Short-term effects of wheat straw incorporation into paddy field as affected by rice transplanting time

Short-term effects of wheat straw incorporation into paddy field include stimulation of CH4 emissions, immobilisation of available N, suppression of rice growth, and accumulation of toxic materials. To study these short-term effects as affected by timing of rice transplantation, a field experiment was conducted at Dapu, China, in 2005. Two levels of wheat straw (0 and 3.75 t/ha) and 2 rice-transplanting times (normal and delayed) were adopted in this experiment. Methane emissions, concentrations of soil mineral N, dry matter accumulations, and grain yields were measured. Delayed rice transplantation had no effect on total CH4 emission from paddy fields incorporated with wheat straw (P > 0.05), but a significant effect on mineralisation of N (P < 0.05), in contrast to the net N immobilisation in the fields where seedlings were transplanted on the normal date. In paddy fields incorporated with wheat straw, delayed transplantation tended to promote rice growth and increase grain yield compared with transplantation on the normal date.