bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Nitrogen Fertilization and Recurrent Selection on Performance of Hybrid Populations of Corn1
Authors: Kamprath E. J. , Moll R. H. , Rodriguez N. 
Published: July 2010

AbstractImproved corn (Zea mays L.) hybrids are generally developed at relatively high N fertility levels. Previous studies have shown that hybrid populations developed by different selection methods vary in their responsiveness to environments. Because N supply is an important factor of the environment which affects yield a field study was conducted to determine the N response of population hybrids improved by intra (full‐sib family) and inter (reciprocal recurrent) selection methods. The responses of the original population hybrid and the two improved population hybrids to N rates of 56, 168, and 280 kg N/ha were studied on an Aquic Paleudult.The improved populations produced more total dry matter and grain at each N level than did the original hybrid. This was associated with an increase in the ear number per plant as the N rate increased. The N concentration of the improved population hybrids at silking was correlated with ear number per plant. Average N use efficiency (grain per unit of N applied) for the improved population hybrids was greater than for the original hybrid. The higher yield of the reciprocal recurrent selection at 56 and 168 kg N/ha as compared with the full‐sib family selection was associated with a higher average N uptake efficiency.
Fifty Years of Minnesota Corn Production: Sources of Yield Increase1
Authors: Cardwell V. B. 
Published: July 2010

AbstractCorn (Zea mays L.) yields in Minnesota have increased from the 2,010 kg/ha yield level of the pre‐1930's to the current 6,290 kg/ha average. This increased yield can he attributed to a series of technological, cultural, and management practices adopted by farmers. My objective is to atlempt an analysis of the magnitude of the changes and the relative contributions to grain yield each practice has made over the 50‐year time period. Only simple linear responses were estimated. No attempt has been made to evaluate the nature nor the magnitude of the interactions among the various management practices.The change from open‐pollinated to hybrid corn combined with the estimated 36.5 kg/ha/year genetic gain has produced 58% of the yield increase. Although each kilogram of applied commercial N has been estimated to increase yields by 18.9 kg of grain per kg for 47% of the gain in yield, the effects of less manure, and reduced N from mineralized organic matter actually produces a net N effect of 19%. Improved weed control by the use of herbicides on 93% of the hectarage has increased yields 23%.Plant densities have increased by 19,130 plantdha contributing 47.4 kg/ha/1,000 plants for a total of 21% of the gain. Better soil drainage, fall plowing, and herbicides have permitted planting 10 days earlier for an average gain of 36.4 kg/ha/day and a total of 8% of the net increase. Drilling corn rather than hill dropping has contributed 8% and fall plowing has contributed 5% to current yields. Row spacing has decreased from 107 to 90 cm for a gain of 10.2 kg/ha/cm or 4% of the gain.Rotation changes have had no net effect on N balance with increases in soybean [Glycine max (L.) Merr.] offsetting decreases in forage legume hectarage. However, there has been a negative effect of more hectares of corn following corn resulting in 3% loss from corn rootworm (Diabrotica spp.) and 7% loss due to the interference effect of corn following corn. Corn borer (Ostrinia nubilalis Hubner) became a problem in the 1940's and has reduced yield potential an average of 5%. Soil erosion has reduced yield potentials 8% over the 50 years. Other negative and unaccounted factors reduce the potential yields by 23%.
Nitrogen Mineralization in Soils Previously Amended with Organic Wastes1
Authors: Griffin G. F. , Laine A. F. 
Published: July 2010

AbstractLong‐term aerobic incubations were conducted on soils previously amended with cow and poultry manure, sewage sludge, and mycelium to determine N mineralization potential (No) and N mineralization rate constant (k). Values for No were higher than those reported by other workers. The k values varied among soils sufficiently so that a single value could not be assumed for any one group of soils. Corn (Zea mays L.) was grown on five of the soils used in the incubation study. Soil moisture and soil temperature data from NoN0 and initial mineral N, estimates of N available to the crop. Yield and N uptake correlated well with the parameter No × k, but No alone proved to be a very poor predictor of yield or N uptake. K values, which can be estimated only from lengthy incubations, are required to obtain accurate estimates of N availability.
Perennial Ryegrass Growth, Water Use, and Soil Aeration Status under Soil Compaction1
Authors: O'Neil K. J. , Carrow R. N. 
Published: July 2010

