bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Double‐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

In 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.
Calibrating the Root Zone Water Quality Model
Authors: Hanson Jonathan D. , Rojas K. W. , Shaffer Marvin J.
Published: July 2010

Techniques to reliably calibrate computer models are needed before the models can be applied to help solve natural resource problems. The USDA‐ARS Root Zone Water Quality Model (RZWQM) is a comprehensive simulation model designed to predict hydrologic and chemical response, including potential for ground‐water contamination, of agricultural management systems. RZWQM Version 3.2 was calibrated and evaluated at sites in Iowa, Minnesota, Missouri, Nebraska, and Ohio as part of the Management Systems Evaluation Areas (MSEA) project and at a site near Sterling in northeastern Colorado. Soil horizon description and a description of the physical and hydraulic properties of the soil were required to initialize the model. Calibration for nutrient cycling involved adjusting the model coefficients for mineralization, infiltration, and denitrification. Initial N pool sizes were estimated using medium to long‐term computer simulations. Maximum N uptake rate, plant respiration, specific leaf area, and the effect of age at the time of propagule development and senescence were used to calibrate the plant production and yield component. To match the observed results for soil water, N, and plant growth, an iterative approach for calibrating the model was followed. When done methodically, total biomass estimates were within 5%, yield estimates were within l0%, and N uptake was within 20% of field measurements. Calibration of the C and N dynamics module produced results that were generally within 20 to 50 kg ha−1 of measured values for soil profile NO−3‐N. Independent evaluations of the calibrated model focused on four indicator output variables related to plant growth—total biomass, yield, N uptake, and N in the soil profile. Predictions matched the observed data in most cases. The crop model is very sensitive to plant N content. Even small errors in simulating N uptake levels can result in substantial errors in estimates of yield and total aboveground biomass. The model predicted biomass and yield well on irrigated and most dryland management systems and adequately simulated crop variables at various positions along the landscape.
Plant Production Model Evaluation for the Root Zone Water Quality Model (RZWQM 3.2) in Ohio
Authors: Landa Feliks M. , Fausey Norman R. , Nokes Sue E. , Hanson Jonathan D.
Published: July 2010

The Ohio Management Systems Evaluation Areas (MSEA) project focused on developing and evaluating improved agricultural management systems and predictive models. The Root Zone Water Quality Model (RZWQM) is an environmental model for simulating water, chemical, and biological response of agricultural management systems. This paper presents calibration and evaluation of the generic plant production model of RZWQM, as well as some evaluation results for the nitrate and soil water content predictions. Corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] biomass data collected at the Ohio MSEA from 1991 to 1993 were used for evaluation. Data from 1992 were used in calibrating RZWQM, and data from two other years (1991 and 1993) at the same site were used for validation. Crop growth predictions were compared with observed values of leaf, stem, and seed biomass collected throughout the growing season. Leaf and stem biomass predictions generally fell within 1 SD of the observed values, but for all years there were dates when predictions were outside of the observed range. RZWQM predicted seed biomass or yield adequately for all 3 years, with predictions falling within 1 SD of the observed values. Soil water content estimates for corn were higher than observed values late in the season, perhaps because of underestimates of evapotranspiration due to errors in leaf area predictions. The model overpredicted nitrate concentrations for the corn plot late in the season. Nitrate concentrations for the soybean plot were generally underpredicted. These differences may be due to underestimates of the fast humus pool of the nutrient model and of the N2 fixation rate for soybean. More evaluation is needed to refine the nitrate and soil water content predictions.
Testing CERES–Wheat with Free‐Air Carbon Dioxide Enrichment (FACE) Experiment Data: CO2 and Water Interactions
Authors: Tubiello Francesco N. , Rosenzweig Cynthia , Kimball Bruce A. , Pinter Paul J. , Wall Gerald W. , Hunsaker Douglas J. , LaMorte Robert L. , Garcia Richard L.
Published: July 2010

Dynamic crop‐growth models are used to project the effects of rising atmospheric CO2 concentration and associated climate change on crop yields. Such model predictions are largely untested in the field, for lack of experimental data. We tested the CERES‐Wheat model, modified to include leaf‐level photosynthesis response to elevated CO2, using field data from 2 yr of Free‐Air Carbon Dioxide Enrichment (FACE) experiments with spring wheat (Triticum aestivum L. cv. Yecora Rojo) in Maricopa, AZ. Two irrigation treatments (well‐watered, WW; water‐deficit stressed, WS) and two atmospheric CO2 concentrations (ambient, 350 (μmol mol−1; elevated, 550 (μmol mol−1) were simulated. The model was evaluated using measurements of crop phenology, aboveground dry matter (DM) production, grain yield, and evapotranspiration (ET). Model calculations of crop phenology were within 2 to 3 d of observed values under WW, ambient CO2 conditions in both years. The model did not simulate the accelerated crop phenology (5–8 d at physiological maturity) observed in the WW and elevated CO2 treatments, indicating the need to include effects of increased stomatal resistance on canopy temperature. Simulations of DM and grain yield were within 10% of measured values, except for a tendency to overcalculate DM response to CO2 by 10 to 15% in Year 1 for WS treatments. The model undercalculated cumulative ET under WW conditions by 15%; model sensitivity analyses suggest that simulation of potential evapotranspiration (PET) was too low for this arid site. The model reproduced measured dynamics of CO2‐water interactions. Simulated reductions in water loss due to elevated CO2 were about 4%, in agreement with measurements. The model simulated larger increases in DM production and yield due to elevated CO2 under WS than under WW conditions. In Year 1, simulated crop response to CO2 was 2% larger (measured: 3%) under WS than under WW conditions; in Year 2, it was 11% larger (measured: 9%). The ability to simulate CO2‐water interactions, though it needs to be further evaluated with additional experimental datasets, is an important attribute of models used to project crop yields under elevated CO2 and climate change.
Estimation of Nitrogen Fixed by Legumes in Long‐Term vs. Short‐Term Cropping Systems
Authors: Papastylianou Ioannis
Published: July 2010

