Evaluating the Effects of Soil Ph on Grain Sorghum (Sorghum bicolor) and Sunflower (Helianthus annuus L.) Production

The transition from conventional tillage to no-tillage production systems has led to the incorporation of grain sorghum and sunflower as rotation crops; however, these crops may not perform well when grown on acidic soils. This study was conducted to determine the quantitative effect of soil pH on grain sorghum and sunflower production. The relationship of relative yield and soil pH were investigated at Lahoma, Perkins, and Haskell, OK with soil pH treatments ranging from 4.0 - 7.0. Soil pH was altered using aluminum sulfate or hydrated lime. Soil acidity negatively affected grain sorghum and sunflower yield. At soil pH 5.42 and 5.27, yield reductions of 10% were observed in grain sorghum and sunflower, respectively. Yield reductions of 20% or more were observed at soil pH 5.14 and 5.08 in grain sorghum and sunflower, respectively. Liming should be considered to increase soil pH if it is below these critical levels where grain sorghum or sunflower will be produced.Department of Plant and Soil Science

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