bluuebunny/crossref_metadata_2025 huggingface dataset:
Moisture‐Stress Effects on the Yield Components of Two Soybean Cultivars1
Authors: Momen N. N. , Carlson R. E. , Shaw R. H. , Arjmand O.
Published: July 2010

Limited soil moisture influences field crop performance by reducing plant height, the size of the assimilating leaf area, and the size and number of potential storage sites for produced dry matter. The effect of moisture stress on plants is complex and very dependent on the stage of development. Therefore, soybeans (Glycine max (L.) Merr.) cultivars ‘Hark’ and ‘Rampage’ were in grown in the field in large potometers filled with the top 15 cm of a Nicollet loam (Aquic Hapludolls, fineloamy mixed mesic). The plants were subjected to four independent moisture stress periods during critical reproductive stages of growth. Soil moisture was controlled by hand watering and the use of an automatic weather shelter, which covered the plots during periods of rainfall. Soil moisture was measured with a neutron soil‐moisture probe, and frequent leaf‐water potential and leaf diffusive resistance measurements were collected to document moisture stress. Final seed yield and components of yield were determined at maturity for all experimental units.

Moisture stress significantly affected most components for both cultivars during the four stress periods, but important cultivar moisture stress interactions were difficult to identify. Although these two cultivars differed greatly in some specific components of yield (Le., seed number, seed size, etc.), compensation between the different yield components resulted in no consistent yield differences between these two cultivars.
Differential Cultivar Tolerance in Soybean to Phytotoxic Levels of Soil Zn. I. Range of Cultivar Response1
Authors: White M. C. , Decker A. M. , Chaney R. L.
Published: July 2010

Heavy metals in waste materials added to agricultural soils can severely inhibit subsequent crop growth. This study was conducted to evaluate the variation in tolerance among cultivars of an agriculturally important plant species to phytotoxic levels of added soil Zn. Twenty soybean (Glycine max L. Merr.) cultivars were screened, through greenhouse pot studies, for their growth response to Zn at pH 5.5 and 6.5 on a Sassafras sandy loam (Fragiudult) amended with 1.31 (control), 131, and 262 ppm Zn. Significant differential responses were found, and the cultivars were grouped into several tolerance and uptake classes, based on the results of the pH 6.5, 262‐ppm Zn treatment: tolerant (9 to 18% leaf dry weight yield reduction [YR], 5 cultivars), normal (20 to 32% YR, 12 cultivars), sensitive (33 to 48% YR, 3 cultivars); accumulator (696 to 730 ppm trifoliolate leaf Zn, 5 cultivars), normal (549 to 675 ppm Zn, 11 cultivars), and excluder (389 to 540 ppm Zn, 4 cultivars). Soil Zn additions significantly increased root and foliar Mn contents to reported phytotoxic levels at both pH 5.5 and 6.5, but did not influence DTPA‐TEA extractable soil Mn. Significant cultivar differences in root and leaf Mn contents were observed. The results of this work illustrate the importance of cultivar selection, not only for field planting of Zn‐enriched soils, but also for its influence on experimental results.
Effects of Sulfur‐coated Urea on California Annual Grassland Yield and Chemical Composition1
Authors: Vaughn C. E. , Jones M. B. , Ruckman J. E.
Published: July 2010

Fall applications of N fertilizers on California annual grasslands are often accompanied by luxury N uptake, excessive N leaching losses, and N deficiencies the following spring. Sulfur‐coated urea (SCU), a slow‐release fertilizer, was applied to a grassland soil (Laughlin, fineloamy, mixed mesic, ultic haploxeroll) to determine whether it could supply adequate N and S and eliminate problems encountered with more soluble N fertilizers.

Urea (U), urea with 100‐mesh elemental S (U + S), and two formulations of SCU were broadcast on resident annual grassland, dominated by annual bromes (Bromus spp.), wild oat (Avena barbata) broadleaf filaree (Erodium botrys), and clover (Trifolium spp.), in a climate with cool, rainy winters and hot, dry summers. Forage ield and N and S uptake were measured seasonally in the 1st year and annually the following 5 years. Seasonal growth distribution was similar from all fertilizers in the 1st year. However, U + S was significantly more productive and gave greater herbage S uptake than the SCU's and U throughout the first growing season, and greater N uptake in the first winter.

Residual studies suggested the long‐term benefit of S fertilization; the U + S and SCU treatments were significantly more productive for the last 5 years. Residual N uptake responses were similar to the yields. Herbage S uptake was similar in the U and check treatments for the entire study. The more heavily coated SCU formulation gave greater S uptake than both U + S treatments in the 4th and 6th years after application.

It was concluded that the SCU's were of no greater benefit than urea combined with fine S in fertilizing California annual grasslands. The slow release of N from SCU did not give any greater apparent residual N response. There was a long‐term response to the larger particles of S in SCU, but it is questionable that this would justify the extra cost of the fertilizer.
Transector: An Inexpensive Device to Measure Ground Cover and Botanical Composition of Swards1
Authors: Andrade J. M. S. , Ocumpaugh W. R.
Published: July 2010

A need for an apparatus capable of simplifying the reading and recording of ground cover and botanical composition on 80 experimental grazing plots prompted the development and testing of the transector.

