红壤水稻土上双季稻氮素减施增效方法比较

目前我国正在大力推进化肥零增长战略,各种减肥增效措施的实际应用效果越来越受到关注。本文通过连续3年的田间定位试验,探索在红壤地区双季稻种植模式下减氮增效的方法。在江西省典型的红壤水稻土上,设置不施氮肥(CK)、常规施氮量下的农民习惯施氮(C1)、减氮30 kg/hm_2下分次施氮(C2)、减氮30 kg/hm_2下20%缓释尿素一次施用(H1)、减氮30 kg/hm_2下50%缓释尿素一次施用(H2)和减氮30 kg/hm_2下80%缓释尿素一次施用(H3)共6个处理。结果表明:C2、H1、H2和H3处理在早晚稻上比C1处理减施氮素30 kg/hm_2的情况下,产量、秸秆生物量、有效穗数、千粒重、籽粒和秸秆的养分含量没有显著性差异(P0.05);同样除CK外,其他处理植株吸氮总量和氮收获指数也没有显著差异(P0.05);试验3年后各处理的土壤全氮和速效养分也没有显著性差异(P0.05)。但是C2、H1、H2和H3处理的氮肥偏肥生产力和氮肥吸收利用率都显著高于C1处理(P0.05),其中C2、H1、H2和H3处理的氮肥偏生产力6季平均分别提升了19.0%、17.8%、19.9%和24.5%,而氮肥吸收利用率6季平均分别提升了61.7%、44.9%、57.3%和72.3%。而C2处理的氮肥偏肥生产力和氮肥吸收利用率与H1、H2和H3处理之间无显著差异(P0.05)。分次施氮和施用缓释尿素两种方法均是红壤水稻土上减氮增效的有效方法。减氮30 kg/hm_2下,普通尿素配合施用20%比例的缓释尿素可以满足水稻生长的需求,而施用更高比例的缓释尿素(50%和80%)并不会提高水稻产量和氮肥利用率。综合考虑成本,一次性施用20%的缓释尿素是更为切实可行的减氮增效方法。

Comparison of Nitrogen Fertilizer Reduction with Efficiency Increase Methods in Double-rice System in Reddish Paddy Soil

For now, China gives great impetus to the strategy of fertilizer zero growth. The actual application effects of many fertilizer reduction with efficiency increase methods have attracted more and more attentions. In this study, the nitrogen fertilizer reduction with efficiency increase methods in double-rice system in red soil region of South China were explored through field experiments carried out in a typical reddish paddy soil in Jiangxi Province. Six treatments were designed, including none N fertilizer control (CK), conventional N application rate(C1), N application with more times with 30 kg/hm² N reduction(C2), 20% slow-release urea application at one time with 30 kg/hm² N reduction (H1), 50% slow-release urea application at one time (H2) with 30 kg/hm² N reduction and 80% slow-release urea application at one time with 30 kg/hm² N reduction (H3). The results showed that C2, H1, H2, H3 with 30 kg/hm² nitrogen reduction had no significant difference in rice yields, effective panicle numbers, thousand-grain mass, nutrient contents in grains and straws, soil total and available nutrients compared with C1 (P>0.05). The total N absorption and N harvest index of C1, C2, H1, H2 and H3 also showed no significant differences (P>0.05). However, C2, H1, H2 and H3 displayed significant higher nitrogen partial factor productivity and nitrogen recovery efficiency than C1 (P<0.05). Compared with C1, the nitrogen partial factor productivity of C2, H1, H2 and H3 averagely increased by 19.0%, 17.8%, 19.9% and 24.5% and the nitrogen recovery efficiency of C2, H1, H2 and H3 averagely increased by 61.7%, 44.9%, 57.3% and 72.3% in three years, respectively. While there were no significant differences in nitrogen partial factor productivity and nitrogen recovery efficiency among H1, H2, H3 and C2 (P>0.05). According to this study, applying nitrogen fertilizer for more times and applying a proportion of slow-release urea at one time increase the nitrogen use efficiency in the same degree and are both effective nitrogen fertilizer reduction methods. Considering the high labor cost and the expensive slow-release urea, application 20% slow-release urea at one time is more operable nitrogen fertilizer reduction method. In the circumstances of 30 kg/hm2 reduction, ordinary urea applied with 20% slow-release urea can meet the needs of rice growth, and more percentage of slow-release urea (50% and 80%) cannot further increase rice yield and nitrogen use efficiency.