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Improving fertility and productivity of a highly-weathered upland soil in subtropical China by incorporating rice straw

Zhu, Hanhua, Wu, Jinshui, Huang, Daoyou, Zhu, Qihong, Liu, Shoulong, Su, Yirong, Wei, Wenxue, Syers, J. Keith, Li, Yong
Plant and soil 2010 v.331 no.1-2 pp. 427-437
bulk density, burning, carbon, carbon sequestration, crop yield, environmental impact, fertilizers, field experimentation, greenhouse gas emissions, highlands, methane, microbial biomass, nitrogen content, organic matter, paddies, phosphorus, porosity, rapeseed, rice straw, soil microorganisms, subtropical soils, sweet potatoes, upland soils, water holding capacity, China
The transfer of rice straw from paddy fields to upland areas was proposed in our study as an innovative practice to improve the fertility of the highly-weathered and poor upland soils, as well as to mitigate environmental impacts from rice production system (e.g., the large application of chemical fertilizers, straw burning, CH₄ emission from decomposed straw) in the subtropical China. Data from an 8-year field experiment with sweet potato and rapeseed show that, the contents of organic matter and total nitrogen (N) in the surface soil (0-20 cm) with rice straw incorporation were increased by 13%, and the amounts of soil microbial biomass carbon (C), N, and phosphorus (P) by 18-43%, compared with the values when chemical fertilizers (NPK) were applied alone. Physical conditions and crop productivity of the test soil were effectively promoted with the straw incorporation, as indicated in significant changes in soil field water-holding capacity, total porosity, and bulk density in the 10-15 cm soil layer, and the rise (about 10% and 20%, respectively) of sweet potato and rapeseed yields. In conclusion, these results suggest that the practice shift from conventional rice straw management (‘on the spot' incorporation) to upland incorporation is effective in improvement in fertility and productivity of the upland soil, which has potentials to reduce the amounts of chemical fertilizers applied and to increase soil C storage in farmlands in the region.