Effects of Different Hydrothermal Regulation Methods on Soil Temperature and Roots Distribution in Apple-Soybean Intercropping Systems

TUdi - Transforming Unsustainable management of soils in key agricultural systems in EU and China. Developing an integrated platform of alternatives to reverse soil degradation. Referencia del proyecto: 101000224. Partner/Coordinador principal: José Alfonso Gómez Calero – Instituto de Agricultura Sostenible IAS- CSIC.
In order to explore the suitable water-heat regulation method for the orchard and farmland intercropping system in the loess area, the typical apple（Malus pumila）-soybean（Glycine max） intercropping system in this area was selected as the object. The effects of different water-heat regulation methods on water consumption, soil temperature and root distribution of the intercropping system were analyzed. Three upper limits of irrigation amount were set: 50%（W1）, 65%（W2） and 80%（W3） of the field water capacity, and two mulching periods: soybean sowing to podding stage（M1） and whole growth period（M2）. The results showed that the water consumption of the irrigation treatment was positively correlated with the irrigation amount, and its water consumption was increased by 1.02%～79.11% compared with the control. The soil temperature increased first and then decreased with the increase of soil depth at branching and podding stages, and the maximum value appeared at 15 cm, while it showed a decreasing trend at filling stage. The soil temperature was increased by 1.13～3.09 ℃ in the early stage of growth though mulching, and decreased by 0.05～2.36 ℃ in the late growth stage. In the intercropping system, the crop roots were mainly distributed in the vertical directions of 0-80 cm depth and the horizontal directions of 0.3 ～ 1.8 m away from the tree row. The soil effective accumulated temperature and root competition intensity generally increased first and then decreased with the increase of irrigation amount, and the maximum value appeared in W2. The root competition intensity of M1 group was 12.69% higher than M2. Correlation analysis showed that there was a significantly negative correlation between soil moisture and root. Moderate level of irrigation combined with film mulching from sowing to podding stage could maximize root density and improve soil physical properties. Therefore, it is recommended that half-growth mulch（M1） combined with 65% of field water capacity should be used as the upper irrigation limit（W2） in young apple-soybean intercropping systems.