长期施肥对黑垆土氨化细菌数量和氨化作用强度的影响

为探讨长期施肥下黑垆土氨化作用的变化,在长期定位试验条件下,分析了长期施肥对黑垆土氨化细菌数量和氨化作用强度的影响。结果表明,在小麦连作下,各施肥处理均可不同程度提高土壤中氨化细菌数量和氨化作用强度,其中单施有机肥及有机无机肥配施的效果更明显。在不同施肥处理中,氮磷配施有机肥处理的土壤氨化细菌数量最多(7.53×108个·g~(-1)),是不施肥处理(CK)的189.2倍,氨化作用强度最高(1.49mg·kg~(-1)),较CK增加55.0%;其次为单施有机肥、氮肥配施有机肥和磷肥配施有机肥处理,其氨化细菌数量和氨化作用强度均显著高于CK。在苜蓿连作下,与CK相比,单施磷肥处理的土壤氨化细菌数量和氨化作用强度均明显降低,降幅分别为99.5%和49.7%。因此,黄土高原黑垆土区小麦连作时,长期施用有机肥及有机无机肥配施均可提高土壤有机氮的转化作用,增强其供氮能力;苜蓿连作时,长期单施磷肥可减弱土壤有机氮的转化作用。

Effect of Long-Term Fertilization on the Amount of Ammonifier and Ammonification Intensity in the Dark Loessial Soil

Soil ammonifier and ammonification intensity has an important significance to soil organic nitrogen conversion and nitrogen supplying capacity. A long-term experiment was conducted to study the effect of long-term fertilization on the amount of ammonifier and the intensity of ammonification in the dark loessial soil. The results show that for the continuous cropping of wheat,all fertilization treatments could increase the amount of soil ammonifier and ammonification in varying degrees,but the impact of organic fertilizer and inorganic fertilizer combined with organic manure were more obvious; under NPM (nitrogen and phosphorus fertilizer with organic fertilizer),soil ammonifying bacteria owned the largest number (7.53×10⁸·g^-1),189.2 times of CK (no fertilizer); and ammonification intensity of NPM was the highest (1.49 mg·kg^-1),which improved 55.0% compared to CK.The quantity of ammonifier and ammonification intensity of M (single organic fertilizer),NM (nitrogen fertilizer with organic fertilizer) and PM (phosphorus fertilizer with organic fertilizer) were all significantly higher than those of CK. For continuous cropping of alfalfa,compared with CK,ammonifier and ammonification of P (single phosphorus fertilizer) soil were evidently lower. Ammonifier decreases by 99.5% in quantity,and intensity of ammonification dropped by 49.7%. For dark loessial soil in Loess Plateau of wheat successive cropping,the long-term application of organic manure and inorganic fertilizer combined with organic manure could improve soil organic nitrogen transformation,meanwhile enhanced its strength for nitrogen; and for continuous cropping of alfalfa,long-term fertilization of phosphate fertilizer could abate the transformation of soil organic nitrogen.