bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Water Potential Components Measured with a Thermocouple Psychrometer and a Pressure Chamber and the Effects of Starch Hydrolysis1
Authors: Bennett J. M. , Cortes P. M. , Lorens G. F.
Published: July 2010

Recent reports have shown that discrepancies exist between water potential components measured with a pressure chamber and those determined with a thermocouple psychrometer. It has been hypothesized that the differences might be attributable to a number of reasons including starch hydrolysis within the tissue during the time required for equilibration when using thermocouple psychrometers. We conducted a series of experiments to (i) compare xylem water potential measured with a pressure chamber (Ψx) with leaf water potential (ΨL) and leaf osmotic potential (Ψs) measured with a thermocouple psychrometer, and (ii) examine changes in starch concentration during the time period required to measure ΨLand Ψswith thermocouple psychrometers for field‐grown alfalfa (Medicago salivaL.), soybean [Glycine max(L.) Merr.], and corn (Zea maysL.) leaves. Good agreement was found between Ψxand ΨLexcept for severely stressed corn leaves where Ψxwas lower than ΨLWhen measuring Ψsand ΨLwith thermocouple psychrometers on flaccid leaves assumed to be at zero turgor potential, Ψsdetermined after freezing and thawing of the tissue agreed well with ΨLmeasured before freezing, suggesting that dilution of cell sap by apoplastic water may be either very small or fully compensated for by production of solutes during equilibration of the tissue. There was a tendency for some starch hydrolysis to occur during the 4‐h period between harvest of leaf material and determination of ΨLwith a thermocouple psychrometer, especially with tissue sampled at midday and late afternoon when leaf starch concentrations were high. However, significant starch hydrolysis between freezing and thawing of the leaf tissue and measurement of Ψswas not detected. Starch hydrolysis was dependent on time of day and species; however, except for soybean leaves having high concentrations of starch, starch hydrolysis during equilibration could potentially account for only small changes (generally <0.1 MPa) in measured ΨLand Ψs
Rice Responses to a Short‐Duration Green Manure. II. N Recovery and Utilization1
Authors: Morris R. A. , Furoc R. E. , Dizon M. A.
Published: July 2010

Recent research demonstrated that fast‐growing tropical legumes [mungbean, Vigna radiata(L.) Wilczek and cowpea, V. unguiculata(L.) Walp.], when used as a green manure for lowland rice (Oryza sativaL.), can increase grain yield by 2 Mg ha−1, and that supplemental inorganic applications increase yield further. To guide research on the combined use of inorganic and green manure N, apparent N recovery (kg N uptake kg−1N applied) and N utilization (kg grain kg 1N uptake) were determined in three experiments. The experiments were conducted on a fine mixed isohyperthermic Aeric Tropaqualf in the Philippines during the 1983 and 1984 wet seasons. In two experiments, factorial combinations of inorganic N (0 and 80 kg N ha 1) and green manure growth duration (20, 30, and 40 days in the first year; 25,35, and 45 days in the second year), were tested. Apparent N recoveries from inorganic fertilizer and green manure were 49% in 1983 and 41% in 1984. At N levels < 51 kg N ha−1, inorganic N utilization was inferior to green manure N utilization in 1983 but similar in 1984. In the third experiment, mungbean was planted at 300 000 and 600 000 plants ha−1and grown for 20, 30, and 40 days before incorporation. Inorganic N (80 kg N ha−1) was applied to plots that were fallow during the green manure growth period. Apparent N recovery from both sources was 33%. Utilization of N from 80 kg inorganic N ha−1was slightly more efficient than from an equivalent quantity of green manure N. Although differences were noted, the experiments suggest that apparent recovery and utilization of N from short‐duration green manures are similar to those from inorganic N fertilizers. Research is required to determine how efficiency from the combined use of both N sources can be maximized.
Effects of Seeding Method and Time of Fertilization on Urea‐Nitrogen‐15 Recovery in Rice1
Authors: Westcott M. P. , Brandon D. M. , Lindau C. W. , Patrick W. H.
Published: July 2010

Both water seeding and dry seeding are utilized in U.S. rice (Oryza sativaL.) cultural systems. Early season N applications are soil incorporated or deep placed prior to planting with water seeding, but are broadcast on the soil surface just prior to permanent flooding with dry seeding. Field studies were conducted on a Crowley silt loam (Typic Albaqualf) and a Sharkey clay (Vertic Haplaquept) to determine the effects of seeding method and time of application on the recovery of urea−15N by rice (var. Lemont). A total rate of 100 kg N/ha was added as (i) a single preplant (water seeded) or preflood (dry seeded) application, or (ii) a split with an initial application (preplant or preflood) of 67 kg N/ha and a topdressing of 33 kg N/ ha broadcast into the floodwater at midseason. Nitrogen‐15‐labeled materials were utilized in microplots (0.255 m2). The plant recovery of preplant N with water seeding (41.7% of the applied N) was significantly greater than the uptake of preflood N with drill seeding (30.2%). Water seeding also increased total N uptake and dry matter production, but grain yields were unaffected by seeding method due to a higher harvest index (HI) for drill‐seeded rice. Topdressed N was taken up with equal efficiency (45.8% recovery) in either seeding method. Soil recovery of labeled N was unaffected by seedling method; differences in total recovery of labeled N in the soil‐plant system at harvest (ranging from 40.0 to 57.7% of the application rate), therefore, primarily reflected differences in plant uptake. Overall, differences between seeding methods reflected a stimulation of early season growth and N uptake characteristics on the part of water seeding.
Crabgrass and Goosegrass Control in a Bentgrass Green in the Transition Zone1
Authors: Callahan Lloyd M.
Published: July 2010

