长期保护性耕作制度下紫色土剖面无机磷变化特征

以1990年建立的耕作制定位试验田紫色土为研究对象,分析了常规中稻-冬水田平作(CF)、中稻-冬水田垄作免耕1(RNT1)、中稻-小麦或油菜垄作免耕2(RNT2)和中稻-小麦或油菜水旱轮作(CR)等耕作方式对紫色土剖面不同形态无机磷分布演变特征的影响.结果表明,与试验前土壤相比,长期不同耕作处理的土壤上下层全磷、有效磷和各形态无机磷均有不同程度的增加,各处理土壤中不同形态无机磷含量大小顺序为RNT2CFCRRNT1.除了Fe-P含量下层土壤高于上部耕层外,Ca_2-P、Ca_8-P、Al~-P、Ca_(10)-P、O-P都表现为耕层高于下层的特征.不同耕作措施对紫色土剖面各形态无机磷含量影响显著,对各形态无机磷有效性影响效果为CRRNTCF.长期水旱轮作更有利于作物对磷的吸收.相关分析表明各组分无机磷对紫色土有效磷的贡献为Ca_2-P(0.936 9)Al~-P(0.915 8)Ca_8-P(0.901 2)Fe-P(0.828 7)Ca_(10)-P(0.805 9)O-P(0.747 2).

Variation Characteristics of Inorganic Phosphorus in Purple Soil Profile Under Different Conservation Tillage Treatments

In this study the effects of tillage methods (rice-winter paddy field conventional farming, CF; rice-winter paddy field combing ridge with no-tillage, RNT1; rice-wheat or rape combing ridge with no-tillage, RNT2; rice-wheat or rape conventional paddy-upland rotation tillage, CR) on purple soil profile of different forms of inorganic phosphorus distribution characteristics were investigated in a long-term experimental site established in 1990, Chongqing City, China. The results showed that compared to the status before the experiment, the total phosphorus, available phosphorus and various morphologies of inorganic phosphorus all increased to a certain degree in the soils with different long-term tillage treatments,and the contents of different forms of inorganic phosphorus in soil size ranked as RNT2> CF> CR> RNT1. Except that the contents of Fe-P in the lower layer were higher than those in the upper layer, contents of Ca₂-P, Ca₈-P, Al-P, Ca₁₀-P and O-P in the arable layers were all higher than those in the lower layers. The effects of farming practices on the availability of various phosphorus forms were significant. They were in the order of CR> RNT> CF. Long-term conventional paddy-upland rotation tillage was more advantageous to crops in the absorption of phosphorus. It was shown by relevant analysis that the contribution of various groups of inorganic phosphorus to purple soil was in the order of Ca₂-P(0.9369)> Al-P(0.9158)> Ca₈-P(0.9012)> Fe-P(0.8287)> Ca₁₀-P(0.8059)> O-P(0.7472).