水炭运筹对寒地黑土区稻田土壤肥料氮素残留的影响

为揭示水炭运筹下肥料氮素在稻田土壤中的残留情况,采用田间小区试验与微区试验相结合的方法,应用15N示踪技术,以传统淹水灌溉作为对比,研究水分管理模式和生物炭施用量二因素全面试验构成的不同水炭运筹模式下水稻收获后基肥、蘖肥、穗肥和肥料整体在稻田土壤中的残留情况,以及各阶段施用的肥料氮素残留在不同深度土层的分布规律。试验结果表明,稻作浅湿干灌溉模式不同生物炭施用水平下施用的氮肥在稻田土壤中的总残留率为28.16%~34.42%,其中基肥、蘖肥和穗肥氮素的残留率分别为27.53%~41.35%、34.32%~43.50%和11.58%~25.67%。当生物炭施加量在0~12.5 t/hm^2时,水稻收获后两种灌溉模式下基肥和蘖肥氮素在土壤中的残留量均随着生物炭施入量的增加而增大,而穗肥氮素在土壤中的残留量随生物炭施入量的增加而减小,相同生物炭施用水平下稻作浅湿干灌溉模式各阶段肥料氮素在土壤中的残留率显著高于传统淹水灌溉(P<0.05),且两种灌溉模式肥料氮素在相同土层深度中的残留量差异显著(P<0.05),不同生物炭施用水平下稻作浅湿干灌溉模式各阶段施用的氮肥在稻田0~20 cm土层中的残留量均高于传统淹水灌溉,而在40~60 cm土层的残留量均低于传统淹水灌溉;施加25 t/hm^2生物炭时,对稻作浅湿干灌溉模式的基肥、蘖肥和穗肥氮素在稻田土壤中的残留产生负效应。合理的水炭运筹模式能够增加耕层土壤(0~20 cm)肥料氮素残留量,减少肥料氮素损失,抑制肥料氮素向深层土壤运移,降低残留在土壤中的肥料氮素对稻田生态环境造成污染的风险。

Effects of Water and Biochar Management on Nitrogen Fertilizer Residue in Paddy Fields of Cold and Black Soil Region

In order to reveal the residual situation of fertilizer nitrogen in paddy soil under water and biochar management,the method of combining field plot experiment with micro-plot was used to label basal fertilizer,tillering fertilizer and panicle fertilizer respectively.Compared with traditional flooding irrigation,the residual situation of basal fertilizer,tillering fertilizer,panicle fertilizer and whole fertilizer in paddy soil after rice harvest and the distribution law of nitrogen residue in different depths soil layer of fertilizer applied at different stages under different water and biochar management modes were studied.The results showed that the total nitrogen residues in paddy soils under different biochar application levels was 28.16%~34.42%under dry-wet-shallow irrigation mode,and the nitrogen residues of basal fertilizer,tillering fertilizer and panicle fertilizer were 27.53%~41.35%,34.32%~43.50%and11.58%~25.67%,respectively.When the application amount of biochar was below 12.5 t/hm^2,the residual amount of basal fertilizer and tillering nitrogen in paddy soil was increased with the increase of biochar application amount under the two irrigation modes after harvest,while the residual amount of panicle fertilizer nitrogen in paddy soil was decreased with the increase of biochar application amount.Under the same application level of biochar,the residual rate of fertilizer nitrogen in soil was significantly higher than that in conventional flooding irrigation(P<0.05),the residual amount of fertilizer nitrogen in the same soil depth under the same biochar application level was significantly different between the two irrigation modes(P<0.05).The residual amount of nitrogen fertilizer applied at different stages under different biochar application levels in paddy field under dry-wet-shallow irrigation mode was higher than that under conventional flooding irrigation,while the residual amount in 40~60 cm soil layer was lower than that under conventional flooding irrigation.And the application of biochar as 25 t/hm^2 had a negative effect on the residual nitrogen of basal fertilizer,tillering fertilizer and panicle fertilizer in paddy soil under dry-shallow-wet irrigation mode.Reasonable water and biochar management model can increase the residual amount of fertilizer nitrogen in plough soil(0~20 cm),reduce the loss of fertilizer nitrogen,inhibit the movement of fertilizer nitrogen to deep soil,and reduce the risk of pollution of fertilizer nitrogen residue in soil to paddy ecological environment.The results can provide theoretical basis and technical support for the application of water and carbon management model in paddy field in cold and black soil region.