bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leaf Area of Strip‐Intercropped Corn in Dry and Normal Growing Seasons
Authors: Fortin M.‐C. , Edwards M. 
Published: July 2010

AbstractCrop growth models need to be adapted for cropping systems other than monoculture. This study was conducted (i) to determine the effect of row position on leaf area of corn (Zea mays L.) strip‐intercropped with soybean [Glycine max (L.) Merr.] and a small grain crop (oat, Avena sativa L., in 1991; barley, Hordeum vulgare L., in 1992) and (ii) to determine whether an established leaf area model developed from monoculture corn data fits the strip‐intercropping data. Corn, soybean, and small grain were planted in north‐south rows on a mixed, mesic Typic Endoaquoll in Nepean, ON. There was 55.1 rainfall from emergence of Leaf 5 to silking in 1991 and 210.6 mm in 1992. Total green leaf area at grain filling varied with row position each year. The corn row next to the small grain had less leaf area than the middle row in 1991 and more leaf area than the middle row in 1992. These variable results were due to differences in weather in the two years. Dry conditions in 1991 resulted in slow expansion of leaves and in small individual leaf area. As thermal time to full expansion of the largest leaf on the plant was similar in both years, the largest leaf in 1991 occurred at an earlier developmental stage than in 1992 (Leaf 10.5 vs. Leaf 12). An existing leaf area model was found to fit the data, provided that adjustments for row position and for the timing of the development of the largest leaf were included.
Nitrogen‐Sulfur Relationships in Corn as Affected by Landscape Attributes and Tillage
Authors: Cassel D. K. , Kamprath Eugene J. , Simmons F. William 
Published: July 2010

AbstractCorn (Zea mays L.) root access to the B horizon is needed for adequate sulfur nutrition on sandy, highly leachable Coastal Plain soils with tillage pans. Deep tillage increases rooting depth on these soils, but the interaction of deep tillage with landscape attributes in complex toposequences is not well understood. The effect of chisel plowing 35 cm deep, subsoiling 25 cm deep, and disking 12 cm deep on N and S accumulation by corn on a well‐drained toposequence of Coastal Plain soil was studied in 1984 and 1985. Nitrogen and S concentrations of aboveground biomass were measured at anthesis (Na and Sa,, respectively) and at harvest (Nh and Sh, respectively). Soil surface curvature (CRV) (i.e., its convexity or concavity), and depth to the B horizon (BDEP) were correlated with Sa in both years. Extreme drought in early 1985 resulted in a stronger negative linear response of Sa with BDEP in the chisel plow and disk treatments compared with the subsoil treatment. The Na/Sa ratio was negatively correlated with BDEP for all treatments and with CRV for chisel plow and disk tillage. Deep tillage had the greatest positive effect on S accumulation by corn at the linear slope position, which was the landscape position with the greatest depth to the B horizon.
Runoff, Erosion, and Forage Production from Established Alfalfa and Smooth Bromegrass
Authors: Zemenchik Robert A. , Wollenhaupt Nyle C. , Albrecht Kenneth A. , Bosworth Andrew H. 
Published: July 2010

AbstractSurface sealing of soils in established alfalfa (Medicago sativa L.) may produce runoff during intensive rainstorms, resulting in soil loss and reduced yield. We hypothesized that smooth bromegrass (Bromus inermus Leyss.) grown in mixture with alfalfa would reduce on‐site runoff and soil loss, and that this should offset any negative effect on forage quality. Alfalfa, smooth bromegrass, and an alfalfa‐smooth bromegrass mixture were established in 1992 on Rozetta silt loam (moderately well drained, fine‐silty, mixed, mesic Typic Hapludalfs) near Lancaster, WI. A 72‐mm h−1 simulated rainfall was applied for 1 h during the growing seasons of 1993 and 1994 to forage regrowth at 4 and 6 wk after first harvest and immediately after second harvest. The addition of smooth bromegrass to alfalfa did not significantly reduce runoff volume, sediment concentration, or total soil loss at any rainfall event at any stage of regrowth in either year. Furthermore, forage yield and concentrations of acid‐detergent fiber and crude protein in the forage were not affected. Averaged over both years and the three sward types, runoff at 6 wk was significantly less than at 0 wk, which was significantly less than at 4 wk. Total soil loss from all sward types summed over six simulated rainstorms was between 0.19 and 0.61 Mg ha−1, much less than the 11.2 Mg ha−1 yr−1 considered tolerable for this soil. Neutraldetergent fiber (NDF) concentration of bromegrass (534 g kg−1) was greater than either the mixture (441 g kg−1) or alfalfa (404 g kg−1). Soil loss and forage quality results do not support adding smooth bromegrass to alfalfa, especially since increased NDF results in lower forage intake by ruminants and reduced milk yield in dairy cattle (Bos taurus); however, livestock operations that could efficiently utilize smooth bromegrass monocultures could reduce soil loss and runoff by doing so.
Ammonia Transport in a Temperate Grassland: I. Seasonal Transport in Relation to Soil Fertility and Crop Management
Authors: Harper Lowry A. , Bussink D. Wim , van der Meer Hugo G. , Corré Wim J. 
Published: July 2010

