Biological response of rice crop cultivated on upland soil condition and the effect of mulching on it

Field experiments of rice cultivated both on upland soil (RCUS) mulched with half decomposed rice straw(HM), horse bean straw(BM), plastic film(FM), paper film(PM), and rice raw straw(RM) and on waterlogged soil (WT) were carried out to study the dynamics of NH4+-N and NO3--N of the soils, N content of the rice at various growing stages, rice yield and yielding components, and irrigating water use efficiency. Results indicated that soil NO3-N was the main form absorbed by the RCUS. It was found that N contents of the different organs of the RCUS was always higher than those of WT. Great absorption and accumulation of N of RCUS happened mostly after jointing stage, while the rice crop in waterlogged soil absorbed N in large amounts from transplanting stage to filling stage. The highest rice yield on upland soil was found in the treatment of the soil mulched with HM but lower than that in waterlogged soil. The water consumption, however, in upland soil was much less than that in waterlogged soil, thus, the irrigating water use efficiency of RCUS was 12 times as much as WT.