秸秆源黑炭还田对水稻土生产力和固碳的影响

为揭示秸秆源黑炭连续还田对太湖平原稻麦轮作农田土壤生产力和固碳作用的影响,设黑炭施加量为0(CK)、4.5和9.0t/hm23个处理,通过2a 4个完整稻麦轮作季的盆栽试验,研究了稻秆来源黑炭每季还田下的稻麦作物产量.养分吸收状况及土壤理化性质的变化. 结果显示,土壤w(TOC)(TOC为总有机碳)和w(全N)随黑炭施加量的增加而增加. 每季黑炭施加量为9.0t/hm2时,土壤w(TOC)和w(全N)可分别提高46.7%~113.0%和9.3%~28.3%. 黑炭施入土壤后能够提高稻麦作物地上部分生物量,籽粒产量增加11.4%~60.5%,秸秆产量增加15.0%~56.8%. 黑炭处理下稻麦作物体内N、P、K、Mg和Ca的累积量显著提高,这一现象与每季结束后土壤w(全N)以及土壤有效元素含量〔w(有效P)、w(有效K)、w(有效Mg)和w(有效Ca)〕的增加相吻合. 黑炭施入可显著提高土壤pH和CEC(阳离子交换量),尤其是黑炭施加量为9.0t/hm2时,pH最高可达6.79,CEC最高达到12.7cmol/kg. 连续三季施入黑炭后,土壤容重比不施黑炭处理降低8.0%~12.2%. 试验结果表明,秸秆来源黑炭施入太湖平原稻麦农田可起到固碳增汇、增加土壤碳库容量的作用,也能改善土壤理化性质,提高土壤生产力. 

Effects of Crop-Straw Biochar on Paddy Soil Productivity and Carbon Sequestration

In order to evaluate effects of crop straw biochar on soil productivity and C sequestration in paddy soil of the Tai Lake plain, the rice/wheat crop growth, nutrient uptake by crop plants as well as soil physicochemical characteristics were investigated after the successive incorporation of biochar from rice straw into a rice-wheat rotated soil during a 2-year (four rice/wheat rotation seasons) pot experiment. The application rates of biochar were set as 0(as control; CK), 4.5and 9.0t/hm2, respectively. Each treatment was replicated in three pots. Each pot was kept the same dosage of NPK fertilizers, the same application methods as well as the similar water management. Before crop season, the biochar (passed through a 2cm sieve) homogeneously was mixed with 0-10cm soil in pots. The results showed that w(soil total organic carbon, TOC) and w(soil total nitrogen, TN) increased with increasing biochar application. TOC and TN increased by 46.7%-113.0% and 9.3%-28.3% at 9.0t/hm2biochar application rate in the four crop seasons, respectively. Biochar application increased the above-ground biomass of rice/wheat (grain yield increased by 11.4%-60.5%, straw yield increased by 15.0%-56.8%) as well as enhanced the accumulations of N, P, K, Mg and Ca. Accordingly, the amount of total nitrogen in the soil increased after biochar application, as well as soil available nutrients (Mehlich Ⅲ extraction) such as w(available P)、w(available K)、w(available Mg)and w(available Ca). In addition, values of pH and cation exchangeable cations (CEC) increased, while soil bulk density decreased. The results demonstrated that the successive application of biochar produced from crop straw could sequester C, enhance C storage capacity as well as ameliorate soil properties, improve soil fertility and enhance crop productivity in rice/wheat paddy soil of the Taihu Lake region.