bluuebunny/crossref_metadata_2025_split huggingface dataset:
Corn Root Growth and Distribution as Influenced by Tillage and Nitrogen Fertilization1
Authors: Anderson E. L. 
Published: July 2010

AbstractTillage alters both soil physical and chemical properties, which in turn alter the environment for root growth and may impact on plant growth, nutrient uptake, and yield. The objective was to compare corn (Zea mays L.) root morphology and distribution in plots under minimum tillage (MT) for 7 yr to conventional tillage (CT) at N fertilization treatments of 0 and 180 kg N/ha. The 3‐yr field study was conducted in the Maryland Piedmont area on a Delanco silt loam (Aquic Hapludult). Three soil cores per plot were taken at vegetative, silking, and dough stages of plant development. A 76‐ mm‐diam steel tube was used to sample to a depth of 0.6 m in the plant row, at midrow (0.38 m), and half way between (0.19 m). The roots collected to 0.6 m accounted for an average of 82% of the total root weight present after grain harvest. Tillage did not significantly affect plant growth or grain yield. Conventional tillage significantly increased root dry weight in only 1 yr. Minimum tillage and N fertilization both increased root weight in the 0‐ to 0.07‐m layer in 2 of the 3 yr. Root mass decreased 90% in the 0‐ to 0.07‐m depth when samples were compared from in the row to 0.19 m away. Nitrogen fertilization decreased milligrams per meter of root and root radius in 2 of the 3 yr, allowing root length to increase in response to N without altering the weight of roots. Root growth was observed under drought and N stress conditions when shoot growth and yield were limited. The period of most rapid root development occurred in the 8 weeks following planting.
Estimation of Biological Nitrogen Fixation Associated with 11 Ecotypes of Panicum maximum Grown in Nitrogen‐15‐labeled Soil1
Authors: Miranda Cesar H. Behling , Boddey Robert M. 
Published: July 2010

AbstractContributions of plant‐associated biological nitrogen fixation (BNF) may be important to N nutrition of grasses. Eleven ecotypes of Panicum maximum were planted in the field in concrete cylinders containing soil (Typic Hapludult) that had a low but stable 15N enrichment. Brachiaria radicans (cv. IRI 442) was used as the non‐fixing control, and the plant aerial tissue was harvested eight times over a 390‐day period. At the first harvest of the experiment (17 May 1984), the concentration of N in all the grasses was high and, subsequently, declined during the first 270 days of growth, reflecting the decreasing availability of soil N. Until soil N availability had become the main factor limiting plant growth, it was thought unlikely that any significant contribution of BNF would occur, and this was confirmed by the 15N‐enrichment data. At later harvests (February–April 1985), the N concentrations in the plants were lower and all the P. maximum ecotypes accumulated more than the B. radicans. Over this period, the 15N enrichment of all the P. maximum ecotypes was significantly lower than that of the B. radicans, indicating a contribution of plant associated BNF to the P. maximum ecotypes. Contributions of associated BNF to the P. maximum ecotypes were estimated to be between 24 and 38% of total N incorporated, equivalent to between 5 and 10 kg N ha−1 per 30 days. The significant differences observed in ISN enrichment between P. maximum genotypes suggest that further screening and selection of P. maximum ecotypes for high associated BNF is a worthwhile objective.
Agronomic Evaluation of Poultry Manure as a Nitrogen Source for Conventional and No‐Tillage Corn1
Authors: Sims J. Thomas 
Published: July 2010

