Research and Extension of Ag-lime Application in Sichuan

The Sichuan basin presently has about 3.27 million hectares (M ha) of acid farmland soils (pH <6.5), among which 49,000 ha have pH values below 5.5. Soil acidity has generally been a result of extensive weathering and a long geo-history and thus, has poor productivity and a number of fertility problems. In contrast, acidity problems in vegetable soils have been mainly attributed to short-term (perhaps a decade) over reliance and misapplication of nitrogen (N) fertilizers. This project is aimed at determining optimal rates, timing, and placement of aglime for Sichuan Province.

Compared to balanced treatment of nitrogen (N), phosphorus (P), and potassium (K), the combination of 4.5 t/ha of calcitic aglime and balanced NPK significantly increased corn yield by 1,960 kg/ha (54%). In vegetables, application of aglime alone (1.5 t/ha) increased cauliflower yield by 24 to 36%, while a combined application of aglime and balanced fertilization increased yield by 35 to 46%. This strategy has proved to be an effective measure for promoting vegetable growth as well as depressing disease incidence. This technique is applicable to large areas of acid soils in southwest China including Sichuan, Chongqing, Yunnan, and Guizhou. The potential for increased P and K consumption is very large if proper liming practices are adopted on its acid soils. Sichu-15