Studies Of Chemical Additives On Straw Decomposition And The Application In Red Soil

In recent years, with the improvement of crop yields, straw yields are increasing, but the disposition of straw is still irrational. In the red soil region, both the organic materials and residual return are deficient and the degradation of soil fertility is severe, the phenomenon of wasting straw resources are not uncommon and make negative effect on agricultural production. Thus, efficient use of straws is important to agricultural residue recycle and sustainable development of local economy. In this study, the experiment of straw decomposition with adding additives was done to select the proper type and amount of compost additives. Soil incubation, pot and field experiments were also conducted to investigate the effect of additive-promoted compost on improvement of degraded red soil and increase of peanut yield. Our final purpose was to provide technical supports on utilization of straw resources and improvement of red soil fertility.Results of the straw decomposition experiment showed that additives could significantly affect the decomposition. Results of peanut straw decomposition showed that: the available nitrogen, phosphorus and potassium of5%alkali slag treatment were more than those of others;5%alkali slag and1%FeSO4treatment brought higher humic substance; the treatment with5%FeSO4could get higher humic acid, HA/FA and E4/E6with values37.22g/kg,0.62and5.35, respectively, than other treatments; and the germination index (GI) of1%FeSO4and5%FeSO4treatments were below80%. Results of rice straw decomposition showed that:nutrients of15%alkali slag treatment were highest; the HS were more than80g/kg and HA were more than48g/kg under the treatments of5%and15%alkali slag treatments; and the GI of5%alkali slag,3%FeSO4and5%alkali slag incorporated with3%FeSO4reached80%. Therefore, considering the compost quality and standard, treatments of5%alkali slag,3%FeSO4and5%alkali slag combined with3%FeSO4were selected to conduct the experiments of soil incubation.Compost promoted by additives could affect the soil physical and biological properties efficiently. Results of peanut straw compost showed that:after90days, the trends of available nitrogen, phosphorus and potassium in soil among treatments were slag alkali> none additives> none fertilizer. In addition, the urease activity and micribal biomass nitrogen (MBN) in treatments with alkali slag were always30%and85%higher than those in the treatment with none fertilizer respectively, and the intervase activity was also13%higher than treatment with none additives. The microbial community diversity in treatments with treatments with alkali slag was relatively higher than others. Results of rice straw compost indicated that the other nutrients except available nitrogen were promoted by additive composts and available phosphorus and potassium were increased by treatment of3%FeSO4significantly, while the soil enzyme activity, microbial biomass and microbial community diversity were increased by treatment of5%alkali slag.Results of pot experiments showed that application of the alkali-slag-promoted compost combined with chemical fertilizer could not only change the soil fertility, but also influence peanut growth, while applying chemical fertilizers alone led to soil acidification and fertility decline easily. Results of peanut straw compost showed that applying5%-alkali-slag compost combined with chemical fertilizer not only slowed down the red soil acidification, improved soil enzyme activity and microbial biomass, but also promoted the growth of peanut seeding significantly. Results of rice straw compost showed that5%-alkali-slag rice compost combined with chemical fertilizer could alleviate soil acidification, improved soil urease activity and microbial biomass. Invertase activity of the FeSO4treatment and microbial biomass carbon (MBC) of alkali slag combined with FeSO4treatment were highest respectively among the treatments. Considering the nutrient and microbiological effects in total, we selected straw compost promoted by5%alkali slag to conduct the field experiment.5%alkali slag was selected as additives to promoted peanut and rice straw compost. Then additive-promoted compost combined chemical fertilizer were applied to field. The results showed that the compost combined with chemical fertilizer alleviated the red soil acidification effectively. The two composts affected soil biological properties differently. Peanut straw compost incorporated with chemical fertilizer increased soil urease and MBC content. After applying of rice compost combined with chemical fertilizer, the soil invertase activity, MBN and microbial community diversity was relatively higher than others. Peanut straw compost combined with chemical fertilizer increased peanut berry weight and led to88.00kg/ha increase of peanut yield. But the yield of peanut in field applying with rice straw compost incorporated with chemical fertilizer was decreased. Alkali-slag-promoted peanut compost combined with chemical fertilizer also increased the total nitrogen, phosphorus and nutrient accumulation in pods and improved the quality of peanut.In summary,5%alkali slag could promote straw decomposing and soil quality. In addition, straw compost promoted by5%alkali slag could alleviate the red soil acidification effectively, improve soil nutrient content and the biological properties, and increase the yield and quality of peanut.