Effects of interplanting on soil aggregate distribution and stability in economic orchard at hilly slope red soil of southern China

Abstract

We investigated the effects of interplanting on soil aggregate distribution and stability of red soil in economic orchard in a new-constructed slope land, based on 12 kiwifruit planting experi-mental plots with a slope of about 12°, a length of 18 m, and a width of 1.5 m. Three types of interplanting patterns were implemented by interplanting purple sweet potato (PSP), hairy vetch (HV), and weeds (W) for three years, respectively, taking the bare land with no vegetation as control (CK) to determine the aggregate indicators at 0-15 cm soil layer. The results showed that the quantity and size of soil water stabilized aggregates (WR>0.25) all tended to increase which ranked in the order of PSP>HV>W>CK. The order of soil aggregate structure damage rate (PAD) and fractal dimension (D) were CK>W>HV>PSP, indicating that soil aggregate in PSP was the most stable, followed by HV treatment. Along the downslope, the content of WR>0.25, mean weight diameter (MWD), and geometric mean diameter (GMD) all tended to decrease, while the PAD and D increased, indicating that soil structure turned to be poorer in downslope of the new-constructed slope land. D was negatively correlated with MWD, GMD, and the content of >0.25 mm aggregates. It was concluded that interplanting could increase the quantity and size of soil aggregates, improve soil structure and soil quality of economic orchard in hilly slope land.