bluuebunny/crossref_metadata_2025 huggingface dataset:
Management of Irrigated Soybeans on a Moderately Coarse‐textured Soil in the Upper Midwest1
Authors: Cassel D. K. , Bauer Armand , Whited D. A.
Published: July 2010

Increased availability of water for supplemental irrigation in the upper Midwest has enhanced an interest in growing soybeans [Glycine max (L.) Merr.] on moderately coarse‐textured soils where they have not previously been introduced. The objectives of this study were to determine the yield potential of supplementally irrigated soybeans on these soils and to develop an irrigation schedule for efficient water management. The study, conducted on Maddock sandy loam from 1972 to 1974, employed a splitsplit plot design with water level as the main block and N fertility rates (0, 56, 112, and 224 kg/ha) as sub‐plots. Water levels were Wl (dryland), W2 (under‐irrigation), W3 (optimum) and W4 (over‐irrigation). Sub‐sub plots were planting dates in 1972 and cultivars in 1973 and 1974. Soil samples were collected from 15 to 30 cm intervals to depths of 90, 150, or 270 cm throughout the study and analyzed for NO3‐N in the soil profile under irrigated conditions. Grain yields were significantly different for water levels during each of the 3 years. Threeyear yield means were 543, 1,823, 2,428, and 2,164 kg/ha for Wl, W2, W3 and W4, respectively. The application of 24 kg/ha N fertilizer in 1972 increased grain yield at the 0.95 probability level. The seed was not inoculated that year but was inoculated in 1973 and 1974. Soybeans planted 10 May 1972, outyielded soybeans planted 6 June by 356 kg/ha. ‘Anoka’ outyielded the ‘SRF‐100’ cultivar by 137 kg/ha in both 1973 and 1974. An irrigation schedule based upon tensiometers placed at the 30 cm depth until 15 July (growth stage R2) and at the 45 cm depth after 15 July proved effective in applying irrigation water. Analysis of NO3‐N in the soil profile at different dates during the 3‐year period showed that under heavy fertilizer NO3‐N applications, the NO3‐N moved below the crop rooting zone when excess water was applied. Based upon results of this study, soybeans can be seriously considered as a crop to be included in cropping systems for irrigated, moderately coarse‐textured soils in the Upper Midwest.
Wheat Seed Germination under Low Temperature and Moisture Stress1
Authors: Ashraf C. M. , Abu‐Shakra S.
Published: July 2010

Cultivate differ inherently in their response towards drought. Only those adapted to arid and semiarid conditions become established into uniform and vigorous stands during germination under moisture stress and suboptimal temperature. Seed germination of four wheat cultivars, ‘Najah’ and ‘Mexi‐pak’ (Triticum aestivum L.), and ‘Hurani’ and ‘Jori’ (Triticum durum L.), were compared under suboptimal temperatures and various levels of simulated moisture stress. Components of water uptake, germination percentage, speed of germination, root growth, respiration rate, and germination recovery from stress were measured. The rate of water uptake decreased and the time required for germination increased when the seeds were incubated at 6 atm and higher. Seeds of the four cultivars germinated when their moisture content was approximately 50% on a fresh weight basis. Total germination was not affected by moisture stress levels up to 12 atm but was significantly reduced at 15 and 18 atm osmotic tensions. Rate of root growth, speed of germination, and respiration rates were inversely related to moisture stress. Low moisture stress (3 atm) did not inhibit root growth. Significant differences were found among cultivars in the parameters studied. Perforating the pericarps did not eliminate the differences in water uptake and respiration rates between cultivars. Prolonged exposure of ungerminated seed to high osmotic tensions at low temperatures showed high seed germination recovery. These data suggest that any of the germination criteria used can be effective in selecting droughtresistant cultivars.
Competitive Effects of Several Grass Species and Weeds on the Establishment of Birdsfoot Trefoil1
Authors: Laskey B. C. , Wakefield R. C.
Published: July 2010

Establishment of legume‐grass mixtures on highway rights‐of‐way is complicated by the requirement that seedings be made over an extended period as construction proceeds and erosion control become critical. Permanent seedings are frequently required during the late spring‐early summer period and the late summer‐early fall period when weather conditions are likely to be critical and competition from grasses and weeds may severely retard legume growth. Studies were conducted to determine the competitive effects of three grasses, perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), red fescue (Festuca rubra L.) and also weeds on establishment of birdsfoot trefoil (Lotus corniculatus L.) in the field at four times of the year, September, April, May and June. Plots were established on Enfield silt loam (mixed Typic Distrochrepts). Birdsfoot trefoil plant counts at the seedling and bloom stages showed that ryegrass was the most and red fescue the least competitive grass. Plant establishment of birdsfoot trefoil was significantly higher for the April seeding than for other seeding dates. Growth of birdsfoot trefoil was greater when seeded with Kentucky bluegrass or red fescue than when seeded with ryegrass. Weed competition reduced establishment of birdsfoot trefoil and growth of the legume at all seeding dates. When birdsfoot trefoil was grown alone, weeds produced more competing growth than grasses. However, grasses virtually eliminated weed growth. Reduced stands and yields of birdsfoot trefoil when grown with perennial ryegrass appeared to be due to rapid seedling emergence of the grass at a critical stage in the early growth and development of birdsfoot trefoil. The slower growing grasses, Kentucky bluegrass and red fescue, did not inhibit growth of birdsfoot trefoil since yields were comparable to the legume grown alone. An exception was the September seeding when winter‐killing severely depleted stands of birdsfoot trefoil grown alone.
Investigation and Treatment of Localized Dry Spots on Sand Golf Greens1
Authors: Wilkinson J. F. , Miller R. H.
Published: July 2010

