基于甘蔗生产全程机械化的肥料氮利用与土壤氮迁移研究

Guangxi is the largest sugarcane production bases in China, and promoting completely mechanized sugarcane production in Guangxi is the important strategy for the development of Chinese sugar and sugarcane industry. The completely mechanized sugarcane production is an integrated agronomic measure，which can strongly impact soil physics property and sugarcane growth, and maybe influence the utilization, migration and loss of nitrogen nutrient in soil-sugarcane system, or maybe produce negative effects to environment. At present, the mentioned-above related researches are reported rarely. On these grounds, we will carry out an experiment of different mechanized pattern during four years of sugarcane production (one new-planting and three ratoon cropping) on Guangxi Double-high Sugarcane Base. The nitrogen utilization efficiency of seasonable fertilizer, residual fertilizer and cane leaf returning to field will be studied by applying 15N-urea; the accumulation and distribution of fertilizer nitrogen in soil will be determined.The accumulation and distribution of total nitrogen, nitrate nitrogen, ammonium nitrogen and organic nitrogen in soil are measured by applying common urea, the contents of total nitrogen, nitrate nitrogen, ammonium nitrogen, organic nitrogen in shallow groundwater and soil penetrants, as well as nitrate nitrogen elution content of soil. Furthermore, the migrating loss of soil nitrogen nutrient and its environmental negative effects will be analyzed and evaluated. The study is to clarify the effects of completely mechanized sugarcane production on nitrogen fertilizer utilization and soil nitrogen migration, and put forward the strategies of nitrogen fertilizer high-efficiency for sugarcane and reasonable cultivation for sugarcane field, which will provide theoretical basis on optimizing completely mechanized technologic patterns for sugarcane and promote sustainable application of complete mechanization in sugarcane production.

广西是我国最大的糖料蔗生产基地，推进广西甘蔗生产全程机械化是国家战略。甘蔗生产全程机械化是一项综合农艺措施，强烈影响土壤物理性状和甘蔗生长，也可能影响土壤—甘蔗系统氮养分利用、迁移及损失或引起环境负面效应，但有关这方面的研究很少。课题拟在广西“双高”糖料蔗基地进行为期4年（1季新植蔗后续3季宿根蔗）的不同机械化模式作业，施用15N标记尿素研究当季肥料氮利用率、残留肥料氮利用率、蔗叶还田肥料氮利用率、肥料氮在土壤的累积与分布；施用普通尿素研究蔗地土壤总氮、硝态氮、铵态氮及有机氮的累积与分布，浅层地下水和土壤渗透液总氮、硝态氮、铵态氮及有机氮含量，以及土壤硝态氮淋洗量。分析评价土壤氮养分的迁移损失量及其环境负面效应。从而阐明甘蔗生产全程机械化对氮肥利用与土壤氮素迁移的影响，提出甘蔗氮肥高效利用和蔗地合理耕作策略，为优化甘蔗生产全程机械化技术模式提供理论依据，促进甘蔗生产全程机械化的可持续应用。

甘蔗是我国重要的糖料作物和经济作物。广西甘蔗年种植面积约1150万亩，约占全国的60%。近年来，广西把发展甘蔗生产全程机械化作为破解甘蔗产业发展困局的重要路径。为此，我们于2019-2022年在广西柳州市“双高”糖料蔗基地进行4种机械化模式的田间作业，研究1季新植蔗和后续3季宿根蔗产量、氮积累及氮肥利用效率，以及土壤氮积累、分布及淋洗等。结果表明：机种、机收模式特别是采用甘蔗联合收获机作业的甘蔗株高、有效茎数、蔗茎产量及氮积累量低于人工摆种收获模式的；在人工摆种收获下，深松深翻尤其是深松作业的氮肥利用率、残留率明显高于浅耕的，但氮肥损失率低于浅耕的；在新植季，浅耕作业提高0~20cm土层全氮、硝态氮、铵态氮及有机氮累积量，而深松深翻尤其是深松提高40~60cm土层全氮、硝态氮、铵态氮及有机氮累积量；连续采用机械特别是甘蔗联合收获机收获甘蔗后，蔗地表层土壤氮增加较突出；在前3季甘蔗，深松深翻尤其是深松作业的60cm、80cm土层硝态氮、铵态氮的淋洗量明显大于浅耕的，但在第4季甘蔗不同生产模式间的硝态氮、铵态氮淋洗量无差异。可见，深松深翻尤其是深松促进氮向40cm以下土层运移主要发生在新植季和1年宿根季，但深松深翻与机种机收联合作业的甘蔗产量较低、氮吸收较少。因此，甘蔗机种、机收技术优化亟需进一步研究。项目研究结果为优化甘蔗生产机械化技术提供了理论依据，对促进甘蔗生产机械化的发展具有积极意义。