Effects of continuous no-tillage on crop yield and soil fertility in double rice cropping system | 双季抛栽条件下连续免耕对水稻产量和土壤肥力的影响

Chinese. 【目的】研究连续免耕对双季水稻产量和土壤肥力的影响,为南方稻区土壤合理耕作和水稻免耕抛秧栽培技术的推广应用提供参考依据。【方法】2005―2009年在大田试验条件下,以翻耕抛栽为对照,探讨稻田连续免耕抛栽对水稻产量、土壤容重、总孔隙度、非毛管孔隙度、土壤保水性、土壤养分、土壤微生物和土壤酶活性的影响。【结果】稻田免耕1―2年(4季),早、晚稻产量较翻耕处理的产量分别增加了2.70%和1.87%,但与对照差异不显著。随着免耕时间的延长,早、晚稻产量均表现为下降,尤其是免耕5年水稻产量下降更为显著,下降幅度分别为9.16%和12.56%;稻田免耕1年(2季),有利于土壤物理性状的改善,随着免耕时间的延长,土壤物理性质变差,较翻耕相比,容重增幅为1.68%―8.01%,总孔隙度减少0.69%―4.48%,非毛管孔隙度下降15.42%―37.92%;免耕有利于土壤养分在表层土壤富集,但不利于土壤水分的保持;土壤中三大类微生物总量免耕处理小于翻耕处理,免耕土壤细菌的数量增加,而放线菌和真菌的数量减少;免耕土壤中脲酶活性增加;脲酶,过氧化氢酶和多酚氧化酶的活性均与土壤有机质、全氮含量呈极显著相关,而过氧化物酶活性则与土壤全氮和速效钾含量呈极显著相关。【结论】稻田免耕1―2年(4季)产量与翻耕无显著差异,免耕1年有利于土壤物理性状的改善,随着免耕时间的延长,土壤物理性质变差,早、晚稻产量均表现为下降。免耕有利于土壤养分在表层土壤富集,但不利于土壤水分的保持。免耕土壤细菌的数量增加,而放线菌和真菌的数量减少,免耕土壤中脲酶活性增加。

English. 【Objective】 Continuous no-tillage effects on crop yield and soil fertility in double rice cropping system were studied in order to provide valuable references to technique selection of soil management and rice cast-transplantation for this cropping system in South China. 【Method】 No-tillage with cast-transplanting has been conducted in paddy field with double rice cropping system since 2005 in Nanchang city, Jiangxi Province. Crop yield and soil fertility indexes, such as density, porosity, water retention property, nutrient, microbe and enzymes activities were simultaneously determined in this study.【Result】 The early and later rice grain yield were 2.70% and 1.87% higher than that under conventional tillage, respectively, under no-tillage treatment of one and two years (four crops), but crop yield in different treatments was not different significantly. As the time of no-tillage prolonged,early and later rice grain yield decreased, particularly no-tillage of five years decreased by 9.16% and 12.56%. The no-tillage treatment of one year (two crops) improved soil physical properties, but as the time of no-tillage prolonged, worsened soil physical properties, the density was 1.68%-8.01% higher than that under conventional tillage,and the porosity decreased by 0.69%-4.48%,and non-capillary porosity decreased by 15.42%-37.92%. The no-tillage treatment helped nutrient enrichment in the surface soil layer, but decreased soil water retention property. Soil analysis showed that the no-tillage field was less than the control, plowed field in total amount of three groups of soil microbes. However, in no-tillage field, the amount of soil bacteria increased, while that of soil actinomyces and fungi decreased, and urease activity in surface layer soil increased. Significant positive correlations were observed in soil organic matter and total N with urease, catalase and polyphenol oxidase activity. Significant positive correlations of soil total N and available K with peroxidase activity were also obsearved. 【Conclusion】 In comparison to conventional tillage, crop yield in no-tillage treatment of one and two years (four crops) was not differ significantly, no-tillage treatment of one year improved soil physical properties, but as the time of no-tillage prolonged, worsened soil physical properties,early and late rice grain yield decreased. The no-tillage treatment helped nutrient enrichment in the surface soil layer, but decreased soil water-retention property. In no-tillage field, the amount of soil bacteria increased, while that of soil actinomyces and fungi decreased, and urease activity in surface layer soil increased.