A critical evaluation of legumes should consider both the above‐and belowground contribution to N2 fixation. Based on the amount of N in crops and correcting for the changes of soil N as a result of cropping, 15 equations are presented for estimation of the apparent net amount of atmospheric N2 fixed by legumes grown in short‐ and long‐term cropping systems. In the final equation, all components of a legume‐cereal rotation system were considered. In estimating N2 fixation, including in the equation the non‐N2–fixing crop that follows the legume in the rotation is an innovation of the method, in addition to the system approach concept. The validity and accuracy of each equation in estimating N2 fixation by legumes is discussed. An example is provided using data from long‐term vetch‐barley (Vicia sativa L.‐Hordeum vulgare L.) rotation studies in Cyprus. The estimated amount of apparent net N2 fixation by vetch was 184 kg N ha−1, a quantity twice that usually estimated using only the aboveground vetch production. This result shows the importance of calculating apparent net N2 fixation by considering above‐ and belowground system components.
Spring‐Applied Nitrogen and Productivity of Cool‐Season Grass Seed Crops
Authors: Young William C. , Chilcote David O. , Youngberg Harold W.
Published: July 2010

Understanding effects of spring N rates and application timing on seed yield and yield components of cool‐season grass seed crops will help improve N fertilization management. We tested effects of 90, 120, 150, 180, and 210 kg N ha−1, applied at the double‐ridge (DR) stage of development on seed yield and yield components of Chewing's fescue [Festuca rubra L.subsp. fallax (Thuill.) Nyman; syn. F. rubra var. commutata Gaudin], tall fescue (F. arundinacea Schreb.), and orchardgrass (Dactylis glomerata L.) in 1985 and 1986. In a second study, effects of 120 kg N ha−1, applied either at DR, at spikelet initiation (SI), or equally split between the two stages, were tested. Soil type for both experiments was fine‐silty, mixed, mesic Aquultic Argixerolls. Chewing's fescue seed yield was not affected by N rates in 1985 and was the greatest at 90 kg N ha−1 in 1986. Averaged across years, orchardgrass seed yield was the greatest at 120 kg N ha−1. Nitrogen rates did not affect seed yield of tall fescue. Seed yield of all species was most closely correlated with the number of seeds produced per unit area. Seed number per unit area was primarily correlated with the number of seeds produced per panicle in all species; in orchardgrass, the number of panicles per unit area also contributed to total number of seeds produced. Seed yields of all three species were the greatest when N was applied at DR. Split application was not better than application of all N at DR or SI. We concluded that in western Oregon spring application of 90 kg N ha−1 for Chewing's fescue and tall fescue and 120 kg N ha−1 for orchardgrass should be adequate for seed production. For all species, spring N should be applied in one application at DR.
A Comparative Study of Interpolation Methods for Mapping Soil Properties
Authors: Kravchenko Alexandra , Bullock Donald G.
Published: July 2010

The choice of an optimal interpolation technique for estimating soil properties at unsampled locations is an important issue in site‐specific management. The objective of this study was to evaluate inverse distance (InvD) weighting, ordinary kriging (KO), and lognormal ordinary kriging (KOlog) to determine the optimal interpolation method for mapping soil properties. Relationships between statistical properties of the data and performance of the methods were analyzed using soil test P and K data from 30 agricultural fields. For InvD weighting, we used powers of 1, 2, 3, and 4. The numbers of the closest neighboring points ranged from 5 to 30 for the three methods. The results suggest that KOlog can improve estimation precision compared with KO for lognormally distributed data. The criteria helpful in deciding whether KOlog is applicable for the given data set were the Kolmogorov‐Smirnov goodness‐of‐fit statistic, coefficient of variation, skewness, kurtosis, and the size of the data set. Careful choice of the exponent value for InvD weighting and of the number of the closest neighbors for both InvD weighting and kriging (KO or KOlog) significantly improved the estimation accuracy (P≤ 0.05). However, no a priori decision could be made about the optimal exponent and the number of the closest neighbors based on the statistical properties of the data. For the majority of the data sets, kriging with the optimal number of the neighboring points, a carefully selected variogram model, and appropriate log‐transformation of the data performed better than InvD weighting. Correlation coefficients between experimental data and estimated results of kriging were higher than those of InvD for 57 out of a total of 60 data sets, kriging mean absolute errors were lower for 44 data sets, and kriging mean errors were lower than those of InvD weighting for 31 data sets.
Soil Management and Supplemental Irrigation Effects on Potato: II. Root Growth
Authors: Opena Geraldine B. , Porter Gregory A.
Published: July 2010

