bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grain Yield is Reduced More by Weed Interference in an Old than in a New Maize Hybrid
Authors: Tollenaar Matthijs , Aguilera Alberto , Nissanka Sarath P. 
Published: July 2010

AbstractGrain yield improvement of maize (Zea mays L.) hybrids in Ontario has been associated with increased stress tolerance of newer hybrids. This study was conducted to assess the effect of low soil N, weed interference, and soil water deficit on dry matter accumulation and grain yield of an older and a more recent hybrid. Studies were carried out at the Elora Research Station in 1992, 1993, and 1994 on a London loam (Aquic Hapludalf) that had been tile drained. The experiment was arranged in a split‐split‐split‐plot design with four replications. Treatments consisted of two soil‐N levels (70 and 225 kg ha−1), weedfree all season and weedy from the 3‐ to 4‐leaf stage of maize, irrigation and no irrigation, and the hybrids ‘Pioneer 3902’ (new) and ‘Pride 5’ (old). Maize phenology, dry matter accumulation, grain yield, stomatal conductance, leaf chlorophyll fluorescence, and leaf chlorophyll content were measured. Irrigation generally did not influence the measured parameters. Silking date and stomatal conductance during the grain‐filling period were affected less by low soil N and weed interference in Pioneer 3902 than in Pride 5. Aboveground dry matter at silking and maturity was reduced about 20% by single stresses of low soil N and weed interference and about 55% by the combination of both stresses. Hybrid × stress treatment interactions for dry matter were not significant. The reduction in grain yield due to weed interference was 21% greater in Pride 5 than in Pioneer 3902. The hybrid × N interaction for grain yield was not significant, because a smaller reduction in harvest index due to N stress in the new than in the old hybrid was offset by a larger reduction in dry matter accumulation during the grain‐filling period. The differential response of the two hybrids to stress was greatest during the silking period, as indicated by the greater reduction in harvest index and kernel number in the old than in the new hybrid due to stress.
Fallow Management Effects on Soil Water Storage and Wheat Yields in the Pacific Northwest
Authors: Pannkuk Chris D. , Papendick Robert I. , Saxton Keith E. 
Published: July 2010

AbstractConservation tillage practices are adopted by farmers to control soil erosion and in some cases to reduce production costs. Conventional tillage practices usually rely on extensive tillage to control weeds and conserve water. In other cases, grazing animals may be used to control weeds and utilize crop residues for animal fodder on the fallowed land. These intensive systems leave the soil surface bare and susceptible to erosion. A five‐year study was conducted in the winter wheat (Triticum aestivum)‐fallow area of eastern Washington to evaluate the effects of tillage, weed control, and residue management on soil water storage and wheat yields. Tillage treatments were (i) conventional (early spring sweep and summer cultivation), (ii) delayed spring (late spring sweep and chemical weed control), and (iii) no‐till (chemical fallow). Residue management treatments were (i) all residues removed at the beginning of the 22‐mo fallow, (ii) all residues and vegetation removed after the first winter rainy season, and (iii) residues not removed. Weed control treatments were (i) weeds not controlled during the first winter rainy season but controlled thereafter and (ii) weeds controlled throughout the fallow period. Soil water storage was greater every year where crop residues were not removed, or removed after the first winter of the fallow period, compared with residue removal at the beginning of the 22‐mo fallow. Weedy fallow (weeds allowed to grow during the first winter rainy season) had no effect on fallow efficiency or wheat yields compared with fallow with weed control. Wheat yields were increased in one year out of five by the retention of surface residues and in one year by tillage and, thus, for the most part did not reflect differences in water storage efficiencies. Weedy fallow provided greater residue cover through erosive periods, but did not adversely affect soil water storage and wheat yields compared with fallow with weed control.
Validation of the Soil Temperature Subroutine HEAT in the Cotton Simulation Model GOSSYM
Authors: Khorsandi Farhad , Boone Mariquita Y. L. , Weerakkody Govinda , Whisler Frank D. 
Published: July 2010

