黑土区农田氮磷淋溶消减措施

Mitigation of nitrogen and phosphorus leaching from black soil croplands in Northeast China

黑土是我国重要的土壤资源,承载了全国50%以上的玉米产量。但过量的化肥施入和不合理的农业管理造成黑土土壤氮磷大量残留,氮磷淋溶风险增强。相关研究表明,尽管黑土区旱地农田氮磷淋溶损失相对较低,肥料残留效应仍致使其潜在淋溶风险增强。因此,本研究综合分析了环境因子和农业管理措施对黑土区农田氮磷淋溶特征的影响规律,明确了黑土氮磷淋溶消减措施,并针对玉米农田和蔬菜地提出消减策略。具体结果如下:施肥和降水是影响黑土农田氮磷淋溶的重要因素,灌溉是影响蔬菜地氮磷淋溶的关键农田管理措施;按需施肥、有机无机配施、避免雨热同期追肥、节水灌溉、免耕秸秆覆盖、不同作物轮作和添加生物炭等均是适合于当地气候和土壤条件的氮磷淋溶阻控措施。建议玉米农田采用一次性基肥施入,有机肥占比50%~70%,采用免耕秸秆覆盖技术;蔬菜地在常规施肥和灌溉频次下分别降低20%的施肥量和灌溉量,推荐蔬菜秋季收获后秸秆粉碎深埋等管理措施。本研究明确了黑土区农田氮磷淋溶消减策略,有助于实现黑土区农业绿色可持续发展和绿色生态环境的构建。

Black soil(Mollisol)is a fertile and productive soil type found in Northeast China and is important for China’s maize production.Large amounts of synthetic fertilizers are applied to meet the increasing cereal production demands but have low efficiency,leaving excessive nitrogen and phosphorus in the soil.This excess increases the risk of agricultural nonpoint pollution,black soil degradation,and surface/underground water pollution,threatening drinking water security.Studies conducted in the black soil region indicate that nitrogen and phosphorus leaching intensities are lower in the cereal croplands than in the other regions,especially those in the North China Plain.However,residual nitrogen and phosphorus remaining in soils owing to high fertilizer application levels increase the leaching potential,especially with intense precipitation.Environmental factors and field management practices were analyzed to identify effective control measures for nitrogen and phosphorus leaching and propose leaching reduction strategies for rain-fed maize and vegetation fields in the black soil region.Fertilization and precipitation are the primary drivers of nitrogen and phosphorus leaching in cultivated black soils,and irrigation is correlated to leaching intensity in vegetation fields.New strategies should be adopted to mitigate leaching,such as setting maximum fertilizer thresholds based on crop demands,adjusting fertilization timing to avoid high precipitation seasons,and using water-saving irrigation.Replacing synthetic fertilizer with manure,combining inorganic and organic fertilizers,and using no-tillage with maize stover mulching,crop rotations,and biochar are other field management practices to reduce the nitrogen and phosphorus pollution risk.In the maize croplands,only basal fertilizer should be applied during the growing season,an organic and synthetic fertilizer combination(50%−70%organic)should be used,and no-tillage with maize stover mulching should be considered to control the nitrogen and phosphorus leaching intensities.Reducing fertilizer amounts and irrigation water use by 20%and deeply burying the crushed straw after the autumn harvest are also recommended for vegetation fields.Practical strategies for nitrogen and phosphorus pollution prevention are important for sustainable agricultural development and maintenance in the black soil region.