施肥和生物炭添加对高粱-玉米轮作土壤呼吸的影响

Effect of Fertilization and Biochar Addition on Soil Respiration in a Sorghum-Maize Rotation Agroecosystem

[目的]探明农田生态系统中施肥和生物炭添加对土壤呼吸(R_(s))、环境因子和植被指数的影响,及生物因子和非生物因子对土壤呼吸的影响,为农田生态系统作物生长和碳排放评估提供依据。[方法]以太原盆地高粱—玉米轮作地连续5年(2011—2015年)施肥和生物炭添加4种处理(对照:CK;生物炭:B;无机肥:INF;无机肥+生物炭:INF+B)下的土壤为研究对象,利用连续2年(2015—2016年)对生育期的R_(s)、生物因子和非生物因子定期观测数据,分析4种处理对R_(s)及其与生物因子、非生物因子关系的影响。[结果](1)与CK处理相比,B,INF和INF+B处理降低土壤温度(2.8%~4.2%),提高R_(s)的温度敏感性(Q_(10))(4.5%~20.2%)、R_(s)速率(0.5%~8.8%)和3种植被指数(VI):增强植被指数(EVI)(1.5%~6.2%)、差值植被指数(DVI)(0.7%~6.0%)、归一化植被指数(NDVI)(1.2%~5.4%),但其对这些因子的影响均未达显著水平(p>0.05)。(2) B,INF和INF+B处理对R_(s)的影响在不同生育期不同,它们均提高了生育前期的R_(s),而生育后期CK处理的R_(s)高于其他处理(除灌浆期的B处理),导致各处理R_(s)在整个生育期无显著差异。(3) 3种植被指数中,DVI的季节变化对R_(s)季节变化的解释度最高,为75.5%,10 cm深度的土壤温度(T_(10))和土壤湿度(W_(s))分别解释R_(s)季节变化的30.8%和20.1%。从R^(2)和AIC值来看,以T_(10),W_(s)和DVI为自变量的三因子模型对R_(s)季节变化的预测效果较好。[结论]高粱全生育期4个处理间R_(s)均无显著差异,施肥和生物炭添加并未增加R_(s)。研究结果可为无机肥和生物炭施加对农田土壤碳排放与土壤改良、农作物生长之间的影响关系提供依据。

[Objective] The aims of this study are to explore the effects of fertilization and biochar addition on soil respiration(R_(s)),environmental factors and vegetation index,and the effects of biotic factors and abiotic factors on soil respiration,and to provide the reference for the assessment of crop growth and carbon emission in farmland ecosystem.[Methods] In a sorghum-corn rotation agroecosystem of Taiyuan basin after a continuous 5-year(2011—2015) fertilization and biochar additon with 4 treatments(control:CK,biochar:B:inorganic fertilizer:INF and inorganic fertilizer+biochar:INF+B),based on periodic observations of R_(s),biological and abiotic factors for 2 consecutive years(2015—2016),we analyzed the effects of the 4 treatments on R_(s) and its relationship with biological and abiotic factors.[Results](1) Compared with CK,B,INF and INF+B reduced soil temperature(2.8%~4.2%),and increased temperature sensitivity(Q_(10)) of soil respiration(4.5%~20.2%) and soil respiration rate(0.5%~8.8%),increased the enhanced vegetation index(EVI) by 1.5%~6.2%,difference vegetation index(DVI) by 0.7%~6.0%,normalized vegetation index(NDVI) by 1.2%~5.4%,respectively;but the influence on these factors did not reach a significant level(p>0.05).(2) The effects of B,INF and INF+B on R_(s) differed in different growth stages.B,INF and INF+B increased the R_(s) in the early growth stage,while the R_(s) of CK treatment was higher than that in other treatments(except B treatment in the grouting stage)(p<0.05) in the later growth stage,resulting in no significant difference in R_(s) among all treatments in the whole growing stage.(3) Among the three vegetation indices,the seasonal variation of DVI showed the highest interpretation of the seasonal variation in R_(s) at 75.5%.Soil temperature in 10 cm depth(T_(10)) and soil moisture over 0—10 cm depth(W_(s)) explained 30.8% and 20.1% of the seasonal variation of R_(s),respectively.From the R^(2) and AIC values,the three-factor model with T_(10),W_(s) and DVI as independent variables predicted the seasonal change of R_(s) well.[Conclusion] There was no significant difference in R_(s) between the four treatments in whole sorghum,and R_(s) did not increase by fertilization and biochar addition.The results provided the basis for the relationship between inorganic fertilizer and biochar application on soil carbon emission,soil improvement and crop growth.