长期秸秆还田下有机无机配施及微量元素和缓释肥的施用对双季稻产量和肥料利用率的影响

Impact of manure incorporation,microelements and slow release fertilizer application on double rice yield and fertilizer use efficiency under long-term straw return condition

长期秸秆还田背景下,集成几种养分高效利用施肥模式,研究其对红壤水稻产量、吸氮量和土壤地力的影响,为红壤区养分持续高效利用和水稻增产提供依据。2013~2016年在江西省宜春市高安县渡埠农场布置田间定位试验,集成有机替代无机,添加微量元素Si、Zn、S,缓释肥替代化肥,减氮20%等养分高效利用施肥模式。研究不同施肥模式对产量与肥料利用率的影响。结果表明,与常规只施尿素相比,8季有机替代,添加微量元素Si、Zn、S,缓释肥替代,都没有显著增加产量;有机肥处理地上部吸氮量相对更高(P<0.05);减氮20%降低产量,但没有达到显著水平,地上部吸氮量下降显著(P<0.05)。不同年份早、晚稻产量波动较大;早稻与晚稻相比,产量有高有低。早、晚稻的农学效率分别为20.6~24.8 kg/kg及14.5~18.4 kg/kg;早、晚稻的氮肥表观利用率分别为31.6%~40.0%及26.0%~35.4%。缓释肥表观利用率最高,但与化肥相比没有达到显著差异(P=0.07)。4年结束后,不同施肥处理耕层(0~20 cm)土壤有效磷和速效钾含量差异显著(P<0.05),土壤有机质、全氮、pH及微生物量碳氮都没有显著差异。长期秸秆还田红壤稻田,通过8季20%有机替代,添加Si、Zn、S微量元素及缓释肥施用等增产增效模式都没有显著增加双季稻产量、土壤有机质和全氮,说明长期秸秆还田对产量和地力影响很大,在此基础上增加有机肥具有增产趋势,但需更长时间达到显著水平;同时,秸秆加有机肥可以满足水稻对微量元素的需求。

Under long-term rice straw return condition,fertilizer management methods which can increase rice yield and fertilizer use efficiency have been integrated to see if they can increase rice yield and rice nitrogen(N)uptake in red paddy soil.Four-year(2013~2016)experiment was carried out in Dufu farm in Gaoan county,Yichun city,Jiangxi province.Six fertilizer management methods were chosen,including partial substitution of fertilizer with manure and/or slow release fertilizer,incorporation of microelement(Si,Zn,and S),and nitrogen input decreased by 20%.Rice yield and straw weight were measured at each season.Nitrogen and phosphate uptake in rice and straw were measured.Both nitrogen use efficiency and agronomic efficiency of fertilizer N were calculated.Soil properties and microbial biomass were analyzed after the late rice was harvested in 2016.The results showed that there were no significant differences in rice yields under different fertilizer treatments.Above ground N uptakes were significantly higher under manure application(P<0.05).Rice yield decreased when fertilizer N was cut by 20%;however,the decrease was not significant.Above ground N uptake decreased significantly under 20%N cutoff.Early rice yield and late rice yield varied in different years.Late rice yield was not always larger than early rice yield.Nitrogen agronomic efficiency for early and late rice was 20.6~24.8 kg/kg and 14.5~18.4 kg/kg,respectively.Nitrogen recovery fraction for early and late rice was 31.6%~40.0%and 26.0%~35.4%,respectively.Nitrogen recovery fraction for slow release fertilizer was larger than other fertilizer treatments,but the difference was not significant(P=0.07).There were no significant differences in soil organic matter,total N,pH,and microbial biomass C,microbial biomass N in arable layer under all treatments except available potassium and phosphate.Double rice yield,soil organic matter and total N did not increase under manure incorporation,micronutrient input and slow release fertilizer application over four-year field experiment.This implied that long-term straw return had great effects on rice yield,therefore,it takes longer time to increase rice yield to a significant level under manure incorporation.Furthermore,soil provided enough micronutrients for double rice growth under straw and manure application because extra application of micronutrients did not result in an increase of rice yield and N uptake over eight seasons.