AbstractAn understanding of N cycling in agricultural systems is necessary to optimize N‐use efficiency and reduce N losses to the environment. The objectives of this research were to evaluate N cycling in a highly fertilized grassland in a humid temperate climate and to observe the effects of N surplus and deficit on NH3 absorption‐desorption by the grass. Soil, plant, and weather measurements were taken concurrently and soil‐plant‐atmosphere N transport were determined. After N application, soil inorganic N decreased rapidly to background levels, due to possible microbial immobilization and plant N demand. Much of the immobilized N was remobilized during the growth period, but at insufficient rates to avoid N stress by the crop, as shown by absorption of NH3. During spring, 45% of the plant N was derived from applied fertilizer, with the balance obtained from mineralized organic N (49%) and absorption of NH3 (6%). During summer, fertilizer N accounted for 60% of accumulated grass N and NH3 absorption accounted for 11% of N not derived from fertilizer (4% of the total N), with the balance coming from mineralized organic N. Soil water content and wind speed were the dominant factors influencing the crop NH3 compensation point (CP). The daily NH3 CP was variable, but the average seasonal NH3 CP was about 14 μg m−3.
Regression Models for Calculating Gas Fluxes Measured with a Closed Chamber
Authors: Wagner Steven W. , Reicosky Donald C. , Alessi R. Samuel 
Published: July 2010

AbstractPortable closed chambers provide a valuable tool for measuring crop photosynthesis and evapotranspiration. Typically, the rates of change of CO2 and water vapor concentration are assumed to be constant in the short time required to make the closed‐chamber measurement, and a linear regression model is used to estimate the CO2 and H2O fluxes. However, due to the physical and physiological effects the measurement system has on the measured process, assuming a constant rate and using a linear model may underestimate the flux. Our objective was to provide a model that estimates the CO2 and H2O exchange rates at the time of chamber closure. We compared the linear regression model with a quadratic regression model using field measurements from two studies. Generally, 60 to 100% of all chamber measurement data sets were significantly nonlinear, causing the quadratic model to yield fluxes 10 to 40% greater than those calculated with the linear regression model. The frequency and degree of nonlinearity were related to the measured rate and chamber volume. Closedchamber data should be tested for nonlinearity and an appropriate model used to calculate flux. The quadratic model provides users of well‐mixed closed chambers an alternative to a simple linear model for data sets with significant nonlinearity.
Apparent Atmospheric Nitrogen Loss from Hydroponically Grown Corn
Authors: Sharpe Ronald R. , Harper Lowry A. 
Published: July 2010

AbstractIsotopic 15N tracers have been important tools in the understanding of N cycling in agricultural and natural soil‐plant systems. The objectives of this research were to quantify losses of 15N under controlled conditions, evaluate 15NH3 transport between plants, and assess the potential for error associated with the use of N isotopes. Corn (Zea mays L.) was grown hydroponically in 5‐ to 15‐mm‐diam. gravel in twelve 162‐L barrels. All N was applied as NO3 with enrichment periods of full season, planting through anthesis, anthesis to harvest, or no 15N applied. Plant growth and total N accumulation followed normal growth curves and maximum N content was obtained at anthesis. When 15N treatments stopped at anthesis, plants lost 15N (presumably as 15NH3) equivalent to about 23% of total plant N between anthesis and harvest. In treatments in which 15N applications started at anthesis, total N content in the leaves and stems decreased between anthesis and harvest while 15N content increased indicating a substitution of recently absorbed N for N compounds translocated to the fruit. Volatile losses of N indicate that caution must be exercised when conducting and interpreting 15N experiments. Significant plant‐to‐plant transport of 15NH3 showed that decreases in plant 15N content could not be used to estimate NH3 volatilization for an entire field.
Yield and Green‐Manure Benefits of Interseeded Legumes in a High Desert Environment
Authors: Guldan Steven J. , Martin Charles A. , Lindemann William C. , Cueto‐Wong Jose , Steiner Robert L. 
Published: July 2010