Several experimental sand golf greens were seeded in 1972 to ‘Penncross’ creeping bentgrass (Agrostis palustris Huds.) in Columbus. Localized dry spots became serious problem during the summer of 1974. Despite heavy, frequent irrigation the soil remained hydrophobic, resulting in patches of dead or severely wilted turf. The turf and thatch would wet, but water would not penetrate the thatch/soil interface. Infiltration rate within the dry spots was studied in the laboratory using a permeameter, and by placing water droplets along horizontally positioned soil cores. Several wetting agent and soil cultivation treatments were utilized in a field study to alleviate the dry spots. The cause of the dry spots was investigated by observing individual sand particles under a scanning electron microscope.

The hydrophobic condition was restricted to the upper 2 cm of soil. Infiltration rate within the dry spots was 20% of that for normal turf. Hydro‐Wet and Aqua‐Gro reduced the severity of the dry spots, but a combination of coring plus wetting agent proved most beneficial. Maintaining moist soil conditions was the best defense against the dry spots. Allowing the soil to become dry makes the hydrophobic condition worse.

Scanning electron micrographs provided evidence of a coating surrounding individual sand particles. The coating had the appearance of fungal mycelium and was organic and acidic in nature. No specific fungus was isolated that could be shown to be the cause of the dry spots.
Effect of Lime Application on No‐Tillage and Conventionally Tilled Corn1
Authors: Blevins R. L. , Murdock L. W. , Thomas G. W.
Published: July 2010

Soil management to control soil acidity resulting from surface applied N fertilizer is an important factor in continuous no‐tillage corn (Zea mays L.) production. The objective of this study was to evaluate the effectiveness of surface‐applied lime in maintaining a favorable soil pH level under continuous no‐tillage and conventional tillage corn systems.

Experiment 1 was established in 1971 on a moderately well‐drained Tilsit silt loam (Typic Fragiudults) soil. Lime treatments for both no‐tillage and conventional tillage included: (1) 0 (check), (2) 3.36 mt/ha, (3) 10.08 (4) 3.36 initially + 1.12 mt/ha applied each year, (5) 3.36 initially + 2.24 mt/ha applied every year, and (6) 3.36 initially + 3.36 mt/ha applied after 3 years. After 5 years of continuous no‐tillage corn production the soil surface receiving no lime became extremely acid, pH 4.6. In the no‐tillage plots lime additions resulted in a statistically significant increase in grain yield. Little difference was observed for yield or soil pH changes for the lime treatments that included different frequencies of application. The lime rate based on a soil buffer test recommendation of 3.36 mt/ha was effective in maintaining favorable soil pH and yield levels.

Comparison of limed and unlimed treatments in Experiment 2 on deep, well‐drained Maury (Typic Paleu‐ dalfs) soil showed increased yields for liming no‐tillage plots as N‐rates increased, but no significant yield response for lime on conventionally tilled treatments. The surface soil pH level decreased to pH 4.3 on unlimed, no‐ tillage treatments receiving 336 kg N/ha after 7 years of continuous corn. It is concluded that surface liming without incorporation is an efficient way to overcome soil acidity caused by N fertilization of no‐tillage corn.
Effects of Shading on the N2‐Fixation, Yield, and Plant Composition of Field‐Grown Soybeans1
Authors: Wahua T. A. T. , Miller D. A.
Published: July 2010

Soybeans (Glycine max L. Merr.) are becoming important in cropping systems that increase competition for light among crops. One of the products of N2‐fixation is protein production. A field study was conducted to determine the effects of various degrees of shading (0,20,47, 63, 80, and 93%) on soybean No‐fixation, grain yield, and plant composition. The soil was a Flanagan series, a fine, montmorillonitic, mesic Aquic Argiudoll. Ambient illumination was 124.2 klux. Various degrees of shading were obtained by using different screens. Acetylene‐ethylene assay was used to determine N2‐fixation.

Shading accelerated the rate of loss of total nodule N2‐fixing activity (TNA) as plants developed. The average TNA and dry weight of plant tops were highest at 20% shade (99.3 Klux) and decreased curvilinearly as shading increased, while specific nodule activity decreased linearly. Grain yields under 20, 47, 63, 80, and 93% shade were 90, 75, 48, 18, and 2% of unshaded plants. Seed percent protein and oil content of the seed were virtually unaffected between 20 and 80% shade. The highest percent protein and lowest percent oil occurred at 93% shade. Number of pods per plant percent leaf N, total stem N, TNA, and grain yield were highly correlated with shading and may be good selection indices for soybean shade tolerance. Soybean N2‐fixation was positively correlated with seed protein content (r = 0.77) but negatively correlated with seed protein (r = −0.44). Cropping practices should allow at least 80% ambient illumination measured at the height of 50 cm for substantial soybean No‐fixation.
Influence of K on the Uptake, Translocation, and Reduction of Nitrate by Barley Seedlings1
Authors: Blevins Dale G. , Hiatt A. J. , Lowe R. H. , Leggett J. E.
Published: July 2010

