bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen Deficiency Detection Using Reflected Shortwave Radiation from Irrigated Corn Canopies
Authors: Blackmer Tracy M. , Schepers James S. , Varvel Gary E. , Walter‐Shea Elizabeth A. 
Published: July 2010

AbstractTechniques that measure the N status of corn (Zea mays L.) can aid in management decisions that have economic and environmental implications. This study was conducted to identify reflected electromagnetic wavelengths most sensitive to detecting N deficiencies in a corn canopy with the possibility for use as a management tool. Reflected shortwave radiation was measured from an irrigated corn N response trial with four hybrids and five N rates at 0, 40, 80, 120, and 160 kg N ha−1 in 1992 and 0, 50, 100, 150, and 200 kg N ha−1 in 1993. A portable spectroradiometer was used to measure reflected radiation (400–1100 nm in 1992, 350–1050 nm in 1993) from corn canopies at approximately the R5 growth stage. Regression analyses revealed that refiected radiation near 550 and 710 nm was superior to refiected radiation near 450 or 650 nm for detecting N deficiencies. The ratio of light reflectance between 550 and 600 nm to light reflectance between 800 and 900 nm also provided sensitive detection of N stress. In 1993, an inexpensive photometricc ell, which has peak sensitivity to light centereda t 550 nm, was also used to measurer eflected radiation from a corn canopy. Photometric ceil readings correlated with relative grain yield (P < 0.001, r2 = 0.74), but more research will be required to develop procedures to account for varying daylight conditions. These results provide information needed for the development of variable‐rate fertilizer N application technology.
Tillage and Rotation Crop Effects on Weed Dynamics in Potato Production Systems
Authors: Liebman Matt , Drummond Francis A. , Corson Sue , Zhang Jianxin 
Published: July 2010

AbstractConcern over undesirable environmental impacts and low profitability of conventional potato (Solanum tuberosum L.) production systems has led to efforts to reduce agrichemical use while improving yield and net returns. Weed management based on a better understanding of weed responses to tillage and other cropping practices is a key to success in these efforts. We conducted a 4‐yr field experiment on a Caribou gravelly loam (coarse‐loamy, mixed, frigid Typic Haplorthods) in Presque Isle, ME, in which potato was grown in alternating years with either oat (Avena sativa L.) or berseem clover (Trifolium alexandrinum L.), in plots that were either moldboard plowed (MP) or chisel plowed (CP). To determine yield losses due to weed interference, potato was grown either in weed‐free conditions or with weeds that survived cultivation and hilling. Seed density, plant density, and biomass of dominant weed species (Chenopodium album L. and Brassica and Raphanus spp.) were lower following MP than CP. Average loss of U.S. No. 1 tubers due to weed interference was 12% with MP, compared with 43% with CP. Weed and potato responses to rotation crops differed between years. Weed biomass production was lower in oat than in berseem clover during the 1990 rotation crop phase. In the subsequent 1991 potato crop, yield loss due to weed infestation was 13% following oat, compared with 38% following berseem clover. No difference in weed growth was evident between oat and clover rotation crops in 1992, and there were no rotation crop effects on weed‐related yield loss in the subsequent 1993 potato crop. We present a conceptual model that incorporates these data, links weed life stages and crop performance, and illustrates the effects of interference between weed species. The model suggests that, if weed growth in rotation crops can be strongly suppressed, chisel plowing should result in low densities of annual weed species and minimal yield loss in subsequent potato crops.
SUNDIAL: A PC‐Based System for Simulating Nitrogen Dynamics in Arable Land
Authors: Smith J. U. , Bradbury N. J. , Addiscott T. M. 
Published: July 2010