AbstractThe empirical soil temperature subroutine of the cotton simulation model GOSSYM did not perform well under bare and cotton‐cropped (Gossypium hirsutum L.) surface conditions in the field. Therefore, it was replaced by a mechanistic soil temperature subroutine called HEAT. The HEAT subroutine was validated against soil temperature data collected in the field under bare and cotton‐cropped surface conditions, and was compared with the empirical TMPSOL subroutine of GOSSYM. Soil temperatures were collected in the field under bare and cotton‐cropped surface conditions at two locations (row and furrow) and four depths (5, 10, 25, and 60 cm) during the growing seasons of 1991 and 1992. Under bare surface conditions, HEAT underpredicted the average daily soil temperatures by 1 to 7°C at all locations and depths. However, under cotton‐cropped surface conditions, HEAT calculated the soil temperature adequately, especially after canopy closure. Under bare surface conditions, the temperatures calculated by TMPSOL were closer to the measured values than those calculated by HEAT, but were still beyond the standard deviations of the measured values. It is recommended that the TMPSOL subroutine in GOSSYM be replaced by the HEAT subroutine.
Kill Date of Vetch, Rye, and a Vetch—Rye Mixture: II. Soil Moisture and Corn Yield
Authors: Clark Andrew J. , Decker Alvin M. , Meisinger John J. , McIntosh Marla S. 
Published: July 2010

AbstractSpring cover crop kill date effects on N and water availability to subsequent no‐till corn (Zea mays L.) have not been studied. This 2‐yr study was conducted in 1990 and 1991 at Coastal Plain and Piedmont locations in Maryland to evaluate soil moisture and corn responses to three cover crop kill dates, three corn planting dates, and four fertilizer N (FN) rates following cover crops of hairy vetch (Vicia villosa Roth), cereal rye (Secale cereale L.), and vetch‐rye mixture. No‐cover checks were included for each corn planting date. Corn yield ranged from 0.8 to 13.3 Mg ha−1 in 1990, and from 3.9 to 12.6 Mg ha−1 in 1991. Corn grain yield without FN was greatest following vetch or vetch‐rye mixture. Late April or early May kill dates consistently resulted in greater corn yield than earlier kill dates, probably due to differences in N availability and moisture conservation. Cover crops killed late did not deplete surface soil moisture. The economic FN rate reflected N contributions and moisture conservation by each cover crop. At the Coastal Plain location, economic FN rates were 30 to 76 kg ha−1 for corn following vetch, 65 to 193 kg ha−1 following vetch‐rye mixture, 161 to 247 kg ha−1 following rye, and 201 kg ha−1 following no cover crop. Similar rankings were observed for the Piedmont location, but maximum yield was lower following rye, and lower FN rates were required to attain that yield. Summer soil water conservation by cover crop residues was more important than spring moisture depletion by growing cover crops in determining final corn yield.
Turfgrass Response to Slow‐Release Nitrogen Fertilizers
Authors: Carrow Robert N. 
Published: July 2010

AbstractNew polymer coatings have been developed and used to coat sulfurcoated urea (SCU) and other core N materials. These polymer‐coated S‐coated ureas (PCSCU) and polymer‐coated S‐coated N‐P‐K fertilizers (PCSCF) require evaluation for their N‐release properties turfgrass culture. Also, N carriers from three different classes of N sources were included: polymer‐coated urea (PCU), ureaformaldehyde (UF) reaction products, and natural organics. Initial and longterm N release were determined as demonstrated by visual quality, total shoot growth, and number of mowings of ‘Tifway’ hybrid bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt‐Davey] grown on an Appling sandy clay loam (clayey, kaolinitic, thermic Typic Kanhapludults). All N carriers were compared within their N class and across all carriers, using urea applied at 98 kg N ha−1 in early summer of 1994 and 1995 as the base of comparison. Other fertilizers were also applied at this rate and timing, except for three urea‐UF reaction products applied in equal, split treatments in early and mid summer. At 0 to 30 d of treatment, PCSCU and PCSCF product performance varied, with 14 to 57% of visual quality ratings equal to or greater than (≥) urea plots; at 61 to 95 d, 14 to 57% of ratings were > urea ratings. Greater long‐term quality response was related to higher S and/or polymer content in the coating of PCSCU and PCU products, but not to larger particle size for PCSCUs. For PCUs, the 0‐ to 30‐d visual quality response ranged from 14 to 43% of ratings ≥ urea, and at 61 to 95 d from 29 to 71% of ratings > urea. Natural organics and UF reaction products also demonstrated wide variation within their class of initial and long‐term N release. Within each N class, the wide diversity of N‐release patterns indicates the need to evaluate each carrier, and shows that placement of a specific N source within an N class provides only very broad implications as to its performance.
Suppression of Junglerice [Echinochloa colona (L.) Link] by Irrigated Rice Cultivars in Latin America
Authors: Fischer Albert , Ramírez Hector V. , Lozano Jaime 
Published: July 2010

