Effects of Long-Term Application of Sulfur-Containing and Chloride-Containing Chemical Fertilizers on Rice Yield and Its Components

Abstract

Impacts of 33-yr of application of S-containing and Cl-containing chemical fertilizers on rice ( Oryza sativa L.) yield and its components were investigated in a red paddy field experiment, south China. The treatments included: 1) adding 302 kg SO 4 2−-S ha −1 yr −1 with application of (NH 4) 2SO 4, K 2SO 4, and calcium superphosphate (SO 4 2−); 2) adding 56 kg SO 4 2−-S and 176 kg Cl ha −1 yr −1 with application of urea, calcium superphosphate, and KCl (Cl −+SO 4 2−); 3) adding 516 kg Cl ha −1 yr −1 with application of NH 4Cl, KCl, and KH 2PO 4 (Cl −). Under each treatment, the applied N, P, and K nutrients were controlled at conventional rates of 150 kg N ha −1 yr −1, 75 kg P 2O 5 ha −1 yr −1, 225 kg K 2O ha −1 yr −1, respectively. Under the S-containing fertilizer application, soil SO 4 2−-S content showed a first increasing then decreasing trend with years, and was significantly negatively correlated with annual rice yield. Average annual yield significantly declined in an order of Cl −, Cl −+SO 4 2−, and SO 4 2−. Under the Cl − treatment, soil SO 4 2−-S content was maintained at about 26.5 mg kg −1, not showing deficiency. From 1990 to 2000, rice yield declined rapidly under the SO 4 2− treatment, and was significantly lower than that under the Cl − treatment. After then, there was no significant difference in yield among the treatments. Our results demonstrated that long-term application of S-containing fertilizer could result in excessive accumulation of SO 4 2−-S in the red paddy soils of south China, therefore producing a certain threat to rice growth. The Cl-containing fertilizer could be relatively safe.