减氮配施秸秆生物炭对双季稻产量和硅、氮营养的影响

Effects of N fertilizer reduction combined with straw biochar application on the yield,Si,and N nutrition of double-cropping rice

氮和硅都是水稻重要的营养元素,但实际生产中经常过量施加氮肥而忽视硅肥的补充。秸秆生物炭含有丰富的硅,可作为一种潜在的硅肥。本研究通过连续3年的田间定位试验,探究氮肥减量配施秸秆生物炭对水稻产量和硅、氮营养的影响。试验包括5个处理:常规施氮(180 kg·hm^(-2),N_(100))、减氮20%(N_(80))、减氮20%配施15 t·hm^(-2)生物炭(N_(80)+BC)、减氮40%(N_(60))、减氮40%配施15 t·hm^(-2)生物炭(N_(60)+BC)。结果表明:与N_(100)相比,减氮20%对水稻的硅、氮累积没有影响;减氮40%导致水稻叶片氮吸收量下降,却显著增加其硅含量(增幅14.0%~18.8%);而减氮配施生物炭大幅增加了水稻叶片硅累积,硅含量增幅达38.0%~63.3%,硅吸收量增幅达32.3%~49.9%,但进一步减少了水稻叶片氮含量。Pearson相关分析表明,成熟期水稻叶片硅含量与氮含量呈显著负相关,而硅吸收量与氮吸收量之间无相关关系。与N_(100)相比,减氮或减氮配施生物炭对土壤铵态氮和硝态氮的影响不大,却在一定程度上提高了土壤pH,减氮配施生物炭显著增加了土壤有机质和有效硅含量,增幅分别达28.8%~41.9%和21.1%~26.9%,且两者呈极显著正相关。此外,与N_(100)相比,减氮40%会降低水稻产量和籽粒结实率,而减氮20%和减氮配施生物炭不会影响水稻产量及产量性状。综上,适量减氮并配施秸秆生物炭在减少氮肥投入的同时,可提升土壤肥力和硅素供应,在双季稻生产中有一定的应用前景。

Nitrogen(N)and silicon(Si)are important nutritional elements for rice.However,excessive N fertili-zer application and the ignorance of Si fertilizer are common in practice.Straw biochar is rich in Si,which can be used as a potential Si fertilizer.In this study,we conducted a consecutive 3-year field experiment to explore the effects of N fertilizer reduction combined with straw biochar application on rice yield,Si and N nutrition.There were five treatments:conventional N application(180 kg·hm^(-2),N_(100)),20%N reduction(N_(80)),20%N reduction with 15 t·hm^(-2)biochar(N_(80)+BC),40%N reduction(N_(60)),and 40%N reduction with 15 t·hm^(-2)biochar(N_(60)+BC).The results showed that compared with N_(100),20%N reduction did not affect the accumulation of Si and N in rice;40%N reduction reduced foliar N absorption,but significantly increased foliar Si concentration by 14.0%-18.8%;while combined application of biochar significantly increased foliar Si accumulation,with an increase of Si concentration by 38.0%-63.3%and Si absorption by 32.3%-49.9%,but further reduced foliar N concentration.There was a significant negative correlation between Si and N concentration in mature rice leaves,but no correlation between Si and N absorption.Compared with N_(100),N reduction or combined application of biochar did not affect soil ammonium N and nitrate N,but increased soil pH.Nitrogen reduction combined application of biochar significantly increased soil organic matter by 28.8%-41.9%and available Si content by 21.1%-26.9%,with a significant positive correlation between them.Compared with N_(100),40%N reduction reduced rice yield and grain setting rate,while 20%N reduction and combined application of biochar did not influence rice yield and yield components.In summary,appropriate N reduction and combined with straw biochar can not only reduce N fertilizer input,but also improve soil fertility and Si supply,which is a promising fertilization method in double-cropping rice fields.