The objective of this manuscript is to describe how to construct and use the device to measure ground cover and/or botanical composition of grazed swards. The transector is a device that uses the line interception method, developed over 25 years ago, to simplify the logistics of pasture sampling and subsequent data analysis. The transector is a lightweight, simple, inexpensive device that is easily constructed and maintained. The only essential materials neded for the transector are two pieces of aluminum patio extrusion. This device makes it possible to take direct readings along a 5‐m long line without moving the transector. Since this device permits a direct reading along the line, it also simplifies the subsequent accumulation of the data for determining ground cover or botanical composition percentages.
Use of Slow‐Release N Fertilizers on Native Mixed Prairie1
Authors: Power J. F.
Published: July 2010

Although it is known that the native mixed prairie grasses will respond to N fertilization, little is known concerning the recovery and fate of different fertilizer N sources applied to this ecosystem. Possibly by using slow‐release N fertilizers, changes in stands of the different grass species could be controlled in a manner that would improve productivity. Consequently, a 4‐year field experiment was conducted at Mandan, North Dakota, to compare the effects of S‐coated urea and ureaformaldehyde with ammonium nitrate on production of mixed native prairie vegetation. In general, all fertilizers at all rates of application decreased Boulettoua gracilis (blue grama) density, while Agropyron smithii (western wheatgrass) density generally increased at rates above 56 kg N/ha annually. Dry matter production from all rates of N application was greatest for ammonium nitrate and least for ureaformaldehyde, with intermediate production for the S‐coated ureas. Fertilizer N recovery in harvested forage followed this same order. Assuming that about 100 kg fertilizer N was immobilized in grass roots, and that fertilizer N not accounted for in tops, roots, and soil inorganic N forms estimates gaseous losses, presumed gaseous losses varied from less than 10% of the amount of N applied as ammonium nitrate to about 60% for ureaformaldehyde. In general, the mixed prairie grasses used N from urea‐containing fertilizers less efficiently than that from ammonium nitrate.
Sulfur Nutrition of Rice. I. A Survey of Soils of South Sulawesi, Indonesia1
Authors: Blair Graeme J. , Mamaril C. P. , Pangerang Umar A. , Momuat E. O. , Momuat Christine
Published: July 2010

Rice (Oryza sativa L.) yields in South Sulawesi, Indonesia have declined in some areas despite the use of significant quantities of urea and triple superphosphate (TSP). Chlorotic plants were observed to be growing on these low‐yielding areas despite the application of N. A series of field trials were conducted to examine the S status of soils in the area.

In these experiments S was applied in various forms and yields were measured from unfertilized, NP, and NPS treatments at each of 28 sites. Responses in rice grain yield to applied S were measured at 18 sites. The magnitude of the responses ranged up to 278% with an average grain yield response over the 28 sites of 18.6%. The widespread nature of the responses in soils derived from varying parent material and in different river basins suggest that some 60 to 70% of the agricultural areas of the province is deficient in S.
Differential Mobility of Nitrapyrin and Ammonium in a Sandy Soil and Its Effect on Nitrapyrin Efficiency1
Authors: Rudert B. D. , Locascio S. J.
Published: July 2010

Nitrification inhibition by 2‐chloro‐6‐(trichloromethyl) pyridine (nitrapyrin) has not been consistent on sandy soils. This study was conducted to evaluate movement of nitrapyrin and N in a fine sand as influenced by water rate and leaching period. In greenhouse studies, nitrapyrin reduced NO8‐N loss from a Kanapaha fine sand (loamy, siliceous, hyperthermic Grossarenic Paleaquult) for only the first 2 weeks of a 5‐week leaching period. In segmented soil columns, nitrapyrin was placed in the soil at a depth from 13 to 15.5 cm. After the soil was leached at water rates of 0, 2.5, and 5 cm/week for 2 and 4 weeks, soil samples were incubated with NH4‐N. Nitrification bioassay of soil above and below nitrapyrin placement showed that nitrapyrin movement was affected more by volatility than by water rate. Movement of NH4‐N from a 13.0 to 15 cm depth was studied in soil columnsthat contained 20 ppm nitrapyrin in the soil. After leaching, NH4‐N and NO3‐N levels were determined at various soil depths. With increases in the rate of water applied and in the leaching period, higher levels of NH4‐N moved to lower depths than nitrapyrin. Movement of NH4‐N away from nitrapyrin may account for the reduced nitrapyrin effectiveness often observed for sandy soils.
Compensatory Growth of Tall Fescue Following Drought1
Authors: Horst G. L. , Nelson C. J.
Published: July 2010

Enhancement of growth following short periods of drought stress has been reported in several crop species. If such enhancement follows summer drought‐stress of cool‐season forage grasses, the increased yield from summer irrigation may be offset partially by compensatory growth during fall. Therefore, a 3 year field study was conducted to compare growth responses of tall fescue (Festuca arundinacea Schreb.) grown with and without supplemental irrigation from June through August. Soil was Mexico silt loam (Udollic Ochraqualf) and fertilizer was applied in spring and following each cutting. Plots were harvested six times in 1971, five times in 1972, and four times in 1973. A residual harvest was made on 21 May 1974.

During summer the plants that were irrigated had greater forage yields, greater tiller density, greater weight per tiller, higher leaf elongation rates, and higher concentration of water‐soluble carbohydrates (WSC) in leaf tissue as compared with plants that were water‐stressed. Concentration of WSC in stem bases during summer was higher in the water‐stressed plants. Fall growth of plants that had been water‐stressed during summer was greater than that of those that had been irrigated. The enhancement of growth or compensatory effect was associated with higher concentration of WSC in stem bases during late summer, and faster leaf elongation and greater weight per tiller during fall of the previously water‐stressed plants as compared with the summer‐irrigated plants.