A creeping bentgrass (Agrostis palustris Huds. cv. Penncross) high porosity green was treated with ethofumesate (2‐ethoxy‐2,3‐dihydro‐3,3‐dimethyl‐5‐benzofuranyl methanesulfonate), metribuzin [4‐amino‐6‐(1,1‐dimethylethyl)‐3‐(methylthio)‐1,2,4,‐triazin‐5(4H)‐one], NC‐20484 (structure undisclosed, belongs to benzofuran group), napropamide [N,N‐diethyl‐2‐(l‐naphthalenyloxy)propanamide], oxadiazon {3‐[2,4‐dichloro‐5‐(1‐methylethoxy)phenyl]‐5‐(1,1‐dimethylethyl)‐1,3,4‐oxadiazol‐2‐(3H)‐one}, and prosulfalin (N‐[4‐(dipropylamino)‐3,5‐dinitrophenyl]sulfonyl}‐S,S‐dimethylsulfilimine) to determine phytotoxicity and effectiveness in controlling large crabgrass (Digitaria sanguinalis L. Scop.) and goosegrass [Eleusine indica (L.) Gaertn.]. No sod loss occurred with a 1‐yr treatment of prosulfalin at 3.4 and 6.7 kg ha−1 or ethofumesate at 1.1 kg ha−1. Repeat treatments for 3 more years at reduced rates resulted in no sod loss with ethofumesate or NC‐20484 at 0.6 and 1.1 kg ha−1, oxadiazon at 2.2 and 4.5 kg ha−1, and prosulfalin at 1.7 and 3.4 kg ha−1. Single and sequential treatments of oxadiazon and prosulfalin, at both rates for each, gave 96 to 100% control of crabgrass. Only oxadiazon at 4.5 kg ha−1 and prosulfalin at 3.4 kg ha−1 gave 91 to 100% control of goosegrass. There was no evidence of herbicide residue buildup from treatments to the same plots during four successive years in the high porosity green (95.3% sand, 3% silt, 1% clay, 0.7% OM by weight).
Forage Growth, Consumption, and Performance of Steers Grazing Bermudagrass and Fescue Mixtures1
Authors: Mitchell Ronald L. , McLaren J. B. , Fribourg Henry A.
Published: July 2010

Detailed information regarding forage quality and pasture productivity of various species and combinations that support rapid animal gains in the southeastern USA is needed for successful stocker cattle performance prior to feedlot placement. To evaluate productivity and quality of pastures for grazing beef (Bos taurus L.) steers, an experiment was conducted in 1979–1981 on a Typic Hapludalf. The 1.2 ha pastures were (i) Midland bermudagrass [Cynodon dactylon (L.) Pers.] + tall fescue (Festuca arundinacea Schreb.) seeded in 25‐cm rows + N, (ii) Midland + fescue in 25‐cm rows + legumes, (iii) Midland + fescue in 50‐cm rows + legumes, (iv) fescue + legumes, (v) common bermudagrass + fescue in 25‐cm rows + legumes, and (vi) orchardgrass (Dactylis glomerata L.) + ladino clover (Trifolium repens L.). Legumes refer to overseedings of ladino clover, red clover (T. pratense L.) and ‘Kobe’ lespedeza (Lespedeza striata (Thunb.) H & A). Midland + fescue at 25 cm + N pastures were topdressed with 290 kg N ha−1 each year. Pastures were grazed using a continuous put‐and‐take grazing management with stocking rate adjustments made to maintain orchardgrass at 8 to 14 cm and other pasture combinations at 5 to 8 cm. Forage growth and consumption were estimated by the cage‐and‐strip method. Yearling beef steers averaging 230 kg in the spring grazed 131 to 168 days and were weighed at 21‐day intervals. Forage dry matter (DM) yield was 14.2 Mg ha−1 for Midland + fescue at 25 cm and ranged between 6.8 and 9.1 Mg ha−1 for the other treatments. Forage consumption was 70% or more of growth in all treatments. Crude protein ranged from 134 to 158 g kg−1. Neutral detergent fiber ranged from 600 to 670 g kg−1, and acid detergent fiber was 390 g kg−1. Stocking rates were between 3.2 and 7.7 steers ha−1. Average daily gains were greatest on orchardgrass + clover (869 g day−1) and ranged from 478 to 821 g day−1 for the other pastures. Productivity was 591 animal grazing days ha−1 for common + fescue at 25 cm + legumes, 1537 for Midland + fescue at 25 cm, and ranged from 605 to 833 for the other pastures. Daily forage DM intake was 6.3 to 9.9 kg steer−1. Beef production was 392, 474, 510, 545, 597, and 630 kg ha−1 for common + fescue at 25 cm + legumes, Midland + fescue at 50 cm + legumes, Midland + fescue at 25 cm + legumes, orchardgrass + clover, fescue + legumes, and Midland + fescue at 25 cm + N, respectively.
Development and Testing of an Improved Soil‐Root Sampling Technique for Rice in Flooded Puddled Soil1
Authors: Thangaraj M. , O'Toole J. C.
Published: July 2010