AbstractPoultry manure is useful as a source of N for corn (Zea mays L.) production. An approach to predict available N in poultry manure (PM) was evaluated in a 3‐year (1983–1985) field study with conventional (CT) and no‐tillage (NT) corn. Poultry manure and ammonium nitrate (AN) were applied to an Evesboro loamy sand soil (mesic, coated Typic Quartzipsamments) at rates designed to supply 0, 84,168, and 252 kg potentially available N/ha. Potentially available N (PAN) in the PM was defined as PAN = 80% Ni + 60% No, where N1 = NH+4‐N + NO−3‐N and No = total N ‐ Ni. Soil N1 (0–0.6 m), plant N, corn N uptake, and grain yields were measured. Cover crop N concentrations and N uptake, as well as soil N1 prior to planting and post‐harvest were also determined to estimate residual N from PM and AN. Soil N1 levels and N leaching (to 0.4–0.6 m) were generally higher with AN than PM. Plant N concentrations, N uptake, and corn grain yields were seldom significantly different with PM, compared to AN in 1983 and 1985, but were consistently lower with PM in 1984. Conventional tillage significantly increased grain yields, relative to NT, in 1984 (7.6 and 7.2 Mg/ha, respectively) and 1985 (7.7 and 5.5 Mg/ha, respectively). Little residual N was detected in 1984 or 1985 from prior applications of PM. Based on N budget calculations, the potential existed for considerable leaching losses of N. The efficiency of recovery of added N (ef) averaged 0.56 kg/kg for AN and 0.36 kg/kg for PM. Excess N (NEX) remaining in the soil, based on these ef values, was as high as 265 kg N/ha for PM and 166 kg N/ha for AN. Therefore, despite the selection of PM rates that resulted in soil N, plant N, and corn grain and dry matter yields comparable to those obtained with recommended rates of AN, N leaching may still occur when PM is used on coarse‐textured soils
Dry Season Sweet Corn Response to Mulching and Antitranspirants1
Authors: Shekour G. M. , Brathwaite R. A. I. , McDavid C. R. 
Published: July 2010

AbstractSweet corn (Zea mays L. var. saccharata Sturt.) production in Trinidad and Tobago is limited to the rainy season, and the country's requirements is met mainly through imports. Extending the production period into the dry season is desirable for increased local production. The objective of this study was to determine the effect of lucuntu grass (Ischaemum timorense Kunth.) mulch and the antitranspirants phenylmercuric acetate (PMA), alachlor [2‐chloro‐2'‐6'‐diethyl‐N‐(methoxymethyl)‐acetanilide], and Vapor Gard (poly‐1‐p‐menthen‐8‐9‐diyl) on the growth and yield of dry‐season cropped sweet corn. The replicated field trial was established on a River Estate loam (Fluventic Eutropept) at Valsayn, Trinidad and Tobago. The mulch (3.5 Mg/ha) was applied at 38 days after planting (DAP), and the antitranspirants (79.9 and 106.5 g/ha and 24.4 L/ha, respectively) at 38 and 52 DAP. The mulch and antitranspirant treatments resulted in mean increases in plant height and leaf area of 21.1 and 4.8, and 34.5 and 5.7%, respectively, and fresh ear and total dry matter mean increases of 75.0 and 20.0, and 89.7 and 42.0%, respectively, as compared to the limited irrigated control. Only the mulched treatment produced growth and yield similar to the irrigated control. Mulching, PMA, and Vapor Gard, in descending order, were found promising in conserving moisture and improving yield.
Bermudagrass Turf Response to Mowing Practices and Fertilizer1
Authors: Johnson B. J. , Carrow R. N. , Burns R. E. 
Published: July 2010

AbstractThe overall quality of ‘Tifway’ bermudagrass [Cynodon transvaalensis Burtt‐Davies × Cynodon dactylon (L.) Pers.] turf is often determined by the type of mower and fertilizer, and whether clippings are removed or returned. The purpose of this field research study was to determine bermudagrass turf response to N at 100 to 300 kg ha−1 and to K at 50 to 300 kg ha−1 as related to mowing treatments. Treatments were arranged in a split block with subunits in strips. The primary strips were mowing treatments, and subunit strips were fertilizer treatments. The soil type was a Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludult). A rotary mulching mower maintained the highest quality of bermudagrass, and flail mowing the lowest turf quality throughout the 3‐yr study. Turf quality was not consistent each year. Quality was higher when grass clippings were returned than when removed. In most instances, bermudagrass did not respond to N at rates above 200 kg ha−1. Turf quality and shoot density were as good when K was applied at 50 kg ha−1 as at higher rates. Neither fertilizer treatments nor returning grass clippings influenced thatch accumulation. However, turf cut with a rotary mulching mower had a greater thatch accumulation than did turf cut with a flail mower. Dollar spot (Moellerodiscus spp. and Lanzia spp.) disease occurred more frequently at the lowest N treatment.
Relationships between the Areas of Successive Leaves on Grain Sorghum1
Authors: Maas S. J. , Arkin G. F. , Rosenthal W. D. 
Published: July 2010

