bluuebunny/crossref_metadata_2025_split huggingface dataset:
Control of Nutrient Mixing and Uptake by Irrigation Frequency and Relative Humidity
Authors: Kargbo D. , Skopp J. , Knudsen D. 
Published: July 2010

AbstractThe distribution of nutrients and water between mobile and immobile pores should influence nutrient uptake. The distribution can be regulated through control of the water‐filled pore space. This research was conducted to determine the effect of varying soil‐water content and water uptake upon nutrient uptake. Corn (Zea mays L.) was grown in a growth chamber for 2 wk at 35 or 55% relative humidity (RH). Three soils [Boelus LS, 5% slope (sandy over loamy, mixed, mesic Udic Haplustoll); Boelus LS, 2% slope; and Plano Soil (fine‐silty, mixed, thermic Typic Haplustolf)] were watered to field capacity (θmax). Plants on each soil were allowed to extract water to one of three minimal levels (θmin1, θmin2, θmin3) before rewatering. After harvest, P and K content and other root and leaf parameters were determined. The values of θmin were chosen so that, for each soil, the three values ensured no low‐water stress. Effective diffusion coefficients were determined for the three Increased Omin for a soil required for frequent watering, which led to greater mixing of solutes between pores. At 55% RH, no water treatment significantly affected P and K flux, despite significant differences in diffusion coefficients. At 35% RH, however, phosphate flux to roots increased as θmin increased. The significant increase of phosphate flux with more frequent watering at low RH suggests that plant uptake is affected by soil physical processes other than simple diffusion and convection to individual roots. More frequent watering results in greater mixing of solute between pores containing mobile and immobile water and, consequently, greater uptake.
Mechanisms for Overyielding in a Sunflower/Mustard Intercrop
Authors: Putnam D.H. , Allan D.L. 
Published: July 2010

AbstractTwo intercrop patterns and sole crops of mustard (Brassica hirta Moench) and sunflower (Helianthus annuus L.) were planted in 1988 and 1989 on a Waukegan silt loam soil (fine‐silty over sandy or sandyskeletal, mixed, mesic Typic Hapludoll) at Rosemount, MN, to examine mechanisms for overyielding [Land Equivalent Ratio (LER) > 1.0] in this intercrop system. We hypothesized that reduced competition between species for N and water were the mechanisms for previously observed yield benefits in both crops. Secondary objectives were to examine the importance of intercrop structure and N fertilizers on resource use and yield advantage. A strip intercrop pattern where 2.28‐m strips of sunflower (76‐cm rows) alternated with 2.28‐ m strips of mustard (15‐cm rows) was compared with a more intimate row intercrop pattern of 76‐cm sunflower rows interplanted with four 15‐cm rows of mustard. Nitrogen was applied at planting at 0 or 112 kg N ha−1 to whole plots, with planting patterns allocated to subplots in a split‐plot design. Soil water content, nitrate N, and total N were measured at different locations and depths in the intercrop and sole crop patterns during the growing season. Mustard rows adjacent to sunflower in the strip intercrop yielded an average of 61% more than sole crop rows. Sunflower rows adjacent to mustard in the strip intercrop yielded an average of 40% more than sole crop rows. Yields of both sunflower and mustard were lower in the row intercrop compared with respective sole crops. Land equivalent ratios ranged from 0.96 to 1.43 in the strip intercrop and were generally below 1.0 in the row intercrop. Application of N did not consistently affect LER. Soil depletion patterns indicated that border rows of mustard obtained both soil water and N from the strips planted to sunflower at a time when demand for these resources by sunflower was low. Sunflower border rows obtained water and N from mustard strips later in the season. These data implicate complementary use of water and N as important mechanisms for the positive land equivalent ratio observed in this strip intercrop.
Potassium in Two Humid Tropical Ultisols under a Corn and Soybean Cropping System: I. Management
Authors: Cox F.R. , Uribe E. 
Published: July 2010

