Soil Nutrition Management for Sustainable Agriculture in Shaanxi

Apple, grape, kiwi fruit, and hot pepper provide the main source of income for thousands of farmers in Shaanxi, with respective planted areas of 369,000 ha, 15,000 ha, 11,000 ha, and 20,000 ha. Potassium (K) fertilizer field experiments were carried out for apple in Heyang County, as well as for grape, kiwi fruit, and hot pepper in Fufeng County. Both sites are located in the loess plateau and regarded as ‘K-rich’. As a result, little K fertilizer is used and K fertilizer can not be easily found in the marketplace.

The apple experiment showed that K enhanced nutrient uptake in trees and this improved yield. Fruit quality analysis found K application at 333 kg K₂O/ha along with nitrogen (N) [422 kg N/ha] and phosphorus (P) [310 kg P₂O₅ /ha] improved vitamin C (Vc) content by 1.7 mg/100g, with sugar content increasing from 17.8% to 21.1% and total acidity decreasing from 0.96% to 0.74%. Potassium application increased apple yield by 2.7 t/ha (11.8%), and production value by US$2,542/ha.

Grape quality improved with K applied at 300 kg K₂O/ha along with 712 kg N/ha and 375 kg P₂O₅ /ha. Vc content increased by 1.0 mg/100g, sugar content increased from 10.5% to 12.1%, and total acidity decreased from 0.69% to 0.58%. Grape tree growth was enhanced with K, and grape yield was increased by 2.3 t/ha (11.9%).

Kiwi fruit quality improved with K applied at 1,080 kg K₂O/ha along with 1,440 kg N/ha and 720 kg P₂O₅/ha. Vc content in kiwi fruit increased by 19.0 mg/100g, sugar contained increased from 6.8% to 8.7%, and total acidity decreased from 1.85% to 1.68%. Single fruit weight increased by 5.7g and fruit yield by 3.7 t/ha, a production value increase of US$1,089/ha.

A nutrient omission trial for hot pepper determined the optimum to be 300-225-300 kg N-P₂O₅-K₂O/ha, which produced a highest yield of 17.3 t/ha. Omission of N, P, or K from the optimum resulted in yield reductions of 29%, 4.2%, and 22%, respectively, providing an indication of the importance of these three nutrients to hot pepper production. Shaanxi-NMS02