Assessment on the storage and value of soil nutrient under different grade of rocky desert in karst hilly region: A case study in small karst watersheds Wuqing and Pianyan of Guizhou Province

In order to discuss the impacts of different grades of rocky desert on soil nutrient storage and economic value, the soil nutrient storage and its potential value in different grades of rocky deserts are assessed by means of soil nutrient pool calculation method and value substitution method. The basis of the assessment in this paper is the studying on the variations of soil nutrient contents in rocky deserts with potential desertification (Ⅱ), mild desertification (Ⅲ) and moderate desertification (Ⅳ) as well as severe desertification (Ⅴ) in comparison to the farmland without karst desertification(Ⅰ). The results show that, firstly the contents of organic matter(OM), total N(TN), available N(AN), total P(TP), available P(AP), total K(TK) and available K(AK) of soil in 0 to 40 cm depth is 32.31~104.12 g/kg, 1.35~2.87 g/kg, 76.90~124.00 mg/kg, 0.49~1.12 g/kg, 1.03~10.71 mg/kg, 12.25~26.22 g/kg and 114.35~245.35 mg/kg respectively; secondly, the storages of total soil nutrients, OM, TN, TP and TK is 3.79~61.41 t/hm2, 2.55~48.56 t/hm2, 0.13~1.36 t/hm2, 0.04~0.52 t/hm2 and 1.07~10.97 t/hm2 respectively; thirdly, the values of total soil nutrients, OM, TN, TP and TK is 0.86~9.80×104 yuan/hm2, 0.08~1.55×104 yuan/hm2, 0.29~3.08×104 yuan/hm2, 0.04~0.53×104 yuan/hm2 and 0.45~4.64×104 yuan/hm2 respectively; fourthly, soil nutrient storage and value are the highest in gradeⅠand lowest in gradeⅤ, and the content, storage and value of soil nutrient decrease with the aggravating of rocky desertification.