Abstract
Nitrogen is normally the nutrient most limiting production of maize (Zea mays) — the main staple food crop — in southern Africa. We conducted a field study to determine the effect of N sources on soil nitrate dynamics at three landscape positions in farmers' fields in southern Malawi. The landscape positions were dambo valley or bottomland, dambo margin, and steep slopes. The N sources were calcium ammonium nitrate fertilizer applied at 120 kg N ha−1, biomass from Sesbania sesban, and no added N. Sesbania biomass was produced in situ in the previous season from sesbania relay cropped with maize. Nitrate in the topsoil (0 to 15 cm depth) increased to 85 days after maize planting (mean = 48 kg N ha−1) and then decreased markedly. Application of N fertilizer and sesbania biomass increased soil nitrate, and nitrate-N in topsoil correlated positively with amount of incorporated sesbania biomass. The strongest correlation between sesbania biomass added before maize planting and topsoil nitrate was observed at 85 days after maize planting. This suggests that the sesbania biomass (mean N content = 2.3%) mineralized slowly. Inorganic N accumulated in the subsoil at the end of the maize cropping season when N fertilizer and sesbania were applied. This study demonstrated the challenges associated with moderate quality organic N sources produced in smallholder farmer's fields. Soil nitrate levels indicated that N was released by sesbania residues in the first year of incorporation, but relay cropping of sesbania with maize may need to be supplemented with appropriately timed application of N fertilizer.
Similar content being viewed by others
References
Anderson JM and Ingram JSI (1993) Tropical Soil Biology and Fertility: A Handbook of Methods. CAB International, Wallingford, UK
Cawse PA (1967) The determination of nitrate in soil solutions by ultraviolet spectrophotometry. Analyst 92: 311–315
Ghai SK, Rao DLN and Batra L (1985) Comparative study of the potential of sesbanias for green manuring. Tropical Agriculture (Trinidad) 62: 52–56
Hartemink AE, Buresh RJ, Jama B and Janssen BH (1996) Soil nitrate and water dynamics in sesbania fallows, weed fallows and maize. Soil Science Society of America Journal 60: 568–574
Kanyama-Phiri GY, Snapp SS and Minae S (1998) Partnership with Malawian farmers to develop organic matter technologies. Outlook on Agriculture 27: 167–175
Moutonnet P and Fardeau JC (1997) Inorganic nitrogen in solution collected with tensionic samplers. Soil Science Society of America Journal 61: 822–825
Olsen RJ, Hensler RF, Attoe OJ, Witzel SA and Peterson LA (1970) Fertilizer nitrogen and crop rotation in relation to movement on nitrate nitrogen through soil profiles. Soil Science Society of America Proceedings 34: 448–452
Phiri ADK, Kanyama-Phiri GY and Snapp SS (1999) Maize and sesbania production in relay cropping at three landscape positions in Malawi. Agroforestry Systems (this issue)
Saka AR, Green RI and Ng'ong'ola DH (1995) Soil management in sub-Saharan Africa. Proposed soil management action plan in Malawi. Report to the World Bank. Lilongwe, Malawi, 111 pp
Snapp SS, Mafongoya PL and Waddington S (1998) Organic matter technologies to improve nutrient cycling in smallholder cropping systems of southern Africa. Agriculture Ecosystems and Environment 71: 185–200
Thornton PK, Saka AR, Singh U, Kumwenda JDT, Brink JE and Dent JB (1995) Application of a maize crop simulation model in the central region of Malawi. Experimental Agriculture 31: 213–226
Weber G, Chude V, Pleysier J and Oikeh S (1995) On-farm evaluation of nitrate-nitrogen dynamics under maize in the northern guinea savanna of Nigeria. Experimental Agriculture 31: 333–344
Yamoah C (1988) The potential of alley cropping for hillside farming in Rwanda. Appropriate Intermediate Technology 15(1): 28–30
Yamoah CF and Burleigh JR (1990) Alley cropping Sesbania sesban (L.) Merill with food crops in the highland region of Rwanda. Agroforestry Systems 10: 169–181
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Phiri, R.H., Snapp, S. & Kanyama-Phiri, G.Y. Soil nitrate dynamics in relation to nitrogen source and landscape position in Malawi. Agroforestry Systems 47, 253–262 (1999). https://doi.org/10.1023/A:1006279817228
Issue Date:
DOI: https://doi.org/10.1023/A:1006279817228