AbstractContinuous rice (Oryza sativa L.) cropping in Latin America and the Caribbean has resulted in serious weed problems and herbicide overuse. Competitive rice cultivars could help reduce herbicide dependence. A study was conducted during 1994 and 1995 at Palmira, Colombia, to (i) assess the competitiveness of semidwarf irrigated rice plant types adapted to Latin America and the Caribbean's direct‐seeding systems, (ii) identify plant traits responsible for such competitiveness, and (iii) detect adverse effects of competitiveness on rice yield potential. Pregerminated seed of 10 and 14 semidwarf rice cultivars was sown on drained puddled soil in 1994 and 1995, respectively. Cultivars were grown weed‐free or with junglerice [Echinochloa colona (L.) Link] (40 viable seeds m−2, broadcast immediately after seeding rice), and were intermittently irrigated to keep the soil near saturation. Rice and junglerice biomass, leaf area index, tiller number, and height were recorded at 20, 40, 60, 90, and 120 days after emergence (DAE). Rice cultivars differed in their competitiveness against junglerice. Average yield losses ranged from 27 to 62% under saturating junglerice infestations of up to 5.9 Mg DM ha−1. Leaf area index, tiller number, and canopy light interception recorded in competition, and not much before 40 DAE, correlated positively with rice competitiveness. Competitive semidwarf cultivars can substantially reduce the number of herbicide applications in systems where suboptimal water control does not allow weed suppression by flooding. Breeding to enhance rice competitiveness appears as a valid objective, since competitive and also highly productive cultivars were identified in this study.
Residue and Fertility Effects on Yield of No‐Till Wheat
Authors: Rasmussen Paul E. , Rickman Ron W. , Kleeper Betty L. 
Published: July 2010

AbstractHigh levels of crop residue can adversely affect wheat (Triticum aestivum L.) yield, thereby slowing adoption of conservation tillage practices that effectively control soil erosion. This study was conducted to determine the influence of standing wheat residue and fertilizer application on the yield of no‐till wheat. Winter wheat was grown in even years and spring wheat in odd years on the same site from 1984 through 1988. The soil (a Walla Walla silt loam; coarse silty, mixed mesic Typic Haploxeroll) is considered highly deficient in N and marginally deficient in P and S for annual cereal production. Crop residue was finely chopped in 1984 and burned in 1985 to 1988, to compare with stubble left standing. Fertility treatments consisted of increasing rates of N, P, and S [none (0–0–0 kg N–P–S ha−1), low (56–6–9), moderate (112–11–18), and high (168–17–27)], banded cm below the seed. Grain yield, straw yield, grain protein, head density, kernels per head, and kernel weight were determined at harvest. Standing stubble decreased grain yield of winter wheat 13% and straw yield 15%, compared with chopping or burning; it decreased spring wheat grain and straw yields <5%. Standing residue affected straw and grain yields similarly, but had little effect on grain protein. Fertilizer increased grain and straw yield every year, and more so in winter than in spring wheat. Average grain yields for none, low, moderate, and high fertility were 1.12, 3.02, 4.75, and 5.08 t ha−1, respectively, for winter wheat and 1.17, 2.64, 3.18, and 3.20 t ha−1 for spring wheat. Increasing fertilization increased head numbers, had variable effect on head size, and generally decreased kernel weight. Most of the yield reduction in winter wheat due to standing residue was attributed to lower head numbers, not compensated by increased head size or kernel weight. Fertility × residue interaction did not occur in yield or grain protein responses, but was found in kernel yield and kernel weight. Lack of such interaction suggests that inadequate nutrition was not the cause of reduced yield in no‐till wheat with residue left standing.
Agronomic and Economic Evaluation of Organic and Inorganic Sources of Phosphorus in Western Kenya
Authors: Jama Bashir , Swinkels Rob A. , Buresh Roland J. 
Published: July 2010