Undisturbed, intact root and soil samples have rarely been acquired from rice (Oryza sativa L.) grown in flooded, puddled lowland soils. Common sampling techniques used in aerobic dry soil conditions are useless under the flooded conditions of a rice field. This note presents an improved volumetric soil‐root sampling method and associated root isolation techniques for accurately measuring root length and root weight of rice in flooded soils. The metal field sampler was used to extract a soil monolith 0.2 by 0.2 by 0.5 m deep. The sampler and soil monolith were then frozen for 12 to 14 h. In a frozen state, the previously unmanageable flooded soil sample could be moved to a sample holder that facilitated cutting the monolith into sections 0.2 m by 0.2 m by 50 mm. The individual sections were treated to remove soil and organic matter from the roots. Root samples were then available for root length measurement or any other analytical procedure. Analysis of root lengths at 50‐mm vertical increments at three different growth stages of the rice crop illustrated the reliability of the sampler and analysis techniques. Coefficients of variation (CV) were less than 10% for samples between 0 and 0.25‐m depths. Below this level to 0.4 m, CV's were about 15%. We conclude that the soil‐root sampler and associated analytical techniques provide a means of overcoming the inherent problems of soil and root sampling in flooded rice fields.
Preliminary DRIS Norms for Alfalfa in the Southeastern United States and a Comparison with Midwestern Norms1
Authors: Walworth J. L. , Sumner M. E. , Isaac R. A. , Plank C. O.
Published: July 2010

Foliar tissue norms were developed for ‘Apollo’ alfalfa (Medicago sativa L.) grown on two highly weathered soils in the Georgia Piedmont for use in the diagnosis and recommendation integrated systems (DRIS). These norms were generated from a data bank comprised of tissue nutrient composition and plant yield and consisting of 3915 field observations. A yield of 3.5 Mg ha−1 per cut was used to divide high yielding from low yielding members. Norms were generated by averaging values from the high yielding segment for all possible ratios of N, P, K, Ca, Mg, Zn, Cu, B, and dry matter (DM) and compared to those previously calculated from midwestern data. Values from Georgia were generally similar to those from the Midwest, except for Mg, which was lower, and B, which was higher. Differences in Mg norms were attributed to soil conditions. Norms generated in Georgia correctly diagnosed nutrient requirements of plants grown in Georgia, but differences between the two sets of norms indicate some regionality in DRIS norms for alfalfa. The DM index was demonstrated to adequately separate nutrients present in sufficient and insufficient quantities for recommendation purposes.
Amaranth Seedling Emergence as Affected by Seeding Depth and Temperature on a Thermogradient Plate1
Authors: Webb D. M. , Smith C. W. , Schulz‐Schaeffer J.
Published: July 2010

Seedling emergence studies are normally conducted in growth chambers, greenhouses, or field plots and require much space, equipment, and time when several factors are considered. Amaranth (Amaranthus spp.) is a new crop in the United States that often exhibits inadequate field emergence because of environmental constraints. Two seedlots, one white seeded and one black seeded, from the same population of Amaranthus hypochondriacus L. were assessed for emergence index and percentage emergence in a peat‐sand medium over a range of temperatures and seeding depths using a modified thermogradient plate. Seed color produced no difference in emergence, but significant differences in emergence were caused by temperature, seeding depth, and temperature × depth interaction. A predictive response surface shows expected amaranth seedling emergence index at temperatures between 15 and 42°C and seeding depths between 13 and 51 mm. Highest amaranth emergence index and percentage emergence on the thermogradient plate occurred from the 13‐mm seeding depth and at temperatures between 24 and 34°C; these data suggest field emergence may be satisfactory with soil temperatures between 18.5 and 24°C.
Estimating Corn Growth, Yield, and Grain Moisture from Air Growing Degree Days and Residue Cover1
Authors: Swan J. B. , Schneider E. C. , Moncrief J. F. , Paulson W. H. , Peterson A. E.
Published: July 2010

Low spring soil temperatures commonly restrict the early growth of corn (Zea mays L.) in the northern Corn Belt. A quantitative assessment of the effects of tillage and residue management practices on soil temperature would improve tillage recommendations in this region. The effect of tillage and surface residue cover on seedbed soil temperatures and subsequent corn growth were studied at four sites in the northern Corn Belt that differed widely in soil characteristics including drainage, texture, slope, and organic matter content. Tillage systems included no‐tillage, chisel plow, moldboard plow, paraplow, ridge plant, and wheeltrack plant. A wide range of surface residue cover was imposed on each system at three sites. Corn emergence and leaf number to the six‐leaf stage were closely related to percent in‐row cover and air temperature growing degree days (air GDD) through their mutual relationship to soil temperature growing degree days (soil GDD) at all sites. For a given site and year, percent in‐row cover following planting was the major factor affecting corn growth rate until the six‐leaf stage. Corn planted under high percent residue cover required more time and consequently more air GDD to reach the six‐leaf stage. This added time represents a growth delay that can be expressed as the additional air GDD required to reach the six‐leaf stage. Such delays were related to increased grain moisture and decreased corn grain yield when net cumulative air GDD were less than the threshold value of 1319 and water stress was minimal. In‐row residue cover due to tillage and previous crop can have a major impact on the growth and development of corn in the northern Corn Belt. These factors should be considered in selecting tillage systems in this region.
Effects of Grazing Management on Establishment and Productivity of Aeschynomene Overseeded in Limpograss Pastures1
Authors: Sollenberger L. E. , Quesenberry K. H. , Moore J. E.
Published: July 2010