AbstractSUNDIAL (SimUlation of Nitrogen Dynamics In Arable Land) is a user‐friendly, PC‐based version of the Rothamsted Nitrogen Turnover Model. It comprises a menu‐driven system that allows agricultural advisers, even with minimal computing experience, to enter details of a particular field or farm and simulate N turnover. The processes involved are described by a set of parameterized zero and first‐order equations. The addition of a novel facility for calculating crop parameters enables instantaneous estimation of parameters for rough but immediate simulations of a new crop, graphical visualization of the expressions used in SUNDIAL, comparison of the parameterized expressions with experimental measurements, and further refinement of parameters by fitting individual expressions to measured data or by iteratively adjusting parameters to improve the fit of simulated results to soil and crop N and 15N measurements. The facilities in SUNDIAL for displaying the various outputs in graphical form make it particularly useful for examining the impact of different management strategies on the N cycle in arable agriculture. Graphical facilities include balance sheets, graphical plots, pie charts, and flow diagrams.
Establishment of Rhizoma Perennial Peanut with Varied Rhizome Nitrogen and Carbohydrate Concentrations
Authors: Rice Ronald W. , Sollenberger Lynn E. , Quesenberry Kenneth H. , Prine Gordon M. , French Edwin C. 
Published: July 2010

AbstractRhizoma perennial peanut (RPP; Arachis glabrata Benth.) is a vegetatively propagated forage legume characterized by inconsistent establishment, possibly related to the chemical characteristics of RPP rhizomes used for propagation. This field study evaluated effects of chemical composition of ‘Florigraze’ rhizome planting material on emerged shoot number at 80 d after planting (DAP), rhizome and shoot mass accumulation at 180 DAP, percent RPP cover at season end, and herbage yield in June of the second growing season. The soil was a loamy, siliceous, hyperthermic Grossarenic Paleudult. Rhizome planting material was obtained from grazed pastures which, through varied defoliation management, produced rhizomes with a range of total nonstructural carbohydrate (TNC) (62‐383 g kg−1) and N (12.7‐25.8 g kg−1) concentrations. In 1990, a drought year, rhizomes with TNC ranging from 260 to 300 g kg−1 and N = 21 g kg−1 produced maximum responses for shoot number (39 m−2) and rhizome (530 kg ha−1) and shoot mass (1040 kg ha−1) accumulation. During the wetter than normal spring of 1991, rhizomes with TNC and N concentrations similar to those in 1990 supported 40 to 55% greater shoot counts and almost double (1050 kg ha−1) the rhizome mass accumulation. Because much RPP production occurs on nonirrigated sandy soils, and rainfall constraints are prevalent following planting in most years, assessment of rhizome planting material quality should be based on the 1990 results. In that year, rhizomes with TNC of 230 to 250 g kg−1 and N of 20 to 20.5 g kg−1 performed well, about 70 to 90% of the maximum responses indicated above. Rhizomes with TNC of 190 to 220 g kg−1 and N of 18 to 19 g kg−1 performed at about 40 to 65% of maximum responses. Planting rhizomes with TNC ≤ 180 g kg−1 and N ≤ 17 g kg−1 is not recommended unless irrigation is available, since establishment performance was ≤ 40% of maximum predicted responses.
Total Nitrogen Determination in Plant Material by Persulfate Digestion
Authors: Purcell Larry C. , King C. Andy 
Published: July 2010

AbstractDetermination of total plant N concentration is important in understanding crop nutritional value, nutritional requirements, and physiological responses to the environment. Nitrogen analysis by either the Kjeldahl or Dumas method is expensive and requires specialized equipment. An alternative procedure, developed primarily for use on water samples, was optimized for digestion of vegetative soybean [Glycine max (L.) Merr.] tissue and compared with the Dumas method. Finely ground plant material (0.425 mm) was digested in alkaline potassium persulfate (K2S2O8) at 120°C (0.1 MPa) for 1.5 h in an autoclave, converting organic N to NO‐3. Nitrate in the digest was reduced to NO‐2 and quantified by the sulfanilamide‐α‐naphthyl‐ethylenediamine dihydrochloride procedure. Persulfate digests of soybean material agreed closely with determinations made by the Dumas method (r = 0.99). Digestion of NIST standard tomato (Lycopersicon esculentum Mill.) leaves (4.8 g N 100 g−1) indicated complete N recovery (4.9 ± 0.1 g N 100 g−1). Persulfate digestion of total plant N was accurate and precise, and required little initial investment.
Planting Date and Residue Rate Effects on Growth, Partitioning, and Yield of Corn
Authors: Swanson Stephan P. , Wilhelm Wallace W. 
Published: July 2010

