The Evaluation of Sawdust Swine Waste Compost on the Soil Ecosystem, Pollution and Vegetable Production

We have successfully developed so called “biological sawdust bed pig-feeding technique” to prevent the production of swine waste water and reduction of offensive odor from piggeries by means of a specific microbial agent under mesophilic, aerobic and solid fermentation conditions. The mixture of swine feces, urine, microbial agent and sawdust is the only by-product in this pig-feeding technique. This type of compost is called “sawdust swine waste compost or SSW compost.” The main characteristics of SSW compost include as follows: pH 8.0, moisture content 40%, total N 2.2%, P2O5 3.9%, K20 3.0%, Zn 480 ppm, Cu 190 ppm, total C 39.8%, C/N ratio 18.0 and some special microorganisms such as Asperqillusterreus, Bacillussubtilis etc. Field experiment has shown that when the SSW compost was applied to the acidic soil (pH 5.0) and neutral soil (pH 7.1) at the rate of 50 Tons/ha (w/w), respectively, after 1 year application, the amount of Zn and Cu in acidic soil was significantly increased from 15 to 22.8 ppm and 14.5 to 26.7 ppm, respectively. However, the amount of Zn and Cu in neutral soil was only slightly increased from 5.7 to 6.3 ppm and 6.5 to 7.0ppm, respectively, as compared with the check (noncompost) treatment. Furthermore, the production of Chinese cabbage in acidic soil was remarkably increased 18-19% in 25 and 50 Tons/ha SSW compost treatment and Zn and Cu content of leaves in SSW compost treatment was 30-36% and 20-30% higher than in check treatment, respectively. The proper application of SSW compost not only improves the soilfertilitybut also increases the vegetable production. However, the accumulation of Zn and Cu in acidic soil and in crop leaves should be carefully considered if the compost was treated for the long term application.