Effect of rice straw mat and other mulching on apple root architecture and soil environment in root-zone

The experiment was carried out using three-year-old potted apple trees (Malus domestica 'Starkrimson') mulched with rice straw mat (RSM), agricultural carpet (AC), transparent-plastic film (TPF) and horticultural fabric (HF). The variations in root architecture and activity, soil moisture, temperature, total organic carbon and available nutrients in root-zone were investigated. Results showed that the new root volume, root fractal dimension and root activity increased significantly with mulching. Root tip number,root fractal dimension and the soil relative water content were the highest after mulching with RSM, while root diameter, root volume and surface-area were the largest after mulching with AC. RSM made root structure more complex. In summer and early autumn, the soil temperature was highest under TPF mulching and lowest after RSM mulching. In late autumn, the soil temperature was highest under RSM mulching while RSM and AP made soil temperature more stable. RSM, AP and HF mulching all increased total organic carbon content in the root-zone soil. From a comprehensive point of view, the order of beneficial effects from high to low was RSM, AC, HF and TPF. Considering the overall beneficial effect of improving roots and stabilizing soil environment the four mulches were straw mulch, agricultural carpet, horticultural cloth and transparent plastic film.