AbstractSoil compaction is a serious problem on recreational turfgrass sites because the altered soil physical properties can adversely affect plant growth and irrigation management. Soil compaction was examined in a greenhouse study for its effect on turfgrass growth, water use, and soil aeration using a Chase silt loam soil (fine, montmorillonitic, mesic, Aquic Arquidolls). Perennial ryegrass (Lolium perenne L. ’Derby’) was subjected to three compaction levels: 1) none—no compaction, 2) moderate—360 joules energy, and 3) heavy—720 joules energy. The soil was compacted by dropping a 11.5 kg weight from a height of 65 cm. When tensiometers (installed at a depth of 5 cm) read −0.65 bar, 5 cm of water was applied. Pots were 30.5 cm I.D. by 76.2 cm long PVC pipe with bottom drainage. Soil compaction increased bulk density; reduced aeration porosity, visual quality, and shoot density; altered root distribution; and reduced root density in the 10 to 25 cm soil zone. It had, however, slight effect on verdure and individual shoot weight. Total clip ping weights were reduced by 38 and 53% for the moderate and heavy compaction treatments, respectively. Clipping yield decreased immediately after compaction treatment, while root changes were not apparent until after 12 weeks. During the study, water use was reduced by 21 and 49% for the moderate and heavy compaction treatments, respectively. Water extraction from the 10 to 25 cm soil zone decreased from 69 to 27% of the total water extracted in the heavy compacted pots by the end of the study. With heavy compaction, oxygen diffusion rates (ODR) were below 20 × l0−8 g cm‐2 min‐1 for at least 53 hours after irrigation. The noncompacted soil achieved acceptable ODR within 5 hours. The combined effects of compaction reducing rooting, slowing shoot growth, and increasing moisture retention, caused the compacted soil to remain at a reduced aeration status longer than the noncompacted soil after irrigation.
Foliar Fertilization of Soybeans. I. Effect of Fertilizer Sources, Rates, and Frequency of Application1
Authors: Poole W. D. , Randall G. W. , Ham G. E. 
Published: July 2010

AbstractFoliar applications of fertilizer NPKS to soybeans [Glycine max (L.) Merr.] during the podfill stages of growth have been shown to increase yields. However, results have been inconsistent and in some cases severe yield depressions have occurred. The purpose of this study was to evaluate NPKS sources, rates of application, and frequency of application along with micronutrients, a fungicide, and a growth regulator on soybean seed yield, seed weight, and seed composition over several soybean genotypes and experimental locations during a 3‐year period. In 16 cultivar‐location‐year trials, soybean seed yields were increased significantly by the foliar fertilizer treatments over the control only once. Generally, yields were decreased when urea‐ammonium nitrate solution (UAN) and ammonium polyphosphate (APP) were substituted for urea and K‐polyphosphate in the basic NPKS formulation (24 + 2.4 + 7.2 + 1.2 kg/ha N + P + K + S). A positive relationship between leaf injury and yield depression by the various materials was noted; especially when the materials were applied during midday rather than in the early morning or late afternoon hours. The inclusion of micronutrients, a fungicide (Benlate), a growth regulator (Regime 8), or commercially available liquid fertilizers did not increase yields significantly. Seed weights were generally decreased with many of the foliar fertilizers and with the growth regulator. Seed N percentage and protein were increased and seed oil percentage decreased with four applications of the base NPKS formulation. These data indicate that further basic research is needed before the practice of foliar fertilization can be recommended.
Root Distribution and Water Use Efficiency of Alfalfa as Influenced by Depth of Irrigation1
Authors: Jodari‐Karimi Farman , Watson Vance , Hodges Harry , Whisler Frank 
Published: July 2010