AbstractMany soils in the highlands of East and Central Africa are depleted of soil nutrients, particularly P. Our objective was to compare cattle manure, Calliandra calothyrsus Meissner leaf biomass, and triple superphosphate (TSP) as sources of P for maize (Zea mays L.), both individually and as mixtures of organic (manure or calliandra) and inorganic (TSP + urea) sources. Field experiments were conducted on a Kandiudalf at two sites in western Kenya. Net benefits were computed as the difference between the value of additional maize yield accruing from nutrient inputs and the associated additional costs. Maize grain yield was 0.6 Mg ha−1 for application of urea without P. Application of 10 kg P ha−1 as organic, inorganic, and mixtures of organic and inorganic sources significantly increased maize yield. Grain yield for manure at least equaled and sometimes exceeded (P ≤ 0.05) yield for calliandra and TSP + urea. Net benefits in U.S. dollars (USD) for two seasons were highest for manure spot placed in the planting hole (293 USD ha−1), broadcast manure (255 USD ha−1), and broadcast TSP + 44 kg urea‐N ha−1 (313 USD ha−1 at P = 30 kg ha−1 and 98 USD ha−1 at P = 10 kg ha−1). Net benefits for calliandra leaf biomass were highest (136 USD ha−1) when biomass was valued at cost of production and integrated with TSP, such that it provided all the N for maize and TSP provided the additional P not supplied by calliandra. Calliandra valued at its opportunity cost as a protein supplement for dairy cattle was not an economic source of P. Sensitivity analyses suggest that organic materials most suitable for use as P sources have high P content and low cost of production.
Corn Growth and Nitrogen Uptake with Furrow Irrigation and Fertilizer Bands
Authors: Benjamin Joseph G. , Porter Lynn K. , Duke Harold R. , Ahuja Lajpat R. 
Published: July 2010

AbstractFurrow irrigation is commonly used to provide supplemental water to row crops. Alternate‐furrow irrigation has been proposed as a method to decrease deep percolation water losses as well as the leaching of fertilizer and pesticides. A study was conducted on a Ulm clay loam (fine, smectitic, mesic Ustic Haplargids) in 1994 and 1995 near Fort Collins, CO. Corn (Zea mays L.) growth and N uptake were measured under alternate‐furrow and every‐furrow irrigation water applications, each with fertilizer bands placed either in the row or in the furrow. Nitrogen‐15‐depleted (NH4)2SO4 fertilizer was used to distinguish plant uptake of fertilizer N from uptake of naturally occurring N. There were no differences in plant response to alternate‐furrow or every‐furrow irrigation water placement for the same amount of water applied. Greater fertilizer‐N uptake occurred with row placement than with furrow placement of N fertilizer. Early in the growing season, fertilizer‐N uptake from row placement was from 2 to 10 times the fertilizer‐N uptake from furrow placement. By the end of the growing season, the average total‐N uptake from row placement was 12% greater than for furrow placement. Placing the fertilizer in the nonirrigated furrow of the alternate‐furrow irrigation treatment decreased N availability by 20% compared with the average of the other treatments. If alternate‐furrow irrigation is used to increase water use efficiency in furrow‐irrigated fields, placing the N fertilizer in the nonirrigated furrow of the alternate‐furrow irrigation system could decrease N availability because of drier soil conditions in the nonirrigated furrow. Row placement of N fertilizer seems to be beneficial in both alternate‐furrow and every‐furrow irrigation applications.
Yield Accumulation in Irrigated Sugarcane: I. Effect of Crop Age and Cultivar
Authors: Evensen Carl I. , Muchow Russell C. , El‐Swaify Samir A. , Osgood Robert V. 
Published: July 2010

AbstractBecause the duration of growth for commercial sugarcane (Saccharum spp. hybrids) production can vary from 9 to 36 mo, determining the optimum age at crop harvest is important to profitability. To account for variable climate across seasons and locations, there is a need to understand the physiology of yield accumulation and quantitatively describe the effects of crop age on productivity. Few field studies have been conducted to determine the factors responsible for yield variation in different cultivars of sugarcane at different crop ages, and the physiology of yield accumulation has rarely been examined on a dry matter basis with all yield components, including tops, millable stalk, trash, and roots. This paper compares above‐ and belowground biomass accumulation with crop age in two current cultivars grown in field experiments under drip irrigation in Hawaii from 1991 to 1993, and reanalyzes earlier experiments conducted in Hawaii in the 1930s and 1940s to examine historical changes in the pattern of yield accumulation in sugarcane. The key findings from this analysis are that (i) differences in yield accumulation during the first 12 mo of growth were not necessarily reflected in final yields at harvest at 18 to 24 mo; (ii) yield accumulation was less efficient in the second year of growth for current cultivars, but not necessarily so for older cultivars; (iii) belowground biomass decreased from 17% of total biomass at 6 mo to 11% of total biomass from 12 to 24 mo; (iv) there was no indication that older cultivars were less productive than current cultivars; and (v) yields rarely increased beyond 18 mo of age.
Soil Moisture and Larval Western Corn Rootworm Injury: Influence on Gas Exchange Parameters in Corn
Authors: Hou Xin , Meinke Lance J. , Arkebauer Timothy J. 
Published: July 2010

