秸秆黑炭对竹林土壤氮行为的影响机制

It is well known that nitrogen is the most important nutrient to plant growth. In order to get higher yields, people put more and more fertilisers into the soil. However, excessive N additions may deplete the soils ability to store additional N, and loss of reactive N from soil to waters is becoming increasingly problematic. So, the utilization ratio of nitrogen fertilizer has always been a major concern. According to statistics, the average utilization ratio of nitrogen fertilizer is 40-60% in the world, but it is only 30-35% in China. Moreover, nitrogen use efficiency in forest mangement is much lower than this level. Biochar is a predominantly stable, recalcitrant organic carbon(C) compound, due to its charaeteristics of high stability against decay and high capbility of adsorption, biochar plays a significant role in global climate change, carbon cycle in biogeochemical proeess and environmental system. Possible benefits from biochar is enhancing the nitrogen use efficiency and storing carbon in soil and supporting nitrogen fixation. Biochar amendment in croplands had been proposed worldwide as one effective countermeasure to increase SOC stock while improve soil fertility and ecosystem functioning regarded with climate change mitigation in agriculture..The 15N enriched fertilizers is an ideal tool for studying the efficiency of N use. The isotope technology based on 15N is often used for monitoring the fate and transformations of N applied .Now it has been widely utilized in the agroecosystem. The effect of biochar on the nitrogen dynamics was studied by using 15N isotope tracing technique in order to discuss the influence of biochar on the nitrogen uptake, transportation and allocation of bamboo. The function of biochar in the course of nitrogen supply by soil and absorbtion by plant would be determined. These works would provide some theoretical guidance for the control technology of nitrogen loss and measurement of nitrogen regulation. If the related mechanism of influence was clarified, the nitrogen use efficiency would be increased, and soil properties would be improved, and agricultural non-point pollution would be remissed.

世界氮肥的平均利用率为40%-60%，而我国目前仅为30%-35%，林业经营过程中的氮肥利用效率更远远低于该水平，肥料氮素的流失直接导致了土壤质量下降、水体污染、温室效应加剧等严重的环境问题。而生物质炭因其特殊的理化及生物学特性，有望在提高氮肥利用效率、控制农业面源污染等方面发挥重要作用，同时也为农林废弃生物质资源化利用提供新的思路。本项目运用15N同位素示踪技术，开展秸秆黑炭对竹林土壤氮行为的影响机制研究，探讨秸秆黑炭对竹林土壤氮素的吸附机制及其对肥料氮素利用效率的影响，揭示秸秆黑炭施入集约经营竹林土壤在降低氮素流失、提高氮素利用效率中所起的作用，从而为我国竹林集约经营过程中采取科学的氮素流失控制技术及氮素调控措施提供理论指导。

以小麦、水稻、棉花和玉米在不同温度和不同活化浓度条件下制备得到的生物炭，各类生物炭都具较高的pH和C含量。不同生物炭的比表面积差异巨大，原料性质不同、裂解温度不同、活化条件不同，都不同程度上影响了生物炭的理化性质。. 添加生物炭对经营五年、十年的土壤氮的淋溶影响无显著差异，但在经营十五年的竹林土壤中施加生物炭能显著减少土壤氮的淋溶。不同添加量对肥料氮素的利用效率影响不同，随着添加量的提高，肥料氮素在土壤中的残留率提高，竹炭施入土壤对肥料氮素的固持效果效果要优于水稻炭，在添加量2%时，肥料氮素的流失率只有8.65%，相比于未添加生物炭的竹林，氮素利用效率提高40.75%。