套种对南方红壤坡耕地经济果园土壤团聚体分布及稳定性的影响

为研究红壤丘岗区经济果园套种模式对新改坡耕地土壤团聚体分布及稳定性的影响,以坡度约12°、坡长18 m、宽度1.5 m的12个猕猴桃种植试验小区为对象,设计连续3年套种紫薯(PSP)、毛叶苕子(HV)、荒草(W)3种模式,以无植被覆盖裸地(CK)为对照,测定不同坡位0～15 cm表层土壤团聚体指标。结果表明:套种处理的土壤水稳定性团聚体(WR_>0.25)数量和大小均有不同程度增大趋势,其增幅顺序为PSP>HV>W>CK。土壤团聚体结构破坏率(PAD)和分形维数(D)的顺序为CK>W>HV>PSP,表明套种紫薯坡地土壤团聚体的稳定性最好,毛叶苕子次之。沿顺坡方向,所有处理WR_>0.25含量、团聚体平均重量直径(MWD)和几何平均直径(GMD)均呈减小趋势,而PAD和D呈逐渐增大趋势,表明新改坡耕地土壤的结构性沿坡长方向呈现变差的趋势。D与MWD、GMD、>0.25 mm团聚体含量均呈显著负相关。套种能够增加丘岗坡地经济果园土壤团聚体数量和大小,改善土壤团粒结构,提高土壤质量。

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

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.