碱解还原扩散法测定缓释复合肥氮素释放特性研究

以自制的新型非包膜有机无机缓释复合肥料（简称缓释复合肥，Slow-release compound fertilizer，SRCF）为供试材料，采用连续碱解还原扩散法研究氮素养分缓释过程。试验结果表明，1）以硼酸为吸收液时，NaOH浓度在0～0.1 mol/L范围内， SRCF在40 d时的氮素累积扩散率随碱的浓度增加而提高，且累积扩散率显著高于较高浓度碱液（0.5～2 mol/L NaOH）的处理效果；2）同一NaOH浓度下，0.1 mol/L H2SO4作吸收液时，SRCF的累积扩散率高于0.1 mol/L H3BO3作吸收液的累积扩散率；3）0.05和0.01 mol/L NaOH浓度下，SRCF的氮素扩散特征与土壤肥包培养下的氮素矿化过程具有较好的相似性，能充分指示有机无机缓释复合肥氮素形态的多样性。连续还原扩散法测定有机无机缓释复合肥氮素扩散释放的适宜条件为:0.05～0.1 mol/L NaOH为扩散介质，0.1 mol/L H2SO4为吸收介质，25℃恒温培养（40 d），在不同时段滴定吸收介质。

Study on characteristics of nitrogen from slow-release compound fertilizers using alkali-hydrolyzed reduction diffusing method

In this study, SRCFs developed and produced by ourselves were employed to investigate the N release process using continuous alkali-hydrolyzed reduction diffusing method. The results showed: 1）When absorbing solution was H3BO3, the N accumulated diffusing rate of SRCF increased with the increasing content of NaOH (0-0.1 mol/L). In the meantime, it was higher than that of 0.5-2 mol/L NaOH. 2）Under the same content of NaOH, the N accumulated diffusing rate of SRCF was greater in 0.1mol/L H2SO4 than in 0.1 mol/L H3BO3. 3）When NaOH was used in 0.05 mol/L or 0.1 mol/L, the N diffusing character of SRCF were similar to the N mineralization process of SRCF cultured by means of the soil-fertilizer-packet method. Thus, the ideal operation conditions of continuous alkali-hydrolyzed reduction diffusing method were 0.05-0.1 mol/L NaOH (diffusing solution), 0.1mol/L H2SO4 (absorbing solution), continuously cultured for 40 days at 25℃ and titrated the absorbing solution in different periods.