This study was conducted to determine if supplemental irrigation and/or application of soil amendments rich in organic matter can improve root growth of potato (Solanum tuberosum L.). Root length density (RLD) and root dry matter production of potato were studied under two levels of supplemental irrigation (nonirrigated check vs. moderate irrigation) and two levels of soil amendments [none vs. amended with compost and manure from beef cattle (Bos taurus L.)] during 1993 and 1994. Amendments significantly increased RLD during both growing seasons and these increases occurred consistently throughout each growing season. Irrigation effects were not observed in 1993, while irrigation significantly increased RLD during 1994. Approximately 85% of the root length was concentrated in the upper 30‐cm layer of the soil. The supplemental irrigation and soil amendment treatments did not affect the proportional distribution of roots among the soil layers. Root‐to‐shoot ratio was not affected by irrigation or amendment during either growing season. The RLD and leaf area index (LAI) at all four sample dates during 1994 were significantly correlated with final tuber yields, indicating that growth patterns early in the season were important in establishing the productivity of the potato crop. Root length density tended to have a higher correlation with yields than did LAI (r = 0.58* to 0.80** vs. 0.51* to 0.68**).
Grassland Legume Establishment with Imazethapyr and Imazapic
Authors: Beran Daniel D. , Masters Robert A. , Gaussoin Roch E.
Published: July 2010

Legumes are important components of grassland communities in North America and have potential to improve grassland productivity and diversity. Weeds can interfere with the establishment of legumes and increase probability of stand failure. Four experiments were conducted from 1994 to 1997 to determine if the imidazolinone herbicides imazethapyr [2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl]‐5‐ethyl‐3‐pyridinecarboxylic acid] and imazapic [(±)‐2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl]‐5‐methyl‐3‐pyridinecarboxylic acid] applied preemergence at 70 g a.i. ha−1 could reduce weed interference and improve establishment of seeded grassland legumes. Six native legumes and one introduced legume, crownvetch (Coronilla varia L.), were planted into prepared seedbeds at sites near Mead, NE. Legume response to the herbicides varied among species and sites. Crownvetch, partridgepea [Chamaecrista fasciculata (Michx.) Greene; syn. Cassia chamaecrista L.), and purple prairieclover (Dalea purpurea Vent.) exhibited tolerance to both imazethapyr and imazapic in most experiments and their establishment, as indicated by stem density and/or forage yield collected 14 mo after planting, was improved when treated with the herbicides in weedy environments. Imazapic treatment injured leadplant (Amorpha canescens Pursh), Canada tickclover [Desmodium canadense (L.) DC.], and roundhead lespedeza (Lespedeza capitata Michx.), resulting in lower stem densities and/or forage yields than when imazethapyr was applied. Based on these findings, preemergence application of imazethapyr and imazapic can be used to reduce weed interference and improve the establishment of certain grassland legumes.
Surface Residue and Soil Moisture Affect Fertilizer Loss in Simulated Runoff on a Heavy Clay Soil
Authors: Torbert H. Allen , Potter Kenneth N. , Hoffman Dennis W. , Gerik Thomas J. , Richardson C. W.
Published: July 2010

The potential for non‐point‐source pollution of surface waters from agricultural lands continues to be a concern. Our objective was to determine the effect of surface residue management and fertilizer application timing in regards to soil moisture conditions on nutrient losses in runoff. Studies were conducted using a rainfall simulator that applied 125 mm h−1 for 3 h to an Austin (Udorthentic Haplustoll) clay soil. Soil surface residue treatments were chisel tillage with no added corn (Zea mays L.) residue (CT‐NAR), chisel tillage with added corn residue (CT‐AR), and bermudagrass [Cynodon dactylon (L.) Pers.] sod (sod). Rainfall simulation was made following fertilizer (16–9–0 N–P–K) application to relatively dry (350 g kg−1 moisture) and relatively wet (500 g kg−1) soil on each of the residue treatments. Runoff samples collected from a 1‐m2 area were analyzed for NO−3–N, NH+4–N, and PO−4–P concentration and amount (kg ha−1). When fertilizer was applied to relatively dry soil, nutrient losses from both wet and dry runs combined were less than the losses with fertilizer applied to relatively wet soil. For wet runs, the CT‐AR treatment reduced total PO−4–P loss nearly sevenfold and NH+4–N loss fivefold compared with CT‐NAR (1.2 vs. 8.0 kg PO−4–P ha−1; 3.9 vs. 18.9 kg ha−1 NH+4–N), due to increases in time before initiation of runoff and lower nutrient concentrations in runoff. For our conditions, therefore, reduction in nutrient losses in runoff can be achieved by maintaining surface crop residue and applying N and P fertilizers to relatively dry soils. The largest loss of fertilizer nutrients occurred with sod treatments: losses of PO−4–P for the relatively wet soil were ≈41% of PO−4–P fertilizer applied (51.9 kg PO−4–P ha−1). This indicates that granular fertilizer application to pastures on heavy clay soils with vertic properties may make a significant contribution to non‐point‐source pollution; careful management of granular fertilizer applications is thus called for, especially soil water content, when fertilizing sod.
Relationships among Soil Nitrate, Leaf Nitrate, and Leaf Yield of Burley Tobacco
Authors: MacKown Charles T. , Crafts‐Brandner Steven J. , Sutton Tommy G.
Published: July 2010

