秸秆还田量对直播稻苗期生长和土壤的影响

Effects of different amount of wheat-residue application on growth of direct-seeding rice and characteristics of soil

以徐稻3号为材料,进行盆栽试验,设置3 t/hm2（S1）、4.5 t/hm2（S2）、6 t/hm2（S3）和7.5t/hm2（S4）4种秸秆还田量,以秸秆不还田（S0）为对照,测定不同秸秆还田量下直播稻的出苗率、干物重、根长、根系活性、秸秆腐解动态、土壤p H及有机酸含量等指标,探讨不同秸秆还田量对直播水稻出苗与苗期生长的影响以及土壤特性差异。结果表明：秸秆还田显著降低直播水稻的出苗率,出苗率降低13.1~31.6个百分点,少量秸秆还田处理（S1）对直播水稻的根系形态、根系活性及植株干重无显著影响,随着秸秆还田量的增加,直播稻苗期生长发育速度及根系活性均降低,但出苗20 d后,S3与S4处理植株形态及根系活性无显著差异;秸秆还田降低了土壤pH值及秸秆的腐解率,增加了土壤中秸秆腐解量与土壤中有机酸含量,但在S3与S4处理下无显著差异;相关分析表明,直播水稻出苗率与土壤有机酸含量呈极显著负相关。

More than half of wheat-residue are burnt or discarded for years in China, which not only wastes organic fertilizer source, but also pollutes the environment. To investigate the effects of different amount of wheat- residue application on emergence in direct-seeding rice and physiological bases, a mid-season japonica rice cultivar of Xudao 3 was directly sown in the pot, four treatments of wheat-residue application, 3 t/hm2 （ S1 ） , 4.5 t/hm2 （ S2 ） , 6 t/hm2 （ S3 ） and 7.5 t/hm2 （ S4 ） were set, the indicators like seedling emergence, dry matter weight, and root length, root activity, decomposing and dynamic of straw, soil pH and organic acid content were determined. The results showed that the wheat-residue application （ the residue was incorporated into soil ） reduced seedling emergence by 13.1%-31.7% compared with the wheat-residue removal treatment. There was no significant difference in morphological and physiological activity in direct-seeding rice between small amount of wheat-residue returning （ S1 ） with the wheat-residue removal treatment. With the increase of wheat-residue amount, morphological and physiological activity of direct-seeding rice decreased, while no obvious difference was found between S3 and S4 treatment after 20 days of seedling. Wheat-residue application reduced the soil pH and straw decomposing rate, increased the amount of decomposing quantity and organic acid content in the soil, but there was no significant difference under S3 and S4 treatment. Seedling emergence in direct-seeding rice was significantly correlated with the soil organic acid content, the correlation coefficient reached 0.8951. Reasons for the characteristics of soil in direct-seeding rice, growth and development under different amount of residue returning were discussed, to provide theoretical basis for clean and light simplified cultivation in rice.