塿土冬小麦–夏玉米轮作体系有机肥替代化肥比例研究

Replacement ratio of chemical fertilizer nitrogen with manure under the winter wheat–summer maize rotation system in Lou soil

【目的】有机肥替代部分化肥是实现我国化肥零增长目标的重要措施之一。探讨特定环境条件下有机肥替代化肥比例的作物产量效应及氮效率,可为合理利用有机肥资源提供科学依据。【方法】通过两年不同有机无机配施比例探讨陕西关中塿土冬小麦–夏玉米轮作体系产量及氮效率的响应。试验设对照不施肥(CK)、氮磷钾100%由化肥提供(NPK)、75%NPK+25%有机肥氮(25%M)、50%NPK+50%有机肥氮(50%M)、25%NPK+75%有机肥氮(75%M)和全部氮由有机肥提供(100%M),共6个处理。【结果】与对照相比,各施肥处理均能不同程度地提高小麦、玉米产量及其总产量。在不同有机无机配比的处理中,随着有机氮替代比例的增加产量表现为先增加后降低的趋势,75%M处理的作物产量最高。不同施肥处理,两个轮作年氮回收率的变化范围分别为35%~43%和38%~61%;氮农学效率的范围分别为12.3~18.3 kg/kg和17~24 kg/kg;氮偏生产力范围分别为41.4~46.5 kg/kg和44~51 kg/kg;氮生理效率范围分别为31~47 kg/kg和34~46 kg/kg。总体而言,75%M处理的氮效率高于其它处理。小麦–玉米轮作两年之后,施肥处理0—100 cm土层硝态氮残留量为11~133 kg/hm^2,以NPK处理最高。氮平衡结果显示,50%M、75%M和100%M均有一定的氮素盈余,盈余量为33~120 kg/hm^2,其中以100%M处理的盈余量最大。25%M和NPK处理有一定亏缺,分别为N 19.6 kg/hm^2和40.3 kg/hm^2。另外,两个轮作年的年均经济收益大小为75%M>50%M>25%M>NPK>100%M,其中75%M处理的年收益最高为19906元/hm^2,100%M处理的年收益最低为16634元/hm^2。【结论】经过小麦–玉米两个轮作年,有机肥替代75%化肥氮可以提高作物产量和氮效率,增加年经济效益,同时有效减少土壤硝态氮的残留量。

[Objectives] Replacing certain amount of chemical nutrients with manure is an important way to achieve the goal of zero-increase of total fertilizer consumption in the near future in China. This paper studied the responses of crops to the replacement, in order to realize the rational use of organic manure resource.[Methods] A field experiment was carried out in two-year winter wheat-summer maize rotation system in Guanzhong Plain of Shaanxi Province. There were 6 treatments, i.e. no fertilization input as control （CK）, 100% chemical fertilizers （NPK）, 25%, 50%, 75% and 100% of the N supplied by manures, recorded as 25%M, 50%M, 75%M, and 100%M. The yields and nitrogen use efficiencies of crops were analyzed.[Results] Crop yields were increased with the increase of organic N substitution ratios, and the treatment of 75%M had the highest crop yields. During two rotation years, the N recovery efficiencies were 35%-43% and 38%-61%; the N agronomic efficiencies were 12.3-18.3 kg/kg and 17-24 kg/kg; the N partial factor productivities were 41.4-46.5 kg/kg and 44-51 kg/kg; the N physiology efficiencies were 31-47 kg/kg and 34-46 kg/kg, respectively. All the N efficiencies were the highest under the 75%M treatment. The residual NO3--N contents at 0-100 cm depth ranged from 11 to 133 kg/hm^2, and the highest residual was in NPK treatment after the two-years’ experiment. The N balance showed that the treatments of 50%M, 75%M and 100%M had N surplus of 33-120 kg/hm^2, with the highest surplus in the 100%M treatment, while the 25%M and NPK treatments had N deficit of 19.6 kg/hm^2 and 40.3 kg/hm^2, respectively. The average annual economic benefit was in a decreased order as 75%M 〉 50%M 〉 25%M 〉 NPK 〉 100%M. The highest annual income was about 19906 yuan/hm^2 and the lowest was about 16634 yuan/hm^2.[Conclusions] Substituting 75% of chemical N input with manure could effectively increase crop yields, N efficiency and economic benefits, and reduce soil nitrate nitrogen residues. However, it still needs to be further studied how combining organic manure with chemical fertilizer affects crop productivity and nutrient use efficiency in a long-term.