Burley tobacco (Nicotiana tabacum L.) requires large amounts of fertilizer N to produce high yields of cured leaf with the quality traits demanded by buyers. However, excessive N use produces air‐cured leaves with undesirable levels of NO−3, is uneconomical, and is environmentally unsound if substantial levels of residual soil NO−3 remain following harvest. Effects of N fertilizer on relationships among leaf yield, NO−3 concentrations of air‐cured leaves, and soil NO−3 levels were investigated in 1991 and 1992 at two locations near Lexington, KY. Fertilizer N was broadcast at 0 to 448 kg ha−1 (56‐kg increments) before transplanting or banded at 168 kg ha−1 about 5 wk after transplanting. Soils were a well‐drained Maury silt loam (fine, mixed, mesic Typic Paleudalf) and a moderately well‐drained Captina silt loam (fine, silty, siliceous, mesic Typic Fragiudult). Cured leaf yield and lamina NO−3 increased with increasing amounts of broadcast fertilizer N. Yield increased 3.7% with banded N, compared with an equivalent amount of broadcast N. Banding N also increased the NO−3 level of cured leaf lamina by 37% for bottom leaves and 17% for middle leaves; top leaves were unaffected. Soil mineral N (NH+4 + NO−3) was proportional to the amount of broadcast N applied, and NO−3 levels in the upper 30 cm of soil declined during the growing season. For predicted maximum leaf yields of 90%, critical soil mineral N values of 46 and 88 mg kg−1 (for Captina and Maury soils, respectively) were estimated from average mineral N concentrations in the upper 30 cm at 3 and 5 wk after transplanting. Early‐season soil NO−3 testing to predict the NO−3 level of cured leaf lamina was not useful; a nearly twofold difference in lamina NO−3 was observed among years when soil NO−3 levels were equivalent. At 280 kg N ha−1, a rate commonly recommended for burley tobacco, as much as 37 mg NO−3–N kg−1 soil was found in the upper 30 cm of soil following harvest. Decreasing the amount of fertilizer N broadcast just before transplanting to 168 kg N ha−1 caused a 10% reduction in yield, a 37 to 65% decrease in lamina NO−3, and about a 60% decrease in residual soil NO−3 at harvest. Better N management can reduce both the NO−3 level of cured leaves and the amount of residual NO−3 following harvest.
Early‐ and Late‐Season Grazing of Orchardgrass and Fescue Hayfields Overseeded with Red Clover
Authors: Prigge Edward C. , Bryan William B. , Goldman‐Innis Esther S.
Published: July 2010

Low‐cost alternatives to hay feeding for wintering the beef herd (Bos taurus L.) are needed to design sustainable production systems for northern Appalachia. This study was conducted to compare forage production, quality, and botanical composition of hayfields overseeded with a legume when grazed by beef cattle in early spring and late fall. Four management systems were applied to fields containing either tall fescue [Festuca arundinacea Schreb.] or orchardgrass [Dactylis glomerata L.], each overseeded with red clover [Trifolium pratense L.]: (i) early spring grazing, one hay cutting, late fall grazing (GHG); (ii) two hay cuttings (HH); (iii) early spring grazing followed by two hay cuttings (GHH); and (iv) one hay cutting followed by grazing in late fall (HG). Total dry matter (DM) was highest for the HG management. Early spring grazing (GHH and GHG) reduced spring hay yield; quality, however, as indicated by crude protein, acid‐detergent fiber, and in vitro dry matter disappearance, was higher than for hay not grazed in spring (HH and HG). Fall grazing increased quality of forage grazed in early spring. Tall fescue produced more DM than orchardgrass, primarily in spring hay yield. Red clover contributed 50% of the DM of spring hay in the first year after seeding. Fall grazing extended the life of the red clover by one year; however, almost no red clover persisted into the fourth year after seeding. Results suggest that fall grazing after a single hay cutting has the potential to be a viable alternative to exclusively relying on hay for wintering the beef herd.
Vapor Transport vs. Seed–Soil Contact in Wheat Germination
Authors: Wuest Stewart B. , Albrecht Stephen L. , Skirvin Katherine W.
Published: July 2010

