稻田长期水旱轮作对土壤肥力的影响研究

经过10a的稻田水旱轮作(小麦或油菜—中稻)和1a只种1季中稻(中稻—中稻即水水连作)定位试验研究,结果表明:稻田长期水旱轮作0～10cm土层的土壤容重比1季中稻处理高23.4%,土壤收缩量小38.2%,水旱轮作有利于土壤水稳团聚体的形成,<0.01mm土粒团聚度增大,水旱轮作消除了因长期淹水对土壤结构的不良影响;随着种植年限增加,不论哪一种耕作方式均可使土壤有机质、全N、全P含量增加,土壤速效N,P,K养分差异不大;长期水旱轮作稻田土壤呼吸强度和酶活性比1季中稻处理高,试验结果还表明长期水旱轮作稻田土壤pH有降低的趋势。

EFFECT OF LONG-TERM "PADDY-UPLAND" ROTATION ON SOIL FERTILITY OF PADDY FIELDS

A "paddy-upland" (wheat/rape-semilate rice, WR) rotation system was practiced on fixed locations in Chongqing for 10 successive years and its effect on soil fertility was studied by comparing it with continuous cropping of semilate rice (RR). The volume weight of the 0~10 cm layer soil of WR was 23.4% higher than that of RR and constriction was 28.4% lower. WR treatment seemed beneficial to the formation of water-steady aggregation and relieved the negative effect of long-term inundation on soil structure. WR increased respiration intensity and enzyme activity in the soil and tended to decrease soil pH as compared with RR. As for organic matter in the soil, total N and total P, they increased in both WR and RR treatments while available N, P and K hardly changed.