不同来源氮素配合施用提高东北春玉米氮素利用与改善土壤肥力的可持续性研究

Effects of combined application of nitrogen from different source on nitrogen utilization of spring maize and sustainability of soil fertility in Northeast China

【目的】研究不同氮素形态对东北春玉米氮素利用和土壤肥效的影响,为氮素养分持续高效利用和培肥土壤提供理论依据。【方法】2013~2015年连续三年在东北典型春玉米种植区开展田间定位试验,在相同磷钾肥施用前提下,试验设4个处理:1)50%玉米秸秆氮(N0);2)100%速效氮165 kg/hm^2(N1);3)60%速效氮+20%有机肥氮+20%缓释氮,施氮量165 kg/hm^2(N2);4)N2+生物炭,生物炭量相当于50%玉米秸秆(N3)。收获期测定耕层土壤基本理化指标、作物产量及氮素利用率、基肥和追肥后土壤N_2O排放量。【结果】1)三年玉米平均产量N1、N2和N3处理分别比N0处理显著增加了62.7%、67.7%和80.1%(P<0.05);N2和N3处理分别比N1处理增产3.0%和10.7%;N3处理玉米产量可持续性指数(SYI)最高,产量可持续性最好。2)与N1处理相比,2013年和2014年累计化肥氮利用率N2和N3处理分别增加了8.4%和12.7%、10.2%和15.5%,2015年分别显著增加了8.4%和12.7%(P<0.05)。N2和N3处理累计化肥氮利用率呈现逐年增加的趋势,且N3处理增加幅度大于N2处理,说明N3处理氮肥的后效更加明显。3)施氮处理显著提高了土壤N_2O累积排放量(P<0.05),N3处理较N1处理显著降低了53.2%;4)N3处理的综合土壤肥力指数(IFI)最高,N3处理在农学、土壤肥力和环境效应评价中最优。【结论】在总氮施用量不变的前提下,以添加适宜比例生物炭、有机肥和缓释氮肥替代部分速效化肥氮,可协同实现东北春玉米持续稳产、氮素养分持续高效利用和土壤肥力的可持续改善。

[ Objectives ] This paper focused on sustaining high use of nitrogen （N） and improving soil fertility by applying different N forms in Northeast China. [ Methods ] A 3-year field experiment was conducted in Heilongjiang Province, China during 2013 to 2015. Under the same rates of P and K input, four treatments were designed： 1） only 50% maize straw （NO）; 2） 100% chemical N fertilizer （N 165 kg/hm2, N1）; 3） 80% chemical N fertilizer （60% fast released and 20% slow released N） ＋ 20% organic N fertilizer, as N 165 kg/hm2 （N2）; and 4） N2 ＋ biochar, with the same amount as 50% maize straw （N3）. The plant and soil samples （0-20 cm depth）were collected at the harvest, the related items were analyzed using regular methods. N20 emission was analyzed after the basic and topdressing fertilization. [ Results ] Compared with the NO, the average yields of the N1, N2 and N3 from 2013 to 2015 were significantly increased by 62.7%, 67.7% and 80.1% （P 〈 0.05）, respectively. The average maize yield of three years in the N1 was 10421 kg/hm2 which was 3.0% and 10.7% lower than those of the N2 and N3, respectively. The sustainable yield index （SYI） in the N3 was higher than those in other treatments. Compared with N1, the cumulative chemical N use efficiencies of the N2 and N3 were increased by 8.4% and 12.7% in 2013, by 10.2% and 15.5% in 2014, and significantly increased by 8.4% and 12.7% in 2015 （P 〈 0.05）. The cumulative chemical N use efficiencies of the N2 and N3 showed increasing trend year after year and the increase in the N3 was bigger than in the N2. The single application of fast release N fertilizer resulted in greater soil N20 emission. Soil N20 emission in the N3 was significantly decreased by 53.2% compared to the N1 （P 〈 0.05）. The integrated fertility indexes （IF1） in the N3 was higher than those in other treatments. [ Conclusions ] The optimum N managements can be coordinated to achieve high maize yield and high N use efficiency in Northeast China by regulating the amount of N fertilizer with adding biochar and substituting chemical fertilizer N with organic fertilizer N and slow release N.