The assumption that seed–soil contact is important for germination of seeds has influenced imbibition research and equipment design but has not been tested. This study compared germination with and without seed–soil contact. Over a temperature range from 3 to 28°C, wheat (Triticum aestivum L.) seed was either provided with good seed–soil contact or separated from soil by fiberglass cloth. The germination system was sealed to prevent evaporation. At soil water potentials of −4.5 and −2.3 MPa, no seeds germinated in either treatment. When the soil water potential was −1.1 to −0.15 MPa, the average increase in germination time due to the absence of seed–soil contact was 0.3 d (5.6%). Days to germination ranged from 1.1 d at −0.15 MPa and 28°C, to 18.3 d at −1.1 MPa and 3°C. These results show that vapor transport may be the most important mechanism for imbibition and that liquid transport through seed–soil contact may make little contribution. Recognition of vapor transport as a sufficient, and perhaps dominant, mechanism for water transport between seed and soil should improve modeling efforts and planting equipment designs.
Corn Hybrid Response to Planting Date in the Northern Corn Belt
Authors: Lauer Joseph G. , Carter Paul R. , Wood Timothy M. , Diezel G. , Wiersma Daniel W. , Rand Robert E. , Mlynarek Michael J.
Published: July 2010

Growers frequently are concerned about the response of corn (Zea mays L.) to planting date. Early planting of corn is recommended because full‐season hybrids utilize the entire growing season, achieve physiological maturity before a killing frost, and start to dry, thereby increasing profit through reduced drying costs. The objective was to evaluate the influence of planting date and hybrid maturity on corn grain yield and harvest moisture in Wisconsin. Two or three corn hybrids ranging in relative maturity from 80 to 115 d were planted between 19 April and 22 June at six locations in Wisconsin from 1991 to 1994. In southern Wisconsin locations, the optimum planting date for grain yield of full‐ and shorter‐season hybrids ranged between 1 and 7 May, and was still at 95% of optimum between 9 and 18 May. In northern Wisconsin, the optimum planting date for grain yield of hybrids ranged between 8 and 14 May, and was still at 95% of optimum between 15 and 23 May. Grain yield did not change much when corn was planted between 24 April and 8 May. Grain yield of corn planted after 8 May in southern Wisconsin declined at the rate of 0.5 to 1.1% d−1 over the next 2 wk, accelerating to 1.3 to 1.9% d−1 and 2.0 to 2.8% d−1 over the next two 2‐wk periods. Grain yield of corn planted after 8 May in northern Wisconsin declined at the rate of 0.2 to 1.7% d−1 over the next 2 wk, accelerating to 1.7 to 2.2% d−1 and 3.2 to 3.8% d−1 over the next two 2‐wk periods. The decision to begin planting corn early should be based on soil temperature and field conditions. After 20 April, planting of full‐season hybrids should proceed as rapidly as field conditions allow. The date to switch from full‐season to shorter‐season hybrids depends on numerous factors, including corn price and drying costs, but generally occurs by mid‐May in southern and by late May in northern Wisconsin.
Temperature Regime and Carbon Dioxide Enrichment Alter Cotton Boll Development and Fiber Properties
Authors: Reddy K. Raja , Davidonis Gayle H. , Johnson Ann S. , Vinyard Bryan T.
Published: July 2010

Temperature and atmospheric carbon dioxide concentration [CO2] affect cotton (Gossypium hirsutum L.) growth and development, but the interaction of these two factors on boll and fiber properties has not been studied. An experiment was conducted in naturally lit plant growth chambers to determine the influence of temperature and atmospheric [CO2] on cotton (cv. DPL‐51) boll and fiber growth parameters. Five temperature regimes were evaluated: the 1995 temperature at Mississippi State, MS; the 1995 temperature minus 2°C; and the 1995 temperature plus 2, 5, and 7°C. Daily and seasonal variation and amplitudes were maintained. Atmospheric [CO2] treatments were 360 (ambient) and 720 μL L−1. Boll number, boll growth, and fiber properties were measured. Boll size and maturation periods decreased as temperature increased. Boll growth increased with temperature to 25°C and then declined at the highest temperature. Boll maturation period, size, and growth rates were not affected by atmospheric [CO2]. The most temperature‐sensitive aspect of cotton development is boll retention. Almost no bolls were retained to maturity at 1995 plus 5 or 7°C, but squares and bolls were continuously produced even at those high temperatures. Therefore, the upper limit for cotton boll survival is 32°C, or 5°C warmer than the 1995 U.S. Mid‐South ambient temperatures. The 720 μL L−1 atmospheric [CO2] had about 40% more squares and bolls across temperatures than the 360 μL L−1 [CO2]. Fibers were longer when bolls grew at less than optimal temperatures (25°C) for boll growth. As temperature increased, fiber length distributions were more uniform. Fiber fineness and maturity increased linearly with the increase in temperature up to 26°C, but decreased at 32°C. Short‐fiber content declined linearly from 17 to 26°C, but was higher at higher temperature. As for boll growth and developmental parameters, elevated atmospheric [CO2] did not affect any of the fiber parameters. Changes in temperature, however, had a dramatic effect on boll set and fiber properties. The relationships between temperature and boll growth and developmental rate functions and fiber properties provide the necessary functional parameters to build fiber models under optimum water and nutrient conditions.
Response of In Situ Leaf Psychrometer to Cuticle Removal by Abrasion
Authors: Campbell Colin S. , McInnes Kevin J.
Published: July 2010

