Carbon, nitrogen and phosphorus dynamics under continuous cultivation as influenced by farmyard manure and inorganic fertilizers in the savanna of northern Nigeria.

摘要

Changes in the C, N and P status of a savanna Alfisol from the title region under continuous cultivation, complemented with farmyard manure (FYM) and inorganic fertilizers (N+P and N+P+K fertilizers) for 45 years, were determined. Continuous cultivation caused significant losses of C, N, and P, and N+P or N+P+K fertilization could not mitigate these losses. Losses of N and P were mainly in organic forms. However, a combination of FYM with N+P and N+P+K fertilization enabled C, N, and P to be maintained equal to, or greater than, the native site soil. It was concluded that FYM applied alone, or in combination with N+P or N+P+K fertilization, was effective in maintaining soil quality under continuous cultivation in the savanna. In contrast, continuous inorganic fertilization was deleterious to soil quality because of depletion of organic matter, the reservoir of plant available N, and P in weathered, tropical soils.