekly for insects and percent leaf defoliation when insect populations began to increase in late summer. Data were analyzed with blend treated as a linear trend. Insect counts of six major pests showed that, of 18 possible year‐insect combinations, in only three cases were there significant population differences due to blend. In late season, the percent defoliation of Crockett increased in all 3 yr as the percentage of Crockett in the blend increased. By contrast, as the percentage of Dowling in the blend increased, the percent defoliation of Dowling decreased in 2 of the 3 yr. Therefore, blending Crockett and Dowling did not offer insect defoliation protection for Dowling and may have had an opposite effect. Maximum percent defoliation for Crockett was generally 40 to 50% less than that for Dowling. In 1990 and 1991, blending had no effect on yield or seed quality. In 1992, there was a significant, negative effect on yield (b = −4.46) and seed quality (b = 0.01) as the percentage of Crockett increased in the blend. Blends of these cultivars did not improve yield of Dowling under conditions of insect pressure compared with a pure stand of Dowling. A blend of insect resistant and susceptible cultivars did not appear to be a suitable insect control management strategy in soybean.
Bermudagrass Response to High Nitrogen Rates, Source, and Season of Application
Authors: Osborne Shannon L. , Raun William R. , Johnson Gordon V. , Rogers Jerry L. , Altom Wadell 
Published: July 2010

AbstractHigh N rates and source of N have been thoroughly evaluated in bermudagrass [Cynodon dactylon (L.) Pers.] forage production, but less is known concerning season of application and estimated fertilizer N recovery in these systems. Two field studies (Ardmore, OK: Wilson silt loam, Vertic Haplustalfs; Burneyville, OK: Minco fine sandy loam, Udic Haplustolls) were conducted at two locations over two years to evaluate the effects of rate, timing, and source of N on bermudagrass forage yield, total N, NO3 concentration, and estimated fertilizer N recovery. Nitrogen was applied at rates of 112, 224, 448, 672, and 1344 kg N ha−1 as NH4NO3 or urea in early spring (March) and late summer (August). Fertilizer N recovery can be maximized at rates of 112 and 224 kg N ha−1 applied in the early spring and late summer, respectively. Even when N rates of 1344 kg N ha−1 were applied annually, bermudagrass forage NO3‐N was seldom above 2000 mg kg−1, which is below published toxic levels (2400–4500 mg kg−1) for cattle (Bos taurus) consumption. Early‐spring applied N increased yields, N removal, and fertilizer recovery compared with late‐summer applied N. Fertilizer N recovery was higher for NH4NO3 than for urea, especially when applied in late summer. Late‐summer applications of urea should be avoided, due to increased NH3 volatilization losses. Nitrogen applied at 112 kg N ha−1 in early spring can result in fertilizer recoveries in excess of 85%. These high recoveries in forage production systems are possibly a result of continuous preanthesis forage harvesting when gaseous plant N losses are small, but which increase following anthesis.
A Procedure for Control of pH in Cation Uptake Studies with Excised Barley Roots
Authors: Parr J. F. , Norman A. G. 
Published: July 2010

AbstractA procedure for the control of pH of salt solutions in cation uptake studies with excised roots is described. Through the addition of small increments of an anionic exchange resin in OH‐ form during the absorption period, it was possible to maintain the pH at a desirable physiological level and within quite narrow limits. Whole excised barley roots exhibited maximum K+ absorption activity when pH of solutions was resin‐controlled. The rapid change in external cation concentration which occurs in high root‐to‐solution ratio experiments is not accompanied by a reduction in uptake rate between the first and sixth hour. Good reproducibility was observed with this procedure not only between replicates but also with different batches of roots.Potassium absorption by whole excised roots and shorter root segments cut from the same barley root culture was compared. With the whole excised roots as a control, the amount of K+ absorbed at the end of 6 hours was reduced by 12% for 3‐cm. segments and by 25% in the case of 1‐cm. segments. Any apparent advantage of cutting roots into short segments to achieve greater homogeneity of subsamples is out‐weighed by a lowered net cation absorption capacity.
Photosynthesis in K‐ and Mg‐Deficient Maize (Zea mays L.) Leaves
Authors: Peaslee D. E. , Moss D. N. 
Published: July 2010

