Comparison Of Soil Available P Extraction Methods And Their Abundant And Deficit Indices In Sugarcane-growing Areas

Guangxi is one of main sugarcane-producing areas in China, occupying more than 50% of national sugarcane cultivation. But for sugarcane-growing areas, soil available P extraction methods and their abundant and deficit indices have not been determined. In our study, laboratory analysis, pot test and field investigation was used to study the relationship between soil P content and soil pH, comparison of both soil available P extraction methods and and their abundant and deficit index system, and soil and plant P status in sugar cane-growing areas of Guangxi. Main results are outlined as follows:1. Soil available P contents extracted by Mehlich 3 (M3) and Olsen methods were negatively correlated with soil pH, i.e. the higher soil pH, the lower soil available P content.2. Soil available P content extracted by M3 method was significantly correlated with that extracted by Olsen-P, with correlation coefficient of 0.9658-0.9732, therefore both methods can be applied to determine soil available P of sugarcane-growing areas in Guangxi. 3. Based on the results of pot test, the abundant and deficit index system of soil available P was respectively established for the M3 and Olsen methods. As for the Olsen method, soil available P content of lower than 7 mg /kg indicates very low level; 7-11 mg /kg low level; 11-16.5 mg /kg middle level; greater than 16.5 mg / kg high level.4. Most of soils in the sugarcane-growing area of Guangxi were acidic -slightly acidic, with higher level of soil available P content. About 48.3% of soil available P content was at the higher and middle levels, and 13.8% at low level.