Effects of rice straw on the physicochemical properties and nitrogen transformation of aerobic composting of sheep manure
In order to evaluate the effects of rice straw on the physicochemical properties and nitrogen transformation of sheep manure aerobic compost,sheep manure and rice straw with different wet-mass ratios were used as raw materials for aerobic composting.The wet-mass ratios of sheep manure and rice straw were 9∶1,8∶2,7∶3,6∶4 and 5∶5,respectively.The effects of the combination of rice straw and sheep manure on the composting process,physical and chemical properties,gas emission,nitrogen loss of sheep manure were studied.The characteristics of different compost products were compared,and the composting maturity was comprehensively evaluated by principal component analysis.The results showed that the addition of rice straw could accelerate the composting process of sheep manure and the decomposition of organic matter,and the compost entered the high temperature period within 3 days,and the high temperature period lasted for 13-21 days.The maximum temperature of the compost with a wet mass ratio of sheep manure to rice straw of 8∶2(C/N ratio of 19.75)was 73.88℃,the duration of the high temperature stage(≥50℃)was the longest(27 days),and the seed germination index reached more than 80%(81.8%)at 30 days.The O2 content in composting was negatively correlated with temperature(R=-0.615,P<0.001).The total nitrogen loss of sheep manure and rice straw were 20.54,17.91,17.07,15.28 g and 13.26 g when the wet-mass ratio of sheep manure to rice straw was 9∶1,8∶2,7∶3,6∶4 and 5∶5,respectively,indicating that the lower the initial C/N ratio,the higher the total nitrogen loss rate.Adding rice straw in sheep manure composting could shorten the time of high temperature fermentation and speed up the composting process.The higher the initial C/N ratio,the smaller the cumulative emission of NH3 and N2O,and the smaller the loss rate of NH4+-N,NO3--N and total Kjelner nitrogen(TKN).The comprehensive evaluation results of principal component analysis showed that the mixed compost of sheep manure and rice straw was the best according to the wet-mass ratio of 8∶2,and the compost was the fastest.
sheep manurerice strawaerobic compostingphysical and chemical propertynitrogen transformation
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