Compensatory growth following drought stress was still evident the following spring, as indicated by the higher tiller density and greater forage yield. However, the collective compensatory yield of the water‐stressed plants during fall and spring was not great enough to compensate for lower yields during summer. In the third year of the study normal rainfall during summer was higher than duing the first 2 years, and no compensatory growth was noted during fall or the following spring.

During the 3‐year study, total yield for the irrigated treatments was 4% larger than that for the water‐stressed treatment. The major response to irrigation was a shift in season of production. Management and breeding objectives should consider the effect of summer irrigation or summer drought on the subsequent performance of cool‐season forage grasses.
Effects of Stage of Maturity on P and S Critical Levels in Subterranean Clover1
Authors: Drlica D. M. , Jackson T. L.
Published: July 2010

Subterranean clover is widely used for pastures in western Oregon; however, little information is available on the effects of stage of maturity on P and S critical levels. The response to P and S fertilization, nutrient contents at different sampling dates, and total yields at harvest were evaluated at two locations in Oregon. The soil at one location is mapped as a complex of Oakland and Nonpareil series, which are well‐drained, hillslope soils developed from sedimentary rock. The soil at the second location is a Veneta silt loam, a moderately well‐drained soil formed from old mixed alluvium. On both sites, the P concentration of the mixed grass and clover forage at harvest was higher in plants that had received P fertilization (0.20%) than in plants that had not (0.14%). The concentration of P in the clover component remained relatively stable from mid‐March to mid‐April in both fertilized and unfertilized treatments. The critical level of P for subterranean clover leaflets and petioles collected between mid‐March and mid‐April was approximately 0.25% P. Sulfur fertilization increased yield 45% and more than doubled S concentration of mixed forage. Added S increased S concentrations in the clover at every sampling date. Sulfur concentrations were relatively constant from mid March to mid‐April, and approximately 0.20% S was identified as the critical level for clover samples collected during this time.
Soybean Yield, Leaf Manganese, and Soil Manganese as Affected by Sources and Rates of Manganese and Soil pH1
Authors: Shuman L. M. , Boswell F. C. , Ohki K. , Parker M. B. , Wilson D. O.
Published: July 2010

Manganese deficiencies in soybeans [Gycine max (L.) Merr.] grown on certain southern Coastal Plain soils of southeastern USA have required that supplemental Mn be applied to obtain maximum yields. The objective of this experiment was to determine sources and rates of Mn needed for optimum yields at two soil pH levels. Soybeans (‘Ransom’) were grown for three years on an Olustee‐Leefield sand (Ultic Haplaquod‐Arenic Plinthaquic Paleudult) with Mn sulfate, manganous oxide, and fritted Mn as sources at 0, 5.6, 11.2, and 22.4 kg/ha rates. Chelated Mn as MnEDTA was used at one‐tenth the rate of the others. Treatments were evaluated by leaf and soil analysis and grain yields.

The Mn sulfate, manganous oxide, and fritted Mn were all satisfactory sources and produced relatively high yields. The Mn chelate did not increak yields above the check, except at the highest rate the final year at the higher pH level. Leaf and soil Mn were increased by the sources in the following order: Mn sulfate > Mn oxide > Mn frit > Mn chelate. The rate of Mn from the Mn sulfate and manganous oxide sources that produced optimum yields was 11.2 kg Mn/ha in the final year where soil pH values were 6.9 and Mn was severely deficient on check plots. The frit source may need higher rates to be equal to the other two source since increased yields were observed at the 22.4 kg %/ha rate for frit.
Relay Intercropping Soybeans into Winter Wheat and Spring Oats1
Authors: Chan L. M. , Johnson R. R. , Brown C. M.
Published: July 2010

Relay intercropping of soybeans [Glycine max (L.) Merr.] into small grains might allow the two‐crops‐in‐1 year concept to be moved further northward in the U.S. Corn Belt. The small grain crops in such a system might also provide protection against soil erosion on sloping soils currently in conventional soybean production. The objective of this study was to compare monoculture oat (Avena saliva L.), wheat (Triticum aestivum L.), and soybean yields with soybeans relay intercropped into spring oats or winter wheat. Variables considered included small grain and soybean row widths, soybean planting date, and soybean cultivar. Field experiments were conducted on Typic Haploquoll and Typic Argiudoll soils in central Illinois.

Interseeding soybeans into small grains did not affect small grain yields. In three of four environments tested, small grain yields in rows 41, 61, and 81‐cm wide averaged yields of 91, 72, and 58%, respectively, of small grains in 21‐cm row widths. In a fourth experiment, where winter wheat rows wider than 21‐cm were created by spring removal of intervening rows, yield reductions were greater than for those planted in wider rows. Monoculture soybeans produced significantly higher yields and taller plants than intercropped soybeans. Reduced growth of intercropped soybeans, especially in narrow rows, was associated with below normal precipitation during both years of experimentation. Soybeans intercropped between 41 and 61‐cm small grain rows yielded between 7 and 93% of monoculture soybeans grown in similar row widths. Soybeans aerially seeded into small grain stands failed to establish a stand, but soybeans conventionally placed in the soil produced acceptable stands. A short determinate soybean cultivar did not appear to withstand early season stress associated with intercropping as well as a tall indeterminate cultivar. In years with normal early season precipitation, successful relay intercropping of soybeans into small grains should be possible.
Influence of Soil Moisture on Soil Solution Cation Concentrations and the Tetany Potential of Wheat Forage1
Authors: Karlen D. L. , Ellis R. , Whitney D. A. , Grunes D. L.
Published: July 2010