AbstractSub‐optimum soil K levels often limit corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] production in humid tropical Ultisols. The objectives of this study were to determine soil and plant critical levels of K and optimum rates of K fertilization for corn and soybean grown in the Amazon Basin of Peru. Two field experiments were conducted on Typic Paleudults, a loam and a sandy loam. Five K rates, ranging from 0 to 120 kg ha−1, were broadcast and incorporated prior to planting the first crop of a corn, corn, soybean rotation at both sites. At the loam site, K treatments were reapplied at the end of this rotation and three more corn crops grown. The corn stover was returned while the soybean stover was removed. Critical exchangeable K levels for corn were 110 kg ha−1 on the loam and 90 kg ha−1 on the sandy loam, while for soybean it was 75 kg ha−1 for both soils. The critical levels of K in plant tissue at flowering were 13 g kg−1 in corn and 12 g kg−1 in soybean. Soybean seemed to lower exchangeable K to where K was released from non‐exchangeable sources. An annual cropping system of corn and soybean with an intervening cover crop during the rainy season is proposed for the region. Potassium fertilization is recommended only prior to growing corn at 90 kg ha−1 on a loam and 60 kg ha−1 on a sandy loam.
Simulating Winter Wheat Production in Three Tillage Systems Using the Nitrogen Tillage Residue Management Model
Authors: Davidoff B. , Wilhelm W. W. , Skopp J. 
Published: July 2010

AbstractCrop production system analysis is necessary to identify tillage and residue management practices that affect crop production. The objective of this study was to evaluate the potential of using the Nitrogen Tillage Residue Management (NTRM) model to evaluate the influence of tillage practices on winter wheat (Triticum aestivum L.) yield. Modifications of the NTRM model were required to simulate winter wheat production. The model was calibrated using site‐specific information obtained from a tillage‐nitrogen rate experiment conducted at the High Plains Agricultural Laboratory near Sidney, NE, on an Alliance silt loam (fine silty, mixed, mesic Aridic Argiustoll). Model output was compared to measured yields of winter wheat grown on three tillage treatments [moldboard plow, subsurface tillage (1.5 in‐wide “V” blade), and no tillage] during three seasons. Simulations within the year of calibration agreed within ± 28% of measured yields for the moldboard plow and subsurface tillage treatments. Deviations were observed between predicted and measured yields when using data outside the year of calibration. Crop coefficients, determined in the calibration process, affected the yield predictions of NTRM. Grain yield predictions by NTRM were very sensitive to initial and stabilized soil bulk density values within the range of 1.2 to 1.3 Mg m−3 (1% change in input value caused a five‐fold change in predicted yield). Usefulness of the model could be enhanced through greater documentation on calibration procedures and explanation of calibration coefficients. Results obtained here should alert users to the need for care in application of results obtained from complex, highly interlinked models, such as NTRM.
Ammonia Emission from Soybean‐Amended Calcareous Soil with Various Soil Temperature and Moisture Levels
Authors: O'Deen W. A. , Follett R. F. 
Published: July 2010

AbstractHigh soil temperature, moisture, and crop residue levels were found to combine for maximum volatilization of ammonia from calcareous soil amended with soybean [Glycine max (L.) Merr.] tissue in this study. An unusually large amount of ammonia was liberated to the atmosphere and provided the opportunity to measure accurately isotope separation of 15N and 14N atoms resulting from the diffusion process. Soybean tissue (early reproductive stage) was mixed with a calcareous soil (Aridic Paleustoll) at two different levels (25 and 50 g kg−1). The two soil soybean‐tissue mixtures were wetted to the desired moisture content (20, 60, and 100% field capacity) and incubated 7 d at either 10, 20, or 30 °C. After incubation, ammonia evolution and moisture loss were determined during either a 4‐ or 7‐d dry‐down period in which dry NH3‐free air was passed across the soil surface. We found more NH3 volatilized at 100ɐ FC than at 20 or 60% FC, at 30 than at 10 or 20 °C, and at 50 than at 25 g kg−1 residue rate. Maximum loss of NH3 was about 5% of soybean‐tissue N measured in an experiment in which four wet‐dry cycles were used. Maximum loss was directly related to water evaporation rate. These results indicate that soil temperature, moisture, and crop‐residue rates all influence NH3 losses from soybean‐tissue amended soil. Isotopic ratios of the NH3−N evolved were measured and ammonia content of the first fraction of ammonia volatilized was lower in atom % 15N than the last fraction. These results indicate that, for the conditions of this study, diffusion is an important process since the 14N atoms volatilized more quickly as NH3 than did the 15N atoms.
Alfalfa Development after Simulated Alfalfa Weevil Injury
Authors: Peterson Robert K. D. , Danielson Stephen D. , Higley Leon G. 
Published: July 2010

