Effect of Maize and Soybean Intercropping on Root System and Soil Aggregate Stability

PurposeTo reveal the effects of root morphology and root exudates of maize and soybean on the stability of soil water stable aggregates under different planting patterns in red soil sloping land.

MethodsField plot experiment was used to set up three planting patterns: maize monoculture, soybean monoculture and maize-soybean intercropping. The root morphological parameters, secretion of root exudates and stability of soil aggregates were measured at different growth periods of maize and soybean. The effects of crop root morphology and exudates on stability of soil aggregates were analyzed under different planting patterns.

ResultsAt the tasseling period, root dry weight, root length, root surface area, total sugar and total organic acid contents of intercropping maize were significantly increased compared with that of monoculture maize (P<0.05), with the increase rates of 15.17%, 58.49%, 45.67%, 34.30% and 15.67%, respectively; percentage content of aggregate greater than 0.25 mm (R_0.25), mean weight diameter (MWD) and geometric mean diameter (GMD) were significantly increased by 2.64%, 3.37% and 6.06% (P<0.05), respectively; and the fractal dimension (D) of soil decreased significantly by 0.82% (P<0.05). At the podding period, root dry weight, total root length, root surface area, root volume, total sugar and total organic acid contents of intercropping soybean were significantly increased compared with that of monoculture soybean, with the increase rates of 17.25%, 63.91%, 54.32%, 42.77%, 37.21% and 28.16%, respectively; and R_0.25, MWD and GMD were significantly increased by 1.54%, 2.99% and 6.78% (P<0.05), respectively; and D of soil significantly decreased by 0.73% (P<0.05). Root dry weight, root length, root surface area, root volume, total sugar and total organic acid were significantly positively correlated with R_0.25 (P<0.01), MWD and GMD, and significantly negatively correlated with D (P<0.01).

ConclusionMaize-soybean intercropping can improve the root morphology of crops, increase the secretion of root exudates of crops, and then improve the stability of soil aggregates, which has beneficial effects on improving fertility and reducing soil erosion of red soil sloping land.