Effect of Different Winter Legumes As Nitrogen Sources for Switchgrass (Panicum Virgatum L.) Grown for Cellulosic Ethanol, and Effect of Foliar-Applied Phosphite on Growth and Yield of Corn (Zea Mays L.)

Scope and Method of Study:Increasing fertilizer price has motivated scientists to find alternative sources of nitrogen to reduce cost of crop production. Because winter legumes may provide significant amount of nitrogen while conserving soil quality, the role of legumes intercropped with switchgrass (Panicum virgatum L.) warrants renewed attention. The objectives of this study were to investigate the effects of different winter legumes as a source of nitrogen on switchgrass dry matter yield, forage quality for biofuel production, and soil fertility status. A field experiment was carried out in which six winter legumes and four rates (0, 56, 112, and 168 kg ha-1) of fertilizer nitrogen were studied over a 3-year period. The second study was conducted to determine the effect of foliar-applied phosphite on growth and yield of corn (Zea mays L.). One major problem that affects the efficiency of foliar fertilization is the form of phosphorus. Phosphite is more reactive than widely used phosphate. A field study and a greenhouse study were conducted over a 2-year period in which the effect of foliar-applied phophite, soil-applied nitrogen and phosphorus were investigated on corn biomass yield, grain yield; grain, stem, and leaf P concentrations.Findings and Conclusions:Winter legumes did not increase switchgrass dry matter yield, cellulose, lignin, and hemicellulose content. The rate of 112 kg nitrogen ha-1 was required to achieve highest dry matter yield. Soil nitrate nitrogen, pH, and mineral content were largely unaffected. Soil organic matter depleted up to 33% after three years. As a replacement of fertilizer nitrogen, and to conserve soil productivity, winter legume-switchgrass intercropping system may not be recommended. In the field studies where phosphorus status was not significantly limited, foliar phosphite increased corn grain and biomass yield with soil-applied nitrogen fertilizer. No treatment effects were found in the greenhouse where initial soil phosphorus status was very low. In both studies, grain, stem, and leaf phosphorus concentration were largely unaffected by foliar phosphite. We concluded that, phosphite may be used as a partial supplement; however, may not be recommended when the soil phosphorus status is very low.Plant & Soil Scienc

Determining Critical Soil pH for Grain Sorghum Production

Grain sorghum (Sorghum bicolor L.) has become a popular rotation crop in the Great Plains. The transition from conventional tillage to no-tillage production systems has led to an increase in the need for crop rotations. Some of the soils of the Great Plains are acidic, and there is concern that grain sorghum production may be limited when grown on acidic soils. The objective of this study was to evaluate the effect of soil pH for grain sorghum production. Potassium chloride-exchangeable aluminum was also analyzed to determine grain sorghum’s sensitivity to soil aluminum (Al) concentration. The relationship between relative yield and soil pH was investigated at Lahoma, Perkins, and Haskell, Oklahoma, USA with soil pH treatments ranging from 4.0–7.0. Soil pH was altered using aluminum sulfate or hydrated lime. Soil acidity reduced grain sorghum yield, resulting in a 10% reduction in yield at soil pH 5.42. Potassium chloride-exchangeable aluminum levels above 18 mg kg−1 resulted in yield reductions of 10% or greater. Liming should be considered to increase soil pH if it is below these critical levels where grain sorghum will be produced

Determining Critical Soil pH for Sunflower Production

Soil acidity has become a major yield-limiting factor in cropping systems of the Southern Great Plains, in which winter wheat (Triticum aestivum L.) is the predominant crop. Sunflower (Helianthus annuus L.) is a strong rotational crop with winter wheat due to its draught and heat tolerance. However, the effects of low soil pH on sunflower productivity have not been explored. The objective of this study was to determine the critical soil pH and aluminum concentration (AlKCl) for sunflower. Sunflower was grown in a randomized complete block design with three replications of a pH gradient ranging from 4.0 to 7.0 at three locations with varying soil types. Soil pH was altered using aluminum sulfate (Al2(SO4)3) and hydrated lime (Ca(OH)2). Plant height, vigor, and survivability were all negatively affected by soil acidity. Sunflower yield was reduced by 10% at or below soil pH 4.7 to 5.3 dependent upon location and soil type. Levels of AlKCl above 6.35 mg kg−1 reduced seed yield by 10% or greater. We concluded that sunflower may serve as a better rotational crop with winter wheat under acidic conditions when compared to other adaptable crops

Response of Winter Wheat Grain Yield and Phosphorus Uptake to Foliar Phosphite Fertilization

One of the major problems that potentially hinders the use of foliar fertilization as a tool to improve nutrient use efficiency is the lack of effective formulations. A phosphite based product, Nutri-phite (3% N, 8.7% P, and 5.8% K) was used as model phosphite formulation for foliar application in winter wheat (Triticum aestivum L). Five field trials were established in the fall of 2009 and 2010 at Perkins, Perry, and Morrison, OK. Treatments encompassed the application of nitrogen (N) at 100 or 75% of crop need and phosphorus at 100 (P 100%) and 80% (P 80%) sufficiency with and without Nutri-phite. Nutri-phite was applied at one and/or two stages of wheat; GS 13 to 14 and GS 49 to 53 at the rate of 433 and 148 g ha−1 P and N, respectively. Grain yield was increased by Nutri-phite treatments, especially at Morrison. Grain P concentration of plots treated with two applications of Nutri-phite ranged from 13 to 55% more than the nontreated and standard NP received plots at Perkins in 2009/10 and Perry in 2010/11. Grain P uptake was increased due to application of Nutri-phite at Perkins in 2009/10 and Morrison and Perry in 2010/11. Combined over three year-locations, Nutri-phite increased grain P concentration by 11.6%. The higher grain P concentration of plots treated with Nutri-phite compared to the other treatments clearly demonstrates its potential in improving P status of wheat grain