Outbreaks of grass tetany occur more frequently when cattle are grazing coolseason forages growing on soils that are nearly water saturated. Therefore, we conducted two experiments to study the interaction between soil moisture, cation availability, and cation uptake by winter wheat (Triticum aestivum). Equilibrium soil solution was extracted from three soil types and analyzed for K, Ca, and Mg concentrations. Wheat was then grown in growth chambers on these soils under wet (partially saturated) and dry (below field capacity) moisture regimes to determine if changes found in the cation concentrations in the equilibrium soil solution would be reflected in the cation composition of the wheat. The potential for outbreaks of grass tetany in cattle consuming the forage was estimated from the equivalent ratio K/(Ca + Mg).

Soil solution K, Ca, and Mg concentrations increased as the soil water content decreased from approximately 40 to 10 volume percent. Changes in cation concentraions were nonproportional as predicted by the principles of thermodynamics. Potassium concentrations did not change as much as the Ca and Mg concentrations as the soil water content decreased. The K/(Ca + Mg) molar ratio in the extracted soil solution and the equivalent ratio in the wheat forage showed similar changes as soil water content increased in both experiments. These studies showed that, in addition to the effects of increased soil water content on aeration and ion transport mechanisms, changes in cation concentrations in the soil solution may influence the composition of wheat forage and thus increase its potential for inducing grass tetany in grazing cattle.
Precautions on the Use of Anhydrous Ammonia Applicators in Research Plots1
Authors: Moraghan J. T.
Published: July 2010

Use of anhydrous NH3 presents certain difficulties not encountered in research involving solid fertilizers. Little information is available concerning the problem of obtaining uniformity of distribution of anhydrous NH3 among injection blades of applicators used in field‐research studies. The influence of orifice size, and flow‐equalizer manifold sleeves on distribution of different NH3 flows from a pressure‐regulator device (John Blue Nitrolator) by a radial manifold was investigated. The work was done with four and seven‐blade applicators with blade spacings of 76 and 30.5 cm, respectively, by collecting released NH3 in water. Variability in distribution was affected by choice of manifold outlet, orifice size, and NH3‐flow rates. Particularly high variability was generally encountered with excessively low, <0.35 kg/ cm2, and excessively high, >3.5 kg/cm2, manifold pressures. Optimal performance for commonly used fertilizer rates was obtained with 0.635 and 0.119‐cm orifices for the four and seven‐blade units, respectively. Uniform spacing of manifold outlets around a radial manifold was efficacious. Some problems commonly encountered when using anhydrous NH3 in experimental work are described and discussed. Researchers using anhydrous NH3 should calibrate applicators for both total quantity of NH3 applied per unit area and uniformity of distribution among injection units.
Portable System for Overhead Irrigation of Small Plots1
Authors: Heatherly Larry G. , Ginn L. H.
Published: July 2010

A tractor‐mounted apparatus designed for overhead irrigation of small plots has been constructed with 1.9‐cm diam. thin‐walled electrical conduit. The 3OO‐cm long assembly has ten 1.3‐cm diam. polyvinyl chloride lateral water lines clamped across the 200‐cm width of the framework. Water is supplied to the apparatus by a power‐take‐off pump from a front‐mounted tank on the tractor and is forced through 0.3‐cm diam. holes spaced 15 cm apart on the bottoms of each of the 10 water lines. The front‐mounted tank is graduated in 75‐liter increments and allows water to be applied to a 300 ✕ 200‐cm surface area in multiples of 1.25 cm. An in‐line pressure regulator is used to vary rate of water application. The system, which can be easily dismounted from the tractor, can irrigate 8 to 15 four‐row plots 6 m in length per day, depending on both rate and amount of water applied to individual plots.
Dry Matter Accumulation, Mineral Concentrations, and Nutrient Distribution in Winter Wheat1
Authors: Karlen D. L. , Whitney D. A.
Published: July 2010

Asbtract

Few studies measuring dry matter accumulation and nutrient distribution in hard red winter wheat (Triticum aestivum L.) over the life cycle of the plant have been reported. Therefore, we established an experiment to study the growth and development pattern of ‘Centurk’ wheat in eastern Kansas and to measure changes in the N, P, K, Ca, Mg, Cu, Mn, and Zn concentrations in various plant parts collected throughout the growing season. Total dry matter accumulation was measured by collecting all above ground plant material. Plant samples were fractionated into living leaves, senescing leaves, stems, heads, head parts, grain, and crowns which were dried, ground, wet‐digested, and analyzed. Regression analyses were computed to identify significant trends. Total dry matter accumulation averaged 0.8 metric tons/ha in the fall, and reached a maximum of 13.0 metric tons/ha at physiological maturity. Nitrogen, P, K, Ca, and Cu concentrations in whole plant samples collected during the fall decreased gradually, while Mg and Zn concentrations remained relatively constant. The S and Mn concentrations were extremely variable and showed no significant statistical trends. Nitrogen, P, K, Ca, Cu, Mn, and Zn concentrations decreased in whole plants as they approached physiological maturity. Magnesium concentrations were relatively constant at approximately 0.18% during the spring. Analysis of individual plant fractions showed nutrient changes similar to those found in the whole plant samples. Grain yields from these experiments were similar to those reported for ‘Centurk’ wheat in performance trials. We feel that this information is useful in identifying the pattern of dry matter accumulation and in illustrating changes in nutrient concentrations during the life cycle of hard red winter wheat.
Response of Arrowleaf Clover to Postemergence Herbicides1
Authors: Conrad J. D. , Stritzke J. F.
Published: July 2010

