ISSN 2375-088X
African Journal of Soil Science ISSN 2375-088X Vol. 8 (5), pp. 001-008, May, 2020. © International Scholars Journals
Full Length Research Paper
Carbon and nitrogen mineralization from selected organic resources available to smallholder farmers for soil fertility improvement in Zimbabwe
J. Nyamangara1*, F. Mtambanengwe1 and C. Musvoto2
1Department of Soil Science and Agricultural Engineering, University of Zimbabwe, P. O. Box MP167, Mount Pleasant, Harare, Zimbabwe.
2Institute of Environmental Studies, University of Zimbabwe, P. O. Box MP 167, Mount Pleasant, Harare, Zimbabwe.
Accepted 21 January, 2020
Abstract
A study was conducted to assess the N release dynamics of three organic resources widely used by smallholder farmers in sub-Saharan Africa to improve soil fertility. Addition of cattle manure, miombo and mango (Mangifera indica) litter to soil increased (p < 0.05) CO2-C evolution compared to unamended soil. Cumulative CO 2-C evolution in all the three organic amendments followed first order kinetics (R2 = 0.89 - 0.99). Slight N mineralization occurred when cattle manure was added to soil and addition of manure in combination with mineral N had no effect on the extent of N mineralization. Compared to unamended soil, miombo litter induced net immobilization of N for 60 days and thereafter net N mineralization occurred. Both untreated and composted mango litter immobilized N (up to 15 mg N kg-1) during the 77 day incubation. It was concluded that all the three organic resources were poor and inadequate sources of N for plant growth in the short term and should therefore be supplemented with mineral N to reduce N immobilization and consequent N deficiency in plants. However the organic resources may improve the soil physical environment and also contribute to soil organic matter build up in the long term.
Key words: Cattle manure, Mangifera indica, miombo litter, N mineralization and immobilization.