土层厚度对紫色土坡地生产力的影响

摘要

通过紫色土坡地土层厚度的调查与不同土层厚度的小区对比试验,研究紫色土薄层坡地的生产力特性. 结果表明,约73%的紫色土坡耕地土层厚度为20-60 cm.土层厚度是紫色土生产力的基本限制条件.土层越薄, 作物株高、生物量和产量愈低,生产力愈低;土层越厚,生物量、产量愈高,生产力愈高,土层厚度的影响在玉米季尤 为突出,20 cm、40 cm小区夏玉米产量仅为60 cm小区的50%、74%,为80 cm小区的28%、40%,100 cm小区的23%、34%.当土壤厚度超过60 cm,小麦、玉米的株高、生物量及根重差异不显著,而土壤蓄水可抵御紫色丘陵区连续20 d的夏旱,因此,可初步判定60 cm土层为紫色土生产力临界土层.60cm以上厚度的紫色土可维持基本稳定的生产力水平.%Soil survey and field comparison experiments on soil thickness were conducted to study productivity charaeteristics of sloping cmpland of purple soil.Results showed 73%ofcropland of purple soil distributes in 20～60 cm soil.SOil thickness i8 basic limiting condition for purple soil.The thinner the soilis,lower the crop height,biomass,yield and productivity will be.On the contrary,thicker soil had higher productivity.Soil thickness impacted on summer maize more prominently.Maize yields in plots of 20 and 40 cm were only 50%and 74% of those in 60 cm plot,28%and 40%in 80 cm plot,23%and 34%in 100 cm plot,respectively.However.if soil thickness is more than60 cm,there were no significant differences on crop height,biomass and root weight of both whem and maize between different treatments of soil thickness.Meanwhile,the cropland with more than 60 cm thick soil will resist the continuous drought for 20 days in summer.So,the soil thickness of 60 cm would be a critical thickness for purple soil to maintain stable productivity on hillslope.