AbstractCorn (Zea mays L.) growth has been shown to be affected by planting date and amount of residue on the soil surface. The objective of this study was to determine if the adverse effects of cool soil temperatures on early seedling growth often associated with surface residues can be overcome by planting at later dates. Corn was planted at several planting dates (late April through early June) into soil that had residue applied at rates of 0, 33, 66, and 100% of that produced by the previous crop. In general, spring‐applied residue rates had little effect on measured plant responses. Planting corn before or after the optimum date resulted in reduced leaf area index, leaf area duration, total dry matter production, and grain yield. Maximum yield was achieved by planting corn about 10 May (near Lincoln, NE), regardless of the amount of residue applied in the spring. Yield declined with earlier or later planting dates: yield declined more rapidly when planting was delayed than when planting was advanced. Results indicate that, with spring residue application, planting date recommendations can be made independent of residue conditions.
Annual Ryegrass Seed Yield Response to Grazing during Early Stem Elongation
Authors: Young William C. , Chilcote David O. , Youngberg Harold W. 
Published: July 2010

AbstractSpring grazing annual ryegrass (Lolium multiflorum Lam.) seed fields with sheep (Ovis aries) is a common practice. The effects of grazing duration in early stages of stem elongation on seed yield and its components are not well known. We studied four durations of spring grazing annual ryegrass with sheep over a 2‐yr period on an Argiaquic Xeric Argialboll soil. Grazing was begun before onset of stem elongation. Treatments were no grazing (G0) and grazing until one‐third (G1), two‐thirds (G2), or all (G3) primary tillers had their apical meristems removed. Leaf area was progressively reduced by grazing duration. The number of fertile tillers increased with grazing duration in the first year, but the effect was not significant in the second year. Grazing did not affect the number of spikelets per spike or florets per spikelet in the first year. In the second year, G2 and G3 reduced spikelets per spike and had no effect on the number of florets per spikelet, whereas G1 did not affect either character. Both G2 and G3 decreased seed weight in the first year, while G1 had no effect; treatments did not affect seed weight in the second year. Grazing treatment did not affect total herbage dry matter at seed maturity, seed yield, or seed quality in either year. We conclude that, in western Oregon, grazing annual ryegrass in late winter and early spring up to the time when the apical meristem of all primary tillers are removed (G3) does not reduce seed yield. Grazing until about one‐third of primary tillers lose their apical meristem (G1) may actually improve seed yield.
Comparison of Interseeded Legumes and Small Grains for Cover Crop Establishment in Cotton
Authors: Keeling J. Wayne , Matches Arthur G. , Brown C. Philip , Karnezos T. Peter 
Published: July 2010

AbstractWind erosion of soil is a potential problem in unprotected cotton (Gossypium hirsutum L.) fields on the Southern High Plains of Texas during winter and early spring. Our objective was to determine which winter annual forage legumes and small grains may be successfully established by fall interseeding into standing cotton. Thirteen plantings were made over 6 yr at three locations. Both cotton and the interseeded forages were grown under rainfed conditions. The forages were winter wheat (Triticum aestivum L. emend. Thell.), rye (Secale cereale L.), Austrian winter pea [Pisum sativum subsp. pisum var. arvense (L.) Poir.], hairy vetch (Vicia villosa Roth), subterranean clover (Trifolium subterraneum L.; 5 cultivars), rose clover (Trif. hirtum All.; 3 cultivars), crimson clover (Trif. incarnatum L.; 2 cultivars), red clover (Trif. pratense L.), berseem clover (Trif. alexandrinum L.), and barrel medic (Medicago truncatula Gaertn.; 2 cultivars). Successful stands of wheat, rye, winter pea, and hairy vetch were obtained in 69% of the plantings, but in only 53% for the other forages. Establishment of the small‐seeded legumes (clovers and medics), which must be planted at a shallow depth, seemed to be governed by the timing of effective rainfall events after seeding. Establishment of the larger‐seeded wheat, rye, winter pea, and vetch was less dependent on timely rainfall after planting. Of these winter annuals, wheat and rye were the most dependable in producing a soil cover.
Modeling Preemergent Maize Shoot Growth: I. Physiological Temperature Conditions
Authors: Weaich Karl , Bristow Keith L. , Cass Alfred 
Published: July 2010

