Mupondi Lushian Tapiwa, Mnkeni Pearson Nyari Stephano, Muchaonyerwa Pardon, Mupambwa Hupenyu Allan
Department of Agronomy, Faculty of Science and Agriculture, University of Fort Hare, P. Bag X1314, Alice, South Africa.
School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, P. Bag X01, Scottsville, South Africa.
Heliyon. 2018 Aug 22;4(8):e00749. doi: 10.1016/j.heliyon.2018.e00749. eCollection 2018 Aug.
In organic soil fertility management, rock phosphate (RP) is gaining momentum as an acceptable phosphorus source, though much of this P is not bioavailable for plant uptake, particularly in igneous RP. This study evaluated the nutrient solubilization, biodegradation and heavy metal concentration when cow dung - waste paper mixture amended with increasing rates of igneous RP was vermicomposted with . The cow dung was optimized to a C/N ratio of 30 using waste paper and amended with RP to provide 0%; 2%; 4% and 8% of elemental phosphorus on a dry w/w basis. Incorporation of RP at 2% and 8% P enhanced compost biodegradation resulting in a 12% and 22% significantly ( < 0.001) lower final C/N ratio, respectively, compared to the control; together with higher humification parameters. Amending the cow dung - waste paper mixture with 2%, 4% and 8% P as rock phosphate, resulted in a 39%; 50% and 65% more resin extractable P, respectively, relative to the control. Similarly, the bicarbonate extractable P, which represents the bioavailable P fraction, increased consistently by 19%; 28% and 33% following 2%, 4% and 8% RP application, respectively. Though incorporation of RP initially resulted in increased heavy metal levels, reductions of 40%; 35%; 35%; 40% and 45% for Cr, Cu, Cd, Pb and Zn, respectively, were observed in the 8% RP treatment after 8 weeks, due to the presence of earthworms. Vermicomposting with significantly reduced heavy metals to levels below the maximum permissible concentration of potentially toxic elements in soils after 8 weeks. This study demonstrates the potential of optimized vermicomposting with igneous RP for generating nutrient rich organic fertilizers.
在有机土壤肥力管理中，磷矿粉（RP）作为一种可接受的磷源正越来越受到关注，尽管其中大部分磷对植物吸收而言并非生物可利用态，尤其是火成岩磷矿粉中的磷。本研究评估了用不同比例火成岩磷矿粉改良的牛粪 - 废纸混合物在进行蚯蚓堆肥时的养分溶解、生物降解以及重金属浓度情况。利用废纸将牛粪的碳氮比优化至30，并添加磷矿粉以提供基于干重的0%、2%、4%和8%的元素磷。添加2%和8%磷的磷矿粉增强了堆肥的生物降解，与对照相比，最终碳氮比分别显著降低了12%和22%（P < 0.001）；同时腐殖化参数更高。用2%、4%和8%的磷矿粉作为磷源改良牛粪 - 废纸混合物，相对于对照，树脂可提取磷分别增加了39%、50%和65%。同样，代表生物可利用磷部分的碳酸氢盐可提取磷，在分别施用2%、4%和8%的磷矿粉后，分别持续增加了19%、28%和33%。尽管添加磷矿粉最初导致重金属含量增加，但由于蚯蚓的存在，在8周后的8%磷矿粉处理中，铬、铜、镉、铅和锌的含量分别降低了40%、35%、35%、40%和45%。8周后，与蚯蚓一起进行堆肥显著降低了重金属含量，使其低于土壤中潜在有毒元素的最大允许浓度。本研究证明了用火山岩磷矿粉进行优化蚯蚓堆肥以生产富含养分的有机肥料的潜力。
