[Crop root growth and water uptake in maize/soybean strip intercropping]

A field experiment was conducted to study the root distribution and water adsorption of maize and soybean in their strip intercropping. The results showed that under the condition of full irrigation, both maize roots and soybean roots were distributed approximately in triangle-shape in soil profile. Maize roots extended horizontally into a wider area, 58 cm away from the plant row and usually occurred in 16-22 cm soil layer. They were not restricted to maize root zone, but traversed into soybean strip zone. Soybean roots were horizontally distributed in a limited zone near the plant row, and their reached range was within about 26 cm. Both for maize and for soybean, their root mass density decreased with increasing distance from the plant row. About 90% of the root mass of maize and edge-row soybean was presented in 0-30 cm soil layer. The root mass density of maize at 10 cm from maize row was greater than that of soybean, but this density of soybean at 20 cm from maize strip was greater than that of maize. About 85% of root mass was distributed in 0-30 cm soil layer, and the variation of soil water content in intercropping strips also occurred mainly in this soil layer. In the maize/soybean strip intercropping system, soil water content decreased in the order of maize zone > soybean zone > middle zone, indicating that each strip-intercropped crop preferentially absorbed the soil water in its strip and utilized the soil water in intermingled zone later.