Zhang Yang-Yang, Hu Xue-Yu, Zou Juan, Zhang Di, Chen Wei, Wang Xiang-Qian, Chen Yao-Jun, Liu Yang
School of Environmental Studies, China University of Geosciences, Wuhan 430074, China.
Huan Jing Ke Xue. 2017 Apr 8;38(4):1622-1632. doi: 10.13227/j.hjkx.201609149.
Biochar application to soils is currently considered as a means of mitigating climate change by sequestering C, which withdraws CO from the atmosphere and consequently influences the trend of global climate change. However, only a few studies have been done on surface albedo variations on farmland, it might be true that the application of biochar to soil could induce a radiative forcing by changing the surface albedo. Based on this background, this study aiming at the characterization of seasonal changes in albedo on the farmland both with plants and without plants, and its effect on soil temperature, soil moisture, soil respiration and soil organic carbon fractions. There were 3 major treatments in the experiment with 3 repetition of each major treatment, namely, CK (the control treatment), BC0.5 (biochar applied at 0.5 kg·(m·a)) and BC4.5 (biochar applied at 4.5 kg·(m·a)). Each major treatment contained 2 sub-treatments, which were crop cultivation (+) and non-cultivation (-). The experiment results showed that in the early stage of crop growth (maize seedling stage to jointing stage, wheat seedling stage to winter period), the surface albedo of BC4.5+and BC0.5+significantly decreased compared with CK +(<0.05). The biggest surface albedo decline rates of BC4.5 + and BC0.5 + in winter wheat season were 23.7%, 17.9% and 44.5%, 44.9% in summer maize season. The leaf area index of each treatment was remarkably correlated with the surface albedo. The shadow produced by the development of crop canopy structure would cover the change of surface color induced by the input of biochar. Under the condition of bare land, the surface albedo of biochar treatment was significantly decreased compared with the control treatment(<0.05). Compared with the control treatments, the soil CO flux of the biochar treatments was significantly increased(<0.05). With the extension of time, the growth rate of soil CO flux of biochar treatment was decreased gradually. The increase from BC4.5 + to CK + was gradually reduced from 276.7% to 36.1%, and the increase of BC4.5-from to CK-was significantly reduced from 163.5% to 39.8%. The increase of soil CO flux could be derived from the mineralization of the readily decomposed carbon fractions in the biochar-soil system. The decrease of surface albedo caused by the input of biochar had no direct effect on soil respiration, and the input of biochar could reduce the temperature sensitivity of soil respiration. This result could provide a foundation for the verification of the chemical and biological stability of biochar.
目前，将生物炭施用于土壤被视为一种通过碳固存来缓解气候变化的手段，它能从大气中吸收二氧化碳，进而影响全球气候变化趋势。然而，关于农田地表反照率变化的研究较少，生物炭施用于土壤可能会通过改变地表反照率而产生辐射强迫，这可能是事实。基于此背景，本研究旨在表征有植物和无植物农田反照率的季节变化特征，及其对土壤温度、土壤湿度、土壤呼吸和土壤有机碳组分的影响。该实验有3个主要处理，每个主要处理重复3次，分别为CK（对照处理）、BC0.5（以0.5 kg·(m·a)的量施用生物炭）和BC4.5（以4.5 kg·(m·a)的量施用生物炭）。每个主要处理包含2个亚处理，即作物种植（+）和非种植（-）。实验结果表明，在作物生长前期（玉米苗期至拔节期、小麦苗期至越冬期），BC4.5+和BC0.5+的地表反照率与CK+相比显著降低（<0.05）。冬小麦季BC4.5 +和BC0.5 +的最大地表反照率下降率分别为23.7%、17.9%，夏玉米季为44.5%、44.9%。各处理的叶面积指数与地表反照率显著相关。作物冠层结构发育产生的阴影会掩盖生物炭输入引起的地表颜色变化。在裸地条件下，生物炭处理的地表反照率与对照处理相比显著降低（<0.05）。与对照处理相比，生物炭处理的土壤CO通量显著增加（<0.05）。随着时间的延长，生物炭处理的土壤CO通量增长率逐渐降低。从BC4.5 +到CK +的增加幅度从276.7%逐渐降至36.1%，从BC4.5-到CK-的增加幅度从163.5%显著降至39.8%。土壤CO通量的增加可能源于生物炭-土壤系统中易分解碳组分的矿化。生物炭输入导致的地表反照率降低对土壤呼吸没有直接影响，生物炭的输入可以降低土壤呼吸温度敏感性。这一结果可为验证生物炭的化学和生物稳定性提供依据。
