Effects of Municipal Solid Waste Compost on Soil Microbial Populations and Crop Yields in Saline-alkaline Fields

摘要

Application of municipal solid waste compost (MSWC) to saline-alkaline field could help solve urban problems related to the increasing production of waste, but only soil property improvement and environmental conservation can be demonstrated. This study, thus, aimed to detect the effects of four compost levels on soil microbial populations and crop (corn, oil-sunflower, alfalfa, sorghum-Sudan grass) yields. A plot experiment was carried out on a cropped saline-alkaline soil near Hohhot in Inner Mongolia. For each crop, treatments were: a 0 irrigation-0 compost check; compost: (1) MSW compost 75 t ha-1, (2) MSW compost 150 t ha-1 ,(3) MSW compost 225 t ha-1 ; Irrigation: (1) one irrigation on June 15, (2) two irrigations on June 15 and July 15 and (3) three irrigations on June 15, July 15 and August 10. Total quantity of irrigation was 750 t ha-1. The experiment was designed in one hundred and twenty plots (30m2 each) in three replicates, in randomized compete blocks. MSWC was applied once at the beginning of the experiment. The compost had a range of positive impacts on soil microbial populations, activity and biomass, and can provide an important source of nutrients for plants. The results indicated that: (1) with the increase in amounts of MSWC, soil microbial population was promoted at the same irrigation rate; (2) with the increase in number of irrigation, soil microbial population was promoted under the same compost. The treatment with the highest soil microbial population was MSW compost at 225 t ha-1 with three irrigation applications. In addition, the results show: (1) with the increase in amounts of MSWC, all four crop yields were promoted at the same irrigation rate; (2) with the increase in times of irrigation, all four crop yields were promoted under the same compost. The highest yield in all four crops was found at the high rates of MSW compost and irrigation, but at current costs of applying the compost, this treatment did not maximize economic benefits. The economic response was best with oilseed sunflower, at the low (75 t ha-1) rate of compost and three irrigation applications. In conclusion, although MSWC improves soil microbial population which is important for ameliorating soil physical properties and reducing runoff and soil erosion, further research is required to examine the possible contamination of soil and crop by heavy metals when the compost is applied to Saline-alkali soils.