Statistics from the 2nd National Soil Survey in the late 70's and early 80's showed that almost all the soils in southwest China were deficient in P. In the late 90's, however, soil available P nutrient status, according to limited available information, was changed considerably (Table 1). The change was closely related to patterns of land use and fertilizer practices. For example, soils where vegetables are grown have significantly built up P, but in soils where grain is grown, P still remains deficient. This is obviously attributed to the heavy application of N and P fertilizers to vegetables because of their higher economic returns compared to grain crops. Therefore, the phosphate need in agriculture in southwestern China, like K, is still quite large.

Table 1. Available P status of soils where vegetables and grain crops are grown in southwest China

Province	Available P (mg/kg) 1
	Average	Range	Deficient (%)
Vegetable soils
Sichuan	67.6	9.8-24	9.3
Chongqing	30.1	8.5-79	21.4
Grain crop soils
Sichuan	7.8	1-31.3	78
Chongqing	4.9	0.5-19	93
Yunnan	11.8	2.7-21	70
Guizhou	7.4	3.5-21	88
Tibet	-2	7.6-64	-

1. Soils with available P levels below 12 mg/kg are considered deficient in P and crops will most likely respond to P application.
2. Number of soil samples analyzed were too small to get a representative average value for the province.