In situ measurements of leaf water potential by thermocouple psychrometers are useful in monitoring the energy state of water in plants. Excessive equilibration times caused by low vapor conductance across the leaf cuticle and vapor sorption in the psychrometer chamber often make in situ sampling difficult. Several methods of removing the waxy leaf cuticle have been shown to increase water vapor conductance across the epidermis of the leaf, but their relative effectiveness has not been compared and equilibration times are unknown. Six wax removal treatments were compared with an untreated control to determine the most effective technique for increasing water vapor conductance across the leaf surface. The mean time for the leaf psychrometer to reach an equilibrated water potential was estimated for the treatment that produced the greatest conductance. Abrasion treatment of leaves with 600 grit sandpaper produced the greatest increase in cuticular conductance, resulting in a mean equilibration time for psychrometer measurements of 7.5 min.
A Three‐Dimensional Approach to Modeling Light Interception in Heterogeneous Canopies
Authors: Röhrig Manfred , Stützel Hartmut , Alt Christoph
Published: July 2010

The accuracy of plant growth models depends strongly on a precise calculation of radiation uptake. Numerous approaches exist to estimate light absorption in spatially heterogeneous canopies, but these either have restrictions with respect to canopy structure or involve complex and inflexible calculations. The objective of this study was to develop a simulation tool to assess radiation penetration into canopies that should (i) give details on light absorption in heterogeneous canopy architectures and (ii) comprise simple and easily adaptable routines. In the model, the complete canopy volume is subdivided into cubic units that are either empty or filled with leaf area. Leaf area can be distributed in an arbitrarily chosen geometric solid positioned anywhere in the model domain. Transmission through the cubes is calculated by following the path of solar rays from the top of the canopy to ground level. Daily canopy absorption is calculated separately for direct and diffuse radiation, taking reflection and scattering of the direct beam into account. Using only a few readily obtainable parameters, a close agreement between simulated and measured canopy transmission of a cauliflower (Brassica oleracea var. botrytis L.) crop was found Comparing different canopy structures ranging from single‐plant canopies to a closed canopy gave detailed information on the absorption characteristics and the distribution of light absorption in individual plants. Results for closed canopies and row crops were consistent with those of earlier models. It is thus useful as a reference model to identify possible simplifications in the quantification of light interception by heterogeneous crops.
No‐Till Maize Nitrogen Uptake and Yield: Effect of Urease Inhibitor and Application Time
Authors: Rozas Herna´n Sainz , Echeverrı´a Herna´n E. , Studdert Guillermo A. , Andrade Fernando H.
Published: July 2010

No‐tillage affects maize (Zea mays L.) fertilizer N use efficiency when urea is surface‐applied, due to NH3 volatilization. A 3‐year field experiment was conducted at Balcarce, Argentina (37°45′ S, 58°18′ W), on a soil complex of a fine, mixed, thermic Typic Argiudoll and a fine, illitic, thermic Petrocalcic Paleudoll. The objective was to evaluate the effect of surface‐applied urea rate (0, 35, 70, 140, and 210 kg N ha−1), with and without a urease inhibitor [N‐(n‐butyl) thiophosphoric triamide] (nBTPT) at different times (planting; six‐leaf stage, V6) on NH3 volatilization losses, soil mineral N, and maize N uptake and grain yield under no‐tillage. A semiopen static system was used to monitor NH3 volatilization losses. Ammonia N losses from urea without nBTPT ranged between 2.6 and 13.3% of applied N, being greater with higher N rates and when the urea was applied at V6. Volatilization losses with nBTPT were not different than those from the control. The use of nBTPT did not increase soil mineral N consistently and did not increase N uptake nor grain yield. Relative to fertilization at planting, fertilization at V6 increased soil mineral N at flowering, N uptake at physiological maturity (167 and 155 kg ha−1, respectively), and grain yield (11 003 and 10 440 kg ha−1, respectively). For slightly acid and high organic matter soils, the use of nBTPT did not improve urea N use efficiency. Delayed urea application had a greater and more consistent effect than the use of nBTPT on the increase of no‐till maize grain yield and N use efficiency.
A Model Analysis of Yield Differences among Recombinant Inbred Lines in Barley
Authors: Yin Xinyou , Kropff Martin J. , Goudriaan Jan , Stam Piet
Published: July 2010