AbstractAlthough the alfalfa weevil [Hypera postica (Gyllenhal)] is an important insect pest of alfalfa (Medicago sativa L.), relatively little is known about how larval defoliation affects growth processes at specific developmental stages. This study was conducted to characterize the developmental responses of alfalfa to simulated alfalfa weevil injury when injury was initiated at the early‐bud stage of the first growth cycle. The study was conducted on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic, Typic Argiudolls) in a 3.6 ha ‘Haymaker’ alfalfa field near Walton, NE. A total of 16 1‐by 1‐m plots were arranged in a randomized complete block design with four treatments in each of four replicates. Treatments consisted of an undefoliated check and three levels of simulated alfalfa weevil defoliation. Morphological effects of simulated alfalfa weevil injury were determined at five postdefoliation periods. Leaf area indices, leaf area to total dry weight ratios, and leaf dry weight to total dry weight ratios were reduced linearly as defoliation percentages increased. However, defoliation injury did not affect phenological development of the first growth cycle between the completion of injury and first harvest. Most growth rates were not different among treatments, indicating that there was no postdefoliation compensatory growth. Injury initiated at the early‐bud stage of the first growth cycle did not impact alfalfa regrowth after the first harvest. Consequently, the most important effect of defoliation initiated at the early‐bud stage of the first growth cycle was to reduce dry matter yield of the first growth.
Growth of Peanut Roots under Field Conditions
Authors: Ketring D. L. , Reid J. L. 
Published: July 2010

AbstractThe largest detriment to crop productivity in many environments is available water. Biomass accumulation is proportional to water moving through the plant, i.e., transpiration. The supply of water for crop biomass accumulation is provided from the soil reservoir by the root system. Our objective was to quantify peanut (Arachis hypogaea L.) root growth over time by depth and lateral spread in the soil profile. By soil coring techniques, we determined the growth of roots, in response to irrigation treatments imposed under field conditions, of two Virginia‒, runner‐type peanut cultivars over time. Root length density (RLD) and root weight density (RWD) in the soil profile were not significantly different between cultivars or among irrigation treatments. However, significant year differences were observed. Following crop establishment under similar environmental conditions in both years, 1988 was hotter and drier than 1989. Also, postplant rainfall through 45 DAP was less in 1988 than 1989 and total water received by the crop was less in 1988 than 1989. Under these conditions, there was nearly twice and three times as much RLD and RWD in 1988 than 1989. Root length density and RWD significantly increased at each depth increment with days after planting (DAP) until 80 DAP. At 40 to 45 DAP, roots had penetrated to a depth of 120 cm and spread laterally to at least 46 cm (mid‐furrow). The 15‐cm depth increment had the highest mean RLD, which increased to a maximum at 2.1 and 1.7 cm cm−3 at 80 and 83 DAP in 1988 and 1989, respectively. However, over the same time period there was also a simultaneous increase in RLD at depths below 15 cm. Thus, peanut roots were established both deeply and laterally in the soil profile early in the growing season. This could prove advantageous in a drought environment and the knowledge useful for water management of the crop.
Light Transmittance, Soil Temperature, and Soil Moisture under Residue of Hairy Vetch and Rye
Authors: Teasdale J. R. , Mohler C. L. 
Published: July 2010

