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为提高土壤对氮素的吸附能力,减少土壤氮素流失,通过土壤培养试验和等温吸附试验研究了经堆腐的玉米秸秆、膨润土和聚丙烯酰胺(PAM)配制成的复合改良材料对砂质土壤NH4+-N吸附特性的影响。结果表明,复合改良材料对土壤NH4+-N吸附的影响随土培时间的延长呈先增大后减小的趋势,60d时最大。各处理NH4+-N的等温吸附曲线可用Langmuir方程很好地拟合。提高复合改良材料用量使砂质土壤NH4+-N的最大吸附量Qmax提高,吸附常数(k)降低,表明复合改良材料可以提高土壤对NH4+-N的吸附容量,但不能增加其吸附强度。同一用量下,Qmax随改良材料中PAM比例的提高呈先增大后减小的趋势,以PAM比例为0.99%时为最大,k则最低。提高复合改良材料用量使砂质土壤NH4+-N的最大缓冲容量(MBC)减小,改良材料中PAM添加比例对MBC无明显的影响规律。结果说明复合改良材料对土壤NH4+-N的保持量具有明显的促进作用,改良材料中PAM的添加比例以0.99%最佳。
In order to increase soil nitrogen adsorption capacity and decrease soil nitrogen loss, soil compaction and compounded modified corn stalks, bentonite and polyacrylamide (PAM) Effect of Soil NH4 + -N Adsorption Characteristics. The results showed that the effect of composite modified materials on soil NH4 + -N adsorption increased first and then decreased with the extension of soil culture time, and reached the maximum at 60 days. The adsorption isotherms of NH4 + -N can be well fitted by the Langmuir equation. Increasing the amount of composite improving material increased the maximum adsorption capacity of NH4 + -N in sandy soil and decreased the adsorption constant (k), which indicated that the composite improved soil could improve the adsorption capacity of NH4 + -N, but could not increase its adsorption strength. Under the same dosage, Qmax firstly increased and then decreased with the increase of PAM ratio in the modified material, with the maximum at 0.99% PAM and the lowest k. Increasing the amount of composite improvement material reduced the maximum buffer capacity (MBC) of sandy soil NH4 + -N, and the modified PAM addition ratio had no obvious effect on MBC. The results showed that composite modified materials had a significant promoting effect on the retention of soil NH4 + -N. The optimum proportion of PAM in the modified materials was 0.99%.