AbstractRelay intercropping legumes into vegetable crops provides cover and green‐manure benefits to subsequent crops, but has not been adequately researched in high desert regions. This study evaluated the dry matter, N yield, effect on a subsequent forage sorghum [Sorghum bicolor (L.) Moench] crop, and estimated fertilizer‐replacement value (FRV) of several legumes interseeded into sweet corn (Zea mays L.). The study took place under furrow irrigation in north‐central New Mexico (study site elevation, 1737 m) on a Fruitland sandy loam (coarse‐loamy, mixed, calcareous, mesic Typic Torriorthent). Five legumes (hairy vetch, Vicia villosa Roth; barrel medic, Medicago truncatula Gaertn.; alfalfa, Medicago sativa L.; black lentil, Lens culinaris Medik.; and red clover, Trifolium pratense L.) were interseeded into sweet corn at last cultivation or blister stage in 1993 and 1994. Corn ears and stover were harvested in August. The following spring, plots were plowed and seeded to forage sorghum. Estimated FRV for the legumes were calculated from regression equations for sorghum dry matter yield as a function of N fertilizer rate. Herbage N yields in the fall were greatest for hairy vetch and barrel medic and, averaged across interseeding dates, ranged from 55 to 64 kg ha−1 in 1993 and 100 to 108 kg ha−1 in 1994. Whole‐plant N yields (herbage + roots + crowns) in May were greatest for hairy vetch, 205 kg ha−1 in 1994 and 172 kg ha−1 in 1995. Seasonal dry matter yield and N uptake of sorghum were greatest following hairy vetch in 1994, and hairy vetch and alfalfa in 1995. Based on seasonal sorghum yield, hairy vetch and alfalfa had the highest FRV, ranging from 78 to 140 kg ha−1 N.
Swine Lagoon Effluent Disposal by Overland Flow: Effects on Forage Production and Uptake of Nitrogen and Phosphorus
Authors: Liu Fuhan , Mitchell Charles C. , Odom John W. , Hill David T. , Rochester Eugene W. 
Published: July 2010

AbstractSwine (Sus scrofa) production requires economical and environmentally safe waste management systems. The objective of this study was to determine the effect of swine lagoon effluent on dry matter yield and N and P uptake of a mixture of hybrid bermudagrass [Cynodon dactylon (L.) Pers. cv. Russell] and annual ryegrass (Lolium multiflorum Lam.) grown on a Marvyn loamy sand (fine‐loamy, kaolinitic, thermic Typic Kanhapludult). Treatments included a control with no nutrient additions, NH4NO3 at 560 kg N ha−1 yr−1, and swine lagoon effluent at 560, 1120, and 2240 kg N ha−1 yr−1. Effluent was applied using an overland flow technique. The highest lagoon effluent rate added N at 4 times and P at 11 times the normally recommended rates for these forage grasses. Total dry matter yield was significantly increased by NH4NO3 and swine lagoon effluent additions, compared with the control treatment. Dry matter yield for the lowest effluent rate was not significantly different from that for the NH4NO3 treatment, and dry matter yields were not significantly different among the three rates of lagoon effluent. Increasing the effluent rates generally increased total N and total P concentrations in the forage. Recoveries were about 32% for N and 20% for P at the lowest rate of lagoon effluent, and about 13% for N and 9% for P at the highest rate. The low recoveries of N and P with higher than recommended effluent rates could have environmental implications for the quality of soil, groundwater, and surface runoff.
Ammonia Exchange from Corn Foliage during Reproductive Growth
Authors: Francis Dennis D. , Schepers James S. , Sims Albert L. 
Published: July 2010