Crop models can support plant breeding if they can predict differences in performance of different genotypes. In this study, the ability of a crop model to explain yield differences among genotypes in a recombinant inbred line (RIL) population of two‐row barley (Hordeum vulgare L.) was explored. Yield and model‐input traits of 94 RILs and their parents, ‘Prisma’ and ‘Apex’, were measured in field experiments conducted in Wageningen, Netherlands, in 1996 at low and in 1997 at high N levels. The major gene, denso, with the dwarfing allele from Prisma, was segregating in this population. Short denso RILs outyielded tall types in both years, and this yield advantage was stronger in 1997, largely because the tall genotypes lodged. A crop model based on existing routines for biomass production explained only 26 to 38% of the yield variation among genotypes. The model, using input traits measured from the 1997 data, did not accurately predict growth of genotypes in 1996 because some traits varied with plant N status, which the model did not account for. Model analysis in the high‐N environment showed that of the seven model‐input traits examined, only lodging score, preflowering duration, and fraction of biomass partitioned to spikes had a significant effect on yield. When these three traits were used while fixing others at their across‐genotype means, the model explained 65% of yield variation. To allow effective use of crop modeling in breeding, the ability of crop models to explain yield differences among genotypes has to be improved.
Leaf and Stem Mass Characteristics of Cool‐Season Grasses Grown in the Canadian Parkland
Authors: Baron Vern S. , Dick Alistair C. , King Jane R.
Published: July 2010

Grasses adapted to both hay and pasture are lacking in the prairie parkland. ‘Regar’ meadow bromegrass (Bromus riparius Rhem.), ‘Manchar’ smooth bromegrass (B. inermis Leyss.), S9044 (a smooth–meadow bromegrass cross), common meadow foxtail (Alopercurus pratensis L.), and ‘Kay’ orchardgrass (Dactylis glomerata L.) were evaluated for traits useful in dual purpose grass species at early (late May), late (late June), and regrowth (early September) harvests. Herbage, leaf, and stem nutritive value; mass; and leaf/stem ratio were determined. Differences among species were related more to herbage mass and morphology than to leaf and stem quality. Early harvest orchardgrass herbage mass was low at 55% of meadow foxtail (2.9 Mg ha−1). However, stem content of meadow foxtail represented 60% of early herbage mass, limiting its potential. Regrowth mass of meadow bromegrass, S9044, and orchardgrass exceeded 2.5 Mg ha−1, whereas smooth bromegrass and meadow foxtail were as low as 2.1 Mg ha−1. Regrowth leaf mass of the former species exceeded 1.9 Mg ha−1. Late herbage mass of smooth bromegrass was always greater than the other species. Leaf acid detergent fiber (ADF) of S9044 and smooth bromegrass was lower (range 189–242 g kg−1) than meadow bromegrass (range 217–284 g kg−1). By contrast, late and regrowth harvest stem ADF of meadow bromegrass was lower (range 237–360 g kg−1) than S9044 (range 257–366 g kg−1). Variation among Bromus types for late and regrowth yield, and leaf fiber may influence management strategies.
Malate, Citrate, and Amino Acids in Tall Fescue Cultivars: Relationship to Animal Preference
Authors: Mayland Henry F. , Martin Scott A. , Lee Julian , Shewmaker Glenn E.
Published: July 2010

Grazing animals depend on little‐understood chemical and physical cues when selecting forage diets. This study determined malate, citrate, and amino acid concentrations in endophyte‐free tall fescue (Festuca arundinacea Schreb.) and related those concentrations to cultivar, harvest time, and grazing‐animal preference. ‘Barcel’, ‘Kenhy’, ‘Kentucky‐31’, ‘Missouri‐96’, ‘Mozark’, ‘Stargrazer’, and the two accessions C1 and HiMag were established in three replicates within each of three pastures. Organic acids were determined on regrowth within each plot during four seasons and two years; amino acids were determined on regrowth of four cultivars across three replicates during both spring and fall seasons in one year. Malate and citrate were extracted with boiling water and quantified by high‐performance liquid chromatography (HPLC) with an organic acid column. Amino acids were hydrolyzed, separated by ion‐exchange HPLC, and quantified as their ninhydrin derivatives. Both malate and citrate concentrations differed between years. During one year only, malate concentrations were higher in Kenhy (68 g kg−1 dry matter [DM], most preferred) than in Mozark (54 g kg−1 DM, least preferred). Citrate concentrations (13 g kg−1 DM) were not different among cultivars. Eighteen amino acids (including tryptophan) accounted for 75% of total N. Thus, tissue N data were used as covariates to amino acid data in the ANOVA. Kenhy contained higher concentrations of eight amino acids than did other cultivars. These differences may reflect presence of Lolium genes in Kenhy. Cattle (Bos taurus L.) grazing preference (0 = not eaten; 10 = completely eaten) was not related to malate, citrate, or amino acid concentrations among cultivars.
Tomato Crop Response to Short‐Duration Legume Green Manures in Tropical Vegetable Systems
Authors: Tho¨nnissen Carmen , Midmore David J. , Ladha Jagdish K. , Holmer Robert J. , Schmidhalter Urs
Published: July 2010