The absorption, translocation, and metabolism of N is influenced by the source of N and by the availability and mobility of counter ions for transport. The purpose of this study was to determine the influence of K or Ca on nitrate uptake, translocation, and reduction in barley seedlings (Hordeum vulgare. cv. Compana). Six‐day‐old barley seedlings were grown for 2 to 36 hours in solutions of 1.0 meq/liter KNO3 or Ca(NO3)2, each containing 0.4 meq/liter of CaSO4. Experiments were conducted in a growth chamber at 27 C with a photosynthetic irradiance of 5.3 mW cm−2. Seedlings treated with Ca(NO3)2 (low K) had lower levels of nitrate uptake, nitrate reductase activity, and lower organic acid concentrations than seedlings treated with 1 mM KNO3. The solution pH and the expressed sap pH of roots and shoots of the low K seedlings increased during the experiment. The shoots of the low‐K seedlings had much lower nitrate concentrations and lower levels of nitrate reductase activity than the roots, suggesting that K plays a major role in nitrate translocation. These results support the hypothesis that potassium malate is cycled from the tops to the roots where decarboxylation occurs, providing a source of HCO3‐ for exchange with NO3‐ during absorption.
Role of Minimum and Maximum Environmental Temperature on Maturation Period of the Cotton Boll1
Authors: Yfoulis A. , Fasoulas A.
Published: July 2010

Temperature is critical in boll formation, and in temperate climates earliness is one of the main breeding objectives. The effect of night and day temperature on the boll maturation period of five genetically divergent cultivars of cotton (Gossypium hirsutum L.) was studied in a 3‐year field experiment at Sindos, Greece. Under a 24‐hour cycle (mean temperature 18 to 32 C) night temperature shortened the boll period up to five times more than day temperature. Under a range of 16 to 30 C, day temperature favored boll maturation four to six times greater than night temperature did. The favorable or adverse effect of mean day and night temperature depended on the maximum and minimum temperatures.
Illustration of a Cluster Analysis Method for Mean Separation1
Authors: Gates C. E. , Bilbro J. D.
Published: July 2010

New statistical methods of separating means into different groups should be brought to the attention of researchers so they can decide if the new methods can be used advantageously in their research programs. Our objective was to illustrate the use of a cluster analysis method (which we have called the Scott‐Knott method after the developers) and compare it to the commonly used Duncan's multiple range test. We applied the two methods to four sets of data. The results showed that the smaller the variance of the treatment means, the more similar were the separation groupings produced by the respective methods. However, in contrast to Duncart's procedure, the Scott‐Knott method never produced overlapping mean separation groups and distinct groups of non‐overlapping means are often desired by the researcher. The Scott‐Knott method has more complex calculations than Duncan's method, but it is readily programmable for computers and many desk top electronic calculators.
Irrigation Effects on Vegetative and Reproductive Development of Three Soybean Cultivars1
Authors: Ashley D. A. , Ethridge W. J.
Published: July 2010

Previous investigations have demonstrated a response in soybean [Glycine max (L.) Merr.] yields to supplemental water applications during reproductive development, but few have described the effects of irrigation during different development periods on fruiting patterns and vegetative development in relation to yields. Variables included in this field experiment were four moisture regimes — unirrigated, full season irrigation, irrigation begun at bloom stage, and irrigation begun at pod fill stage — and three cultivars, ‘Ransom’, ‘Hamptom 266A’, and ‘Coker 102’. Data were collected for seed yield, pod number and dry weight, dry weight of vegetative components during reproductive development and seasonal soil moisture status. The soil was a sandy loam (Rhodic Paleudult, clayey, kaolinitic, thermic family). Full season and bloom stage irrigation treatments produced higher yields than the unirrigated check except for Hamptom 266A in 1974. Yields from plants receiving the podfill stage irrigation treatment were higher than the unirrigated check in drier seasons of 1972 and 1973 but not in 1974. Irrigation beginning at pod fill produced yields equal to the full season and bloom stage treatments in some cases and somewhat lower yields in other cases. Higher yields and greater response to irrigation was obtained from shorter, less vegetative Ransom plants than the other two cultivars. Water applications prior to blooming greatly increased vegetative dry weight, and number as well as dry weight of pods. Beginning irrigation during reproductive development had little effect on vegetative dry weight, but usually resulted in a greater number of pods late in the season than the unirrigated check.
Effect of Fertilizers on the Yield and Botanical Composition of Pastures in South Sulawesi, Indonesia1
Authors: Blair Graeme J. , Pualillin Phylipus , Samosir Solo
Published: July 2010

Information on the nutrient status of soils of the outer Islands of the Indonesian Archipeligo is limited. Attempts are being made to establish a cattle industry based on legume pastures, and this work has created a need for detailed nutrient investigations. Legumes have generally failed to produce and persist in large areas of South Sulawesi which are presently covered by Imperata cylindrica. A series of field experiments were conducted to investigate the nutrient status of a Glossudalf soil. Such soils cover large areas of upland country in Sulawesi that are used for cattle grazing. P, K, S, Mo, Cu, and Zn containing fertilizers were broadcast onto field plots that were oversown with Centrosema pubescence. Nutrient responses were measured during a 1‐year period by cutting quadrats from the plots. Responses to S, applied as either elemental S (brimstone) or as sulfate (in superphosphate), and Mo were recorded. In one experiment elemental S, applied at 13 kg/ha, lifted the yield of Centro from 4,068 kg/ha (green) to 10,491 kg/ha (green) over a 17‐week period. The increase in Centro production lead to a decline in the production of Imperata cylindrica.
Relationship Between Leaf Area and Dry Matter in Winter Wheat1
Authors: Aase J. K.
Published: July 2010

