抄録
Guangxi province is located in the southern sub-tropical region of China has high temperatures and heavy rainfall, resulting in soils with mainly low cation exchange capacity (CEC), low organic matter, and poor phosphorus (P), potassium (K) and sulphur (S) nutrient content (Zhang et al., 1998). According to the results of 86 trials in Guangxi, application of potassium (K) fertilizer significantly increased yield more than the application of NP fertilizer only, and also increased the quality of crops and fruit markedly. As lateritic red soil, latosol and silicosol in upland soils of Guangxi contain a low amount of exchangeable magnesium of less than 70 mg⁄kg, Mg application also improved crop growth.
The major lowland cropping system is early rice-late rice. Over the years, less and less organic matter has been recycled (Yoshida,1981), because it has been put to commercially as fodder, or fuel. At the same time, for P calcium-magnesium-phosphate (CaMgP) use has increased. With increasing yields, the uptake of S by rice also increased (Morris, 1990). Thus, S deficiency started to become a serious problem.
When K fertilizer was applied to crops, gross income increased between 1,871-4,634 RMB⁄ha. For fruit trees, applying K fertilizer increased gross incomes 4,424-25,043 RMB⁄ha. The benefits from the application of S-fertilizers, rice-rice cropping system, Ammonium sulphate, Single superphosphate, Elemental S and Gypsum resulted in a net income of 1891.9 RMB⁄ha, 1821.3 RMB⁄ha, 1883.0 RMB⁄ha and 1659.0 RMB⁄ha, respectively.
