水洗生物炭对2种类型土壤钾素淋失的影响

为了探究生物炭对潮土和砂土钾素淋失的调控效应,通过土柱淋溶模拟试验,以水洗生物炭为研究对象,比较生物炭水洗前后不同形态钾含量、表面形貌和含氧官能团变化,进而探究不同用量水洗生物炭对2种类型土壤钾素淋失的阻控效应。结果表明:水洗处理可使生物炭水溶性钾含量由13.9 g/kg降至0.06 g/kg,而对生物炭孔隙结构和表面含氧官能团影响较小。水洗生物炭对潮土和砂土水分淋失的影响受其施用量的影响,表现为低量促进、高量抑制的趋势,添加1%水洗生物炭显著增加了2种类型土壤水分淋失总量。生物炭对2种类型土壤钾素淋失的影响各异,添加2%和4%水洗生物炭对砂土钾素淋失表现出显著的阻控效应(P0.05),钾素淋失量分别较不加生物炭处理降低了21.2%和28.3%,而添加1%水洗生物炭却增加了潮土钾素淋失量(P0.05)。另外,生物炭可提升土壤阳离子交换量和表层土交换性钾含量,且提升幅度随生物炭施用量的增加而增加,并且对砂土的提升效果更明显。因此,从钾素淋失角度考虑,生物炭更适用于阳离子交换量较低、保肥能力差的砂质土壤上。

Effects of Water-washed Biochar on Potassium Leaching in Two Types of Soil

In order to explore the regulation effect of biochar on potassium leaching loss in fluvo-aquic soil and sandy soil, a soil column leaching simulation test was conducted, and water washed biochar was used as the research object, the contents of different forms of potassium, surface morphology and oxygen-containing functional groups in biochar before and after washing were compared, and then explore the regulation effects of different amounts of washed biochar on potassium leaching loss in two types of soil. The results showed that the water-soluble potassium content in biochar was decreased from 13.9 g/kg to 0.06 g/kg by water-washed treatment, but the change of pore structure and surface oxygen-containing functional groups of biochar were less affected. Moreover, the effect of water-washed biochar on water leaching loss of fluvo-aquic soil and sandy soil was influenced by its application amount, which showed a trend of low amount of water-washed biochar promoted the water leaching loss, but high amount inhibited the water leaching loss, and adding 1% water-washed biochar significantly increased the total amount of water leaching loss in the two types of soil. The effects of biochar on potassium leaching in two types of soils were different. Adding 2% and 4% washed biochar showed significant inhibition and control effect on potassium leaching in sandy soil, and compared with the treatment without biochar, the total leaching amount of potassium decreased by 21.2% and 28.3%, respectively. While adding 1% washed biochar increased the total amount of potassium leaching in fluvo-aquic soil. In addition, biochar could improve soil cation exchange capacity and exchangeable potassium content of topsoil, and the increasing extent improved with the increasing of biochar application amount, and the improvement effect was more obvious in sand soil. Therefore, for the perspective of potassium leaching, biochar was more suitable for sandy soil with low cation exchange capacity and poor fertilizer retention capacity.