AbstractGrain sorghum [Sorghum bicolor (L.) Moench] plants characteristically exhibit an increase in the areas of successively older leaves on the shoot up to a maximum value, followed thereafter by a decrease in leaf areas. Data from 2 yr of field studies were used to develop empirical functions relating average areas of successive leaves. These functions were representative for a number of published data sets and exhibited the following characteristics: (i) an early exponential phase of leaf area increase apparently terminated by the onset of intraplant competition; (ii) a transition between two linear phases of leaf area increase that appears to be invariant among years, cultivars, and treatments; and (iii) a final phase of decreasing leaf areas that is apparently sensitive to interplant competition and reproductive growth. Data from the literature and studies involving water stress, plant population, and N fertilizer application effects indicate that, while reproductive organ growth may affect some aspects of leaf area development, the onset and severity of intraplant and interplant competition may be more important factors determining individual leaf areas.
No‐Tillage Effects on Population Dynamics of Soybean Cyst Nematode1
Authors: Tyler D. D. , Chambers A. Y. , Young L. D. 
Published: July 2010

AbstractThe soybean [Glycine max (L.) Merr.] cyst nematode (Heterodera glycines Ichinohe) can cause significant reductions in soybean yield in Tennessee. ‘Forrest’ soybean was grown for 4 yr on a Lexington silt loam (Typic Paleudalf) in an experiment comparing soybean production, using six primary tillage methods: five conventional tillage methods (between‐row subsoiling, under‐row subsoiling, chisel plowing, moldboard plowing, and disking) and no‐tillage in chemically killed wheat (Triticum aestivum L.). In the fourth season, cyst numbers were lower in no‐tillage compared to conventional tillage. Race 3 and 4 were present in the experimental area. In the fifth season (1983), two cultivars, Forrest (Race 3 resistant) and ‘Bedford’ (Race 3 and Race 4 resistant), were used. Cyst numbers continued to be higher under conventional tillage with both cultivars. Tillage significantly affected soybean cyst nematode which affected the yield of Forrest but not Bedford. In 1983, yields of Bedford were significantly higher than those of Forrest under conventional tillage but not where the treatment had been no‐tillage for 5 yr. In the sixth season, yields were not significantly affected by tillage. Bedford yielded higher than Forrest across all treatments in the sixth year except in the continuous no‐tillage. In contrast to the fifth season, cyst numbers were lower at the end of the season where Bedford was grown. The two short‐term no‐tillage treatments [one in the previous soybean crop residue (2 yr) and one in wheat (1 yr)] were similar to conventional treatments in yield and cyst counts. Cyst numbers in the continuous 6‐yr no‐tillage were lower than the conventional or short‐term no‐tillage treatments.
Uneven Variation in Plant‐to‐Plant Spacing in Pearl Millet1
Authors: Soman P. , Jayachandran R. , Bidinger F. R. 
Published: July 2010

AbstractPlant‐to‐plant spacing in farmers' fields of pearl millet [Pennisetum americanum (L.) Leeke] is often highly variable. The effect of typical variation in spacing on grain yield was determined in a range of cropping situations. Twenty within‐row plant spacing patterns were designed so that the variance of spacing (Vs) between plants would range from 0 to 2.3 m2, which represented the range measured from farmers' fields in India. These spacing patterns were tested in three trials conducted on an alfisol (Udic Rhodustalf, Patancheru series) in which plant population, fertility, and season varied. In all the trials, seeds were sown in predetermined positions in each row and later thinned to a single plant per position. As Vs increased from 0.01 to 0.05, 0.10, and 0.70 m2, yields declined 21, 29, and 47%, respectively. This reduction in yield did not depend on fertility level, season, or plant population. Most of the yield reduction could be attributed to reduction in panicle number per plant, the major yield determinant in the cultivar studied. The results suggest that the tillering capacity of pearl millet, although it provides the capacity to adjust to a wide range of plant populations per se, does not provide adjustment to major changes in Vs. Emphasis in the design of new seeding technology should therefore be on even distribution of seed, rather than on control of seeding rate.
Nitrogen Cycling in a Wheat Crop: Soil, Plant, and Aerial Nitrogen Transport1
Authors: Harper L. A. , Sharpe> R. R. , Langdale G. W. , Giddens J. E. 
Published: July 2010