AbstractRoot distribution of several crop plants is known to be affected by different patterns of soil moisture. In alfalfa (Medicago sativa L.), however, such results have not been consistently obtained under field conditions. Our objective was to determine the effect of different irrigation depths on alfalfa water use efficiency, water extraction patterns, and root distribution under greenhouse conditions where examination of the entire root systems was possible. ‘Cimmaron’ alfalfa was planted in polyvinylchloride (PVC) containers (120 ✕ 30 cm) filled uniformly with a Leeper fine (fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) sandy loam top soil. Irrigation treatments included: watering to saturate the soil one‐third of the whole root depth, watering to saturate the soil two‐thirds of the whole root depth, and no irrigation. Irrigation was applied when available soil moisture content within the root zone reached 35 % (−2.5 bars soil matric potential). The parameters studied included root distribution pattern, total root growth, water extraction pattern, and water use efficiency. The efficiency of water use was higher in deeply irrigated treatments than in shallow irrigated treatments during June and July (a period of high evapotranspirational demand), but it was not different during September to November. Depth of irrigation did not affect total root production, but it did affect root distribution at the irrigation zone. Deeply irrigated plants produced slightly more roots in the lower depths than shallow irrigated plants. Root production of nonirrigated alfalfa was low under the high evaporational demand conditions which occurred during June and July, but was highest among all treatments during the September to November growing period. Root:shoot ratios of 0.28, 0.22, and 0.62 observed in shallow, deep, and non‐irrigated plants grown in the September to November period, respectively, indicate that the rate of root growth was increased in nonirrigated alfalfa as a result of limited water stress and under low evapotranspirational demand.
Resistances to Evapotranspiration from a St. Augustinegrass Turf Canopy1
Authors: Johns D. , Beard J. B. , van Bavel C. H. M. 
Published: July 2010

AbstractA controlled environment study of evapotranspiration from St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] turf showed that, under adequately watered conditions, evapotranspiration was influenced to a greater extent by environmental factors which were external to the plants rather than by disposition of leaf stomata. Using an Ohm's Law analogue to define a resistance network for the turfgrass canopy, magnitudes of resistances to water loss were measured and compared. Internal resistance was defined as aggregate diffusive resistance of the foliage and was determined from porometer measurements of diffusive resistance of leaves. External resistance was defined as the sum of aerodynamic resistance and resistance to air mass exchange within the canopy and was measured by three different methods. Internal resistance was found to be only one‐fourth to one‐half the external resistance. Under wind speed conditions of 0.6 m/sec, actual evapotranspiration rates of St. Augustinegrass were only slightly lower than potential evapotranspiration rates. It is concluded that chemical or genetic control of stomatal resistance would not result in appreciable savings of irrigation water.
Evaluation of the Need for Copper with Several Soil Extractants1
Authors: Makarim A. K. , Cox F. R. 
Published: July 2010

AbstractCopper deficiencies have been observed in a number of crops grown on both organic and mineral soils in the Atlantic Coastal Plain. In order to recommend fertilization correctly, soil test calibrations are needed for the extractants used in the region. Soybeans (Glycine max), corn (Zea mays), and wheat (Triticum aestivum) were grown in the greenhouse on 15 soils fertilized with Cu at several rates. Percent maximum yield for the plant growth on each untreated soil was calculated from the dry matter produced. Four soil extractants were used: Double acid (DA); Mehlich‐Bowling (MB); Ammonium bicarbonate‐DTPA (AB); and Mehlich‐3 (M3). Percent maximum yield was expressed as a function of Cu released from the untreated soils by each extractant with a linear plateau model. The extractants performed similarly in explaining plant response, with each accounting for about 70% of the variation. The soil critical levels, determined by the junction of the response and the plateau portions of the surface, for DA, MB, AB, and M3 were similar among crops and averaged 0.26, 0.62, 0.53, and 0.37 mg L−1 Cu, respectively. Wheat and soybeans were also grown in the field on seven soils with two rates of Cu. Grain yields of the two crops were related to MB extractable Cu with the Cate‐Nelson method, which indicated a critical level of 0.70 mg L−1. Critical whole plant and leaf Cu concentrations were also determined. The critical whole plant Cu concentrations for soybeans, corn, and wheat, each grown 5 weeks in the greenhouse, were 3.8, 1.8, and 3.8 mg kg−1, respectively. Deficiency symptoms developed on corn and wheat at slightly lower values, 1.5 and 2.9 mg kg−1, respectively. In the field, the critical leaf concentrations at early flowering were 6 mg kg−1 for soybeans and 4 mg kg−1 for wheat.
Leaf Pubescence Effects on the Mass and Energy Exchange Between Soybean Canopies and the Atmosphere1
Authors: Baldocchi D. D. , Verma S. B. , Rosenberg N. J. , Blad B. L. , Garay A. , Specht J. E. 
Published: July 2010