Low protein concentration in limpograss [Hemarthria altissima (Poir.) Stapf et C.E. Hubb.] herbage is thought to limit the performance of grazing animals. In 1983 and 1984 an experiment was conducted on a sandy, siliceous, hyperthermic Ultic Haplaquod soil to evaluate effects of grazing management on establishment and productivity of the legume aeschynomene (Aeschynomene americana L.) seeded in limpograss. Existing limpograss pastures were grazed in the spring to 75‐ or 150‐mm stubble heights. After broadcast seeding aeschynomene, stubble heights were maintained by grazing until (i) legume cotyledons were exserted, (ii) two true leaves were present, or (iii) 2 weeks after the two‐leaf stage. Summer grazing was initiated when aeschynomene plants were 0.20, 0.40, or 0.80 m tall in 1983 and 0.20, 0.40, or 0.60 m tall in 1984. After initiation of grazing, pastures were grazed every 5 weeks. Limpograss stubble height during legume establishment did not affect legume productivity, but there was a trend favoring the 75‐mm level. Extending the period of early season grazing of limpograss until aeschynomene seedlings reached at least the two‐leaf stage controlled grass competition and maximized legume performance. Legume dry matter (DM) accumulation was greatest if initiation of summer grazing was delayed until aeschynomene was 0.80 (1983) or 0.60 (1984) m tall. Initiation of grazing when aeschynomene was 0.20 to 0.40 m tall resulted in more uniform distribution of total and legume DM, higher efficiency of grazing, more vigorous legume regrowth, and a trend toward greater total herbage consumption. These data indicate that aeschynomene can be established into limpograss sods under grazing, and that this association has potential on the large expanses of poorly drained soils in Florida.
Influence of Growth Retardants (Anti‐Gibberellins) on Corn Vegetative Growth, Water Use, and Grain Yield under Different Levels of Water Stress1
Authors: Shanahan J. F. , Nielsen D. C.
Published: July 2010

Corn (Zea mays L.) grown under the semiarid conditions of the Central Great Plains requires supplemental irrigation to obtain maximum yields. This practice has become increasingly less profitable as the cost of application of irrigation water has risen. It may prove to be more cost effective to reduce the water requirement of corn by limiting the vegetative development of the plant. Two anti‐gibberellin, seed‐applied, experimental plant growth regulators (PGRs), BAS 106. .W and BAS 110. .W, were used on corn grown under low and high levels of irrigation in a 2‐yr (1984 and 1985) field study on a Rago silt loam soil (fine, montmorillonitic, mesic Pachic Argiustolls) to determine the effect of these PGRs on vegetative growth, water use, water stress, grain yield, and yield components. The PGRs were applied at three rates in both years (0, 100, and 200 mg a.i. kg−1 of BAS 106. .W in 1984 and 0, 125, and 250 mg a.i. kg−1 of BAS 110. .W in 1985). Increasing application rates of the PGRs caused a significant reduction in early season plant height, leaf area index (monitored in 1985 only), and dry matter accumulation (monitored in 1985 only), resulting in reduced early season evapotranspiration in both years. The PGR treatments reduced plant water stress during silking and early grain fill, particularly under the low irrigation treatment. The changes in plant growth and development associated with the PGRs resulted in a 9 and 16% increase in grain yield in 1984 and 1985, respectively, under the low irrigation treatment and a 7 and 9% reduction in grain yield in 1984 and 1985, respectively, under the high irrigation treatment. Therefore, reducing early season vegetative growth with the PGRs proved to be advantageous to productivity under water stress and counterproductive under nonlimiting water conditions.
Effect of Water Depth on Nitrogen Use Efficiency and Nitrogen‐15 Balance in Lowland Rice1
Authors: De Datta S. K. , Obcemea W. N. , Chen R. Y. , Calabio J. C. , Evangelista R. C.
Published: July 2010

Basic studies to understand and delineate N loss mechanisms and to develop management practices to minimize N losses are vital to increasing rice (Oryza sativa L.) productivity and N use efficiency in lowland rice. In 1984, two field studies in lowland rice evaluated the effect of water depth on potential N loss and N use efficiency on Maahas clay (Andaqueptic Haplaquoll) and 15N balance on Maligaya clay (Vertic Tropaquept). In the first experiment on Maahas clay, the partial pressure of NH3 (ρNH3) in the floodwater was lower when fertilizer was incorporated without standing water than when incorporated with 50 mm water. However, when fertilizer was topdressed 10 days after transplanting (DT), ρNH3 was lower with 100 and 150 cm standing water than with 50 mm water due to dilution and lower floodwater pH and temperature. In the second experiment conducted on Maligaya clay, grain yield from urea applied basally and incorporated without and with 25 mm standing water was similar to that from point‐placed urea supergranules. Yields from fertilizer topdressed 10 DT with 0, 50, and 100 mm standing water were similar but significantly lower than when fertilizer was applied basally and incorporated at all water depths. Nitrogen‐15 balance data show that fertilizer applied basally and incorporated without standing water gave a total 15N recovery of 66% and crop (grain + straw) recovery of 39%. Standing water at depths of 25 and 50 mm during incorporation decreased total 15N recovery by 5 to 7%. Topdressing fertilizer 10 DT without standing water resulted in 59% total N recovery and 38% plant recovery.
A Nitrogen‐15 Microplot Design for Measuring Plant and Soil Recovery of Fertilizer Nitrogen Applied to Corn1
Authors: Jokela W. E. , Randall G. W.
Published: July 2010

