保水剂和微生物菌肥对半干旱区造林和土壤改良的影响

试验分别设置低、中、高浓度保水剂(20,40,60g/株)和微生物菌肥(150,300,450g/株)用于张北半干旱区风沙土樟子松造林。通过分析不同处理对土壤田间持水量、有效水分含量、水稳性团聚体含量、微生物菌落数量和微生物量碳、氮等指标的差异,研究保水剂与微生物菌肥对土壤物理性质、土壤微生物以及樟子松成活率的影响,探究适用于干旱、半干旱区樟子松造林的最佳配比。结果表明:保水剂和微生物菌肥能够显著改良土壤,提高造林成活率,但不同浓度配比对各项指标影响效果不同。高浓度保水剂单施对田间持水量,有效水分含量和水稳性团聚体含量提高最明显,分别较对照组提高了141%,150%,63.8%;中浓度保水剂和高、中浓度菌肥混施显著提高了土壤微生物活性和土壤微生物量,其中真菌,细菌和放线菌分别较对照组高77%,108%,93%,微生物碳、氮分别较对照组增加132%,178%。此外,施加保水剂和微生物菌肥对樟子松生长具有显著促进作用,株高、地径平均值分别较对照组提高6%,12%。保水剂提高樟子松成活率的效果优于其与微生物菌肥混施,且中浓度保水剂条件下造林成活率最高。在干旱、半干旱区造林时,采用中浓度保水剂和微生物菌肥配施可以改良土壤,提高造林成活率。

Research on Soil Absorbent Polymer and Microbial Fertiliser to Improve Semi-arid Soil and Afforestation

The mixed applications of an eco-friendly soil absorbent polymer (SAP) and a compound microbial fertiliser (MF) in the aeolian sandy soil was studied for the improvement project of afforestation in Zhangbei County. The mixed applications with low, moderate or high SAP (20,40,60g/tree) and MF (150,300,450 g/tree) concentrations were used for the afforestation of Scots pine. Differences in field moisture capacities, available water contents, WSA percentages, microbial colony count and soil microbial biomass carbon/nitrogen (S_mbc/S_mbn) at different mixing ratios were analysed. The effects of SAP and MF on soil physical properties, soil microbes and survival rates of Scots pine were examined. The mixing ratio and amount applicable to afforestation in arid and semi-arid regions were explored. Results showed that SAP and MF could remarkably improve soil and increase survival rate, but the effects of the mixing ratio on these indicators varied with concentrations. When a single highly concentrated SAP was used, the field moisture capacity, available water content and WSA content were increased by 141%, 150% and 63.8% respectively compared with the control. The mixed application of moderate SAP concentration and MF significantly increased the microbial activity and microbial colony count. In particular, the microbial activity and microbial colony count of fungi/bacteria/actinomycetes increased by 77%, 108% and 93% compared with the control, respectively, and the S_mbc/S_mbn increased by 132%,178%. The application of SAP and MF significantly promoted plant growth. The plant height and basal diameter respectively increased by 6% and 12% compared with the control. The improvement of survival rate by single SAP was greater than that of the mixed application. The moderate SAP concentrations increased the survival rate of Scots pine. During afforestation in arid and semi-arid regions, the application of moderate SAP concentration mixed with MF could improve soil and increase survival rate of afforestation.