AbstractAn understanding of N cycling in the soil‐plant‐atmosphere components of wheat (Triticum aestivum L.) production systems is necessary to maximize yield and quality. The objectives of this study were to examine N cycling and observe the effects of N surplus and deficit on N absorption/desorption in the soil and atmosphere and to evaluate translocation within the plant. Soil, plant, and microclimate measurements were taken concurrently, and soil, plant, and atmospheric ammonia (NH3) transport determined. During the early vegetative phase, plant N concentration reached a maximum; however, during the remaining growth periods, N concentration decreased even though N uptake from the soil continued until plant maturity. More total N was translocated to grain from leaves than stems, and translocation from the leaves began earlier than that from stems. Isotope and total N studies showed that after anthesis about half of the grain N came from remobilization from leaves and stems and the other half directly from the soil. A progressively larger percentage of N came from mineralized organic matter as the season progressed. Nitrogen was lost as volatile NH3 from the plant after fertilizer application and during the senescence period. Prior to anthesis, atmospheric NH3 absorption was observed during a period when soil N was temporarily unavailable. About 21% equivalent of the applied fertilizer was lost as volatilized NH3. During the period of soil unavailability an amount equivalent to about 1% equivalent of the applied fertilizer was gained from atmospheric NH3 by plant absorption.
Water Deficit Effects on Transpiration and Leaf Growth1
Authors: Rosenthal W. D. , Arkin G. F. , Shouse P. J. , Jordan W. R. 
Published: July 2010

AbstractReductions of leaf development and transpiration are closely related to soil water deficits. Few studies have analyzed the effects of water deficits on both processes during different growth stages. A study was conducted to analyze and quantify the effects of water deficits during different growth stages on leaf development (number, extension, and senescence) and transpiration rates of sorghum [Sorghum bicolor (L.) Moench] and cotton (Gossypium hirsutum L.). The study was conducted at the Blackland Research Center at Temple, TX, in a glasshouse using covered pots and in the field using covered lysimeters. In the glasshouse, the sorghum and cotton pre‐flowering treatments were irrigated at 60, 35, 15, and 0% of water used in the control pots. In the lysimeters, water deficit treatments of 50, 30, and 0% plant available water (PAW) were imposed on sorghum during the vegetative period (before panicle initiation and between panicle initiation and anthesis) and after anthesis. Leaf length and transpiration rates were measured two to three times per week. Leaf extension was reduced to 0% of well‐watered sorghum and cotton when the PAW decreased from 50 to 0%. Transpiration per unit leaf area decreased from 100 to 0% of well‐watered sorghum and cotton when PAW decreased from 28 to 0% for each stressed period. Sorghum leaf senescence was enhanced and leaf number increased in the 0% PAW treatments compared to the well‐watered and 30% treatments. These relationships of leaf development, transpiration, and PAW compare favorably with other published results. The PAW threshold values when each process is affected would be useful in developing criteria for scheduling irrigation and in improving the accuracy of crop growth models in estimating leaf development and transpiration.
Hand‐Operated Rainout Shelter1
Authors: Bittman S. , Jan E. Z. , Simpson G. M. 
Published: July 2010

AbstractRainout shelters are used in drought studies because they provide a means of controlling the input of water. Our objective was to design a hand‐operated rainout shelter that would be inexpensive, sturdy, easy to operate, and large enough to cover a 2.1‐ by 6‐m field plot. The shelter was comprised of a stationary wood frame, a retractable cover of clear polyethylene (0.15 mm), and a tank to collect excluded water. Twelve shelters were built in 1983 and 1984. Each could be covered or uncovered by two people in 1 to 2 min. The shelters withstood winds of 6.9 m s−1, a rainfall rate of 8.8 mm in 15 min, and were effective in creating uniform water deficits for sampling areas of 4.5 m2 as indicated by growth, leaf senescence, leaf rolling, and leaf water potential. The shelters provided an artificial microclimate useful for experiments emphasizing comparisons within, rather than between, moisture regimes. Our shelters are more portable and less costly than automated units but require more labor for operation and maintenance.
Establishment Clipping of Tall Fescue and Companion Annual Ryegrass
Authors: Brede A. D. , Brede J. L. 
Published: July 2010

