DONG Chunhua, ZENG Xibai, LIU Qiang, GAO Jusheng, WEN Shilin
To detect the influence of the yield of late rice and the community of weed by different long-term fertilization, we investigated the production and the growth of late rice, the variation of weed community in rice field with the long-term fertilization treatments of control (CK), organic fertilizer (M), chemical fertilizer (NPK) and combined organic-chemical fertilizers (NPKM) under the same condition of nitrogen, phosphorus and potassium in the year of 2011, based on a long-term fertilization experiment of double cropping rice in red soil set in 1982. The results showed as follows. Fertilization promoted the growth and significantly increased the yield of late rice. That combined application implicated better effects than chemical fertilizer or organic fertilizer alone, and balance application of organic-chemical fertilizers had the best effect on its production which was higher than other combined treatments about 17.6%. In order to increase the yield of late rice in red soil, nitrogen fertilizer should be applied first, and followed by phosphatic and potassic fertilizer based on the same application of organic fertilizer. Application of chemical fertilizer alone displayed the best ability to promote the growth of weeds as the biomass of weeds were averagely higher than other fertilizer treatments about 32.5%, followed by the NKM treatment. The density at weeds was best increased by organic fertilizer alone, however, weeds density was best decreased by balanced treatment of organic-chemical fertilizer that its total weed density of three sampling periods was on average lower than other fertilizer treatments about 34.6%, especially to control the growth of malignant weeds, such as Cynodon dactylon, etc. Among these treatments, the diversity, dominance and evenness of weed communities were raised first and then descend with the treatments of balanced N, P and K (M, NPK, NPKM), NPK. Increasing trends were found from the other treatments (PKM, NKM, NPKM), where the same index were reduced almost 7.0%, 17.8% and 8.1% at initial tillering stage, respectively, compared with the control. The production of late rice and weed biomass at different growth stages implied in significant negative correlation. This study would be helpful to understand how to improve the yield of late rice and regulate the biomass, biomass, density as well as bio-diversity of weeds community in double rice cropping system in red soil by different fertilizing.