Ravindran B, Mnkeni P N S
Department of Agronomy, Faculty of Science and Agriculture, University of Fort Hare, PBX1314, Alice, 5700, South Africa.
Environ Sci Pollut Res Int. 2016 Sep;23(17):16965-76. doi: 10.1007/s11356-016-6873-0. Epub 2016 May 20.
The main objective of the present study was to determine the optimum C/N ratio for converting waste paper and chicken manure to nutrient-rich manure with minimum toxicity. Six treatments of C/N ratio 20, 30, 40, 50, 60, and 70 (T1, T2, T3, T4, T5, and T6, respectively) achieved by mixing chicken manure with shredded paper were used. The study involved a composting stage for 20 days followed by vermicomposting with Eisenia fetida for 7 weeks. The results revealed that 20 days of composting considerably degraded the organic waste mixtures from all treatments and a further 7 weeks of vermiculture significantly improved the bioconversion and nutrient value of all treatments. The C/N ratio of 40 (T3) resulted in the best quality vermicompost compared to the other treatments. Earthworm biomass was highest at T3 and T4 possibly due to a greater reduction of toxic substances in these waste mixtures. The total N, total P, and total K concentrations increased with time while total carbon, C/N ratio, electrical conductivity (EC), and heavy metal content gradually decreased with time during the vermicomposting process. Scanning electron microscopy (SEM) revealed the intrastructural degradation of the chicken manure and shredded paper matrix which confirmed the extent of biodegradation of treatment mixtures as result of the composting and vermicomposting processes. Phytotoxicity evaluation of final vermicomposts using tomato (Lycopersicon esculentum), radish (Raphanus sativus), carrot (Daucus carota), and onion (Allium cepa) as test crops showed the non-phytotoxicity of the vermicomposts to be in the order T3 > T4 > T2 > T1 > T5 > T6. Generally, the results indicated that the combination of composting and vermicomposting processes is a good strategy for the management of chicken manure/paper waste mixtures and that the ideal C/N ratio of the waste mixture is 40 (T3).
本研究的主要目的是确定将废纸和鸡粪转化为毒性最小的富营养肥料的最佳碳氮比。通过将鸡粪与碎纸混合，设置了碳氮比为20、30、40、50、60和70的六个处理组（分别为T1、T2、T3、T4、T5和T6）。该研究包括20天的堆肥阶段，随后用赤子爱胜蚓进行7周的蚯蚓堆肥。结果表明，20天的堆肥显著降解了所有处理组的有机废物混合物，再经过7周的蚯蚓养殖，所有处理组的生物转化率和营养价值都得到了显著提高。与其他处理组相比，碳氮比为40（T3）时得到的蚯蚓堆肥质量最佳。T3和T4处理组的蚯蚓生物量最高，这可能是因为这些废物混合物中的有毒物质减少得更多。在蚯蚓堆肥过程中，总氮、总磷和总钾浓度随时间增加，而总碳、碳氮比、电导率（EC）和重金属含量随时间逐渐降低。扫描电子显微镜（SEM）显示了鸡粪和碎纸基质的内部结构降解，这证实了堆肥和蚯蚓堆肥过程中处理混合物的生物降解程度。以番茄（Lycopersicon esculentum）、萝卜（Raphanus sativus）、胡萝卜（Daucus carota）和洋葱（Allium cepa）为试验作物对最终蚯蚓堆肥进行植物毒性评估，结果表明蚯蚓堆肥的非植物毒性顺序为T3 > T4 > T2 > T1 > T5 > T6。总体而言，结果表明堆肥和蚯蚓堆肥相结合的工艺是处理鸡粪/废纸混合物的良好策略，且废物混合物的理想碳氮比为40（T3）。
