Sulfur deficiency of rice plants in the Lower Volta area, Ghana

Abstract

Rice plants were grown in pots under submerged conditions using a soil from the Lower Volta area in Ghana. Plants experienced severe sulfur deficiency when sulfur was not applied, and responded positively to the addition of sulfur. The relative deficiencies in the soil's nutrient supply were in the order of sulfur ≫phosphorus > potassium = nitrogen. The critical levels for achieving 90% shoot growth at the maximum tillering stage were 1.0 to 1.1 g total-S kg-1 DM (shoot dry matter), 26 to 30 of the total-N/total-S (N/S) ratio, 0.10 to 0.15 g sulfate-S kg-1 DM, and 0.05 to 0.15 of the sulfate-S/total-S ratio. A deficiency diagnosis with a single variable often led to an error of judgement, since several criteria showed a C-shaped response curve for plant growth, and a marginally unbalanced nutrient status induced a positive value in any of the criteria. Therefore, when a sulfur shortage being diagnosed, the evaluation should take several variables into account. The maximum quantity of sulfur needed to alleviate the deficiency was estimated to be about 30% of the nitrogen requirement. However, field trials should be carried out to implement an appropriate fertilizer management. Sulfur deficiency is likely to be widespread in the region, because the nutrient status of the soil in the Lower Volta area is considered to be higher than that of many other soils in West Africa.