AbstractMass and energy exchanges with the atmosphere were compared in two soybean (Glycine max L. Merr. cv. Harosoy) isolines differing in pubescence density. The study was conducted in a field with a Sharpsburg silty clay loam soil (fine, montmorillonitic, mesic Typic Argiudoll) during the summer of 1980 at Mead, Nehr. Mass and energy exchanges were determined by means of micrometeorological techniques. Evapotranspiration (reported in terms of latent heat flux) was reduced in the densely pubescent isoline. Canopy CO2 exchange was unchanged on a per unit land area basis. Water use efficiency (reported in terms of the CO2‐water flux ratio) was, accordingly, greater in the densely pubescent isoline. The increase in pubescence did not significantly alter the net radiation balance, turbulent mixing, canopy CO2 exchange, or plant water status. Observed differences in the partitioning of net radiation into latent and sensible heat can be explained by greater penetration of solar radiation into the densely pubescent canopy. Leaf pubescence appears to alter the spectral characteristics of the leaf and, thus, to facilitate the penetration of solar radiation into the canopy.
Seed Yield of Kentucky Bluegrass as Affected by Post‐Harvest Residue Removal1
Authors: Ensign R. D. , Hickey V. G. , Bernardo M. D. 
Published: July 2010

AbstractField burning of post‐harvest residue has been an established management practice for economical production of Kentucky bluegrass (Poa pratensis L.) seed. Fields not burned soon after harvest usually have poor seed production in the following year. Residue remaining on fields shades, and thereby restricts tiller growth and subsequent seed yield. To explore the hypothesis, polyethylene shade screens which excluded 30 and 67% of sunlight were placed over September field‐burned ‘Baron’ Kentucky bluegrass plants for 75 and 130 days. Other treatments included mechanical vacuum clipping at 2.5, 7.6, and 15.2 cm levels, field burning of residue and no residue removal. The grass was seeded on Thatuna and Naff silt loam series (fine‐silty, mixed, mesic Xeric Argialbolls and fine‐silty, mixed, mesic Ultic Argixerolls, respectively). Tiller numbers from plants where residue was removed to the 2.5, 7.6, and 15.2 cm levels in 1978‐1979 were comparable to tiller numbers from plants shaded at the 30% level. Tiller numbers for plants shaded at 67% were comparable to tiller numbers where residue was removed at 15.2 cm, or where no residue was removed. Leaf and sheath length were generally inversely related to the level of residue removal. Panicle numbers for shading at 67% in 1979‐1980 were comparable to residue removal at 15.2 cm and no removal of residue. Seed yields from artificially shaded plants in 1978‐1979 were 51 to 55% less than yields from plants where residue was not removed. In 1979‐1980, seed yields from shaded plants at the 67% light exclusion for 130 days were 76% of yields from plants of open‐field burn but did not differ from yields from plants where residue was not removed or mechanically clipped to heights of 7.6 or 15.2 cm. It was concluded that reduced Light penetration into the canopy could change plant growth and reduce seed production potential.
Fall Harvest Management of Alfalfa in the Southern Plains1
Authors: Sholar J. R. , Caddel J. L. , Stritzke J. F. , Berberet R. C. 
Published: July 2010

AbstractFall regrowth of alfalfa (Medicago sativa L.) frequently is harvested for hay in the southern plains. Possible detrimental effects of harvesting from mid‐September to late November have not been studied. The objective of this research was to determine the effects of fall cutting dates on root total nonstructural carbohydrate (TNC) concentrations, productivity, and stand persistence of semi‐dormant, dryland alfalfa in the southern plains. From 1978 to 1980, five fall cutting date treatments were imposed on a 4‐year‐old stand of ‘Kanza’ and 2‐year‐old stands of ‘Arc’ and ‘Liberty’ alfalfas grown under dryland conditions on a fine, mixed thermic, Pachic Arguistolls (McClain silt loam). Three harvests per season were made at 10 to 25% bloom prior to the fall cutting date treatments which were made at fourth harvest of the season. Root carbohydrate analyses were made on roots dug 7 December of each year. Forage yields were taken during each growing season subsequent to fall cutting date treatments with a residual harvest taken in April 1981. Stand densities were determined at initiation of the study in 1978 and each fall thereafter. Final stand densities were determined in May 1981. Only forage yields were determined for Liberty. Fall cutting date treatments had little effect on root carbohydrate reserves. Roots dug in 1978 had higher TNC percentages than those dug in 1979 or 1980; however, fall cutting date treatments significantly influenced TNC concentrations only in the fall of 1979. Fall cutting date treatments had a greater effect on first harvest in the subsequent spring than on total yields. Total yields for each season and total yields over the duration of the study for each cultivar indicate that harvesting could take place at any fall date with little effect on productivity in subsequent years. Stands of all cultivars declined over the course of study and at the conclusion of the study in May, 1981 there were no differences in stand persistence that could be attributed to fall cutting date treatments.
Yield and Water Use Efficiency of Grain Sorghum in a Limited Irrigation‐Dryland Farming System1
Authors: Stewart B. A. , Musick J. T. , Dusek D. A. 
Published: July 2010

