水稻秸秆养分垂直分布特征与不同留茬高度下还田养分估算

为了明确水稻植株不同层次的秸秆养分特征,科学估算不同留茬高度下稻秸养分还田量,通过在成熟期采集江苏省生产上主推的水稻品种植株,用分层切断法,将秸秆从基部向上依次截取5段长度为5 cm的秸秆,剩余部分为第6段(分别用0~5、5~10、10~15、15~20、20~25和25 cm表示6段秸秆),对穗部单独进行脱粒处理获取穗轴与枝梗,对植株各部分秸秆分别进行烘干称重,并进行养分分析。结果表明:在植株基部0~25cm范围内5个层次秸秆干重占植株秸秆干重的比例都表现为随基部向上依次减少的趋势。水稻秸秆N与P含量呈现出从冠层向下递增的趋势,而秸秆K含量则表现出从冠层向下递减的趋势。江苏省水稻秸秆N、P和K养分总量分别为16.16×10~4、2.81×10~4和30.21×10~4t,不同留茬高度秸秆养分还田量不同,留茬高度为15 cm时,水稻秸秆N、P和K养分还田量分别为6.02×10~4、1.43×10~4和6.78×10~4t。不同稻区秸秆还田时应根据留茬高度及稻谷产量水平进行估算秸秆养分还田量,同时结合其它条件科学制定肥料运筹策略。

Vertical distribution characteristics of rice straw nutrient and nutrient returning amount of rice straw under different stubble height

In order to understand the vertical distribution characteristics of rice straw nutrient and estimate the nutrient-returning amount of rice straw under different stubble heights,10 leading rice varieties in Jiangsu province were investigated at maturity.Rice stalks below spike were cut into 6 parts from the basal node,and the first 5 parts were in 5 cm length,marked with 0~5,5~10,10~15,15~20,20~25 and>25 cm,respectively.Panicle axis and branch from rice spikes were sampled as the seventh part.Each part of rice straw was dried and weighed,and then the nutrient contents of nitrogen(N),phosphorus(P)and potassium(K)were measured.The results showed that the proportion of each section of straw to the whole rice straw in biomass decreased gradually in the range of 0 to 25 cm from the base.The N and P content of straw increased gradually from the top to the base of the plant,while the trend of the K content of straw decreased gradually from the top to the base.The total nutrients of N,P and K of rice straw in Jiangsu province were 16.16×104 t,2.81×104 t and 30.21×104 t,respectively.When the stubble height left in field was 15 cm,the nutrient return of N,P and K were 6.02×104 t,1.43×104 t and 6.78×104 t,respectively.The nutrient-returning amount of rice straw was estimated according to the grain yield and stubble height of rice.Meanwhile,the fertilizer management strategy should be made scientifically combing with other conditions.