Effect of the pioneer crop on afterreap crop yield, weed community and soil physicochemical property

Objective To explore the mechanism of using sesame for cultivating wasteland in traditional agriculture land.

Method Sesame was planted in the virgin land with red soil in the south area as the pioneer crop, the controls were Glycine max and Zea mays. The yield of afterreap crops, Raphanus sativus and Phaseolus coccineus, physicochemical characteristics of soils and changes of weeds were studied.

Result The yield of R.sativus and P. coccineus increased, and the increase rate was 44.25% and 148.48% respectively. The contents of organic C and available P, and pH in the soil increased. The contents of available N and available K decreased by 89.93% and 47.95% respectively. The dominant weed Saxifraga stolonifera in virgin land was not found after planting sesame, but Amaranthus blitum and Bidens pilosa became dominant. The species and biomass of weeds were affected by afterreap, and there were significant differences of weed species between sesame-radish(11.67 species) or sesame-P.vulgaris(10 species) and sesame-natural grass(5.67 species). Compared with grass-grass, the number of weed species of sesame-grass treatment increased from 4 to 5.67 species, but biomass reduced from 2 698.6 to 944.13 g·m^-2.

Conclusion Sesame, which can enhance afterreap crop yield and inhibit weed growth, is suitable for cultivating wasteland. The fact that the litter and stubble from sesame are easily decomposed can increase organic C and available P contents in soil as well as afterreap crop yield.