AbstractThe western corn rootworm (Diabrotica virgifera virgifera LeConte) is an economically important pest of corn (Zea mays L.) in North America, but little is known about the physiological responses of corn to larval corn rootworm damage. This study was conducted to (i) characterize how larval corn rootworm feeding affects corn photosynthetic rate (Ps), stomatal conductance (gc), and intercellular CO2 concentration (Ci) and (ii) determine the interactive effects of larval injury and soil moisture on Ps, gc, and Ci. To address Objective 1, a greenhouse and a field experiment in randomized complete block design compared rootworm‐infested vs. noninfested Pioneer hybrid 3377 corn. Larval feeding had significant and transient effects on leaf Ps and gc (but not Ci) in both experiments. When the rootworm population was predominately second instar, leaf Ps and gc in infested corn were significantly less (P < 0.05) than in noninfested corn; at the end of the larval period, Ps and gc were not significantly different among rootworm treatments. Two greenhouse experiments addressed Objective 2. A factorial design with high and low moisture levels and rootworm‐infested and noninfested plants was used. In both experiments, soil moisture level interacted with larval injury to significantly (P < 0.05) affect leaf Ps and gc (but not Ci). Within 24 h after the two moisture regimes were established, Ps of the noninfested plants dramatically increased, while rates of rootworm‐infested plants did not change in plants that received supplemental water. Over 5 d, Ps rose in rootworm‐infested plants until rates equilibrated among rootworm treatments that were given supplemental water. These results suggest that irrigation of infested corn may not immediately reduce the stress caused by larval injury. A combination of factors (e.g., water uptake reduction, hormone synthesis in roots) may be involved in the injury‐plant response process.
Analysis of a Randomized Block Design with Unequal Subclass Numbers
Authors: Piepho Hans‐Peter 
Published: July 2010

AbstractFor some types of agricultural experiments, there are many observations per experimental unit; i.e., the subclass number is greater than one. In this article, the focus is on the randomized complete block design. Practitioners are often faced with unequal subclass numbers due to unpredicted experimental problems. The present paper discusses the statistical analysis of such unbalanced data, where subclass numbers vary independently of treatment variables and the response variable is not influenced by subclass number. In an example using the SAS statistical package to analyze data from a randomized complete block greenhouse experiment, an analysis of cell means compared favorably with a more elaborate Satterthwaite method. Monte Carlo simulations yielded similar results for both methods. It is concluded that, in practice, the cell means analysis is preferable for its simplicity.
Nitrogen Release from Surface‐Applied Cover Crop Residues: Evaluating the CERES‐N Submodel
Authors: Quemada Miguel , Cabrera Miguel L. , McCracken Daniel V. 
Published: July 2010

AbstractFurther improvement of residue decomposition models may help to optimize the use of N released from cover crop residues. CERES models are widely used to simulate crop‐soil systems and have a common subroutine that describes N dynamics (CERES‐N). In this work, we tested CERES‐N with results from a litterbag study over 120 d in which crimson clover (Trifolium incarnatum (L.), rye (Secale cereale( L.), wheat (Triticum aestivum( L.), and oat (Avena sativa L.) residues were allowed to decompose on the soil surface. The field data were used to (i) evaluate the original CERES‐N and a modification of CERES‐N that allows users to enter actual sizes for the carbohydrates, cellulose, and lignin pools and (ii) determine the best‐fitting rate constants for decomposition of the carbohydrates and cellulose pools in the original CERES‐N and in CERES‐N with user‐supplied pool sizes. CERES‐N with the original rate constants or with rate constants and parameters proposed by other workers either underestimated (root mean square error RMSE = 1.23 g N m−2) or overestimated (RMSE = 2.18 g N m−2) N remaining in the crop residues after 120 d of decomposition. CERES‐N with user‐supplied pool sizes improved the simulation of N remaining after 120 d (RMSE = 0.69 g N m−2), but the simulated values generally tended to overestimate the field data. The best‐fitting rate constants for carbohydrates and cellulose pools were 0.67 and 0.021 d−1, respectively, for the original CERES‐N (RMSE = 0.77 g N m−2), and 0.17 and 0.011 d−1 for CERES‐N with user‐supplied pool sizes (RMSE = 0.55 g N m−2). Future work should further evaluate these fitted rate constants under field conditions.