不同施肥年限下作物产量及土壤碳氮库容对增施有机物料的响应

Responses of Crop Yields, Soil Carbon and Nitrogen Stocks to Additional Application of Organic Materials in Different Fertilization Years

【目的】研究不同年限下增施有机肥及秸秆还田对作物产量及剖面土壤碳氮库容的影响,旨在为华北平原冬小麦-夏玉米轮作区增强土壤肥力、提高作物产量提供依据。【方法】以农业部昌平潮褐土生态环境重点野外科学观测试验站为平台,分别在长达11年和27年的2个不同施肥年限试验区采集4个施肥处理,即氮磷钾(NPK)、氮磷钾+22.5 t·hm^(-2)有机肥(NPKM)、氮磷钾+33.75 t·hm^(-2)有机肥(NPKM+)、氮磷钾+秸秆还田(NPKS)不同土层深度的土壤样品,分析冬小麦-夏玉米产量和土壤碳氮库容剖面分布特征。【结果】(1)增施有机肥及秸秆还田处理对作物的增产效应随施肥年限的延长而逐渐增强。与NPK处理相比,施肥11年限的NPKM、NPKM+和NPKS处理分别提高小麦和玉米产量为18.6%、15.8%、3.5%和39%、42%、35%;而27年的各施肥处理对小麦和玉米产量的增产幅度分别为41%、51.5%、23%和31%、33%、58%。(2)随着施肥年限的延长,增施有机肥及秸秆还田均能持续提升土壤碳、氮库容。连续施肥11年后,土壤碳、氮库容分别为25—114 Mg·hm^(-2)、2.2—9.0 Mg·hm^(-2);而27年后土壤碳、氮库容分别为29—146 Mg·hm^(-2)、2.5—12.1 Mg·hm^(-2)。随着土壤剖面的加深,不同施肥年限中土壤碳、氮库容均表现为先逐渐增加后逐渐降低的趋势,均在80 cm处达到峰值。在80 cm土层峰值处,27年施肥处理中NPK、NPKM、NPKM+、NPKS土壤碳库和氮库分别为102、128、146、123 Mg·hm^(-2)和8.3、9.7、12.1、9.1 Mg·hm^(-2),而11年施肥年限内各处理土壤碳、氮库均表现为差异不显著(P>0.05)。和NPK相比,不同年限中增施有机肥及秸秆还田均降低了不同土层的土壤碳氮比。同时,随着施肥年限的延长,土壤碳氮比越稳定。(3)随着施肥年限的延长,各处理土壤累积碳、氮库均呈现增加趋势。连续施肥11年后,NPKM、NPKM+、NPKS比NPK提升土壤累积碳、氮库容分别为5.2%、11.2%、9.2%和21.2%、26.6%、38.8%;连续施肥27年后NPKM、NPKM+、NPKS比NPK提升土壤累积碳、氮库容分别为26.3%、41.1%、21.8%和26.2%、44.9%、4.0%,且随着施肥年限的延长,施用有机肥对土壤累积碳库容的提升高于秸秆还田的趋势愈加明显,而对土壤累积氮库容的提升效果低于秸秆还田。【结论】在氮磷钾化肥基础上增施有机肥及秸秆还田会提高作物产量、增强土壤碳氮库容、提升土壤肥力,且随着施肥年限的延长,效果愈加明显。同时,施用有机肥对作物产量、碳库的增强效应强于秸秆还田,而对氮库的提升效果低于秸秆还田。

【Objective】In order to improve crop yield and soil fertility for rotation of winter wheat and summer maize in North China Plain, it is necessary to study the effects of long-term additional application of manure and straw incorporation on crop yield,soil carbon and nitrogen stocks. 【Method】 Taking the key experimental station on ecological environment of Drab Fluvo-aquic soil in Changping, Ministry of Agriculture as the research platform, two application histories(11 years and 27 years) and four application treatments(NPK, chemical fertilizers;NPKM, NPK+22.5 t·hm-2 manure;NPKM+, NPK+33.75 t·hm-2 manure;NPKS, NPK+ straw)were conducted, and yield of winter wheat and summer maize as well as soil carbon and nitrogen stocks were analyzed. 【Result】Results showed that long-term additional application of manure or straw could increase crop yield. Compared with NPK, the yield of wheat and maize could be increased by 18.6%, 15.8%, 3.5% and 39%, 42%, 35% under NPKM, NPKM+ and NPKS, respectively,after 11 years. Meanwhile, yield of wheat and maize could be increased by 41%, 51.5%, 23% and 31%, 33%, 58% under NPKM,NPKM+ and NPKS, respectively, relative to NPK after 27 years. Soil organic carbon(SOC) and total nitrogen(TN) were increased after manure and straw added with the time prolonged. Specifically, stocks of soil carbon and nitrogen were 25-114 Mg·hm-2 and2.2-9.0 Mg·hm-2, respectively, after 10 years, which were 29-146 Mg·hm-2, 2.5-12.1 Mg·hm-2, respectively, after 27 years. Both SOC and TN stocks presented the same trend which increased firstly and then decreased with the increasing of soil depth, reaching a peak at 80 cm. Peaks of SOC and TN pools were 102, 128, 146, 123 Mg·hm-2 and 8.3, 9.7, 12.1, 9.1 Mg·hm-2 for NPK, NPKM,NPKM+ and NPKS, respectively, after 27 years. However, no significant difference was observed under these treatments after 10 years(P>0.05). Soil ratios of C to N were reduced in different soil layers after two application histories with different organic material application, and soil C/N was obtained stability with the prolonged of fertilization years. Both SOC and TN stocks presented increasing trends with time. Compared with NPK, the accumulation stocks of SOC and TN could increase 5.2%, 11.2%,9.2% and 21.2%, 26.6%, 38.8% under NPKM, NPKM+ and NPKS, respectively, after 11 years, which could increase 26.3%, 41.1%,21.8% and 26.2%, 44.9%, 4.0% under NPKM, NPKM+, and NPKS, respectively, after 27 years. For a longer time, additional application of manure was better than straw for promoting SOC accumulation, while it was opposite for TN accumulation.【Conclusion】Based on the conventional fertilization, long-term additional application of manure or straw could increase crop yield, SOC and TN stocks thus promoted soil fertility. A great impact was observed with fertilization years added. In addition,application of manure had a more remarkable effect than straw incorporation, especially for a much long time, but on the contrary for accumulation stocks of TN.