AbstractPrediction of seedling emergence is an important first step in predicting crop establishment. There are numerous models that, under nonlimiting seedbed physical conditions, can adequately predict time to emergence using heat sums based on average daily temperatures. Under more adverse seedbed physical conditions, however, such as occur in the semiarid tropics, use of such coarse indices will tend to obscure the strong influence that even temporary extremes in soil temperature or strength can have on the time and extent of emergence, yet it is in these situations that final crop establishment and ultimately yield will be particularly sensitive to emergence predictions. One way to quantify the effect that temporary extremes in seedbed conditions have on emergence is to model the emergence process (namely, preemergent shoot growth). In this paper, we model preemergent maize (Zea mays L.) shoot growth as a first step in characterizing seedling response to a high soil temperature and strength environment. The model, developed from shoot length data obtained under constant temperature conditions ranging from 20 to 40°C, uses an exponential function that predicts coleoptile and first internode growth rates as a function of temperature and sums the output to predict shoot length. Comparison of model predictions with independent measurements carried out in the 20 to 40°C range show that the model is capable of accurately simulating preemergent shoot growth under conditions where (i) temperatures are constant with time, (ii) temperatures of the whole seedbed vary diurnally, and (iii) temperatures within the seedbed vary with time and depth in the seedbed. However, the model was unable to predict shoot growth in situations where seedlings had been exposed to temperatures in excess of 40°C, indicating that further work is needed to assist modeling within the high temperature range.
Forage Potential of Dwarf Napiergrass and a Pearl Millet ✕ Napiergrass Hybrid
Authors: Cuomo Greg J. , Blouin David C. , Beatty James F. 
Published: July 2010

AbstractNapiergrass [Pennisetum purpureum (L.) Schum.] and pearl millet [Pennisetum americanum (L.) Leeke; syn. Pennisetum glaucum (L.) R. Br.] ✕ napiergrass (PMN) hybrids have potential to fill a forage production void during fall months in the southeastern USA. In a 2‐yr study, ‘Mott’ dwarf napiergrass, a PMN hybrid, and pearl millet were harvested five, four, and three times per year. Objectives were to evaluate forage mass production and distribution, persistence, and forage nutritive value of these Pennisetum spp. Season total forage mass was less for pearl millet (13.2 Mg ha−1) than for napiergrass (17.5 Mg ha−1) and the PMN hybrid (18.9 Mg ha−1). Forage mass differences were the result of napiergrass producing 4.0 Mg ha−2 and the PMN hybrid 5.4 Mg ha−2 during the fall months. Pearl millet produced no herbage during this time. Leaf percent of fall regrowth was greater for napiergrass (90%) than for the PMN hybrid (56%) when averaged over years. Generally, forage nutritive value was similar among species in this study; however, napiergrass had higher crude protein (CP) (136 g kg−1) than pearl millet (127 g kg−1) or the PMN hybrid (123 g kg−1). Napiergrass was the only species to perennate in this study. There were no differences for number of napiergrass tillers in early spring among harvest management treatments. All Pennisetum spp. produced large amounts of forage through late summer; however, napiergrass and the PMN hybrid continued to grow and produce forage until frost and have the potential to fill the fall forage deficit in the southeast USA.
Tillage Systems for Cotton on Silty Upland Soils
Authors: Triplett Glover B. , Dabney Seth M. , Siefker James H. 
Published: July 2010

AbstractNo‐tillage systems for cotton (Gossypium hirsutum L.) production on sloping, upland sites have not been widely adopted in the Mid‐South of the USA, even though conventional cotton production creates a serious erosion hazard. A field study was established following sod on a site with loess soils to evaluate tillage system effect on cotton yield and earliness. The sod was tilled prior to establishment of treatments, which included conventional (chisel, disk, bed, cultivate), ridge till (remove ridge tops at planting, cultivate postemergence to rebuild ridges), no‐tillage [wheat (Triticum aestivum L.) cover seeded following cotton harvest, killed prior to planting], and minimum tillage (one pass with a mulch finisher prior to planting, cultivate postemergence). During the first year of the study, no‐tillage cotton yields were lower and maturity delayed compared with conventional tillage. During Years 3 to 5, no‐tillage crop yields were 18 to 42% greater and crop maturity was 6 to 10 d earlier than conventional tillage. Minimum tillage yields were similar to conventional tillage while ridge tillage was lower in two of the last 3 yr of the study. Results of this study indicate viable no‐tillage production systems for cotton can be developed for highly erosive loess soils in the Mid‐South.
Irrigation Starting Time Effects on Cotton under High‐Frequency Irrigation
Authors: Wanjura Donald F. , Mahan James R. , Upchurch Dan R. 
Published: July 2010