Models of plant growth and plant water use often require leaf‐area measurements, a potentially time‐consuming and costly process. The objective of this study was to determine if by establishing a relationship between leaf area and dry matter in winter wheat (Triticum aestivum L. em Thell), that dry matter can be substituted for leaf area. Four cultivars of winter wheat were seeded on Dooley sandy loam and Williams loam (fine‐loamy, mixed, Typic Argiborolls) in northeastern Montana in three divergent growing seasons. Leaf area and dry matter determinations, from random 30‐cm row plant samples cut at ground level, were made weekly throughout the season. Leaf area and leaf dry matter were closely correlated (r2= 0.951). Leaf area vs. plant dry matter also was closely correlated (r2 = 0.948) through the fifth growth stage (leaf sheaths strongly erect, tillering complete). Thus it appears that in studies and modeling efforts where leaf area indices are needed, at least for winter wheat, leaf dry matter may be substituted for leaf area index.
Tall Fescue Yield, Tillering, and Invaders as Related to Management1
Authors: Dobson James W. , Beaty E. R. , Fisher C. D.
Published: July 2010

Tall fescue (Festuca arundinacea Schreb.) is widely grown as a winter perennial forage in the upper South. It is primarily used for cool‐season grazing by cattle producers, and improved digestibility and increased fall and winter forage production would be useful. A field experiment was conducted for 3 years on a tall fescue sod growing on a member of fine loamy mixed family of Cumulic Haplumbrepts to establish the effect of four clipping schedules, 5‐ and 10‐cm clipping heights and 56‐ and 224‐kg/ha N‐rates on dry forage yields, tiller numbers, and percent invaders.

Forage yields varied from slightly more than 3,600 kg/ha when fertilized with 56 kg/ha of N and clipped at a height of 10 cm to more than 8,820 kg/ha when fertilized with 224 kg/ha N and clipped at 5 cm. Reducing the clipping height from 10 to 5 cm increased average forage yield from 5,512 to 6,735 kg/ha or 22%. Increasing N fertilization from 56 to 224 kg/ha doubled dry forage production from 4,137 to 8,111 kg/ha. Tillers/unit area were highest at the 5‐cm clipping height, 224 kg/ha rate, and frequent clipping schedule. Lowest numbers of tillers/area were obtained on plots clipped at 10 cm, fertilized with 56 kg/ha N, and clipped infrequently.

Invaders were limited almost exclusively to plots clipped at a height of 5 cm where 56 kg/ha N was applied. Very few invaders were present on plots clipped at 10 cm. More invaders were present on 56‐kg/ha N plots than on 224‐kg/ha N plots.

Tall fescue responded to management treatments applied. However, it is probable that new treatments can be developed that will more uniformly distribute forage production through the season, facilitate the introduction of invaders (clovers), and stabilize tillers/area for increased fall and winter growth and improve forage quality (digestibility). These additions would add appreciably to the value of tall fescue as a forage crop in the Southeast.
Seedling Emergence as Related to Temperature and Moisture Tension1
Authors: Wright D. L. , Blaser R. E. , Woodruff J. M.
Published: July 2010

Mixtures of seed that provide quick germination and seedling growth during most seasons are important for controlling erosion and establishing an aesthetically pleasing turf in highway corridors. To aid in selection of species for mixtures, we designed an experiment to determine total emergence and rates of emergence of several grass and legume species and cultivars under various soils moisture and temperature regimes. Rates of seedling emergence for 12 grass and legume species or cultivars were determined in the laboratory on a Groseclose (clayey, mixed, mesic, Typic, Hapludult) subsoil maintained at soil water potentials of −1/3, −3, −6, and −9 bars and at 21 and 28 C over a 19‐day period. Abruzzi rye (Secale cereale L), German millet (Setaria italica L.), perennial and annual ryegrasses (Lolium perenne L. and L. multiflorum Lam), weeping lovegrass (Eragrostis curvula Schrad. Nees), and redtop (Agrostis alba L.) were considered aggressive species. After 4 days at −1/3 bar of soil water potential, seedling emergence for these species ranged from 54 to 100% emergence and by day 6 total emergence was the highest for all groups at either temperature. Intermediate species included creeping red rescue (Festuca rubra L.) Kentucky bluegrass (Poa pratensis L.), Kentucky 31 tall fescue (Festuca arundinacea Schreb.), crownvetch (Coronilla varia L.) at 21 C, and common bermudagrass (Cynodon dactylon L.) at 28 C. Emergence at 21 C and −1/3 bar generally began on day 3 or 4 and near maximum emergence rates of the intermediate species occurred by day 8 at 21 C and −1/3 bar. Total emergence was less than observed for the aggressive group. Emergence was also sharply reduced at −6 and −9 bars as compared to Abruzzi rye, German millet, and perennial ryegrass. Common bermudagrass at 21 C and Sericea (Lespedeza cuneata G. Don.), and crownvetch at 28 C had few seedlings emerge until day 8 in the soil maintained at −1/3 bar, and their total emergence was the lowest of all species with near maximum occurring between day 10 and 13; therefore, they were considered non‐aggressive species. Generally, as temperature and moisture tension increased, the rate of emergence and total emergence of all species declined. Of the aggressive species, only Abruzzi rye, German millet, and perennial ryegrass had above 50% relative emergence after 19 days at a soil water potential of −9 bars and 21 C. Seed mixtures for different planting seasons should be designed with species adapted to various temperature and moisture extremes.
Physical Characteristics of Le Sueur Clay Loam Soil Following No‐till and Conventional Tillage1
Authors: Gantzer C. J. , Blake G. R.
Published: July 2010