Presently there are no herbicides cleared for weed control in arrowleaf clover (Trifolium vesiculosum Savi.) a proven legume for pasture mixtures in the sunbelt. The objective of the study was to determine the selectiveness of 2,4‐DB [4‐(2,4dichlorophenoxy)butyric acid], 2,4‐D [ (24dichlorophenoxy)acetic acid], bromoxynil [3,5dibromo‐4‐hydroxbenzonitrile], MCPA [((4‐chloro‐o‐to1yl)oxy) acetic acid], and dicamba [3,6dichloro‐oanistic acid] for the control of various broadleaf weeds in arrowleaf clover. Field studies were conducted at three locations. Soil classification for these location are: Aquic Paleudolls for location I, Ultic Haplustalfs for location II, and Mollis Albaqualfs for location III. At all three locations the herbicides were applied postemergence to actively growing arrowleaf plants (5 to 15 cm in height) in late March or early April. Visual damage to arrowleaf clover and weeds was estimated after several weeks. Forage production from the various treatments was determined from June samplings and seed production of arrowleaf was determined from July samplings. Of the herbicides evaluated, 2,4DB at 0.56 kg/ha was consistently selective to arrowleaf clover and adequately controlled the broadleaf weeds including seed stalk formation of curly dock (Rumex crispus L.). MCPA at 0.56 kg/ha also controlled the broadleaf weeds but was not consistently selective on arrowleaf clover. The 0.56 kg/ha rate of 2,4‐D also controlled the broadleaf weeds and significantly reduced the forage production of arrowleaf clover. Seed production with the 2,4‐D treatment (0.56 kg/ha rate) was not suppressed as much as forage production and the decrease was only significant at one location. A combination of 2,4D and banvel (0.42 and 0.14 kg/ha respectively) severely damaged the arrowleaf and could be used as a treatment to control arrowleaf clover.
Preemergence Weed Control in Seeded Bermudagrass Stands1
Authors: Fermanian T. W. , Huffine W. W. , Morrison R. D.
Published: July 2010

Weed competition is a major cause of poor bermudagrass (Cynodon dactylon (L.) Pers.). stands established from seed. Two separate experiments were undertaken to find a selective preemergence herbicide to minimize weed competition when establishing bermudagrass from seed. In a greenhouse experiment, four preemergence herbicides, each at four rates were applied to three bermudagrass hybrids in two soil types, a Kirkland silt loam (Thermis Uderic Paleustoll), and a Doughtery loamy sand (Thermic Arenic Hoslustalf). After 3 weeks the germinated and growing seedlings were counted. A highway cut slope was the site of the field experiment which consisted of two Preemergence herbicides (terbutryn and metribuzin) applied to four, seeded, bermudagrass strains. Phytotoxic effects of the herbicides on emergence of the bermudagrass and estimates of weed populations were made at 30‐day intervals.

Analyses of the greenhouse data indicated metribuzin and terbutryn were relatively non‐toxic to bermudagrass. Oxadiazon and siduron were highly toxic, and eliminated from further consideration. No significant differences were found among rates for any of the herbicides. The bermudagrass cross, Guymon × 10978, had significantly greater germination than the other bermudagrass with optimum germination observed in a Kirkland silt loam soil. Common bermudagrass germinated the quickest and provided the most dense cover of all bermudagrass types used in the field experiment. Greater weed control was obtained with terbutryn than metribuzin. The application of terbutryn at 2.71 kg/ha was the most toxic treatment to the bermudagrass. Terbutryn at 1.36 kg/ha provided good weed control at an acceptable level of toxicity.
Differential Tolerance of Weeping Lovegrass Genotypes to Acid Coal Mine Spoils1
Authors: Foy C. D. , Voigt P. W. , Schwartz J. W.
Published: July 2010

Plant genotypes having greater tolerance to mineral stress are needed for use on problem soils. Two examples of such stress are mineral element toxicity (excess Al, Mn, etc.) in strongly acid soils and mine spoils, and Fe‐related chlorosis in certain calcareous soils. Previous studies showed that genotypes of weeping lovegrass (Eragrostis curvula (Schrad.) (Nees) and Lehmann lovegrass (Eragrostis lehmanniana Nees) different widely in their susceptibilities to an Fe‐related chlorosis on calcareous soils. Preliminary observations suggested that certain genotypes also differed in tolerance to acid mine spoils. To test this hypothesis more precisely, 16 genotypes of weeping lovegrass were grown in greenhouse pots of a Pound, Va., coal mine spoil adjusted to pH 3.5 and 4.7 with CaCO3, and in a Beckley, W.Va., spoil having a natural pH of 4.3.

