Abstract:

Biochar based long-term fertilizer can be prepared by extrusion granulation process with cow dung biochar， digestate， chemical fertilizer and ferric oxide as main materials and quicklime， portland cement and pregelatinize starch as auxiliary materials. In order to study the influence of addition of excipients on the stability of biochar based long-acting fertilizer in water immersion， 8 treatments according to the differences in the addition of excipients were set up. By analyzing the compressive strength， soaking resistance， soaking quality loss， soaking nutrient release rate， pH， electrical conductivity（EC） and other indexes of fertilizers in different treatments， the influence of different excipients on the stability of fertilizers in water immersion was comprehensively evaluated. The results showed that the addition of portland cement and quicklime could reduce the compressive strength of fertilizer particles， but could significantly improve the stability of fertilizer particles in water immersion. The addition of pregelatinize starch not only significantly reduced the compressive strength of fertilizer particles， but also was not conducive to improving the stability of fertilizer particles in water immersion. compared with no excipients， the soaking resistance of adding quicklime only， adding portland cement only and without adding pregelatinized starch increased by 24.00%， 19.20% and 45.60%， respectively， and the soaking quality loss decreased by 8.61%， 6.96% and 12.04%， respectively； within 56 d， the cumulative release of nutrients was reduced by 16.20%， 11.87% and 21.34%， respectively. Compared with adding 3 excipients， the nitrogen accumulation rate of without adding quicklime， without adding portland cement and without adding pregelatinized starch increased by 2.11%， 1.27% and -8.66%， respectively， and the phosphorus cumulative release rate increased by 19.66%， 15.30% and -8.93%， respectively， during 56 d of immersion； the cumulative potassium release rate decreased by 1.95%， 0.92% and -5.15%， the mass loss increased by 2.32%， 1.29% and -8.86%， and the soaking resistance decreased by 10.07%， 5.04% and -30.94%， respectively. Therefore， when using this technology to produce biochar based fertilizer， portland cement and quicklime could be recommended as auxiliary materials to improve the water stability of fertilizer， and it was not recommended to add pregelatinized starch.

Key words: biochar based fertilizers, excipients, immersion stability in water

摘要：

以牛粪生物质炭、沼渣、化肥、氧化铁为主料，以生石灰、硅酸盐水泥、预胶化淀粉为辅料，采用挤压造粒工艺可以制备得到生物炭基长效肥。为研究辅料添加对生物炭基长效肥浸水稳定性的影响，根据辅料添加的差异设置8个处理，分析不同处理间肥料的抗压强度、浸水耐泡性能、浸水质量损失、浸水养分释放率、pH、电导率（electrical conductivity，EC）等指标，综合评价不同辅料添加对肥料浸水稳定性的影响。结果表明，硅酸盐水泥和生石灰的添加会降低肥料颗粒的抗压强度，但能显著提高肥料颗粒的浸水稳定性；预胶化淀粉的添加不仅显著降低肥料的抗压强度，也不利于提高肥料颗粒浸水稳定性。与不添加辅料相比，仅添加生石灰、仅添加硅酸盐水泥、不添加预胶化淀粉处理的浸水耐泡性能分别提高24.00%、19.20%和45.60%，浸水质量损失分别降低8.61%，6.96%，12.04%，56 d内浸水养分累积释放总量分别降低16.20%、11.87%和21.34%。与3种辅料组配相比，不添加生石灰、不添加硅酸盐水泥、不添加预胶化淀粉处理在浸水56 d内氮素累积率分别提高2.11%、1.27%、-8.66%，磷素累积释放率分别提高19.66%、15.30%、-8.93%，钾素累积释放率分别降低1.95%、0.92%、-5.15%，质量损失分别增加2.32%、1.29%、-8.86%，浸水耐泡性能分别降低10.07%、5.04%、-30.94%。因此，在利用该技术生产生物炭基肥时，为提高肥料的浸水稳定性推荐使用硅酸盐水泥和生石灰作为辅料，不宜添加预胶化淀粉。

关键词: 炭基肥, 辅料, 浸水稳定性