Application of the stable isotope I5N to a small area, or microplot, within a larger field plot reduces the cost of measuring plant uptake and soil recovery of fertilizer‐derived N (FN). The objective of this study was to evaluate a specific microplot design for corn (Zea mays L.), including determining maximum plant sampling area. Nitrogen as (NH4)2SO4 was applied to 6‐ by 9‐m plots of corn at rates of 200 and 150 kg N ha−1 on a Webster clay loam (fine‐loamy, mixed, mesic Typic Haplaquoll) and a Mt. Carroll silt loam (fine‐silty, mixed, mesic Mollic Hapludalf), respectively, in 1982 and 1983. Enriched 15N was applied to 1.52‐ by 2.29‐m microplots located in opposite halves of the large plot in each year of the study. This allowed separate measurement of plant and soil recovery of FN for the two application years as well as for residual years. Each microplot was centered lengthwise on one row and bordered by the two adjacent rows, so that the center row was 0.76 m from each side of the microplot and the adjacent rows were on the microplot edge. To assure incorporation and uniform distribution, labeled N solution was injected with a syringe to a depth of 0.08 m on a grid pattern with 0.19‐m spacings. Grain and stover samples and soil samples to a 0.4‐m depth were taken at maturity from various positions within and outside the microplots, and percentage of N derived from fertilizer was determined. Results showed that this microplot design provided reliable FN recovery data for corn in 0.76‐m rows when plant samples were taken from the center row at least 0.38 m from the end of the microplot and when soil was sampled from a 0.76‐ by 1.14‐m area in the center of the microplot. Measurement of FN in plants from the two edge rows indicated that use of a microplot 0.76 m in width would not always provide reliable FN data.
Thatch and Quality of Tifway Bermudagrass Turf in Relation to Fertility and Cultivation1
Authors: Carrow R. N. , Johnson B. J. , Burns R. E.
Published: July 2010

Secondary cultural practices, such as core aeration, vertical mowing, and topdressing, are being used on homelawn turf to a greater extent, even though specific problems may not warrant their application. In a field study (clayey, kaolinitic, thermic Typic Hapludult soil), we applied secondary cultural practices on ‘Tifway’ bermudagrass [Cynodon dactylon (L.) Pers. ✕ C. transvaalensis (Burtt‐Davis)] in conjunction with annual N rates of 98, 196, and 296 kg ha−1 and K at 49, 98, and 196 kg ha−1. Neither N nor K influenced thatch accumulation, but a minimum of 196 kg N ha−1 was necessary for adequate shoot density and color. The 49 kg K ha−1 resulted in as good or better shoot density and color than did higher K rates. Three to four times more dollar spot (Moellerodiscus spp. and Lanzia spp.) occurred at the lowest N rate, while K had much less influence on disease incidence. Core aeration applied once or twice per year caused a loss of stand density and did not reduce thatch accumulation regardless of whether cores were removed or returned. Vertical mowing twice per year decreased thatch by 8% but shoot density was adversely affected. At the end of 4 yr, topdressing with sand reduced thatch by 44 to 62% for one or two applications, respectively, while maintaining adequate shoot density and color. Increasing N or K did not offset the adverse effects of core aeration or vertical mowing. Thus, under homelawn conditions, core aeration and vertical mowing should only be used if a specific problem exists and not as routine practices to prevent thatch accumulation.
Dormant‐Season Irrigation: Grain Yield, Water Use, and Water Loss1
Authors: Stone L. R. , Gwin R. E. , Gallagher P. J. , Hattendorf M. J.
Published: July 2010

Research results are lacking that compare the yield benefit from a limited amount of irrigation water applied off‐season vs. in‐season. Also lacking is a partitioning of field water losses during winter into the profile drainage and evaporation components. The objectives of this work were: (i) to examine grain yield and water use of corn (Zea mays L.) and Winter what (Triticum aestivum L.) in irrigation schemes that use fall vs. spring irrigations; and (ii) to partition field water loss during winter into the profile drainage and evaporation components. The field work was done near Tribune, KS, on a Ulysses silt loam soil (fine‐silty, mixed, mesic Aridic Haplustoll). Timing of the off‐season irrigation (fall vs. spring) did not influence corn grain yield. In irrigation schemes identical except that off‐season irrigation was or was not applied, off‐season irrigation did not influence corn grain yield significantly. Maximum grain yield benefit in corn from irrigation was achieved when water was applied in‐season. In winter wheat receiving only one irrigation, fall irrigated wheat yielded 2055 kg ha−1 more grain (3‐yr mean) than wheat irrigated only in spring. Among the irrigation schemes containing fall irrigation, there was no significant difference in winter wheat grain yield, even though the total irrigation amount ranged from 152 to 456 mm. Drainage losses during winter were less than 5% as much as evaporation losses at mean profile water contents during winter of less than 50% available soil water. At greater than 50% available soil water, the relative contribution of drainage in profile water loss increased with increasing profile water content. Drainage losses equalled evaporation losses at a mean profile water content during winter of 0.57 m (80% available soil water). Off‐season irrigation of corn was not a water efficient practice. Fall irrigation of winter wheat was a water efficient practice that allowed continuous cropping in a region where some rotation that includes fallow is the dryland alternative.
Effects of Cover Inoculation of Soybean on Nodulation, Nitrogen Fixation, and Yield1
Authors: Ciafardini G. , Barbieri C.
Published: July 2010

In clay soils with no indigenous Bradyrhizobium japonicum, seed or soil implant inoculation of soybean [Glycine max (L.) Merr.] often results in nodules distributed mainly on the primary root and the initial portions of the secondary root, due to the poor mobility of B. japonicum in soil. To increase nodulation of soybean in silty clay loam soil (Vertic Xerothent), we used B. japonicum (USDA strain 122) cover‐inoculated with 100 m3 of irrigation water at the third node (V3) stage. Inoculation treatments included: (i) seed inoculation; (ii) seed and cover inoculation; and (iii) a control without inoculation. Two soybean cultivars were used. Seed plus cover inoculation doubled the biomass of the nodules compared to plants with seed inoculation only. Nodules produced after cover inoculation were very active in nitrogen fixation and showed increased nitrogenase activity during the reproductive stage of the plant. As a consequence, there was an increase in the N concentration in the stem, in seed protein (+6.7% in ‘Evans’, +16.0% in ‘Swift’), and in seed production per hectare (+16.1% in Evans, +10.5% in Swift).
Water Use, Yield, and Dry Matter Accumulation by Determinate Soybean Grown in a Humid Region1
Authors: Scott H. D. , Ferguson J. A. , Wood L. S.
Published: July 2010