AbstractDeciding when to begin irrigating cotton (Gossypium hirsutum L.) is difficult because the positive effect of eliminating water stress may be offset by the negative effect of lowered soil temperature. Different starting times for high‐frequency drip irrigation of cotton were investigated in a field having Olton clay loam soil (fine, mixed, thermic Aridic Paleustolls). Early irrigation (EI), started when seedlings had 3 mainstem nodes, was compared with delayed irrigation (DI‐L), started at squaring when there were 7 mainstem nodes. Another delayed irrigation treatment (DI‐H) received an initial large irrigation that equaled the cumulative amount of water applied by that time to the EI treatment. During the early irrigation period, 130 mm of water was applied in 1993 and 120 mm in 1994. Average soil temperature in the top 1000 mm during the early irrigation period was 25°C in the EI treatment, compared with 27°C in the DI treatment. During the late irrigation period, the average soil temperature was 24.5°C for EI and 25.5°C for DI. At first bloom, plants were 30 mm taller in 1993 and 70 mm taller in 1994 in the EI irrigation treatment, compared with the DI‐L treatment. Lint production was greatest in the DI‐L treatment in both years (1548 and 1630 kg ha−), compared with the DI‐H treatment (1467 and 1460 kg ha−1) and the EI treatment (1447 and 1481 kg ha−1). Water use efficiency, based on the total of irrigation and rainfall, averaged 3.33, 2.42, and 2.36 kg lint ha‐mm−1 for the DI‐L, DI‐H, and EI irrigation treatments, respectively. Initiating automated irrigation scheduling before squaring in cotton increased seedling height but decreased lint yield and the efficiency of use of total applied water.
Application of SORKAM to Simulate Shattercane Growth Using Forage Sorghum
Authors: Retta Amare , Vanderlip Richard L. , Higgins Randall A. , Moshier Loren J. 
Published: July 2010

AbstractShattercane [Sorghum bicolor (L.) Moench] is a serious weed problem. Few methods are available to assess the impact of shattercane competition on crop growth and yield. This study evaluated model sensitivity to variations in light, water, and plant density and assessed the applicability of the SORKAM model for simulating forage sorghum (used to represent shattercane) growth and development. Sensitivity analysis of SORKAM to photosynthetically active radiation (50, 75, and 100% of actual); water (50, 75, and 100% of actual precipitation, and no water stress); and plant densities of 3, 6, 12, 24, 48, and 96 plants m−2 was performed. ‘Rox Orange’ forage sorghum (used to represent shattercane) was grown at three densities, under irrigated and dryland environments over a 3‐yr period. Experiments were conducted on Eudora (coarse‐silty, mixed, mesic Fluventic Hapludoll) and Kahola silt loam (fine‐silty, mixed, mesic Cumulic Hapludoll) soils, in Manhattan, KS. The sensitivity analysis showed that SORKAM responded to a broad range of light, water, and plant density environments, with significant light by water interaction for biomass, and light by density interaction for biomass, leaf area index (LAI), and tillering. The SORKAM model simulated growth of Rox Orange from inputs of weather, soil, and plant data were compared with measured values. There was good agreement between simulated and measured LAI through 60 d after planting (r2 = 0.82, intercept not significantly different from 0, and slope = 0.83). Accurate estimation of LAI during this period of vegetative growth is important, because LAI determines the competition between a crop and shattercane for light and water. Agreement of measured and simulated biomass was good for low plant densities (slope and intercept not significantly different from 1 and 0 with high r2 = 0.78), with progressively greater underestimation at higher densities. Tiller number was generally underestimated, with no apparent correlation to model under‐ or overestimation of LAI or biomass. The sensitivity analysis and comparison of measured and simulated LAI indicates that the SORKAM model can be used to assess Rox Orange (shattercane) competition.