Nutrient Management for Sorghum

Sorghum is a key ingredient in Chinese liquor production. In recent years, as the demand for liquor has increased, the area planted to sorghum has also increased. The aim of this experiment was to determine the best nutrient management guides for sorghum in Chongqing. The experiment consisted of ten treatments, including four application rates of N (0, 110, 220, 330 kg N/ha), four rates of P (0, 60, 120, 180 kg P₂O₅/ha) and four rates of K (0, 65, 130, 195 kg K₂O/ha). Nitrogen was used as urea (N 46%), P as single superphosphate (SSP - 12% P₂O₅) and K as (KCl - 60% K₂O). All P, 40% of N and 50% of K were applied as basal fertilizers at seeding, and the rest of the N and K fertilizers were topdressed at elongation stage.

Sorghum yields were significantly boosted with an increase in the application rates of N, P and K, reaching the highest yields of 7,817 kg/ha at the set-optimal rates of 220-120-130 kg N-P₂O₅-K₂O/ha. This implies that the set-optimal rates can be used in the region before any adjustment is made through future field experiments. Yield increases with nutrient application followed the order: N (18%) > P (12%) > K (9%). The agronomic efficiency of N fertilizer was highest at the set-optimal rate, while those for P and K decreased with an increase in fertilizer rates. The net income was also the highest (US$3,418/ha) for the set-optimal fertilizer rates, which was 26, 24 and 10% higher than the treatments omitting N, P and K, respectively. The ratios of nutrient partitioning in grain to straw decreased with an increase in N and P rates, but remained relatively constant for K rates. This indicated strong K-absorption ability of sorghum even at high grain yields.