AbstractCover crop residue on the surface of soils in no‐tillage systems can suppress weed emergence and growth. Although allelopathy often is invoked to explain weed suppression by residue, physical alterations of the seed environment could be important as well. This experiment was conducted to determine the light, temperature, and moisture conditions under cover crop residue. Hairy vetch (Vicia villosa Roth) and rye (Secale cereale L.) were desiccated with a contact herbicide and residue rates ranging from one‐fourth to four times the natural residue biomass were established in experiments at Beltsville, MD and Ithaca, NY. Photosynthetic photon flux density (PPFD) was determined above and below residue at approximately monthly intervals after initiation of the experiment. Transmittance of PPFD through residue declined according to an exponential decay function of residue biomass. Transmittance was similar through hairy vetch and rye residue initially, but as the experiment progressed, transmittance through hairy vetch residue was greater than that through rye because of faster decomposition of hairy vetch residue. Spectral analysis from 400 to 1100 nm showed a slight increase in transmittance as wavelength increased resulting in a slight lowering of the red (660 nm) to far‐red (730 nm ratio relative to that of unobstructed sunlight. Soil maximum temperature and daily soil temperature amplitude were reduced by cover crop residue. Residue prevented the decline of soil water content during droughty periods. Results indicated that reductions in light transmittance and daily soil temperature amplitude by cover crop residue were sufficient to reduce emergence of weeds but that maintenance of soil moisture could increase weed emergence.
Nitrogen Efficiency Component Analysis: An Evaluation of Cropping System Differences in Productivity
Authors: Huggins D. R. , Pan W. L. 
Published: July 2010

AbstractThe development of cropping systems that use N efficiently requires methods that evaluate system differences in N use. A procedure, based conceptually on soil and plant processes that affect N use, was developed to evaluate differences in N use efficiency among cropping systems. The method uses measurements of yield, grain N, aboveground plant N, applied N, and postharvest inorganic soil N to partition cropping system differences in yield and grain N into N efficiency components. The components consist of N supply, available N efficiency, available N uptake efficiency, N utilization efficiency, grain Naccumulation efficiency, and N harvest index. The N efficiency component analysis was demonstrated for a field study with hard red spring wheat (Triticum aestivum L. ‘WB 906R’) where conventional tillage had a greater yield and grain N than no‐tillage. At low N rates, 78% of the difference in yield between the two was attributed to N supply and available N efficiency components. At high levels of applied N, 88% of the yield difference was attributed to the N utilization efficiency component. Differences in grain N were attributed to N supply and available N efficiency components, whereas components of grain N accumulation efficiency, available N uptake efficiency, and N harvest index were nonsignificant. Overall, this new approach transcends empirical analyses and provides insight into underlying mechanisms of cropping system differences in N use.
Quantifying Wheat Water Stress with the Crop Water Stress Index to Schedule Irrigations
Authors: Garrot Donald J. , Ottman Michael J. , Fangmeier D.D. , Husman Stephen H. 
Published: July 2010

AbstractThe relationship between the timing and amount of applied irrigation water and grain yield has not been well defined for durum wheat (Triticum turgidum L. var. durum) grown under irrigation in arid regions. With rising water costs and decreasing water supplies, grain growers will have to optimize yield for given levels of water inputs if they are to remain profitable. Small‐plot field studies were conducted in 1986 and 1987 at Marana, AZ, to (i) test the feasibility of using the crop water stress index (CWSI) to schedule wheat irrigations and (ii) determine relationships among CWSI, grain production, and water applied. Highest grain production was attained when irrigations were scheduled at CWSI values averaging 0.37 units in 1986 and 0.30 units in 1987. Scheduling irrigations with lower CWSI values did not increase grain production, but required more water. Delaying irrigation by scheduling irrigations at CWSI values exceeding the optimum values reduced grain production.
Management and Environment Effects on Brassica Forage Quality
Authors: Wiedenhoeft M. Hagemann , Barton B. A. 
Published: July 2010