AbstractDeveloping solutions to atmospheric environmental problems requires a better understanding of chemical processes occurring in each component of the ecosystem. Volatile NH3 loss from plant foliage complicates the assessment of NH3 emissions from agricultural activities. The objective of this study was to use 15N methodology to identify time of occurrence, magnitude, and direction of NH3 exchange between corn (Zea mays L.) fertilized with enriched 15N and the atmosphere during reproductive growth. Ammonia was collected by drawing air over leaves, ear shoots, and whole plants and trapping the NH3 on oxalic acid‐impregnated filter disks. Filter disks were analyzed by ANCA‐MS procedures for total N and atom % 15N. An exchange of NH3 between corn plants and the atmosphere was found to occur during all sampling periods. This suggests that the release and capture of free NH3 is an active component of the metabolic processes taking place in corn plants during reproductive growth. For corn under non‐limiting N fertility, the direction, rate, and magnitude of NH3 exchange from leaves does not appear to be a function of ambient atmospheric NH3 concentrations. Determining the true loss or gain in N between corn plants and the atmosphere during reproductive growth is very difficult as a result of this continuous exchange of NH3. The amount of net N lost from a corn crop will be less than the amount indicated by measurements of isotopic loss, because both interchange between plants and deposition on soil and plants may take place within the field.
Post‐Harvest Residue Management of Creeping Red and Chewings Fescue Seed Crops
Authors: Young William C. , Gingrich Gale A. , Silberstein Thomas B , Quebbeman Bryon M. 
Published: July 2010

AbstractLegislative actions in the Pacific Northwest have greatly restricted the total area of grass seed crops that can be burned each year. Grass seed growers are searching for alternatives to postharvest residue burning. In on‐farm experiments in western Oregon, we compared four postharvest residue management methods for effects on seed yield of creeping red fescue (Festuca rubra L. subsp. rubra cv. Cindy) and Chewings fescue (Festuca rubra L. subsp. commutata Gaudin cv. Center). Treatments were (i) straw residue removed and stubble flail‐chopped (flail‐chop), (ii) straw residue removed and stubble close‐clipped and vacuum‐swept (close‐clip), (iii) straw residue removed and stubble propane‐burned (propane‐burn), and (iv) residue and stubble open‐burned with full straw load (open‐burn). Seed yield components were also measured, to identify the component through which treatments affected yield. Treatment effects on seed yield of both crops interacted with years. Averaged across years, creeping red fescue seed yield was 993, 903, 804, and 620 kg ha−1 for open‐burn, propane‐burn, close‐clip, and flail‐chop treatments, respectively. The greatest treatment effect was on number of panicles, and consequently on number of floret sites and seeds produced per unit area. The number of spikelets per panicle, florets per spikelet, and seeds produced per panicle were unaffected. Open‐burn also resulted in the fewest weed seeds and the highest purity of the harvested seed. Treatments affected Chewings fescue seed yield in only one year, when seed yield was 750, 680, 477, and 553 kg ha−1 for open‐burn, propaneburn, close‐clip, and flail‐chop treatments, respectively. Treatments did not affect the number of panicles or seeds produced per unit area in Chewings fescue, the number of weed seeds, or the purity of the harvested seed. We concluded that mechanical removal of postharvest residue in Chewings fescue can maintain seed yield and seed quality similar to open‐burn. In contrast, open‐burn is required to achieve maximum seed yield and seed quality in creeping red fescue.
Intrablock Variance among Duplicate Treatments for Nearest‐Neighbor Analyses
Authors: Helms Theodore C. , Scott Roy A. , Hammond James J. 
Published: July 2010

AbstractNearest‐neighbor analysis (NNA) adjusts for spatially correlated residuals, with the goal of increasing precision. The magnitude of the block × treatment interaction mean square is commonly used to evaluate the precision of the NNA model. An alternative method of evaluating the precision of the NNA and classical unadjusted (UNADJ) randomized complete block (RCB) analysis would be to use the pooled variance between duplicate treatments within each block. We defined pure error as variation between plots that are treated alike within a block. Within each location, each genotype was randomly assigned to two plots within each block of an RCB design. The pure error of soybean [Glycine mar (L.) Merr.] genotypes was evaluated at eight locations. Our objective was to compare the block × treatment and pure error mean squares for yield, physiological maturity, and plant height to determine whether the NNA or UNADJ analysis reduces intrablock variation. The NNA analysis always decreased the magnitude of the block × treatment interaction mean squares, compared with the UNADJ analysis. In some comparisons, the pure error mean square of the NNA analysis was significantly smaller than the pure error of the UNADJ analysis. The magnitude of the block × treatment mean square is not useful for comparing the relative precision of these two analyses. When the pure error mean square was used to measure precision, the NNA was at least as precise as the UNADJ analysis.
Modifications of Soil Nitrogen Pools in Response to Alfalfa Root Systems and Shoot Mulch
Authors: Rasse Daniel P. , Smucker Alvin J. M. , Schabenberger Oliver 
Published: July 2010