Although the effects of no‐till on crop yields has been widely investigated, there are virtually no data on its physical effects on clay loam soils like those in the Corn Belt. In order to compare the effects of no‐till with conventional fall plow tillage on a south‐central Minnesota clay loam soil (Aquic Argiudoll), we measured some soil physical properties 6 years after beginning a field experiment with corn (Zea mays L.). Data show that soil under no‐till had significantly greater bulk density, both in spring and fall, for samples in the surface 30 cm. Densities of no‐till soil ranged from 1.24 to 1.32 g/cm3 in in contrast to those of conventional tillage, which ranged from 1.05 to 1.12 g/cm3. Air‐filled porosities of surface samples under no‐till were lower at all potentials measured. At −100 rob, no‐till averaged 0.143 cm3/cm3 compared to 0.198 cm3/cm3 for conventional tillage. Mean number of channels 1 mm and greater created by earthworms and decomposed rootlets were significantly greater for no‐till, ranging from 666 to 1,732/m2 compared to 243 to 1,475/m2 for conventional tillage. Volumetric water contents were also greater for no‐till surface samples, ranging from 0.35 to 0.28 cm3/cm3 vs. 0.31 to 0.25 cm3/cm3 for conventional tillage. Saturated hydraulic conductivities of spring surface samples were lower under no‐till than conventional tillage averaging 14.6 cm/hour and 38.2 cm/hour, respectively. Generally. differences in measured parameters between treatments were smaller for samples collected in fall before harvest, than those in spring. Significant differences for tillage treatment were not found below 30 cm depth. At high water potentials, lower porosity under no‐till may restrict gaseous exchange and create conditions unfavorable for germination and seedling development. However, higher number of biochannels in the no‐till soil may compensate for this reduced exchange.
A Thermogradient Generating Sand Table1
Authors: Clegg Max D. , Eastin Jerry D.
Published: July 2010

A need to study the effect of a wide range of temperatures on early plant growth as well as seed germination of a wide range of sorghum [Sorghum bicolor (L.) Moench] germplasm led to the construction of a sand thermogradient sand table. The table was constructed so heat was transferred between water baths of two different temperatures. A continuous, linear thermogradient was established when the water baths were at 15 and 45 C. Other temperature differentials produced nearly linear gradients. Temperature deviation at any depth during the experiments never exceeded 1 C and usually was less. Germination and early growth of sorghum and corn (Zea mays L.) were measured to demonstrate the type of response curves that could be obtained with this apparatus. The table lends itself to many applications for physiological studies, including screening genetic material for temperature tolerance.
Effect of Soil pH and Liming on Growth and Nodulation of Soybeans in Histosols1
Authors: Mengel D. B. , Kamprath E. J.
Published: July 2010

Soil acidity severely limits the growth of soybeans [Glycine max. (L.) Merr.] on Histosols in North Carolina. Laboratory and greenhouse studies were conducted to determine the critical soil pH levels for soybean growth and the chemical factors influencing growth. Soybeans were grown on eight organic soils which had been limed with dolomitic limestone to give a pH range from 4 to 5. Lime rates were based on the CaCl2 exchangeable acidity of each soil. Measurements were made of exchangeable soil acidity, exchangeable AI and Ca, and water soluble AI and Ca. Plant variables measured were shoot, root and nodule dry weight, nodule number and concentration of N, P, K, Ca, Mg, and AI in shoots and roots. These measurements were made at 28 and 40 days after planting in order to calculate growth rates and nutrient uptake rates. Growth responses to liming were obtained on all soils. Shoot growth was significantly related to soil pH and water soluble AI and Ca. Nodule number and weight increased significantly as soil pH increased. Both N con. centration and uptake increased markedly as soil pH increased. Critical soil pH for shoot, root, and nodule growth was in the range of 4.6 to 4.8 for most of the soils. The growth responses to liming are attributed to decreasing the exchangeable and water soluble AI, increasing the water soluble Ca and providing a favorable soil pH for rhizobium activity.
Diurnal Changes in Plant Water Potential and Canopy Temperature of Wheat as Affected by Drought1
Authors: Ehrler W. L. , Idso S. B. , Jackson R. D. , Reginato R. J.
Published: July 2010

The diurnal courses of plant water potential (ψplant and temperature (canopy‐air) (ΔT) were determined for 4 days for a wet soil (six levels of water content, θv, corresponding to values of soil water potential (ψm) of −0.1 to −0.5 bars) as compared with a dry soil (six values of ψm, from −1.6 to −18.0 bars), established by withholding irrigations. In wet soil, ψplant decreased from near zero at predawn to −16 bars from solar noon until 1600 hours, and then returned to near zero shortly after sunset. For this treatment, ΔT increased from an initial negative value (−2 to −9 C, depending on the saturation deficit) to either the least negative or a slightly positive value near 1000 hours, and then it gradually decreased and was negative at 1400 hours in five of the six wet plots.

