The relationship between doses of self-produced humic acid (HA) compound fertilizer and nutrient utilization in rape

Based on the best fertilizer chosen according to soil culture experiment, the relationship between different amount of HA compound fertilizer and nutrient utilization of rape (Brassica campestris L. ssp. chinensis L. Makino) was investigated under field conditions. The results showed that HA compound fertilizer promoted the plant absorption of N?P and K, increased the utilization rate of N and P and the recovery rate of K. With fertilizer amount increase, the absorption of N?P and K for rape in inorganic fertilizer and HA compound fertilizer both increased, and the highest value was at 900 kg/hm~2. After this, the nutrient absorption was decreased. On the higher fertility soil and with fertilizer amount increase, the utilization of N?P and K in inorganic fertilizer and K in HA compound fertilizer for rape all tended to decrease. N and P utilization for rape in HA compound fertilizer was the highest when the amount was at 600 kg/hm~2, then it decreased. HA compound fertilizer also simulated the absorption of nutrient and water and the synthesis of dry matter. When HA compound fertilizer was 1 005 kg/hm~2, the highest yield of rape was 69.19 t/hm~2. The second harvest yield of rape indicated HA compound fertilizer had some advantages of slow-release, long-efficiency and high-nutrient-utilization-rate.