Green Manuring Effect on Changes of Soil Nitrogen Fractions, Maize Growth, and Nutrient Uptake

Green manure is a promising, at least partial, substitution for chemical fertilizer in agriculture, especially for nitrogen (N), which in soil can be radically changed by exogenous input. However, it is not well understood how, after green manure incorporation, soil N changes coordinate with crop N uptake and consequently contribute to fertilizer reduction in a maize⁻green manure rotation. A four-year field study was performed consisting of (1) control, no fertilization; (2) F₁₀₀, recommended inorganic fertilization alone; (3) G, green manure incorporation alone; (4) F₇₀ + G (70% of F₁₀₀ plus G); (5) F₈₅ + G; and (6) F₁₀₀ + G. The results show that treatments with 15⁻30% reduction of inorganic fertilizer (i.e., F₇₀ + G and F₈₅ + G) had similar grain yield, dry matter (DM) accumulation, and N uptake as F₁₀₀ treatment. F₁₀₀ + G maize had 17% greater DM and 15% more N uptake at maturity relative to F₁₀₀. Of the five soil N fractions examined, dissolved organic N (DON) and mineral N (N_min) explained over 70% of the variation of maize DM and N accumulation. Partial least squares path modeling further revealed that soil N fractions had positive indirect effects on DM production through N uptake, which might be coordinated with improved DON and N_min status at both early and mid-late stages of maize growth. Overall, the results highlight enhanced maize production with reduced fertilizer inputs based on green manure incorporation in temperate regions.

Abstract licence: CC BY

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