Weeping lovegrass genotypes differed significantly in tolerance to the strongly acid mine spoils. For example, in one experiment the relative top yields (pH 3.5/pH 4.7%) varied from 20.8 to 0%. In certain genotypes, tolerance to acid mine spoil coincided with susceptibility to chlorosis on calcareous soils. For example, Morpa, Beltsville Native, NPMC Hill Culture, and common genotypes were among the most tolerant to the acid mine spoil at pH 3.5, but these were among the most susceptible to chlorosis on calcareous soil at pH 7.8. Conversely, the genotypes FQ 22, FQ 150, FQ 7, and FQ 14 died on the spoil at pH 3.5, but were among the most resistant to chlorosis on calcareous soil. No genotype tested was well adapted to both acid mine spoil at pH 3.5 and calcareous soil at pH 7.8. However, most genotypes studied made reasonable growth on mine spoils of pH 4.3 and 4.7. Results indicated that two commercially available cultivars, Morpa and common, were among the most tolerant tested on mine spoil at pH 3.5; hence, additional genetic diversity will be required to improve acid soil tolerance.

Plant toxicities produced in the acid mine spoils studied were tentatively attributed to interference by Al and Fe in the uptake and use of Ca and P.
Nitrogen Fertilization of Meadowfoam1
Authors: Johnson J. W. , Devine M. B. , Kleiman R. , White G. A.
Published: July 2010

Limnanthes alba Benth. is a potential oil seed crop with unique long chain fatty acids. Information available on the fertility needs for meadowfoam is scarce. Therefore the effects of rate and time of application of N fertilization on seed yield, seed weight, protein, oil, winter survival, flowering date, plant height, and erectness of meadowfoam were studied in the field for 2 years in Maryland. Nitrogen as ammonium nitrate was applied on plots of two plant introductions at the rates of 0, 45, and 90 kg/ha in the fall (planting) or early spring. In 1976, N was also applied in both fall and spring

The seed yield of meadowfoam was decreased as much as 24% with the addition of 90 kg N/ha. Seed yield was linearly related to N application. For each 10 kg/ha applied, the seed yield decreased approximately 3%. The time of N application had no significant effect on seed yield. Seed weight was not affected by rate or time of N application. The protein content of the seed was directly related to the rate of N applied with an increase of 1 and 30%, for each 10 kg N/ha in PI 374790 and 374800, respectively. The combined fall and spring application of N resulted in a 5 and 10% increase in the protein content over the individual fall and spring application, respectively. The addition of 90 kg N/ha resulted in a 12% average reduction in the oil content of the seeds. The time of N application did not affect the oil content for either year. The correlation between seed weight and oil content was positive, r = 0.92 (at the 0.01 level). Increasing N fertilization resulted in significant decrease in seed yield and oil content but an increase in protein content.
Summer Regrowth of Tall Fescue: Stubble Characteristics and Microenvironment1
Authors: Stringer W. C. , Wolf D. D. , Blaser R. E.
Published: July 2010

Stand thinning has been observed when N‐fertilized cool‐season grasses are harvested in late spring. These losses appear to be greater when hot, clear weather follows a harvest. Earlier spring cuts appear to ameliorate the stress. This 2‐year investigation examined effects of spring N at 50 and 160 kg/ha; and spring cutting (biweekly, monthly, and zero spring cuts) to 5 and 10 cm stubbles on regrowth of tall fescue (Festuca arundinacea Schreb.). Stubble canopy structure, microenvironment, and stand regrowth were examined following a June harvest at which all plots were moved at their respective cutting heights (save an unharvested check).

The high N rate caused greater forage yields to be present at the June harvest. Stubble leaf area index (LAI), vegetative tiller density, and live stubble yields were not affected by N rate. Cutting during spring increased tiller density and LAI. Cutting managements had significant effects on the stubble temperafure and soil temperature that were associated negatively with stubble LA1 and tiller density. There was no detrimental effect of cutting management or N rate on stand recovery except in 1975 when lodged areas of spring accumulated swards with high N fertilization had poor regrowth. Stand losses in these area was associated with only 3 to 4% noncarbohydrates (TNC) in the stubble. Lodging is hypothesized to be partially responsible for stand losses in dense stands through detrimental effects on TNC storage and other unknown effects.
Spatial Responses of Contrasting Cotton Cultivars Grown Under Semiarid Conditions1
Authors: Bilbro J. D.
Published: July 2010

The southern Great Plains of Texas, New Mexico, and Oklahoma is the largest nonirrigated, semiarid cotton (Gossypiunz hirsutum L.) production area in the world. To determine if plant spacing is an important factor in crop performance under nonirrigated, semiarid conditions, a 5‐year study was conducted at Lubbock, Texas, on the effects of 5‐, 10‐, 15‐, 20‐, and 25‐cm spacings within rows 1 m apart on seven characters (lint yield, lint percentage, bolls/plant, boll size, 2.5% span length of fiber, fiber strength, and coarseness). The soil was fine‐loamy, mixed thermic Aridic Paleustalf or Paleustoll. Two cultivars, ‘ Paymaster 111’ and ‘ Stripper 31’ were used.

Differences among years were significant for all characters and were larger than differences between cultivars or among spacings. Year X cultivar, and year X spacing interactions were significant for most characters, but the cultivar X spacing interaction was significant only for bolls/plant. The second‐order interaction was significant for only fiber coarseness. The two cultivars differed significantly for all characters except lint yield and lint percentage. Paymaster 111 produced larger bolls and longer, stronger fiber; whereas, Stripper 31 had more bolls/plant and coarser lint. Spacing affected every character, except fiber strength, in at least 1 year. Regression analyses of lint yield‐spacing relationship indicated that spacings of about 16 to 19 cm were optimum in the years when yields were near average (250 to 300 kg/ha). When yields were much above average (over 600 kg/ha), the 5cm spacing was superior. In the year when yields were much below average (less than 100 kg/ha), there was no significant yield‐spacing relationship. Spacing had no significant effect on fiber strength in any year. Bolls/plant increased linearly as spacing was increased. The effects of spacing on lint percentage, fiber length, and micronaire were not consistent. The 5‐cm spacing produced the smallest bolls.