AbstractA Limited Irrigation‐Dryland (LID) farming system for the conjunctive use of rainfall and limited irrigation of graded furrows was developed and field tested. The unique feature of the LID system is that it actually adjusts, during the crop growing season, the amount of land irrigated since more land can be irrigated during above‐average rainfall years with a limited amount of irrigation water than during below‐average years. The design used a limited water supply to irrigate a larger area than could be conventionally irrigated. A graded furrow field, 600 m long on a 0.3 to 0.4% slope was divided into three water management sections. The upper half of the field was managed as “fully irrigated.” The next one‐fourth was managed as a “tailwater runoff” section that utilized furrow runoff from the fully irrigated section. The lower one‐fourth was managed as a “dryland” section capable of utilizing runoff from either rainfall or irrigation on the wetter sections. The system was field tested for 3 years with grain sorghum (Sorghum bicolor (L.) Moench) on a Pullman clay loam (fine, mixed, thermic family of Torretic Paleustolls). Seasonal rainfall values were 224 mm in 1979, 103 mm in 1980, and 424 mm in 1981 as compared to the average of about 250 mm. The LID system was successful in increasing the utilization efficiency of irrigation water. Irrigation water added to a field can be transpired, evaporated, percolated, lost as runoff, or left stored in the soil after harvest. The LID system tended to reduce all losses other than transpiration. When 125 mm or 185 mm of irrigation water were added with the LID system, the evapotranspiration by grain sorghum was increased by an almost equal amount. This increased grain yield an average of 154 kg/ha for each 10 mm added irrigation, compared to 92 kg/ha for each 10 mm under conventional irrigation practices.
Nitrogen Use Efficiency of Trickle‐irrigated Tomatoes Receiving Continuous Injection of N1
Authors: Stark J. C. , Jarrell W. M. , Letey J. , Valoras N. 
Published: July 2010

AbstractThe practice of applying N fertilizer through trickle irrigation systems is rapidly increasing in popularity. Fertilizer N requirements are usually divided into small increments and then applied at regular intervals during the season. This field study, conducted on an Arlington loam (coarseloamy, mixed, thermic Haplic Durixeralf), was designed to investigate the uptake and partitioning of N by trickle‐irrigated tomatoes (Lycopersicum esculentum Mill.) and the potential for denitrification when N is continuously metered into the irrigation water. Solutions containing 1.8, 3.6, or 5.4 mol N m−3 were applied when the soil matric potential at the 25 cm depth reached either −10 or −30 kPa. The resulting N application totals ranged from 120 to 585 kg N ha−1. Early in the season, large differences in petiole NO3‐N concentrations were observed which appeared to be directly related to the rate of N supply. However, these differences gradually decreased as the season progressed. Total N uptake, which was linearly related to N application, was less than the amount applied at N rates greater than 300 kg ha−1. As the N application rate increased, an increasingly greater proportion of total plant N was partitioned into the vines. Denitrification N losses, as indicated by direct field measurements of N flux during a 4‐day period, were very small in the two lowest N treatments, ranging from 0.3 to 2.0 μg m−2 s−1. These low rates of denitrification were presumably due to competition between roots and denitrifiers. However, in the high N treatments, where N supply exceeded uptake, N fluxes ranged from 2.0 to 17.5 μg m−2 s−1. Aside from its influence on the rate of N supply, irrigation frequency had little effect on denitrification and N uptake. These results indicate that adequate N can be applied to tomatoes using high‐frequency N fertilization without large denitrification N losses.