Effect of slow-release fertilizer and tillage practice on grain yield and nitrogen efficiency of summer maize (Z. mays L.)

【Objectives】 N release dynamics of fertilizers plays an important role in increasing yield and nitrogen efficiency of maize. Soil tillage practice has remarkable influence on nitrogen use efficiency as well. In this paper, effects of a slow-release fertilizer with different tillage practices on grain yield and nitrogen efficiency of summer maize were compared, to identify the optimum soil tillage for the application of the slow-release fertilizer. 【Methods】 Two factors split plot expernments were conducted in Henan from 2013 to 2014 with summer maize as materials. The main factor was three soil tillage management, rototilling (R), no-tillage (N) and sub-soiling (S); The subplot treatments were nitrogen fertilizer; slow release fertilizer N 270 kg/hm2, conventional fertilizer N 270 kg/hm2 (40% as basal application and 60% at the beginning of male tetrad stage), and no nitrogen fertilizer (control). 【Results】Under the same tillage, the grain yield and nitrogen use efficiency of the slow release fertilizer treatment are higher than those of applying the conventional fertilizer, and the differences are the greatest under the sub-soiling tillage. Among the tillage treatments, the yield of the slow release fertilizer treatment under the sub-soiling tillage (S-SRF) is 13.4%-59.2% higher than those of other treatments, while the agronomic nitrogen use efficiency of nitrogen (AEN) and recovery efficiency of applied nitrogen (REN) of S-SRF are 27.9%-72.7% and 15.1-55.7 percentage points higher, respectively, compared to those for other treatments. The yield and NUE increases are mainly affected by the dry matter accumulation and nitrogen accumulation (especially post-silking). The post-silking dry matter accumulation of applying the slow release fertilizer is 13.0%, 12.7% and 18.7% higher, respectively, compared to those for the conventional fertilizer treatments under rototilling, no-tillage, and sub-soiling. Furthermore, the post-silking nitrogen accumulation of applying the slow release fertilizer is 14.4%, 16.8% and 17.8% higher, respectively, compared to those for the conventional fertilizer treatments under rototilling, no-tillage, and sub-soiling. The post-silking dry matter accumulation and nitrogen accumulation of S-SRF are significantly higher than those of other treatments. 【Conclusions】 The yield and nitrogen use efficiency of maize in the two years are highest under the sub-soiling with the slow release fertilizer application. From the results we can conclude that the combination of sub-soiling and the application of slow release fertilizer could provide an approach for enhancing the nitrogen fertilizer use efficiency and getting high yield.