The overall results indicate that under dryland conditions in the southern Great Plains, the optimum within‐the‐row spacing of cotton plants is probably about 17 cm if the distance between rows is 1 m.
Maize Culture in Reed Canarygrass Sod to Renovate Municipal Wastewater Effluent1
Authors: Marten G. C. , Linden D. R. , Larson W. E. , Clapp C. E.
Published: July 2010

Field conditions that accompany conventional maize (Zea mays L.) culture may not permit adequate infiltration of wastewater effluent needed for optimum yields. Two experiments with randomized complete block designs were conducted over a 3‐year period on effluenttreated soils to assess the effects of suppressing reed canarygrass (Phalaris arundenacea L.) with several types and rates of herbicides on (a) yields of interplanted maize grain and fodder; (b) total crop yields and N removal by maize‐reed canarygrass combinations; (c) feed quality of interplanted maize; (d) water infiltration capacity of the Typic Hapludoll soil; and (e) the N concentration in the soil water at the bottom of the root zone (just above the water table).

Herbicidal suppression of 60% of the reed canarygrass was necessary to obtain maximum grain and fodder yields of the interplanted maize. This degree of suppression was achieved consistently by glyphosate (N‐(phosphonomethy1) glycine) applied at 0.56 kg AI/ha. This treatment holds most promise for use in the type of culture system outlined because: 1) This was the only treatment that suppressed at least 60y0 of the reed canarygrass without completely killing it, 2) The soil under this treatment was capable of sustained infiltration rates of 1.7 cm/hr to prevent the ponding that occurred in killed grass sods, 3) One application of glyphosate was effective over a 2‐year penod. Annually‐applied paraquat (1,l'‐dimethyl‐ 4,4'‐bipyridinium dichloride) at 0.56 kg AI/ha also provided satisfactory (but sometimes lower) yields of maize interplanted in reed canarygrass.

Total N removal by maize‐reed canarygrass combinations was maximum when the grass was not suppressed by herbicides. This was due to the superior capacity of reed canarygrass compared to maize to remove N from effluent‐treated soils. The N concentration in the soil water also reflected N removal by the combined crops, in that minimum soil water N occurred when N removal by the crops was maximum. An effluent‐renovation croping system in which maize is interplanted in herbicide unsuppressed reed canarygrass will remove more N but could lead to much lower maize yields than a system where the grass is suppressed.

Feed quality of maize ears or fodder was not influenced by degree of reed canarygrass suppression, except for two occasions where the crude protein concentration of fodder and/or ears was reduced, and one occasion where the fodder digestibility was increased, when the grass herbicide‐suppressed or was partly suppressed.
Nitrapyrin and Etradiazole Effects on Nitrification and Grain Sorghum Production1
Authors: Westerman R. L. , Edlund M. G. , Minter D. L.
Published: July 2010

Nitrification inhibitors offer the potential to improve efficiency of N applications when climatic and soil conditions are favorable for leaching and/or denitrification.

Grain sorghum [Sorghum bicolor (L.) Moench] was grown in five field experiments at three locations during 1976, 1977, 1978, and 1979, with two nitrification inhibitors and three N sources. Four of these five experiments received supplemental irrigation water. Soil textures at experimental locations were sandy, silt, and clay loams and pH's ranged from 5.2 to 7.8. Nitrification inhibitors evaluated were nitrapyrin and etradiazole. Sources of N were anhydrous ammonia and urea in 1976, urea and urea‐ammonium‐nitrate (UAN) solution in 1977, and UAN hi 1978 and 1979. Treatments consisted of 0.56 kg/ ha of nitrapyrin and multiple rates of etradiazole applied with varying rates of N. Soil samples were taken from selected experiments at varying time intervals and analyzed for urea‐, NH4+−, NO3−, and/or NO3−‐N depending on the year and experiment. Field plots were harvested with a conventional combine and yields were analyzed statistically to assess beneficial effects of treatments.

Soil N forms were altered by nitrification inhibitors at various tune intervals during the growing seasons. However, the changes observed did not lead to increased efficiency of applied N or to an increase in yield of grain sorghum. It was concluded that little if any benefit can be derived from nitrification inhibitors in grain sorghum production in Oklahoma.
Response of Determinate and Indeterminate Soybeans to varying Cultural Practices in the Northern USA1
Authors: Beaver J. S. , Johnson R. R.
Published: July 2010

Determinate soybean [Glycine max (L.) Merr.] cultivars adapted to the northern U.S. soybean growing region have been developed and released in recent years. The purpose of this research was to compare the response of determinate and indeterminate soybean cultivars to varying cultural practices. The determinate cultivars, ‘Gnome’ and ‘Elf’, and the indeterminate cultivars, ‘Beeson’ and ‘Williams’, were grown at two Illiiois locations in planting dates ranging from early May to early July. The soil was Flanagan silt loam (Acquic Argiudoll) at Urbana and Cisne silt loam (Mollis Albaqualf) at Brownstown. Within each planting date, cultivars were planted in 80, 50, and 20 cm row widths. A separate seeding rate study was conducted with the determinate cultivar Elf, using seeding rates of 350,000, 500,000, and 650,000 seeds/ha in both 76 and 20 cm row widths.