Planning of irrigation strategies for soybean [Glycine max (L.) Merr.] requires a knowledge of the year‐to‐year variability associated with water use, dry matter accumulation, and seed yield. This study was undertaken to determine the relationships and variability among these plant responses at the end of vegetative and reproductive growth for irrigated (I) and nonirrigated (N) soybean grown in the field during five seasons under humid climatic conditions. Water balance components were determined by computer simulation based on actual soil, plant, and meteorological data. The soil was a Crowley silt loam (fine, montmorillonitic, thermic Typic Albaqualf). For the N soybean, seed yields ranged from 1.07 to 2.74 Mg ha−1, and dry matter ranged from 4.76 to 9.12 Mg ha−1 as the seasonal rainfall ranged from 290 to 570 mm. Variability of dry matter production was greater at the end of vegetative growth than at the end of reproductive growth. Five‐year mean cumulative values of evapotranspiration (ET) during vegetative growth were 237 and 215 mm for I and N treatments, respectively. At the end of the season the 5‐yr mean ET, transpiration (T), and evaporation (E) from the I soybean were 497,327, and 170 mm, respectively. These corresponding values were greater than those of N soybean of 382, 231, and 151 mm, respectively. However, when the data from the wet season were removed, the variability of ET, T, and E from the I soybean were lower than from N soybean. Under I conditions, the lowest seasonal ET (370 mm) was found in the wetter‐than‐normal season and the highest ET (539 mm) was found in the drier seasons. Under N conditions, ET during the wet season (370 mm) was similar to the 5‐yr mean (382 mm). The year‐to‐year variability in this humid environment depended on soil‐water management as well as the climatic conditions.
Forage Nutritive Value and Palatability of Perennial Weeds
Authors: Marten G. C. , Sheaffer C. C. , Wyse D. L.
Published: July 2010

Knowledge of forage quality of individual weed species is essential for making sound management decisions regarding the control of weeds that invade alfalfa (Medicago sativa L.). Our objective was to determine the nutritive value and palatability of nine perennial forb and grass weeds in comparison to alfalfa and smooth bromegrass (Bromus inermis Leyss.). Field trials were conducted on a fine‐silty over sandy skeletal, mixed, mesic Typic Hapludoll. We used a randomized complete block design with four replicates. Compared to alfalfa, smooth bromegrass and quackgrass [Agropyron repens (L.) Beauv.] consistently had more neutral detergent fiber (NDF), less crude protein (CP), and similar in vitro digestibility (IVDDM). Grasses consistently had more NDF than forbs. Nutritive value varied considerably among forbs. Jerusalem artichoke (Helianthus tuberosus L.), Canada thistle [Cirsium arvense (L.) Scop.], dandelion (Taraxacum officinale Weber in Wiggers), and perennial sowthistle (Sonchus arvnesis L.) had CP and IVDDM concentrations equal to or greater than those of alfalfa, while Jerusalem artichoke, dandelion, and curly dock (Rumex crispus L.) frequently had lower NDF concentrations than that of alfalfa. Forb weeds generally had lower palatability than alfalfa or smooth bromegrass, with several exceptions. Jerusalem artichoke, curly dock, hoary alyssum [Berteroa incana (L.) DC.], and Canada thistle were either completely or nearly completely rejected by grazing lambs (Ovis spp.). Palatability of a quackgrass biotype selected for wide leaves was equal or superior to smooth bromegrass and was equal to alfalfa in two of three trials. Common quackgrass consistently had lower palatability than smooth bromegrass or alfalfa. Because forage quality of perennial weeds varied considerably among species and was sometimes superior to that of alfalfa, we conclude that decisions on whether to implement weed control in established alfalfa should be specific for each situation
Comparative Water Use Characteristics of Six Row Crops
Authors: Hattendorf M. J. , Redelfs M. S. , Amos B. , Stone L. R. , Gwin R. E.
Published: July 2010

To help make decisions on shifting of crop species in water management strategies, information is needed on comparative water use characteristics of the principal row crops. The objective of this study was to compare the water use characteristics of six row crops grown in a replicated and randomized field experiment. Crops were corn (Zea mays L.), grain sorghum [Sorghum bicolor (L.) Moench], pearl millet [Pennisetum amerlcanum (L.) Leeke], pinto bean (Phaseolus vulgaris L.), soybean [Glycine max (L.) Merr.], and sunflower (Helianthus annuus L.). Crops were grown near Manhattan, KS, on Muir silt loam (Cumulic Haplustoll) in 1981 and on Eudora silt loam (Fluventic Hapludoll) in 1982, and near Tribune, KS, on Ulysses silt loam (Aridic Haplustoll) in both 1981 and 1982. Soil water content was determined to the 3.1‐m soil profile depth by the neutron attenuation method. Measured evapotranspiration (ET) was calculated as the sum of soil water depletion, rainfall, and irrigation. Reference ET was calculated by using the original Jensen‐Haise equation. The maximum value of measured ET/reference ET was greater for sunflower (1.35) than for the other five crops (ranged from 1.05 to 1.15). The mean daily water use rate of sunflower (6.1 mm d−1) was 22% greater than the mean of the other five crops (5.0 mm d−1). The mean dry matter water use efficiency was 17.5 Mg ha−1 m−1 for the group of C3 crops (pinto bean, soybean, and sunflower) and 33.3 Mg ha−1 m−1 for the group of C4 crops (corn, grain sorghum, and pearl millet). Sunflower depleted significantly more water from deeper soil depths (0.99‐1.60 m) than the other five crops at Manhattan in 1981 and 1982. Our findings consistently showed that sunflower had a greater daily water use rate than the other five crops.
Row Spacing, Plant Population, and Genotype × Row Spacing Interaction Effects on Yield and Yield Components of Dry Bean
Authors: Grafton K. F. , Schneiter A. A. , Nagle B. J.
Published: July 2010

