生物炭输入对热带地区菜地温室气体排放的影响及机制研究

The anti-season vegetables are widely planted in the tropical region of China, in which has adequate water and thermal conditions. However, a large amount of fertilizer is applied to vegetable fields in tropical region, causing increasing of agricultural greenhouse gas emission and the serious soil acidification. Therefore, it will be an important direction for sustainable development of agriculture in tropical region to reduce the greenhouse gas emission in vegetable fields, with soil improvement and high yield and efficiency of vegetables. The biochar can not only reduce agricultural greenhouse gas emission, but also play a positive role in soil improvement and crop yield improvement. The present study carries out in anti-season cherry tomato field of tropical region, with no biochar field as control and rice straw biochar, banana straw biochar, coconut shell biochar and its different application amount as biochar treatments，to research the laws of greenhouse gas(CO2, CH4 and N2O) emission in different biochar treatments and determine the effect of different biochar treatments on greenhouse gas emission in vegetable field; furthermore, based on the physical-chemical and biological characteristics of soil and morphological-physiological characteristics of cherry tomato, the mechanism of biochar on greenhouse gas emission is revealed, and the biochar application pattern of anti-season tomato is chosen for high yield, high efficiency and low greenhouse gas emission. The present study will provide theoretical and practical guidance for low greenhouse gas emission and high efficiency of vegetable fields, and sustainable development of agriculture in tropical region.

中国热带地区水热条件充足，反季节露地蔬菜被大面积种植。然而该地区化肥的大量施用造成菜地温室气体排放增加，土壤酸化加剧。因此，减少菜地温室气体排放，同时兼顾土壤改良与蔬菜高产高效，将是热带地区农业可持续发展的重要方向。生物炭不仅可以减少农业温室气体排放，而且对土壤改良和作物产量提升都有积极的作用。本项目以热带地区反季节樱桃番茄地为研究对象，以不施生物炭为对照，通过设置水稻秸秆生物炭、香蕉秸秆生物炭和椰壳生物炭及其不同施用量，研究不同生物炭处理下菜地温室气体（CO2、CH4和N2O）的排放规律，明确不同生物炭处理对菜地温室气体排放的影响；并从土壤理化特性、生物学特性和樱桃番茄形态生理特性出发，揭示生物炭对菜地温室气体排放的影响机制，筛选高产、高效、低碳的反季节露地樱桃番茄生物炭施用模式，其将为热带地区菜地低碳高效及农业的可持续发展提供理论和实践支撑。

面对热带地区菜地土壤酸化、质量差且温室气体排放量大等问题，设置生物炭种类（2种：水稻壳生物炭和花生壳生物炭）和生物炭施用量（5个水平：0t ha-1、10t ha-1、20t ha-1、40t ha-1、60t ha-1）两因素试验，研究了生物炭输入对土壤特性和樱桃番茄生长发育及产量品质的影响，并分析了生物炭输入下菜地温室气体排放的规律；在此基础上，揭示生物炭对菜地温室气体排放的影响机制，同时筛选高产、高效、低碳的反季节露地樱桃番茄生物炭施用模式。研究结果表明，生物炭输入能够显著提高热带菜地土壤有机碳、硝态氮、铵态氮含量和pH值，并能增加土壤脲酶和蔗糖酶活性，且在40t ha-1和60t ha-1生物炭时土壤pH值、脲酶活性、有机碳和硝态氮含量最高。另外，生物炭输入还能显著提高樱桃番茄株高、干物质量及光合速率，进而提高樱桃番茄的产量和养分利用效率，且40t ha-1 生物炭施用量下樱桃番茄产量、果实可溶性固形物含量、氮肥和磷肥利用效率最高。温室气体排放量进行比较发现，与CK相比，大多生物炭处理土壤氧化亚氮（N2O）和二氧化碳（CO2）排放量并没有显著增加；且第二季N2O和CO2排放量要低于CK。但不同生物炭施用量下生物炭量的增加可以增加N2O和CO2的排放，但对甲烷排放的影响不大。土壤N2O和CO2的累积排放量分别在60t ha-1和40t ha-1最高，20t ha-1和10t ha-1最低。并且，40t ha-1生物炭量下全球增温潜势值最高，但与60t ha-1间没有显著性差异。这主要因为生物炭提高土壤硝态氮含量、有机质含量和土壤脲酶和蔗糖酶活性，进而提高了温室气体排放量。但由于生物炭的增产作用，生物炭施用后能显著的降低温室气体排放强度。综合分析发现，40t ha-1是一个高产、高效、低碳的热带地区菜地生物炭施用量。但在热带地区菜地，生物炭的长期效应还需要被进一步研究。