生物炭对岩溶区玉米生长、土壤CO2及岩溶作用的影响

为研究生物炭对岩溶区玉米生长、土壤CO₂体积分数和排放速率及岩溶作用的影响，通过野外盆栽试验，将蔗渣生物炭分别以土壤质量分数为0%（CK）、0.5%（T1）、1%（T2）、2%（T3）和5%（T4）添加到石灰土中，并栽培玉米。测定玉米生育期中土壤CO2体积分数和排放速率、土壤淋溶水中Ca2+和 质量分数；并测试玉米收割后土壤有机碳质量分数和容重及玉米生物量。结果表明，添加生物炭增加土壤有机碳质量分数，显著降低了土壤容重；2%和5%生物炭添加显著增加了玉米秸秆干重、玉米棒干重和玉米根干重；在玉米苗期，5%生物炭添加显著增加了土壤CO₂体积分数和排放速率；在玉米拔节期、抽穗期和成熟期，2%和5%生物炭添加显著增加了土壤CO^₂体积分数、排放速率以及在此期间收集的土壤淋溶水Ca²⁺和 质量分数。由此可见，蔗渣生物炭作为岩溶区石灰土改良剂，在一定程度上改良石灰土性质，促进了玉米生长，提高了岩溶区土壤CO2的体积分数和排放速率，加快了岩溶作用。

Effect of Biochar on Maize Growth,Soil CO2 and Karstification in Karst Area

A field pot experiment was conducted to study the effect of biochar on maize growth, soil CO₂ concentration and emission rate, karstification in karst area. Five mass percentage levels of biochar from sugarcane bagasse were added into limestone soil, which were no biochar (CK), 0.5% (T1), 1% (T2), 2% (T3) and 5% (T4), respectively, then maize was planted. The changes of soil CO₂ concentration and emission rate, the concentration of Ca²⁺and in soil leaching water were monitored during the growth period of the corn. The TOC of soil, soil bulk density and biomass of maize were tested after harvest of maize. The results indicated that: the correlation coefficient between the TOC of soil and biochar content was 0.992, however, the correlation coefficient between soil bulk density and biochar content was -0.982. As compared with the control, the biomass of maize straw under T3 and T4 treatment were significantly increased by 12.92% and 33.01%, maize cob were significantly increased by 11.51% and 16.41%, root were significantly increased by 20.88% and 51.13%, respectively. In the seedling stage of maize, soil CO₂ concentration and emission rate were significantly increased by 76.00% and 66.91% under T4 treatment, respectively. In the jointing stage, heading stage and grain filling stage of maize, soil CO₂ concentration of T4 treatment were significantly increased by 172.86%, 149.40% and 54.48%, those of T3 were significantly increased by 91.43%, 44.58% and 18.66%; Soil CO2 emission rate of T4 treatment were significantly increased by 79.52%, 84.49% and 102.22%, and those of T3 were significantly increased by 17.04%, 17.49% and 29.63%, respectively. The main reason of soil CO₂ concentration and emission rate increase was the increase of respiration of maize root, the respiration increase of soil microbe might also contribute to this result. The concentration of Ca2+and in soil leaching water of T3 treatment which were collected after the jointing stage of maize were significantly increased by 16.00%~29.17%, and 17.39%~28.57%, those of T4 treatment were significantly increased by 38.46%~50.00% and 34.78%~52.38%, the increase of soil CO₂ concentration might contribute to those increases. Therefore, to some extent, bagasse biochar as amendment of limestone soil, can improve limestone soil properties, accelerate maize growth, and increase soil CO₂ concentration and emission rate.