AbstractRates of photosynthesis in maize leaves were closely related to K or Mg concentrations in the leaf tissue. The critical concentrations were about 2 mg/g for K and 200 µg/g for Mg on a fresh weight basis. Normal‐appearing leaves of K‐stressed plants had sharply diminished photosynthesis rates, whereas Mg deficiency affected photosynthesis rates only after the appearance of chlorosis. Apparently Mg deficiency exerted an influence through chlorophyll deterioration while K deficiency decreased stomatal apertures. Application of the deficient nutrient caused marked recovery within 24 hours of K‐deficient leaves but not of Mg‐deficient leaves.
Sampling Soil and Foliage in a Pine Plantation
Authors: Metz Louis J. , Wells Carol G. , Swindel Benee F. 
Published: July 2010

AbstractAnalyses were made of N, P, K, Ca, and Mg on foliage from 256 young loblolly pine trees (Pinus taeda L.) growing in a plantation. Soil samples from beneath each tree were also analyzed for the same nutrients. Only a small portion of the variation in foliage content could be accounted for by variation in the nutrient level of the soil. Recommendations (number of plots and number of trees) are given for sampling both foliage and soil.
Generalizing Water Table Data
Authors: Nelson L. A. , Daniels R. B. , Gamble E. E. 
Published: July 2010

AbstractA 17 variable multiple linear regression model was developed to predict water table levels over time for individual sites in the Coastal Plain of North Carolina. Because equations were developed individually for each site, the variables involved were mainly meteorological. They included month of year, cumulative rainfall, antecedent rainfall, and relative humidity. The model fit well in 42 of 48 sites.By using the deviations from prediction for the datum points from which the regression equation for a site was developed, it is possible to isolate instances where the prediction was poor. These usually were cases where the water table was below the bottom of the test well for several weeks as it is frequently in wells ending in fragipan or plinthite horizons. For fall months the model tends to overpredict water levels in dry years and underpredict in wet years.Advantages of the approach described are that it allows evaluation of the relative importance of the factors which together influence the water table, it allows comparisons among sites using the data for the same or different periods of time, and it is simple to use if electronic computational equipment is available.
Experimental Designs to Evaluate Crop Response on Adjacent Soil Mapping Units
Authors: Nelson L. A. , Buol S. W. 
Published: July 2010

AbstractSoil mapping units are scaled representatives of naturally occurring soil properties and serve as reference units for technology transfer. To accurately evaluate the interactions between a given management practice and a range of soil properties represented by a soil mapping unit, tailoring of the experimental design is required. This paper identifies the design principles involved in setting up field experiments to compare the responses to different management treatments of crops grown on areas within different soil mapping units, and suggests experimental designs for this purpose. Representation of the entire soil mapping unit in the area studied is emphasized. Repetition of experiments across locations, years, or both is recommended if the inferences are to apply to more than one environment and if a test of the main effect of the area represented by the soil mapping unit is desired. Procedures for designing a series of experiments and analyzing the resulting data are discussed.
Monitoring Surface Changes of Bare Soils due to Slaking Using Spectral Measurements
Authors: Courault Dominique , Bertuzzi Patrick , Girard Michel‐Claude 
Published: July 2010

AbstractThe structural degradation of the soil surface due to rainfall makes the surface more susceptible to erosion. Loamy soils are particularly vulnerable to slaking, seal development, and crusting. The sealing process occurs in different stages. This study examined the possibility of using visible and near‐infrared reflectances for detecting these surface changes due to rainfall, and for defining optimal conditions for spectral measurements. Experimentation was conducted under field‐controlled conditions using a SPOT satellite simulation radiometer. Radiometric measurements were made at three solar altitudes: 0600, 1200, and 1800 h GMT, at five different stages of surface degradation following simulated rainfall. Ground measurements consisting of Munsell color, water content, and surface roughness were made simultaneously to characterize surface changes. The influence of these various factors on reflectance was analyzed. Soil water was the main source of variation in reflectance, while surface roughness was a factor of secondary importance. Reflectance increased with increased roughness and decreased soil water content. A combination of red and near‐infrared reflectances made it possible to identify different soil lines according to soil water content, solar angle, and slaking stage. Optimal conditions for monitoring surface changes were those where the solar altitude is the lowest for dry soils. Different slaking stages can also be detected by reflectances performed at 1200 h under dry conditions.