炭基微生物肥料制备工艺及性质分析

以稻壳炭与氮磷钾肥及枯草芽孢杆菌孢子粉复合,采用掺混法、吸附法、混合造粒法3种工艺,设置10%、20%和30%三种稻壳炭添加水平,小试制备了9个炭基微生物肥料样品,并对其进行电镜扫描及元素含量、pH值、总养分、有效活菌数、缓释效果等的测定与分析。结果表明,采用混合造粒法制备的炭基微生物肥料负载氮磷钾肥和微生物孢子粉最多,其次是吸附法,掺混法最少。9个炭基微生物肥料样品中各元素含量比较丰富,工艺相同时,随着稻壳炭添加量的增加,C、N含量增加而H含量减少。9个炭基微生物肥料的pH值均呈酸性或接近中性,总养分含量均达到了复合肥国家标准的要求。枯草芽孢杆菌孢子粉与稻壳炭及氮磷钾肥复合60 d后,有效活菌数为3.4×10⁵~7.0×10⁵ g^-1,同种工艺制备的炭基微生物肥料的有效活菌数随稻壳炭添加量的增加而增加。炭基微生物肥料的7 d氮素累积水溶出实验表明,9个肥料样品均有一定的缓释功能,同种工艺制备的炭基微生物肥料的氮素累积释放率随稻壳炭添加量的增加而降低。稻壳炭添加量相同时,缓释效果混合造粒法>吸附法>掺混法。综上,添加30%的稻壳炭、采用混合造粒工艺制备的炭基微生物肥料具有最优的性质,可进一步验证其效果并推广应用。

Preparation technology and properties analysis of biochar-based microbial fertilizers

In the present study, the rice husk biochar, NPK fertilizer, and Bacillus subtilis spores were prepared for the development of new biochar-based microbial fertilizers, by using three manufacture technologies including the mixed method, adsorption method and mixed granulation method. The content of rice husk biochar was set as 10%, 20%, 30%, respectively. The properties of these biochar-based microbial fertilizers, including the pH value, the total nutrients content, the elemental contents, the number of living bacteria, and nutrient release characteristics were determined. It was shown that biochar-based microbial fertilizer prepared with mixed granulation method had the best ability to absorb the NPK fertilizer and microbial spores, and was followed by those prepared by the adsorption method and the mixed method. The elements contents of 9 biochar-based microbial fertilizer samples were rich. The content of C and N increased while the content of H decreased with the increase of the addition amount of rice husk biochar under the same preparation condition. The pH value of the 9 biochar-based microbial fertilizer samples were acid or close to neutral, and the total nutrients contents met the requirement of the national standard for compound fertilizer. The number of living bacteria was 3.4×10⁵-7.0×10⁵ g^-1 after the spores of Bacillus subtilis were compounded with rice husk biochar and NPK fertilizer for 60 days. Under the same process conditions, the number of living bacteria of biochar-based microbial fertilizers increased with the increase of the addition amount of rice husk biochar. The seven days nitrogen accumulated water dissolution experiments showed that the 9 biochar-based microbial fertilizer samples had certain slow release function. The nitrogen release rate of biochar-based microbial fertilizers with the same preparation technology decreased with the increase of the addition amount of rice husk biochar. With the same content of rice husk biochar, mixed granulation method had the best slow release characteristics, and was followed by the adsorption method and the mixed method. Therefore, the biochar-based microbial fertilizer with 30% rice husk biochar made by mixed granulation method had optimal property, and the effect should be further verified by pot or field experiment and to promote its application in small scale.