Dry edible bean (Phaseolus vulgaris L.) production practices in the northern Great Plains have begun to shift from conventional wide (0.76‐m) to narrower row spacings for maximizing seed yields. Field experiments were conducted to determine row spacing and plant population effects for production of dry, edible bean in the northern Great Plains and also to determine if genotypes varied in their seed yield response to row spacing. Yield per hectare of the indeterminate pinto bean ‘UI‐114’ and the determinate navy bean ‘Seafarer’ increased by 52 and 44%, respectively, as row spacing was decreased from 0.75 to 0.25 m during 1977 and 1978. Seed yield of UI‐114 did not increase with increased plant populations, while yield of Seafarer increased as the plant population increased to 222 000 plants ha−1. Row spacing × plant population interaction for yield was nonsignificant for both cultivars. In another experiment, 10 navy bean genotypes were grown at 0.19−, 0.38−, and 0.76‐m row spacings in both 1984 and 1985. Significantly higher yields were obtained as row spacings decreased. Yields of seven genotypes were up to 57% higher when grown at 0.19− compared with 0.76‐m row spacings. Yield rank of the genotypes tested changed within the three row spacings. Genotype − row spacing interactions may necessitate the testing of breeding lines' potential production at specific row spacings.
Seasonal Changes in Smooth Bromegrass Top and Root Growth and Fate of Fertilizer Nitrogen
Authors: Power J. F.
Published: July 2010

While information is available at the end of the growing season on the fate of fertilizer N applied to perennial grasslands, little detailed information is available on the transformations and translocation of N during a growing season. The purpose of this research was to measure the effect of N fertilization on time, quantities, and rates of dry‐matter accumulation by smooth bromegrass (Bromus inermis L.) tops and roots, water use, and fertilizer N transformations and uptake. Ammonium nitrate was surface broadcast at 0, 90, and 270 kg N ha−1 on established smooth bromegrass at Mandan, ND. At approximately 3‐wk intervals, top and root (0–900 mm) dry weights were measured, N uptake calculated, soil inorganic N concentrations determined, and apparent fertilizer N in tops, roots, and as soil inorganic N was calculated (fertilized minus check). Growth and N uptake of tops increased until physiological maturity in July, decreased during a midsummer drought, and increased after August rains. Fertilization greatly increased growth rate. For roots, growth stopped or even declined slightly at time of floral emergence in June, resumed until physiological maturity, remained constant or decreased slightly through the summer drought (when soil water reserves were depleted), then increased rapidly in September after fall rains. Dry matter accumulated at rates in excess of 300 kg ha−1 d−1 in May and September, when N uptake rates exceeded 4 kg ha−1 d−1. Over 40% of the fertilizer N at the 270 kg N rate was immobilized in organic forms other than root growth within 10 d after application, but by physiological maturity, 51% was in tops, 27% in roots, 3% as soil inorganic N, and only 19% was immobilized in other organic forms or lost by gaseous means (no leaching occurred). Results suggest that gaseous losses were no more than 10%. Nitrogen fertilization appeared to enhance three labile N pools—readily available (inorganic), highly labile (probably including microbial biomass), and moderately labile (possibly primarily grass roots).
Corn Growth with Foliar Nitrogen, Soil‐Applied Nitrogen, and Legume Intercrops
Authors: Tomar J. S. , MacKenzie A. F. , Mehuys G. R. , Alli I.
Published: July 2010

Corn (Zea mays L.) production under current N fertilizer recommendations can result in soil degradation and N pollution of groundwater. Sources of N such as intercropped legumes or foliar spray might reduce fertilizer N requirements while improving soil quality through legume growth. The objective of this study was to compare corn growth using combinations of foliar and soil urea applications, as well as legume intercrops in combination with soil fertilizer N. Field experiments were conducted for 3 yr on two Typic Humaquepts, a Ste. Rosalie clay and an Ormstown silty clay. Foliar applications of 20 kg N ha−1 applied in late July or late August, or both, were compared at 0 and 140 kg N ha−1 of soil‐applied urea. The effects of a legume intercrop on corn yield were determined by planting legumes at the same time as corn, at three rates of added N (0, 70, and 140 kg N ha−1). Treatments were placed on the same plots each year, providing an assessment of cumulative effects. Plant dry‐matter yields and soil mineral N were determined. Plots were fall‐plowed each year and planted after conventional soil preparation. Foliar N increased yields only in one site‐year. Intercropping lowered corn yields by about 2 tonnes ha−1 in five site‐years, except for one wet year on the Ormstown site when intercrops did not affect corn yields. Added N increased corn yields independently of intercropping, indicating little cumulative effect of legumes on soil N supply. Legume intercropping and foliar‐applied urea were not effective alternatives to the use of soil‐applied urea N as far as grain corn yield is concerned.
Response of Solid‐Seeded Soybean to Flood Irrigation. II. Flood Duration
Authors: Griffin James L. , Saxton Arnold M.
Published: July 2010

