| Resource & environmental sciences |
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| Effects of carbon-to-nitrogen ratios and nitrogen sources on composting of mushroom residue |
| BAI Yongjuan, XU Weinan, CHANG Xiaoxiao, HU Xiaohui* |
| (Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, College of Horticulture, Northwest A & F University/Shaanxi Province Facility Agriculture Engineering Center, Yangling 712100, Shaanxi, China) |
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Abstract With the increase production of agricultural products by years, large quantitative accumulations of agricultural waste have brought severe environmental problems and wasting of resources. Therefore, recycling and reusing the agricultural waste become urgent. Recently, composting of agricultural waste has become the research focus of soilless culture substrate. With the advantages such as stable physiochemical property, adequate supply of fat, wide variety of sources and low cost, soilless culture substrates have been accepted by majority of farmers, and the demand for substrates increased quickly. Mushroom waste contains large amounts of mycoprotein, a variety of metabolites and underutilized nutrients, which is a good substrate material. In this study, mushroom residue was selected as the main material for composting, the effects of different carbon-to-nitrogen ratios and nitrogen sources on physiochemical properties of composting were investigated, to find the optimal condition for transformation of mushroom residue to soilless culture substrate, to provide optimized composting parameters for the practical production, to offer scientific basis for the widespread application of the mushroom substrates.
The carbon-to-nitrogen (C/N) ratio was set at three levels of 25∶1, 30∶1, and 35∶1. Five different combinations of nitrogen sources were selected, including cow manure, chicken manure, urea, a mixture of cow manure and urea, and a mixture of chicken manure and urea. Actually, the C/N ratio of mushroom was 40∶1, and the dry cow manure, dry chicken manure and urea were used to adjust the C/N ratio. Each treatment contained 100 kg mushroom residue and 3% effective microorganism (EM) agents, and the water content was adjusted to 60%. Static composting at high temperature was applied and the experimental containers were covered by plastic sheeting. The piles were turned over every 10 days, and were sampled every 15 days for a study period of 80 days. Composting temperature, total porosity, air-filled porosity, water holding capacity, air-water ratio, electrical conductivity (EC), pH and bulk density were measured for each sample. The temperature in center of each pile was recorded using a temperature meter every day.
The results showed that during the composting period, the C/N ratios had significant influence on all parameters, while the nitrogen sources had significant influence on all parameters except total porosity. The optimal condition to keep high temperature (>50 ℃, and last for 8, 8 and 9 days, respectively), and to shorten the composting period of mushroom residue was C/N ratio of 30∶1, and adding the mixture of cow manure or chicken manure and urea as an additive nitrogen source. Under the C/N ratio of 30∶1, bulk density and porosity tend to be stable after 70-day fermentation, beneficial to composting of mushroom residue. When the mixture of cow manure or chicken manure and urea was added as nitrogen source, bulk density, water holding capacity, pH and EC values tended to be stable after 70-day composting.
In conclusion, the optimal condition for composting of mushroom residue is the initial C/N ratio of 30∶1 and the mixture of cow manure or chicken manure and urea as the nitrogen source.
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Published: 19 November 2016
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Corresponding Authors:
HU Xiaohui (http://orcid.org/0000-0003-1298-9250),Tel:+86-29-87082452,E-mail:hxh1977@163.com
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不同碳氮比及氮源对菇渣发酵的影响
为探讨菇渣作为无土栽培基质的适宜发酵条件，通过设置不同C/N比（25∶1、30∶1和35∶1）和不同氮源（牛粪、鸡粪和尿素）试验组合，测定分析不同发酵阶段菇渣的发酵温度、积温、体积质量、总孔隙度、通气孔隙度、持水孔隙度、大小孔隙比、电导率（electrical conductivity,EC)值及pH值。结果表明：除氮源对总孔隙度的变化无显著影响外，C/N比和氮源均显著影响其他指标。其中：C/N比为30∶1、氮源为牛粪+尿素和鸡粪+尿素的处理使堆体大于50 ℃的高温分别持续8、8和9 d，即有利于发酵堆体保持较长时间的高温，缩短菇渣发酵腐熟的时间；C/N比为30∶1处理的菇渣体积质量、孔隙度从发酵第70天开始均趋于稳定，有利于菇渣的腐熟；氮源为牛粪+尿素和鸡粪+尿素处理的菇渣体积质量、持水孔隙度、pH值和EC值从发酵第70天开始趋于稳定。综上所述，在本试验条件下，菇渣宜采用初始C/N比为30∶1、氮源为鸡粪+尿素或者牛粪+尿素的组合进行发酵。
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