For dry soil, the ψplant curve reasonably paralleled that for a well watered crop, but was more negative and did not necessarily return to the predawn value after sunset. For dry soil, ΔT increased rapidly after sunrise, peaked near solar noon (rather than at 1000 hours) and decreased only slightly by 1400 hours, and was positive (0.7 to 7.0 C) in all six dry plots.

Because typical diurnal curves for ΔT differed in shape depending on soil water content, canopy temperatures of plants on wet and dry soils differed most near 1400 hours. Thus, it is feasible to use ΔT measured at this time to represent the whole day. Such ΔT measurements can lead to routine monitoring capabilities by remote sensing techniques.
Effect of Nitrogen Fertilization on Yield, Composition, and Quality of Kenaf1
Authors: Adamson W. C. , Long F. L. , Bagby M. O.
Published: July 2010

Kenaf (Hibiscus cannabinus L.), a potential pulp crop, has not shown a consistent yield response to N, and the influence of N on pulp quality factors is unknown. The response of kenaf to lime and the amounts of various elements removed with the harvested crop are also of interest. A field study was conducted to determine the effect of N on yield, mineral composition and quality of kenaf at two pH levels. Tests were conducted for 2 years, 1970 and 1971; in two soil areas, Edisto (Glossaquic Fragiudalf) and Ona (Typic Haplaguod); and in high and low pH areas established by, prior applications of lime. Nitrogen was applied at three levels and in single and three‐way split applications. Nitrogen increased the yield, height and diameter of kenaf. Nitrogen had the favorable effect of increasing woody fiber length, however lignin content was also increased. Cellulose content was unaffected. Split applications of N usually produced higher yields than the same amount in a single application but were only significant for the fist year on limed Edisto soil. Increasing rates of N decreased the P, K, Ca and B content of harvested kenaf. Lime increased the Mg content an1 reduced the Mn, Al, Sr, and Ba contents. Neither N or lime had any significant effect on ZnZ Cu or Mo content.
N Uptake and Corn Yield as Affected by Applications of Nitrapyrin with Anhydrous Ammonia1
Authors: Touchton J. T. , Hoeft R. G. , Welch L. F. , Mulvaney D. L. , Oldham M. G. , Zajicek F. E.
Published: July 2010

The use of nitrapyrin as a nitrification inhibitor of ammonium fertilizers applied to corn (Zea mays L.) has gained widespread interest. Even though initial nitrification rates are usually decreased by nitrapyrin, its use does not always result in increased grain yield. To evaluate the effects of nitrapyrin applied with anhydrous ammonia on yield and N uptake of corn grown on poorly drained soils, field studies were conducted in Illinois at Urbana, Brownstown, and DeKalb. The soil at Urbana and DeKalb was Typic Haplaquoll and Mollic Albaqualf at Brownstown. Anhydrous ammonia was applied with and without nitrapyrin in the fall and spring. Nitrapyrin and N rates ranged from 0 to 1.12 and 0 to 268 kg/ha, respectively.

The addition of nitrapyrin had varied effects on N concentration in the plant tissue and on grain and total dry matter yield; however, these effects were not consistent among N rates, locations, or years. At Urbana, the addition of nitrapyrin increased the N concentration in the plant tissue at the fifth‐leaf growth stage in 1975 by as much as 7% and in the ear leaf at silk in 1976 by as much as 6%, when comparing within N rates and seasons of application. The N concentration in the grain and stover was reduced by as much as 8 and 27%, respectively, by the addition of nitrapyrin at low rates of N. At DeKalb in 1975, nitrapyrin did not affect N in the plant tissue. In 1976, applications of nitrapyrin with fall‐applied N increased N in the ear leaf up to 20% over fall‐applied N without nitrapyrin, and increased it up to the concentration found for spring‐N applications with or without nitrapyrin. At Brownstown in 1975, plants did not respond either to applied N or nitrapyrin. In 1976, plants responded to nitrapyrin, but adverse weather resulted in data that did not follow expected trends.

Grain and stover‐yield increases could not be attributed to applied nitrapyrin when N was applied at levels required for maximum economical yield. Soil moisture during both years was not favorable, however, for N losses that would occur normally through leaching and denitrification.
Tolerance of Soil Acidity in Symbioses of Mung Bean with Rhizobia1
Authors: Munns D. N. , Keyser H. H. , Fogle V. W. , Hohenberg J. S. , Righetti T. L. , Lauter D. L. , Zaroug M. G. , Clarkin K. L. , Whitacre K. W.
Published: July 2010

Variation in tolerance of soil acidity among 40 rhizobial strains was assessed in greenhouse trials in which the strains were applied as separate seed inoculants (5 ✕104 cells per seed) to two cultivars of mung bean (Vigna radiata L.) and performance was measured by nodulation, growth, and N‐yield of the host plant. The plants grew in a low N, low Ca acid subsoil, Goldridge fine sandy loam (Typic Hapludult, fine loamy, mixed, mesic), left at its natural pH of 5.0 (saturation paste) or limed with CaCO3 to pH 6.3. Each pH ✕ strain treatment was triplicated in separate pots.