Flood‐irrigated soybean [Glycine max (L.) Merr.] can be exposed to extended periods of soil‐saturated conditions, depending on the producers method of application, watering capacity, and field size. Field studies were conducted on a Crowley silt loam (fine, montmorillonitic, thermic Typic Albaqualf) soil in southwest Louisiana during 1982 to 1984 to evaluate the effects of flood duration on solidseeded (i.e., nonbedded narrow rows) ‘Ransom’ soybean. Soybean was flooded at the V6 (vegetative), R2 (bloom), or R2 + R5 (bloom and pod fill) growth stages. Within each timing treatment, water was applied to a standing depth of 0.076 m and allowed to stand for 0 (nonflooded control), 1, 2, 4, or 8 d. Soybean stand density did not change as flood duration increased. Yields for individual timing treatments were generally similar when flood periods were 0, 1, or 2 d. When water was held longer than 2 d postflowering, significant yield reductions were noted in all years and were as much as 1390 and 1520 kg ha−1 in 1982, when water was applied at R2 or R2 + R5, respectively. In 1982 and 1984, when water was applied at R2 + R5, average yield reductions associated with increasing flood duration from 2 to 4 d and from 2 to 8 d were 20 and 10% higher, respectively, compared with R2 only. Increasing flood duration at V6 from 4 to 8 d decreased yields in 1982 and 1984 an average of only 340 kg ha−1. For those 2 yr, with flood periods of 4 or 8 d, yields for soybean flooded at V6 were substantially higher than yields from the R2 or R2 + R5 treatments. Increased numbers of both seeds per pod and seeds per plant accounted for the higher yields in the V6 treatment. When flood irrigating solid‐seeded soybean after flowering, attempts should be made to remove standing water within 2 d to avoid yield reductions.
Spring Defoliation to Improve Summer Supply and Quality of Switchgrass
Authors: George J. R. , Obermann Doug
Published: July 2010

Switchgrass (Panicum virgatum L.) normally is lower in forage quality by the time cool‐season forage species are less productive in early summer. The objective of this study was to determine if the major supply of switchgrass herbage could be delayed by use of partial spring defoliation and still maintain adequate herbage quality. Switchgrass plots were fertilized with 0 or 120 kg N ha−1 and defoliated at six time‐intensity combinations. Yield and quality of initial spring and 6‐wk regrowth were measured. Initial 1984 spring defoliation treatments were 1 June at 15 cm; a multiple defoliation at 15, 20, and 25 cm over 1‐wk intervals beginning on 1 June; 15 June at 6 or 20 cm; and 29 June at 6 or 20 cm. All 1985 treatments were 9 d earlier. Fertilization with N increased 6‐wk regrowth dry matter (DM) yields by 79 to 92% for 1 June treatments and by only 38 to 54% for 29 June treatments. Close defoliation on 29 June produced the greatest total seasonal DM yield of 10.5 Mg ha−1 and IVDDM yield of 5.79 Mg ha−1, but only 30% of this was harvested in midsummer after 6 wk of regrowth. Total season DM yield and IVDDM yield were about 20 to 35% less for both 1 June treatments when compared with close defoliation on 29 June, but the 6‐wk regrowth yield accounted for about 75 to 85% of total season DM and IVDDM yields. Little or no difference in leaf or stem IVDDM of the 6‐wk regrowth was observed among defoliation treatments, so partial spring defoliation can delay the major supply of switchgrass herbage with no serious reduction in herbage quality. We conclude that a short period of moderate defoliation of switchgrass in early to mid‐June could benefit grazing programs by providing (i) some very high‐quality switchgrass herbage during early to mid‐June; (ii) a brief rest and regrowth period for the cool‐season pasture; and (iii) relatively high summer yields of quality switchgrass when it is most needed.
Cultivation, Cultivar, and Crop Age Effects on Sugarcane
Authors: Glaz B. , Ulloa M. F. , Parrado R.
Published: July 2010

A practice that may allow farmers to reduce field cultivations is the use of cultivars that have vigorous growth rates early in the growing season. In sugarcane (a complex hybrid of Saccharum spp.) culture, this practice can be disadvantageous to sugarcane processors if these vigorous cultivars have lower sugar concentrations (SC) than the less vigorous cultivars. The objective of this research was to determine the effects of different levels of cultivation on yield characteristics of sugarcane cultivars with varying growth potentials and SCs, from the plant‐cane through the second‐ratoon crop. An experiment with four cultivation levels and three cultivars, representing slow‐growth rate/high SC, moderate‐growth rate/moderate SC, and fast‐growth rate/low SC types was conducted in a field infested primarily by short or prostrate weeds. Stalk heights and stalk counts were measured in the plant‐cane and second‐ratoon crops. Yields of Mg ha−1 of cane (MHC), SC and Mg ha− of sugar (MHS), were measured from the plant‐cane through the secondratoon crop. Although there were significant differences among the cultivars and among levels of cultivation for MHC, SC, and MHS, there were no important relative differences among cultivars across levels of cultivation for any of these characteristics. There were important differences in cultivars and levels of cultivation across crops. The most important conclusions were that cultivar growth rate did not influence number of cultivations necessary to attain maximum yields, and the greatest benefits from cultivating throughout the three‐crop cycle occurred in the last crop.