玉米生物炭和改性炭对土壤无机氮磷淋失影响的研究

Effects of corn biochar and modified carbon on leaching of inorganic nitrogen and phosphorus in soil

利用玉米秸秆为原料制作生物炭,并用氯化铁进行改性,考察了改性前后生物炭对硝态氮和磷的吸附等温和吸附动力学过程,将生物炭和改性炭制作3 cm厚的物理隔离层,施入土柱50 cm处,通过淋溶实验,研究生物炭改性前后对土壤无机氮磷淋失的影响。结果表明,炭化温度为500℃时,铁炭比为0.7的生物炭和改性炭对氮磷的吸附能力最强。吸附动力学和等温吸附曲线分析表明:生物炭改性后对硝态氮和磷的吸附增大,生物炭和改性生物炭对硝态氮的最大吸附量分别为0 mg·g-1和2.414 mg·g-1、对磷的最大吸附量分别为1.723 mg·g-1和16.062 mg·g-1。与对照相比,生物炭处理和改性炭处理硝态氮的淋失量分别降低11.2%和31.6%,磷的淋失量分别显著降低33.1%和82.9%,氨氮的淋失量分别显著降低44.3%和68.6%。淋溶试验后对土壤残留养分分析表明,隔离层的添加并不会对0～50 cm土层内NO-3-N、NH+4-N和PO3-4-P含量产生明显影响,同时改性生物炭能有效减少NH+4-N和PO3-4-P向更深土层中迁移,表明土壤中添加改性生物炭能够有效降低土壤无机氮磷的淋失风险。

In this study,biochar and modified biochar were used to investigate the adsorption kinetics of nitrate and phosphorus.A3cmthick physical barrier of biochar and modified carbon was applied to a depth of50cm.The soil column leaching experiment was used to study the effect of biochar on the leaching of inorganic nitrogen and phosphorus in the soil.The results showed that when the carbonization temperature was500℃and the iron carbon ratio was0.7,the adsorption capacity of the biochar and modified carbon to nitrogen and phosphorus was the strongest.In addition,the kinetics of adsorption isotherm biochars before and after modification were more in line with the Langmuir adsorption equation and dynamics equation of quasi secondary.Biochar modification before adsorption by nitrate into a modified maximum of2.414mg·g^-1,biochar and modified carbon on phosphorus adsorption quantity biggest were1.723mg·g^-1and16.062mg·g^-1.Compared with the control,biochar and modified carbon leaching loss of nitrate nitrogen were decreased by11.2%and31.6%,the leaching amounts of phosphorus were significantly decreased by33.1%and82.9%,respectively,significantly reduced the amount of ammonia nitrogen leaching44.3%and68.6%.Analysis of soil residual nutrients after leaching test showed that the addition of isolation layer did not significantly affect the contents of NO-3-N,NH+4-N and PO3-4-P in0~40cm soil layer,while the modified carbon could effectively reduce NH+4-N and PO34--P migrated to deeper soil layers,indicating that the leaching risk in soil by adding modified biochar can effectively reduce the inorganic nitrogen and phosphorus in soil.