长期施肥对潮棕壤有机氮组分的影响

Effects of long-term fertilization on organic nitrogen fractions in aquic brown soil

依托长期定位试验(从1990年开始)的4个施肥处理(CK,不施肥;M,循环猪圈肥;NPK,单施化肥;NPK+M,化肥配施循环猪圈肥),探讨了长期施肥对潮棕壤有机氮各组分的影响并揭示了其年际变化特征.结果表明:从试验开始至2015年,不同施肥模式下各有机氮组分呈现不同的变化趋势,其中酸解有机氮基本上表现为逐年增加的趋势;M和NPK+M处理氨基酸态氮也逐年上升,而CK和NPK处理氨基酸态氮持续下降,这可能与微生物对土壤中氨基酸的利用有关.在整个试验过程中(1990—2015年的平均值),NPK处理酸解铵态氮大幅度增加,比CK增加31.1%;在施加有机肥的2个处理中(M和NPK+M)有机氮各组分均有所提高.与M相比,NPK+M处理各有机氮组分增加的幅度更加明显,这表明有机无机肥配施能有效增加土壤有机氮,进而增强土壤供氮能力,提高土壤肥力水平.

The purpose of present research was to investigate how different fertilization regimes altered soil organic nitrogen fractions and their inter-annual dynamics based on a series of long-term experiment （initiated at 1990 ）, including ： CK （ non-fertilization ） ; M （ recycled pig manure ） ; NPK （chemical fertilizer NPK） ; NPK ＋ M （recycled pig manure with chemical fertilizer NPK）. The results showed that soil organic nitrogen components under the different fertilization treatments presented eontrastive patterns from the establishment the experiments to 2015. Generally, acid hydrolysable organic nitrogen content increased year by year. The amino acid nitrogen content under CK and NPK treatments consistently declined, although amino acid nitrogen for M and NPK＋M treatments showed a increasing trend. These phenomena were probably ascribed to the utilization of soil amino acids by microbes. From 1990 to 2015, NPK treatment substantially elevated the content of acid-released ammonium nitrogen by 31.1% compared with CK （ mean value across the experi- ment）, and for the treatments using organic manure （M and NPK＋M）, the contents of all fractions of soil organic nitrogen increased. Notably, the increase magnitudes for NPK＋M were more dramatic than those of M. These results demonstrated that combined use of organic and inorganic fertilizers could more effectively elevate soil organic nitrogen, subsequently helping to improve the capacity of soil nitrogen supply and enhance the soil fertility.