Strains demonstrated a large and perhaps continuous variation in acid tolerance. A few were very sensitive: they failed to nodulate at pH 5.0. About half were moderately sensitive: nodulation and growth were significantly impaired at pH 5.0. The remainder were tolerant: like NH4NO3 they supported similar plant growth at both soil pH values. Some strains combined high tolerance with high effectiveness.

A strain's acid tolerance could not be predicted from the abundance or effectiveness with which it nodulated at favorable pH, or from its growth rate or acid production in conventional yeast mannitol medium.

A few strains were sensitive on one host cultivar and tolerant on the other, implying that acid tolerances of symbiotic legumes cannot be compared validly in trials with only one inoculant.
Leaf and Stem Yields and Forage Quality of Three N‐fertilized Warm‐Season Grasses1
Authors: Perry L. J. , Baltensperger D.
Published: July 2010

Nitrogen fertilization of warm‐season tall grasses may increase dry matter yields, percentage crude protein, and in vitro dry matter disappearance (IVDMD). Leaf and stem portions of total dry matter may vary among grasses, years, and fertility levels and during the growing season. Established pure field stands of switchgrass (Panicum virgatum L.), indiangrass [Sorghastrum nutans (L.) Nash], and big bluestem (Andropogon gerardi Vitman) were fertilized annually with 0, 45, and 90 kg N/ha and harvested at six biweekly dates beginning in mid‐June during 1973 and 1974 to determine leaf and stem yields and forage quality of these warm‐season grasses as influenced by N‐rate and plant maturity. Leaf and total dry matter yields decline 50% following the 1st year of clipping due to below average precipitation of 1974 as compared with 1973. Leaf yields increased with N fertilization more at the later harvests. Big bluestem responded with more than double the dry matter (leaf and total) production per kg of N and showed less decline the 2nd year than the other grasses. Leaf material of all grasses comprised approximately 85% of the total forage yield at most N levels both years. Leaf crude protein percentages were increased with N fertilization during the first three harvests; whereas, leaf IVDMD ercentages were increased with N fertilizer during the first five harvests. Leaf IVDMD was highest in indian. grass followed by big bluestem and switchgrass. Rapid declines occurred in leaf crude protein and IVDMD throughout the growing season, indicating that leaf maturation primarily is responsible for declining forage quality rather than increasing plant development, i.e., increasing stem growth, in these grasses.
Variations in the Number of Seeds per Unit Weight Among Turfgrass Cultivars1
Authors: Christians N. E. , Wilkinson J. F. , Martin D. P.
Published: July 2010

Kentucky bluegrass (Poa pratensis L.) and the fine fescues (Festuca rubra L., Festuca rubra var. commutata Gaud. and Festuca ovina var. duriuscula L. Koch) are widely used turfgrasses in temperate regions. Seeding rate recommendations for these species are dependent on seed number per unit weight and are based on counts available in the literature. In recent years, however, breeding and selection have produced cultivars of these species with visible differences in seed size, yet variations in seed numbers have not been documented. This study was conducted to determine seed count variations among several cultivars of Kentucky bluegrass, fine fescue, and among individual lots of Kentucky bluegrass cultivars. Counts for the fine fescues were estimated by calculations made from the weight of 100 seeds. Kentucky bluegrass seed numbers were estimated by the above method and by an electric seed counter.

Differences in seed count existed among cultivars of both turfgrasses. Fine fescue cultivars varied from 1,272 seeds/g to 618 seeds/g with a mean for all cultivars of 1,020 seeds/g. Kentucky bluegrass cultivars varied from 4,413 seedsjg to 1,847 seeds/g with a mean of 2,744 seeds/g. Significant differences in seed count were also found to exist among lots of individual Kentucky bluegrass cultivars. Differences among lots as large as 805 seeds/g for ‘Merion’ and 373 seeds/g for ‘Pennstar’ were recorded.

Six Kentucky bluegrass cultivars with widely varying seed counts were established on a seed count (308 live seed/dm2) and on a weight basis (0.75 kg/are). This part of the investigation was conducted on a Typic Argiaquolls, Fine‐Loamy, mixed mesic soil at the Ohio State Univ. turf plots in Columbus, Ohio.

Initially, cultivars with higher seed counts were established more rapidly than were cultivars with fewer seeds/g, when seeded at the 0.75 kg/are rate. After 6 growing months, no differences in percent cover between either seeding rate or cultivars existed. After 1 year, sod strength determinations were essentially the same among all treatments. If the goal of seeding is rapid establishment, there may be an advantage to seeding Kentucky bluegrass cultivars with fewer seeds/g (larger seeds) at a higher weight/unit area than cultivars with greater seed counts.
Corn Residue Management and Soil Organic Matter1
Authors: Barber Stanley A.
Published: July 2010