AbstractDecomposing alfalfa (Medicago sativa L.) shoots and roots generate large amounts of NO3‐N available to the next crop but also susceptible to deep leaching. This study was aimed at determining the specific contributions of above‐ and belowground alfalfa biomass to soil N pools. Dynamics of soil and plant N pools were studied in a Kalamazoo loam soil (fine‐loamy, mixed, mesic Typic Hapludalfs) over a 2‐yr period under bare fallow (BF), hare fallow to which alfalfa shoot mulch was applied (BFSM), living alfalfa plants with shoots removed after harvest (A), and living alfalfa with shoot mulch remaining on the soil surface after harvest (ASM). Organic N pools were monitored in alfalfa plant parts, soil‐incorporated debris, and soil organic matter to depths of 150 cm. Inorganic N pools were monitored by suction Iysimeters, soil extraction, and evaluation of soil denitrification rates. Living alfalfa stands kept soil inorganic N at very low levels, whether shoot mulch was applied or not. Soluble inorganic N concentrations decreased earlier in the fall in the upper horizons of bare fallow soils receiving alfalfa shoot mulch, suggesting enhanced leaching from bare soil under alfalfa mulch. Alfalfa crown and roots contained an average of 115 kg N ha−1 after 2 yr of treatment. In conclusion, alfalfa shoot mulch contributed little to sustained increases in soil N pools, while crowns and roots contributed larger quantities to the soil N pool.
Soil Response to Acid Deposition, Wind River Mountains, Wyoming: I. Soil Properties
Authors: Clayton James L. , Kennedy Debora A. , Nagel Terry 
Published: July 2010

AbstractIn the western USA, alpine and subalpine ecosystems with shallow soils and large areas of rock outcrop may be particularly sensitive to damaging effects from acid precipitation, especially downwind of pollutant sources. This study was conducted to characterize the capacity of subalpine soils in the Wind River Mountains of Wyoming to neutralize acid deposition through cation exchange and SO4 adsorption, and to relate buffer capacity and SO4‐adsorption isotherms to other soil properties. Although B and C horizons of one Dystric Cryochrept pedon have low exchange capacity (<6 cmolc kg−1) and low base saturation (<0.1), soils in general appear to have sufficient base‐exchange capacity to neutralize anticipated acid‐deposition rates. All other horizons sampled have base saturations in excess of 0.2. Most soils will adsorb SO4, although adsorption maxima are estimated at <1.5 mmol kg−1. High organic‐matter content of A horizons in Humic Cryaquepts interferes with SO4 adsorption. Buffer capacities above pH 4 average 4.00 cmol kg−1 pH−1; below pH 4, soils are more strongly buffered, averaging 18.7 cmol kg−1 pH−1. Base exchange is probably the dominant process controlling buffering above pH 4, and dissolution of Al (OH)3 controls buffering in the pH range 2.8 to 4.
Rubberized Asphalt for Sealing Cores of Shrinking Soil
Authors: Kluitenberg G. J. , Bilskie J. R. , Horton R. 
Published: July 2010

AbstractBecause many soil materials shrink as a result of soil water desorption, it is difficult to seal soil samples into containers for transport experiments when a range of soil matric potentials is to be used. In this note, we introduce the use of a rubberized asphalt product that is capable of changing shape so that a seal between the container and the soil sample can be maintained as the soil shrinks. An experiment was conducted in which the air permeability of two soil materials was measured at a series of soil matric potentials after being sealed with rubberized asphalt or paraffin. The results indicate that the asphalt was able to maintain a better seal than the rigid paraffin as the soil materials dried and shrank. Seal integrity of the asphalt was maintained as matric potentials were reduced from −50 kPa to −750 kPa for soils of moderate and high shrinkage capacity. In contrast, the air‐permeability data indicate that the paraffin failed to provide an adequate seal at −50 kPa, even before the soil was desorbed.