AbstractDue to its soil stabilizing ability, annual ryegrass (Lolium multiflorum Lam.) is sometimes used as a companion crop with tall fescue (Festuca arundinacea Schreb.). Problems arise, however, because of the competitive nature of annual ryegrass. The purpose of this study was to develop a clipping treatment that could be used during turf establishment to allow annual ryegrass to effectively stabilize the soil in a mixture with tall fescue but would result in a small amount of annual ryegrass in the mature stand. Three field studies were conducted over a 3‐yr period on Kirkland silt loam (fine, mixed, thermic, Udertic Paleustoll) in central Oklahoma. In the first study, individual seedlings were clipped in a factorial arrangement of cutting heights, weeks from emergence to first clip, and clipping repetitions. Regression indicated that 22 to 50% of the variability in shoot and root growth at 60 d of age could be attributed to initial clipping treatments. In a second study, on the first day of emergence 90% of ryegrass seedlings had emerged versus 50% of the tall fescue seedlings, suggesting the potential for managing species dominance via clipping. A third study evaluated two seeding rates and seven clipping treatments (developed in the earlier experiments) on 4:l fescue/ryegrass mixture. Waiting 6 wk before initially cutting the turf favored annual ryegrass, whereas tall fescue was generally favored by a single, close clipping (0‐7 mm height) shortly after annual ryegrass emergence (0‐3 d after emergence). Initial clipping treatments reduced ryegrass ground coverage at 60 d from 82% to as little as 46%.
Cotton Main‐Stem Leaves in Relation to Vegetative Development and Yield
Authors: Oosterhuis D. M. , Urwiler M. J. 
Published: July 2010

AbstractUnderstanding the relative contribution of specific leaves to structural growth and yield development is critical in improving the management of cotton (Gossypium hirsutum L.) crops. Studies were conducted to investigate the role of main‐stem leaves in the growth and development of field‐grown cotton. A range of leaf removal treatments was compared to a control with no leaf removal in two field trials in differing localities. Removal of main‐stem leaves as they appeared had a dramatic effect on plant growth and yield. When main‐stem leaves were removed after they had expanded there was a less severe influence on yield but still a large influence on height. Leaf removal had no significant effect on either plant height or yield if the sympodial branch was allowed to develop before the mainstem leaf was removed. Removal of monopodial branches had no effect on yield or plant height. These results indicate that main‐stem leaves are involved in the structural development of the plant necessary to provide an adequate framework with sufficient leaf area and fruiting points for optimum yields. The earlier the main‐stem leaf removal, the more drastic the resulting effect on plant growth and yield. Once the main‐stem leaves had contributed to structural development, their contribution to plant productivity appeared to diminish rapidly.
Influence of Tillage and Crop Rotation on Yields of Corn, Soybean, and Wheat
Authors: Edwards J. H. , Thurlow D. L. , Eason J. T. 
Published: July 2010

AbstractCropping systems for minimum or no tillage have been developed to produce corn (Zea mays L.) yields equal to or higher than yields obtained in conventional tillage systems, but limited research has been conducted with tillage systems involving corn and soybean [Glycine mar (L.) Merr.] rotations. The objective of this study was to compare different cropping sequences of corn, soybean, and wheat (Triticum aestivum L.) in conventional, strip, and no tillage. A field experiment was conducted on a Hartsell fine sandy loam (fine‐loamy, siliceous, thermic Typic Hapludults). In 1981, corn yields with no tillage were 30% lower than those from conventional tillage systems. No corn yield differences were observed in 1982 and 1984 due to tillage or crop rotation; however, in 1983, strip and no tillage in conjunction with soybean in the rotation increased corn grain yields by 12%. Soybean yields in strip and no tillage decreased 16% compared to conventional tillage yields in 1981, but in subsequent years, soybean yields increased with those systems. A significant tillage × rotation interaction in 1981, 1982, and 1983 was caused primarily by a buildup of soybean cyst nematode (Heterodera glycines Ichinohe) (SCN) population with conventional tillage and continuous soybean. Rainfall affected soybean yields more with conventional tillage than with strip or no tillage. The conservation tillage systems (strip or no‐tillage system) in combination with corn‐soybean rotation for both full‐season or double‐cropped soybean gave the most consistent yield increase for the 4 yr.