Organic matter in a soil results from the balance between rate of loss from decomposition of the soil organic matter and rate of gain from formation of organic matter during decomposition of crop residues and roots returned to the soil. Interest in using corn plant residues as a source of energy production raises the question of how much residue removal would reduce soil organic matter and soil productivity. Effect of residue management was studied in field experiments with corn (Zea mays L) on a Raub silt loam (Aquic Arqiudoll) near Lafayette, Ind. One experiment had continuous corn growth for 11 years with residues removed, residues returned, and double residues returned. It also had a continuous fallow treatment. A second experiment had differing levels of residues returned because of N levels used on 12‐year, continuous corn. Soil samples taken from the plow layer during and at the conclusion of the experiments were analyzed for organic carbon. Losses of organic matter from plots fallowed continuously for 6 years indicated a decomposition rate of 2.4% per year. Corn stalk residue removal for 10 years was compared with residue return. About 11% of the C in the residues was synthesized into new organic matter. In a fertility experiment, where level of residues varied with treatment, the change in soil organic matter after 12 years indicated 8% of the C in residues was transformed into C in organic matter. Corn roots also appeared to contribute at least 18% of their C to formation of new organic matter. These results are in agreement with an experiment in Iowa and can be used to estimate the effect of residue management practices on soil organic matter level of similar soils.
Statistical Designs and Response Models for Mixtures of Cultivars1
Authors: Federer W. T.
Published: July 2010

In spite of current interest in growing mixtures (composites) of cultivars and in multiple cropping systems, appropriate response models, definitions, treatment designs, and statistical analyses are not available when more than two cultivars are involved. Since the beneficial or detrimental effects of using mixtures of size k equal to or greater than two cultivars (lines, species) as compared to sole cropping (monoculture) needs to be assessed, the objective of this study is to present response models, treatment designs (the selection of entities or treatments for an experiment), definitions of effects, and statistical analyses for estimating and comparing the various effects involved in experiments on mixtures of k cultivars. The concepts of general mixing (blending), bi‐specific mixing, tri‐specific mixing, . . . , nth specific mixing effects are formulated. Treatment designs are derived from weighing, balanced incomplete block, and supplemented block experiment designs. It is shown that solutions for parameters in the response models are dependent upon the number and types of mixtures used in the treatment design. A statistical analysis is presented for a particular treatment design involving mixtures of all possible pairs of eight dry bean cultivars plus the cultivars themselves. Finally, it is noted that the results may be useful for a number of other types of experiments involving mixtures, such as herbicide, nutrition, medicine, education, etc.
Utility of Stem Diameter Changes as Predictors of Plant Canopy Water Potential1
Authors: So H. B. , Reicosky D. C. , Taylor H. M.
Published: July 2010

Stem diameter fluctuations have been used to monitor changes in plant water potential through a dynamic method to correct for the time lag. The objective of this work was to determine whether a single day's calibration was suitable for long‐term prediction of plant water potential and if the technique was applicable for different species. Plants were grown in a growth chamber, a greenhouse, and in field plots. Changes in stem diameter were monitored continuously, using linear variable differential transformers (LVDT). Leaf water potentials were measured using the pressure‐chamber technique. When the stem diameter‐leaf water potential relationship was corrected for time lag, change in stem diameter was closely related to leaf water potential over several days. The method of deriving leaf water potentials from stem diameter fluctuations was applicable for corn (Zea mays L.) and soybean (Glycine max (L.) Merr.). Water stress caused a decrease in sensitivity for soybean. This fact indicated that the frequency of calibration needs to be increased as the plants become stressed. Changes in stem diameter are a convenient parameter for predicting plantcanopy water potential and the method does not require daily calibration.
Effects of Drought on Florunner Peanuts1
Authors: Pallas J. E. , Stansell J. R. , Koske T. J.
Published: July 2010

Droughty conditions are implicated in causing low yields, poor grades and germination, and an increased incidence of aflatoxin in the peanut (Arachis hypogaea L.). However, very little is known as to when in the growth cycle drought is most critical. Effects of five drought treatments on peanut leaf diffusive resistance, yield, and quality characteristics were studied on rainfall‐protected plots of Tifton loamy sand, a member of the fine, loamy, siliceous, Thermic Plinthic Paleudults. Early, middle, and late drought periods of short duration (35 days) and extended early and midseason droughts (70 days) were imposed by withholding irrigation. Yield, percent sound mature kernels (SMK), germination, leaf‐water potential, and leaf diffusion resistances were measured. Under droughty conditions, leaf‐water potential was lowest during midseason when evaporative demand was greatest. Leaf diffusion resistances, however, in creased with lateness and severeness of drought, reflecting leaf age and plant‐water stress. Leaf‐water potentials of −30 bars were recorded for several treatments during midseason, and values as low as −40 bars were recorded for the 35‐day midseason drought. Although the leaf‐water potentials of control plants decreased as the season progressed, they never became lower than −12 bars. In both stressed and nonstressed plants the diffusion resistances were frequently less on the upper than on the lower surfaces of leaves. Much of the plant‐water stress that developed during drought was relieved the day after irrigation and leaf diffusion resistances also returned to near normal. Vine weight was not decreased by any 35‐day drought, but was significantly reduced by 70‐day droughts.

In general, drought progressively decreased yields as duration and lateness of occurrence in the season increased. The 70‐day extended early season drought caused the greatest reduction is SMK. The late season 35‐day and extended midseason 70‐day droughts lowered subsequent germination 5 and 9% respectively. These studies validate the importance of full‐season irrigation for peanuts in the Southeast. When full‐season irrigation may not be possible because of demands on the system, scheduling irrigation the latter part of the season appears next in importance.