Nutrient management and balanced fertilization in Shaanxi province

Experiments in 2010 targeted nutrient management techniques for improved yield and quality in apple, kiwi, wheat, and corn in Shaanxi Province. The nutrient recommendation for a 16-year-old apple orchard at Heyang County was 0.6-0.24-0.3 kg N-P₂O₅-K₂O/tree (1,667 trees/ha). Two-thirds of the N was applied basally, after harvest, and the remainder was topdressed the following spring. This recommendation produced 48 t/ha, 14.3 t/ha (+42%) more than N omission, 19.4 t/ha (+68%) more than P omission, 7.1 t/ha (+17%) more than K omission, and 11.7 t/ha (+32%) more than farmer practice (1.28-0.46-0 kg/tree). This recommendation also generated an additional USD 7,868/ha over traditional farmer practice. Similar kiwi research at Yangling City determined 0.23-0.12-0.12 kg N-P₂O₅-K₂O/tree (2,000 trees/ha) to be most suitable. This produced 23 t/ha of kiwi fruit, or 22%, 24%, and 11% more than the 1/2N, 1/2P, and 1/2K plots, respectively. These yield gaps were valued (USD) at 1,985/ha, 2,224/ha, and 1,075/ha. Evaluation of an additional treatment supplying 50% more NPK reduced the attainable yield by 5%. The NPK recommendation plus 8 kg farmyard manure generated 6% more yield over NPK alone, and increase valued at USD 522. The NPK recommendation also improved fruit quality by impacting vitamin C content, soluble sugars, and the sugar-to-acid ratio.

A K rate experiment on winter wheat at a K responsive site (available soil K of 146 mg/kg) near Yangling City determined 50 kg K₂O/ha to be more effective that either 25 kg K₂O/ha and 75 kg K₂O/ha if co-applied with 150-50 kg N-P₂O₅/ha. Yield with the 50 kg K₂O/ha rate was 7% and 15% higher than with the 25 kg K₂O/ha and 75 kg K₂O/ha rates, respectively. Various NPK combinations were evaluated on maize in Yangling City, but 180-40-50 kg N-P₂O₅-K₂O/ha produced the highest grain yield of 11.5 t/ha. Combinations using more N and/or less P generated less grain yield and reduced nutrient use efficiency. Shaanxi-NMBF