Organic fertilizer-mediated cultivated land conservation and pollution source control in agricultural ecosystem, Northeast China

Abstract

Little information is available on cultivated land conservation and pollution source control in agricultural ecosystem following organic fertilization. This study established field trails amended with mineral and organic fertilizers across different co-application measures (mineral-to-organic mass ratio, 0 %, 30 %, 60 % and 100 %), to certify the multi-interaction mechanisms underlying nutrient transformation and pollutants release in agricultural system. Compared to treatment amended with mineral fertilizer alone, ammonia nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃^--N) and available phosphorus (Ex-P) in soil were 1.3, 6.7, and 2.8-fold higher in treatment combined with mineral and organic fertilizers (30 %), respectively. Meanwhile, nitrogen and phosphorus in runoff were almost equal between treatments modified with mineral fertilizer alone, or in combination with organic fertilizer (30 %). However, the treatment regarding 60 % reduction in mineral fertilizer significantly increased nitrogen and phosphorus concentration in runoff. Organic (Or-P) and calcium-bound (Ca-P) phosphorus were dominate sources for Ex-P in soil, while iron-bound phosphorus (Fe-P) release led to higher phosphorus loss with runoff. Combined treatment with mineral and organic fertilizers (30 %), was an optimal practice to maximize agricultural and ecological benefits from cultivated land following organic fertilization in black soil regions, which offer valuable insights for optimizing fertilization management in Northeast China.