培肥措施对旱地农田产量可持续性及土壤有机碳库稳定性的影响

阐明黄土高原旱作雨养农业区长期不同培肥措施下产量可持续性和有机碳库稳定性对经济和环境友好兼顾的培肥模式筛选具有重要意义。基于2012年设置在陇中黄土高原旱作区的玉米农田长期定位试验,对比了不施肥(CK)、氮肥(NF)、有机肥(OM)、秸秆(ST)、有机肥结合无机肥(OMNF)处理下产量稳定性、可持续性和土壤有机碳、游离态颗粒有机碳、闭蓄态颗粒有机碳、颗粒态有机碳、矿质结合态有机碳及碳库稳定性。研究结果表明:1)不同培肥措施下2014-2018年平均产量和水分利用效率具有显著差异(P<0.05),OMNF处理具有最高的平均产量、水分利用效率,分别比CK增加了42.75%、108.73%,同时OMNF处理产量稳定性(0.34)和可持续性指数(0.43)最佳,具有高的增产潜力。2)不同培肥处理均能显著提高不同层次有机碳含量(P<0.05),0~30 cm土层有机碳提高幅度为6.80%~18.81%,ST、OM、OMNF等有机物料添加处理均能显著提高各土层土壤游离态颗粒有机碳、闭蓄态颗粒有机碳、颗粒态有机碳和矿质结合态有机碳(P<0.05),0~30 cm土层提高幅度分别为5.24%~57.05%、4.31%~20.69%、4.72%~25.17%、6.58%~7.95%。不同培肥处理土壤有机碳、游离态颗粒有机碳、闭蓄态颗粒有机碳、颗粒态有机碳的含量均随土层加深而降低,而矿质结合态有机碳含量则随土层加深而增加。3)不同培肥模式下土壤有机碳组分均以矿质结合态有机碳为优势组分(55.60%~67.51%),颗粒有机碳以闭蓄态颗粒有机碳为主要组分(19.14%~22.50%)。在0~10 cm各土层,OMNF、NF处理土壤碳库稳定性较高,ST、OM、OMNF处理能促进土壤碳库活性,其他土层变化规律不一致;随土层加深,ST、OM、OMNF处理的碳库稳定性提高。综合来看,OMNF措施可以增加作物产量,提升土壤活力,促进土壤固碳,是该区域玉米种植经济和环境友好兼顾的较好农业生产模式。

Effects of alternative fertilization practices on components of the soil organic carbon pool and yield stability in rain-fed maize production on the Loess Plateau

This research quantified and explored the sustainability status of various soil carbon fractions under different fertilization regimes in land used for rain-fed maize production on the Loess Plateau in Gansu province, China. Sustainability of crop yield and of soil carbon pools are key considerations in the selection of fertilization practices in rain-fed agricultural areas on the Loess Plateau that are both economical and environmentally friendly. A long-term experiment was set up in 2012 on maize-production farmland in the dry farming area of the Loess Plateau in central Gansu. Yield stability and sustainability, soil organic carbon (SOC), free particulate organic carbon (FPOC), occluded particulate organic carbon (OPOC), particulate organic carbon (POC), mineral-associated organic carbon (MOC) and carbon pool stability were compared for 0-5 cm, 5-10 cm and 10-30 cm soil depths under five treatments, as follows: no fertilization (CK), nitrogen fertilizer (NF), organic fertilizer (OM), straw (ST) and organic fertilizer combined with nitrogen fertilizer (OMNF). It was found that: 1) The average yield and water use efficiency from 2014 to 2018 differed significantly (P<0.05) under different fertilization practices. OMNF had the highest average yield and water use efficiency (42.75% and 108.73%, respectively, higher than CK). OMNF also had the highest yield stability index (0.34) and sustainability index (0.43), with a high potential for yield increase. 2) Compared with CK, the various fertilization treatments significantly increased the organic carbon content in the measured soil layers to 30 cm depth by between 6.80%-18.81% (P<0.05). For all three measured soil layers, all treatments (ST, OM and OMNF) significantly improved the FPOC, OPOC, POC and MOC (P<0.05). For the 0-30 cm soil depth, the increase range across fertilization treatments for FPOC, OPOC, POC and MOC was, respectively 5.24%-57.05%, 4.31%-20.69%, 4.72%-25.17% and 6.58-7.95%. With increasing soil depth, the levels of soil organic carbon, FPOC, OPOC and POC all decreased under all fertilization treatments, while MOC increased. 3) The dominant component of soil organic carbon was MOC (range across fertilization regimes 55.60%-67.51%), and the main component of POC was OPOC (range 19.14%-22.50%). In the 0-10 cm soil layer, OMNF and NF treatments conferred high stability of the soil carbon pool, while ST, OM and OMNF treatments promoted soil carbon pool activity, and patterns of variation of other soil layers were inconsistent. With increasing soil depth, the stability of carbon storage increased under ST, OM and OMNF treatments. Overall, OMNF increased crop yield, enhanced soil vitality and promoted soil carbon sequestration, making this treatment a better agricultural production scenario providing both economic benefit in terms of yield and environmentally friendly maize production in the Loess Plateau arid region.