Influence of flood irrigation on digestible sulfur in the Red river delta paddy soil

Abstract

     Among the essential elements, sulfur is very much beneficial for increasing the production of rice. Recently, sulfur deficiencies in rice fields have been reported in different areas of Viet Nam reducing rice production and quality. Sulphur deficiency mainly arises under water-logged rice cultivation land. Sulfur is a sulfide form under anoxic conditions in submerged paddy soils. Free hydrogen sulphide is generated and inhibits the rice root growth in paddy soils. The experiments were laid out on paddy soil in Tien Lu, Hung Yen district during cultivated seasons of 2015. The soil was silt loam having pH 6.5÷6.9, organic matter 1.1%, available S 11.53mg/100g soil. The experiments are carried under continuous water- logged condition (flood irrigation) with water level of 7÷10cm from field surface. The results reveal a reduced redox potential under waterlogged condition (30÷50mV) and a reduction of soil digestible sulfur (0.31÷0.58 mg/100g soil) that limits sulfur nutrient source for rice. A more serious sulfur nutrient deficiency might occur due to anoxic conditions in submerged paddy soils by longer time. Soil toxics including H2S, HS-, S2-generated have negative effects on rice yield and growth.