Effects of different cultivation practices on composition, carbon and nitrogen distribution of soil aggregates in farmlands.

Abstract

The long-term experiments were conducted at two locations with different soil fertility. There were four treatments, including super high-yielding cultivation treatment (SH), high-yielding and high efficiency cultivation treatment (HH), local farmer's practice (FP), and control (CK), respectively. The field experiments were established to study the effects of different cultivation practices on composition, carbon and nitrogen distribution of tillage layer soil aggregates in different soil fertility, with the aim of proposing technological approaches to enhance soil fertility and achieve the sustainable development of increasing yield and efficiency in wheat-maize ecosystem. The results indicated that compared with treatments in low soil fertility (LSF), same treatments in high soil ferti-lity (HSF) had the higher mean mass diameter and geometric mean diameter, contents of organic carbon and total nitrogen, and lower fractal dimension in dried soil aggregates at soil tillage layer, which was beneficial to the formation and stability of large aggregate. Optimizing application of NPK fertilizers and the application of combined chemical fertilizer with organic fertilizer could increase the diameter of soil aggregate, reduce the fractal dimension of aggregate and promote the formation and stability of large aggregates, and the effect on HSF was greater than that on LSF; also they could improve the content and distribution of organic carbon and total nitrogen in large soil aggregate, the contribution rate to >5 mm aggregate in LSF was greater than in HSF, while the contribution rate to 5-0.5 mm aggregates in HSF was greater than in LSF.