水耕时间对低丘水田土壤发育的影响

Effects of Hydroponic Tillage Time on Soil Development in Low Hilly Paddy Field

【目的】了解水耕时间对亚热带低丘水田土壤性态的影响,对水耕土壤进行正确分类。【方法】在浙江省金衢盆地内选择坡麓和岗地二种地貌单元,观测不同水耕时间的第四纪红土发育水田土壤的剖面形态特征,分层采集土样分析土壤理化性状。【结果】随着水耕时间的增加,土壤颜色由红转黄,色调由2.5YR向7.5YR或10YR演变;表层土壤黏粒含量逐渐下降,有机质与全磷及有效磷积累,pH、阳离子交换量和活性铁逐渐增加,土壤游离氧化铁逐渐下移淀积;水耕时间对土壤性状的影响由表层向心土层发展。调查表明,由于水分条件的差异,水耕时间对坡麓地带水田土壤性状的影响大于岗地水田。【结论】由第四纪红土旱地改为水田,形成典型水耕人为土约15 a,形成铁聚水耕人为土约150 a以上,水耕时间低于150 a主要形成简育水耕人为土;随着水稻种植时间的增加,活性有机质占有机质的比例随有机质积累同步增加,水稻土心土层具有较强的固碳潜力。

[Objective]To understand the effect of hydroponic tillage time on the soil properties of paddy fields in the subtropical low hills.[Method]two geomorphic units of valley side and hills in the Jinqu basin of Zhejiang Province were selected for observing the morphological characteristics of Stagnic Anthrosols developed from quaternary red clay with different hydroponic cultivation times.While genetic horizon samples of the soils were collected to characterize the soil physical and chemical properties.[Result]The results showed that the soil color changed from red to yellow,and the hue changed from 2.5YR to 7.5YR or 10YR with the increase of hydraulic tillage time.As hydraulic tillage time increase,the clay contents in the surface soil decreased gradually,the accumulation of organic matter,total phosphorus and available phosphorus,pH,CEC and active iron gradually increased,and the soil free iron oxide gradually moved down and accumulated in the subsurface soil.With increasing time,the influence of hydroponic tillage time on soil properties developed from surface layer to subsurface layer.[Conclusion]The results showed that the effect of hydroponic time on soil properties of paddy field on valley side was greater than those on hills due to different water conditions.It took about 15 years to form the typical Stagnic Anthrosols and more than 150 years to form Fe-accumuli-Stagnic Anthrosols by transforming upland of the quaternary red clay into paddy field.When the hydroponic cultivation time was less than 150 years,the Hapli-Stagnic Anthrosols was generally formed.The results also showed that with the increase of rice planting time,the proportion of active organic matter in total organic matter increased simultaneously with the accumulation of total organic matter,and the subsurface soil of Stagnic Anthrosols had strong carbon fixation potential.