长期不同施肥模式对潮土有机氮组分及剖面分布的影响

Different long-term fertilization patterns affect components of organic nitrogen and the profile distribution of fluvo-aquic soil

为研究长期不同施肥模式下潮土有机氮组分特征及剖面分布,明确不同施肥模式下土壤的供氮潜力,在潮土长期定位试验(1990—2020年)不同施肥措施下,选取对照(CK,不施肥)、单施化肥(NPK)、化肥+秸秆还田(NPKS)、有机无机肥配施(NPKM)4个处理,采用Bremner法测定了不同处理土壤有机氮各组分和全氮含量。结果表明,不同施肥模式对土壤耕层(0~20 cm)全氮、酸解总有机氮及酸解有机氮各组分含量影响显著或极显著(P<0.05或P<0.01)。与NPK处理相比,NPKS处理土壤全氮、酸解总有机氮、酸解铵态氮、酸解氨基酸态氮含量分别显著提高了22.10%、44.03%、39.07%、44.71%,NPKM处理土壤全氮、酸解总有机氮、酸解铵态氮、酸解氨基酸态氮含量分别显著提高了46.09%、54.73%、25.14%、67.06%。相同土层土壤全氮和酸解有机氮各组分含量均在NPKM处理最高,其次为NPKS处理。在0~100 cm土层,各处理土壤有机氮均以铵态氮和氨基酸态氮为主,且酸解总有机氮和各组分氮含量总体上在表层土壤(0~20 cm)最高。0~100 cm土层酸解总有机氮及各组分含量总体上均随土层深度增加而下降。土壤中的氮素以酸解有机氮为主,占全氮含量比例范围为59.01%~92.31%。与CK处理相比,各施肥处理降低了土壤未知态氮占全氮的比例。综上,土壤有机氮组分含量变化与施肥模式密切相关,有机无机肥配施和化肥+秸秆还田能显著增加土壤全氮及酸解有机氮各组分含量,进而提高土壤供氮能力,是华北平原潮土区适宜的施肥模式;从相关性分析结果看,在土壤耕层有机氮组分中酸解铵态氮和氨基酸态氮是土壤氮的主要贡献因子。

This study examined the characteristics of the components of organic nitrogen and the profile distribution of fluvo-aquic soil under different long-term fertilization conditions to clarify the nitrogen supply potential of soil under various fertilization measures and provide a basis for rational fertilization schemes. In a long-term positioning test of fluvo-aquic soil from 1990 to 2020(30 a), four different fertilization treatments were selected:no fertilizer, single chemical fertilizer, chemical fertilizer plus maize straw, and chemical fertilizer plus organic manure. The contents of soil organic nitrogen components and total nitrogen following the different treatments were determined using the Bremner method. Different fertilization methods had significant or extremely significant effects on the total nitrogen content, total acid organic nitrogen, and components of acid organic nitrogen in the plowing layer of the soil(0~20 cm). Compared with single application of chemical fertilizer, the contents of soil total nitrogen, acidolysis of total organic nitrogen, ammonium nitrogen, and amino acid nitrogen in the chemical fertilizer plus straw return groups increased significantly by 22.10%, 44.03%, 39.07%, and 44.71%, respectively;the contents of soil total nitrogen, acidolysis of total organic nitrogen, ammonium nitrogen, and amino acid nitrogen in the chemical fertilizer plus organic manure groups increased by 46.09%, 54.73%, 25.14%, and 67.06%, respectively. In the same soil layer, the soil total nitrogen and acidolysis organic nitrogen contents showed that mineral fertilizers plus organic manure treatment exhibited the highest nitrogen content,followed by chemical fertilizer plus maize straw treatment. In the 0–100 cm soil layer, the contents of acid hydrolyzed ammonium nitrogen and amino acid nitrogen were highest in all treatments, and the contents of acid hydrolyzed total organic nitrogen and acid hydrolyzed component nitrogen were highest in surface soil(0–20 cm);the contents of acid total nitrogen and acid hydrolyzed component nitrogen decreased with increasing soil depth. Nitrogen in the soil is mainly acid-hydrolyzed organic nitrogen, which accounts for 59.01%-92.31%of the total. Compared with the no fertilizer treatment, each fertilization treatment reduced the proportion of soil acid-hydrolyzed unknown nitrogen in the total nitrogen. In conclusion, the change in soil organic nitrogen content was closely related to the fertilization method. Using a combination of organic and inorganic fertilizer and straw returning can significantly increase the soil total nitrogen content and acid organic nitrogen, thereby improving the capacity of the soil to supply nitrogen. This fertilization model is suitable for the tidal soil area of the North China Plain;acidolysis of ammonium nitrogen and amino acid nitrogen are the main factors contributing to soil nitrogen content.