The potential of legume green manure (GM) as an alternative to mineral N fertilizer in tropical horticulture has received scant attention. The feasibility of meeting N needs of tomato (Lycopersicon esculentum Mill.) with GM was studied in six field experiments at three locations in major vegetable growing areas of Taiwan and the Philippines between 1993 and 1995. Legume biomass, N2 fixation and N accumulation, and tomato yield and N uptake were quantified within a 6‐mo experiment cropping pattern. Yields of GM‐amended tomato crops were compared with those amended with fertilizer N (0–150 kg N ha−1). The residual effect of the fertilizing method of a second crop (maize; Zea mays L.) was estimated at AVRDC by measures of biomass and N uptake 30 d after sowing. Legume N recovery in tomato crops was traced with 15N at Mariano Marcos State University (MMSU). Soybean [Glycine max (L.) Merr.] harvested at 60 to 74 d accumulated a minimum of 2.8 Mg ha−1 biomass and 100 kg ha−1 N in all locations and seasons. A maximum of 6 Mg biomass ha−1 and 140 kg N ha−1 was reached in the wet season (WS) at AVRDC. Indigofera (Indigofera tinctoria L.) and mungbean [Vigna radiata (L.) Wilcz.] biomass yields were more variable and always inferior than soybean yields. Tomato yields across locations ranged from 3 to 70 Mg fruit ha−1. Tomato yields responded to GM N in the WS in Taiwan and in the northern Philippines, comparing favorably with fertilizer at 38 to 120 kg N ha−1. No response to GM N was found in the dry season (DS) at AVRDC or at Bukidnon Resources Company, Inc. (BRCI). The 15N experiments showed that only a small fraction of legume N (9–15%) was recovered by the tomato crop at MMSU. Maize biomass and N uptake, following the tomato crop, was increased with soybean GM compared with the control in the AVRDC WS and DS. Tomato yield response to GM N is high on infertile soils and tomato N requirement can be substituted fully or partially by GM, depending on soil N mineralization.
Wheat Nitrogen Use Efficiency in a Bed Planting System in Northwest Mexico
Authors: Limon‐Ortega Agustin , Sayre Kenneth D. , Francis Charles A.
Published: July 2010

Wheat (Triticum aestivum L.) in the Yaqui Valley, northwest Mexico, is planted as a winter crop using a raised‐bed, furrow‐irrigated system and high fertilizer N rates. Wheat residues are usually burned before planting maize (Zea mays L.) as a summer crop. The N use of wheat planted following conventional tillage using a raised‐bed system (CTB) incorporating both wheat and maize residues was compared with wheat planted using permanent raised beds (PB) under four residue management treatments: all straw (wheat and maize) left as stubble, straw partly removed (maize residues removed; wheat residues retained), all straw removed, and all straw burned. Each wheat plot was split into seven N fertilizer (Nf) treatments: five applied at planting (0, 75, 150, 225, and 300 kg ha−1) and two at the 1st node stage (150 and 300 kg ha−1). Maize received a uniform Nf application of 150 kg ha−1. The N use efficiency of wheat with 150 kg Nf ha−1 at the 1st node stage was superior to basal applications at the same rate. Permanent bed–all straw left as stubble and PB–all straw burned had the highest average wheat grain yields (5.57 and 5.52 Mg ha−1, respectively), N use efficiency (28.2 and 29.1 kg grain kg−1 of N supply, respectively), and total N uptake (133 and 137 kg ha−1, respectively). Total N uptake for 150 and 300 kg Nf ha−1 at the 1st node stage was 14 and 8% greater, respectively than at planting. In most tillage–straw treatments, 21% of the difference in wheat grain yields was due to the N supply component at low N rates; at high N rates, 97% was due to N use efficiency.
Row Spacing, Plant Population, and Cultivar Effects on Grain Amaranth in the Northern Great Plains
Authors: Henderson Tracey L. , Johnson Burton L. , Schneiter Albert A.
Published: July 2010

An understanding of plant response to row spacing and plant density is important in developing effective production systems for new crops. Optimum row spacing and plant population for grain amaranth (Amaranthus spp.) production in the northern Great Plains was evaluated at Prosper and Williston, ND, over 6 station‐years. Amaranth cultivars K283, K343, K432, and MT‐3 were established at populations of 74 000, 173 000, and 272 000 plants ha−1 in 30‐ and 76‐cm row spacings. Grain and biomass yield, plant height, harvest index, harvested plant population, and plant lodging were measured. Grain yields were similar among plant populations at each of the drier environments, averaging 1050 and 410 kg ha−1 for Prosper in 1989 and Williston in 1990, respectively. A 12% yield advantage, 160 kg ha−1, was observed at the lowest compared with the highest plant population at Prosper in 1990, but not in 1992. The main effect of row spacing on grain yield was not significant; however, the interaction of row spacing, plant population, and environment indicated population yield ranking differences at the 30‐cm row spacing among environments but not at the 76‐cm row spacing. The two A. cruentus L. cultivars, K283 and MT‐3, generally produced more grain than the two A. hypochondriacus L. × A. hybridus L. cultivars, K343 and K432, especially in dry environments. When considering yield, plant mortality, and potential harvest difficulties, the moderate population (173000 plants ha−1), 76‐cm row spacing, and generally higher‐yielding A. cruentus cultivars would be recommended.