Study on nutrient release characteristics and fertilizer efficiency of controlled-released fertilizers on rice and maize

摘要

This paper concerns a study on the use on rice and maize of controlled release fertilizers with PVA, polyvinyl alcohol, and starch as coaling materials. Pot and field tests were used to study the characteristics of nutrient release with two coating materials with two thicknesses. The results show that the nutrient release of coating material B was better than that of A. In the case of maize, the controlled release of nitrogen of material B with a 5 % coating thickness was better than that with an 8%coating thickness. But for P and K, the thicker the coating material, the longer the nutrient release period and the higher the utilization rate. Without taking account of the price factor, it was preferable to coat PK fertilizers with an 8% coating thickness. On rice, the yields and the N, P and K nutrient utilization rate with coating material B were higher than with coating material A. Throughout the growth of the rice, the total uptake of N as well as of P and K and their utilization rate was higherwith an 8% coating thickness than with a 5% coating thickness. Hence, an 8% coating thickness is preferable for rice. After adding an inhibitor into coating material B, the total nutrient absorption of the maize and rice plants and the fertilizer utilization rate were all lower than that of B treatment without inhibitor. The inhibitors did not enhance the slow-release of nitrogen. The inhibitor increased the water-solubility of the coated material, which reduced the controlled-release function.