Nutrient Management and Optimized Fertilization on Maize in Heilongjiang Province

Soybean, corn, and rice are three major crops in Heilongjiang Province. However, fertilization on these crops is often inadequate and imbalanced. In 2006, field experiments were conducted in Shuangcheng County on spring corn, Hailun County on soybean, and Huachuan County on rice, all with the common objective of promoting balanced fertilization and raising farmers’ income.

In spring corn, the balanced optimum (OPT) of 160-68-90 kg N-P₂O₅^-K₂O/ha plus 135 gypsum/ha + 20 kg zinc sulfate (ZnSO₄)/ha produced the highest yield of 11.7 t/ha and best profit of US$1,401/ha. Nitrogen was the most significant nutrient limitation for corn. The K omission treatment produced 15% less yield and returned 17% less profit. The treatment without Zn produced 15% less yield and 20% less profit. The OPT in soybean was 65-90-83 kg/ha plus 135 gypsum/ha + 20 kg ZnSO₄/ha, which achieved a high yield of 2.4 t/ha. Treatments omitting N, P, and K produced 23%, 35%, and 36% less yield, and returned 28%, 18%, and 60% less profit, respectively. Macronutrient omission would significantly hamper the profitability of soybean production in Heilongjiang. In rice, the OPT of 143-60-75 kg/ha plus 20 kg ZnSO₄/ha + 15 kg Boric acid (B)/ha achieved a high yield of 8.5 t/ha and return of US$2,043/ha. Nitrogen and S were the most significant nutrient limitations for rice. Omission of N or S both resulted in 25% less yield and 33% less profit.

A 14-year fixed-site experiment on corn continues to produce significant responses to K application. Application of 173-120 kg N-P₂O₅/ha plus either 113 kg K₂O/ha or 225 kg K₂O/ha produced grain yields of 9.5 t/ha and 9.2 t/ha, respectively. These yields are 23% and 22% higher than zero K check treatment using N and P only, which translates into increased returns of US$221/ha and US$155/ha compared to the check. Heilongjiang-NMBF