AbstractForage Brassica spp. have been shown to produce adequate amounts of herbage during the cooler months of the fall, thus allowing extension of the grazing season in higher latitudes. The objective of this study was to determine if the nutritive quality of initial and regrowth herbage was influenced by planting and harvest date. In 1987, 1988, and 1989, three Brassica spp. (rape [B. oleracea L.], turnip [B. rapa L.] and turnip hybrid [B. rapa L. × B. pekinensis L.]) were planted in late May to early June, late June to early July, and late July to early August and were harvested each year at 64, 76, or 85 DAP. The plants regrew 60, 70, or 80 d and were harvested. Nutritive components measured were CP, NDF, ADF, Ca, Mg, and P. Nutritive levels declined with warmer temperatures and low soil moisture levels particularly during July and August. Neutral‐detergent fiber and ADF levels were higher, while the CP levels were lower in herbage from the earliest planting date compared with the later planting dates, regardless of species and year. The levels of Ca, Mg, and P were influenced by species and planting date. In general, the regrowth herbage had a lower fiber and a higher protein content than the initial herbage. The variation in nutritive quality among the three species was relatively small. Of more importance to the producer is that the quality of brassica herbage is more comparable to a concentrate than a traditional forage because of the relatively low fiber and high protein content.
Ethephon Alters Corn Growth, Water Use, and Grain Yield Under Drought Stress
Authors: Kasele I. N. , Nyirenda F. , Shanahan J. F. , Nielsen D. C. , d'Andria R. 
Published: July 2010

AbstractThe plant growth regulator ethephon has been used to reduce height and lodging of intensively managed corn (Zea mays L.). However, the impact of ethephon‐induced changes in vegetative growth on water use and grain yield of corn grown at various densities under drought stress conditions has not been widely studied. Field studies were conducted for 2 yr in semiarid eastern Colorado to determine if foliar ethephon application can alter vegetative growth and water use and promote drought stress resistance of corn. In 1989, treatments consisted of a factorial combination of two irrigation levels (low and high), two plant densities (53 333 and 80 000 plants ha−1), and five ethephon treatments (0, 0.28, 0.56, and 0.84 kg ha−1, applied at the 6‐ or 8‐leaf growth stage) at one site. In 1990, treatments consisted of a factorial combination of four plant densities (24 700, 37 045, 49 390, and 61 735 plants ha−1) and three ethephon rates (0, 0.28, and 0.56 kg ha−1 applied at the 6‐leaf stage) at two sites. Plant height, leaf area index (LAI), dry matter yield, cumulative evapotranspiration (ET), and grain yield were measured. In both seasons, ethephon application reduced plant height and LAI by 10 to 40%, relative to the control, and this resulted in early season ET reductions. Ethephon application either had no effect or decreased yields in 1989 under all irrigation and plant density treatments, because of a lack of significant drought stress. However, when drought occurred in 1990, ethephon application decreased yields at low plant densities but enhanced yields at high plant densities at both locations, with a maximum 37% yield increase for the intermediate ethephon rate. Our data indicate that ethephon application has the potential for improving resistance to drought in corn.
Nitrogen Fertilizer Application and Seeding Date Effects on Oat Grain Milling Quality
Authors: Humphreys D. Gavin , Smith Donald L. , Mather Diane E. 
Published: July 2010

AbstractManagement factors such as N fertilizer rate and seeding date can significantly influence oat (Avena sativa L.) grain milling quality. The effects of N fertilizer and seeding date on the grain yield and milling quality of four oat cultivars were evaluated using two N rates (40 kg ha−1 applied at seeding or 40 kg ha−1 applied at seeding plus 20 kg ha−1 applied at the boot stage) and two seeding dates. Studies were conducted at Ste‐Anne‐de‐Bellevue, PQ, Canada, from 1990 to 1992 and at Ste‐Rosalie, PQ, in 1991. Nitrogen treatments had little effect on milling quality at Ste‐Anne‐de‐Bellevue, but hull percentage decreased and plump grain percentage increased with higher N in the Ste‐Rosalie experiment. Delayed seeding reduced yields in all four experiments. In the Ste‐Anne‐de‐Bellevue experiments, delayed seeding reduced test weight, 1000‐grain weight, plump grain percentage, and theoretical milling yield and increased percentage of hull, thin grain, and bosom grain. In the Ste‐Rosalie experiment, opposite effects were observed; this may have resulted from reduced production of secondary and tertiary seeds in the late‐seeded treatments. For most milling quality characteristics, significant differences between cultivars were observed, and cultivars interacted with management treatments. In general, the higher application rate of N did not improve oat grain milling quality sufficiently to warrant its usage. Later seeding resulted in inferior yields at all locations, but did not necessarily reduce milling quality. The correct choice of cultivar seems crucial for production of high‐quality milling oat grain.