Nutrient Management Strategies for Sloping Lands in Guizhou

The influence of alley cropping on soil erosion, and specifically, soil potassium (K) loss is a major agronomic concern in developing sustainable crop production technologies. Our tactic of integrating a balanced fertilization (BF) program has shown substantial promise for these highly erosive landscapes of southwest China. Day lily + Chinese prickly ash (D+C) and polygonum cymosum trev + plum tree (P+P) were selected as two hedgerow cropping patterns which are being compared with traditional engineered terraces (ET). Farmers’ fertilization practice (FP) of applying 270-105-0 kg nitrogen (N)-phosphorus (P₂O₅)-K₂O/ha was compared with the BF treatment of 270-105-105 kg/ha plus 6 kg zinc sulfate (ZnSO₄)/ha.

In year 4, soil erosion under each BF treatment was dramatically lower than under FP (24.9 t/ha). Erosion under the BF, BF+(D+C), and BF+(P+P) treatments was 12.8 t/ha (- 48%), 4.4 t/ha (- 82%), and 6.3 t/ha (- 75%), respectively. Balanced fertilization, alone or in combination with alley cropping, significantly increased corn yield by 951 to 1,520 kg/ha (28 to 44%) compared to FP. The exception is the (P+P) treatment which has created unwanted competition for sunlight and soil nutrients as the plum trees grow, and thus, lower corn yields. Hedgerow cash crops are producing considerable economic returns for farmers. BF+(P+P) and BF+(D+C) treatments returned a net income of US$318/ha and US$615/ha, respectively, while farmers’ practice returned a net loss. This technology is now under sponsorship by the provincial government for large-scale demonstration and extension. Guizhou-NMS03