[Effects of planting pattern and bare rock ratio on spatial distribution of soil nutrients in Karst depression area]

This paper studied the effects of planting pattern and bare rock ratio on the spatial distribution of soil nutrients in Karst depression area of northwest Guangxi. The results showed that planting pattern had significant effects on soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), available nitrogen (AN), available phosphorus (AP), available potassium (AK), and C/N. Bare rock ratio also had significant effects on SOC, TN, TP, TK, AN, AK and C/N, and was the crucial factor in determining the spatial variability of SOC, TN, TP and AN, which was mainly due to the higher intensity of cultivation in the places covered with less bare rock. Fields planted with Cajanus cajan-Castanca mollissima had significantly higher contents of SOC, TN, TN, TK, AN, and AK than those with other planting patterns, suggesting that converting farmland into forestland had positive effects on the accumulation of soil nutrients. Due to the effects of local topography and land use structure, foot slope had a higher content of SOC than depression, while fertilization made the depression have a higher content of AP than foot slope.