Planting date contributed most to variation in seed yield. Seed yield in central Illinois decreased an average of 33% as planting date was delayed from early May to early July. Seed yield of the indeterminate cultivars declined steadily after the early May planting date, whereas, seed yield of the determinate cultivars did not decrease until planting date was delayed past early June. The indeterminate cultivars showed a linear decline in plant height and main stem node number as planting date was delayed, whereas, plant height and main stem node number of the determinate cultivars were greatest in early June plantings. Lowest pod height of the determinate cultivars planted after mid‐June or in drought‐prone soils was sufficiently close to the soil surface (less than 10 cm) to cause concern about excessive harvest losses. Seed yields of both the determinate and indeterminate cultivars increased significantly (9 and 5% at Urbana and Brownstown, respectively) as row widths were narrowed from 80 to 50 cm, whereas, seed yields in 50 and 20 cm row widths did not differ.

The determinate cultivar Elf exhibited the ability to perform well over plant densities at harvest ranging from 279,000 to 494,000 plants/ha. A seeding rate of 400,000 to 500,000 seeds/ha for determinate cultivars appears sufficient to maximize seed yield, reduce potential harvest losses due to low basal pod height, and insure adequate and uniform stands in unfavorable seedbeds.
Forage Quality Response of Four Lovegrasses to Stage, Interval, and Season of Harvest1
Authors: Voigt P. W. , Horn F. P. , Dewald C. L.
Published: July 2010

Despite the importance of weeping lovegrass, Eragrostis curvula (Schrad.) Nees, in Argentina, South Africa, and to a lesser extent in the United States, much remains to be learned about its forage quality. The objectives of this research were to evaluate: a) forage quality of four weeping lovegrass entries, b) seasonal patterns of forage quality, and c) effect of stage of first growth and age of regrowth on forage quality.

Field experiments were conducted on an Enterprise loam (Thermic Typic Ustochrepts) soil at Woodward, Oklahoma. ‘Morpa’, ‘Ermelo’, common, and 673 were harvested under three managements: a) jointing stage and four subsequent 28‐day intervals, b) heading stage and three subsequent 34day intervals, and c) anthesis stage and two subsequent 45‐day intervals. In vitro dry matter disappearance (IVDMD), crude protein, cell contents (CC), hemicellulose, cellulose, and permanganate lignin (PL) were determined. Results were analyzed by ANOVA and regression procedures.

Morpa and Ermelo were similar and higher in IVDMD than common and 673. This higher IVDMD was correlated with lower PL and dry matter contents. Maturity differences among entries did not account for all entry variability in forage quality. Nongenetic correlation coefficients showed that high IVDMD was associated with high crude protein and CC and low cellulose, PL, and dry matter. Seasonal trends in forage quality showed that from jointing to anthesis IVDMD declined 0.46 percentage units per day. Following the initial harvests, IVDMD continued to decline at 0.02 percentage units per day during the remainder of the summer, despite equal interval regrowth harvests. Similar patterns were found for crude protein and CC. Hemicellulose also decreased from jointing to anthesis but then increased during regrowth harvests. Cellulose and PL increased from jointing to anthesis, but showed only small seasonal changes during regrowth harvests. Increasing age of regrowth resulted in lower IVDMD (—0.28 percentage units per day), crude protein, and CC, and higher cellulose and PL. However, changes were more gradual than from joint to anthesis.
Equipment to Mix Chemical Additives with Anhydrous Ammonia during Application to Soil1
Authors: Huber D. M. , Karamesines P. D. , Warren H. L. , Nelson D. W.
Published: July 2010

Etridiazole (5‐ethoxy‐3‐trichloromethyl‐1,2‐4‐triadozole) effectively reduces leaching and denitrification losses of ammoniacal N by inhibiting nitrification; however, it is not soluble or stable in anhydrous ammonia (NH3). Many other potentially beneficial agricultural chemicals are not soluble in or compatible with NH3. To overcome the need for a separate application of some nitrification inhibitors, trace elements, and plant growth regulators, a simple device was constructed to facilitate the simultaneous application of low volume solutions with NH3. This device consists of an adjustable positive displacement pump operated off the tractor electrical system and a black iron injection pipe positioned between the N flow regulator and distributor (NH3 manifold). The additive is carried from its reservoir to the pump and from the pump to the injection pipe in Tygon or plastic NH3 discharge hose. In this arrangement, potentially corrosive additives bypass expensive valves and flow devices, and are mixed in the NH3 stream just prior to injection into soil. Advantages include direct placement of the chemical additive with NH3, reliability, adaptability to most existing field equipment, simple design, and ability to partially treat a field. This equipment was tested by adding nitrapyrin [2‐chloro‐6‐(trichloromethyl)pyridine] and etridiazole (nitrification inhibitors) to the NH3 stream and measuring the total recovery of materials and their distribution between several applcator knives. Recovery of the inhibitors was 96 to 100% with distribution between knives on the applicator ± 7.7%. Simultaneous application of these nitrification inhibitors with NH3 applied to field soil cropped to wheat (Triticum aestivum L.) demonstrated the effectiveness of the equipment in adding the nitrification inhibitors to NH3.