缓/控释氮素肥料对土壤生物学活性的影响

Effect of Slow/Controlled Release Nitrogen Fertilizers on Soil Biological Activities

采用盆栽试验方法,研究施用不同种缓/控释氮素肥料对玉米苗期土壤脲酶、硝酸还原酶活性、微生物生物量碳和氮的影响。结果表明:在玉米苗期,施用脲酶抑制剂(NBPT)涂层大颗粒尿素、硝化抑制剂(DCD)与NBPT混合涂层大颗粒尿素肥料对脲酶活性有显著的抑制作用,脲酶活性为48～50mgNH3-N·kg-1土·24h-1;施用DCD与NBPT混合涂层大颗粒尿素肥料,硝酸还原酶活性最高,为1.43μgN·g-1土·24h-1,施用含有NBPT肥料对硝酸还原酶活性没有显著影响。玉米苗期施用NBPT涂层尿素肥料微生物量碳、氮含量最高,分别为241和57mg·kg-1土,NBPT对土壤微生物量没有产生负面影响。施用不同种缓/控释氮素肥料微生物量氮变化与微生物量碳一致,施用DCD与NBPT混合涂层大颗粒尿素肥料微生物量氮与对照无显著差别,为50mg·kg-1土。施用DCD与NBPT混合涂层大颗粒尿素肥料,玉米苗期微生物固持氮素能力没有受到影响,同种膜材料包膜NBPT/DCD涂层尿素制成的控释氮肥,对土壤生物学活性影响明显强于直接包膜大颗粒尿素制成的控释氮肥的作用效果。不同种缓/控释肥料玉米苗期土壤生物学活性差异表明,丙烯酸树脂包膜尿素制成的控释氮肥,对氮素或抑制剂的控释效果显著好于醋酸酯淀粉包膜尿素制成的控释氮肥。

Using pot experiment, the effects of different slow/controlled release nitrogen fertilizers on soil urease and nitrate reductase activities and microbial C and N were researched at the seedling stage of maize. The coated granular urea amended with N-（n-butyl）thiophosphoric triamide（NBPT） or with NBPT and dicyandiamide （DCD） significantly inhibited the activity of soil urease, being 48-50 mg NH3-N·kg^-1· 24 h^-1, but coated granular urea amended with NBPT and DCD gave the highest activity of soil nitrate reductase, being 1.43 μg N·g^-1·24h^-1. Coated granular urea amended with NBPT had no significant effect on the activity of soil nitrate reductase, but gave the highest soil microbial C and N, being 241 mg. kg^-1 and 57 mg. kg^-1. Soil microbial C and N had the same variation trend under applying different kinds of slow/controlled release nitrogen fertilizers, but soil microbial N under the application of coated granular urea amended with NBPT and DCD had no significant difference with CK, being 50 mg. kg^-1. Coated granular urea amended with NBPT and DCD had little effect on the N immobilization by soil microbes. Compared with the coated granular urea without any amendments, the effects of that with NBPT and/or DCD on soil biological activities were significantly higher. Methyl methacrylate was more effective than starch acetate as coating materials.