Abstract
Many soils of southern Africa are severely N deficient, but inorganic fertilizers are unaffordable for most subsistence farmers. Rotations and intercrops of legumes with crops may alleviate N deficiency through biological N2 fixation and redistribution of subsoil N to the surface. We monitored soil inorganic N dynamics for two seasons in a gliricidia [Gliricidia sepium (Jacq.) Walp.] – maize (Zea mays L.) intercrop in the unimodal rainfall area of southern Malawi. One maize crop per year was grown with or without interplanted gliricidia, in factorial combination with three rates of N (0, 24 or 48 kg N ha-1). Application of gliricidia prunings increased (p < 0.001) topsoil (0 to 20 cm) inorganic N at the end of the dry season and during the early rains. Differences between plus and minus gliricidia treatments were less when total inorganic N to 1-m depth was summed. A greater proportion of the total inorganic N to 1-m depth occurred in the topsoil (0 to 20 cm) when gliricidia was present, suggesting that redistribution of subsoil N to the surface accounted for part of the N increase by gliricidia. Gliricidia lowered (p < 0.05) subsoil water content during drier periods. Gliricidia plots accumulated more (p < 0.01) ammonium-N during the dry season. Nitrate-N remained constant during the dry season but rose rapidly in gliricidia plots after the onset of rains. A 2-factor model including preseason inorganic N and anaerobic N mineralization potential accounted for 84% of the variability in maize yields for the two seasons' data combined. The combination of preseason inorganic N and potential N mineralization appears to provide a good estimate of N supply to maize in systems receiving both organic and inorganic sources of N.
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References
Adams E S and Gachengo C 1997 Organic resource database. Tropical Soil Biology and Fertility Programme, Nairobi, Kenya.
Anderson J M and Ingram J S I 1993 Tropical soil biology and fertility. A handbook of methods. Second edition. CAB International, Wallingford, Oxon, UK. 221 p.
Amara S D, Sanginga N S, Danso KA and Suale D S 1996 Nitrogen contribution by multipurpose trees to rice and cowpea in alley cropping system in Sierra Leone. Agrofor Syst 34, 119-128.
Barrios E, Buresh R J and Sprent J I 1996 Nitrogen mineralization in density fractions of soil organic matter from maize and legume cropping systems. Soil Biol. Biochem. 28, 1459-1465.
Barrios E F, Kwesiga F, Buresh R J, Sprent J I and Coe R 1998 Relating preseason soil nitrogen to maize yield in tree legume-maize rotations. Soil Sci. Soc. Am. J. 62, 1604-1609.
Birch H F 1958 The effect of soil drying on humus decomposition and nitrogen availability. Plant Soil 10, 9-31.
Birch H F 1960 Nitrification in soils after different periods of dryness. Plant Soil 12, 81-96.
Dorich R A and Nelson D W 1984 Evaluation of manual cadmium reduction methods for the determination of nitrate in potassium chloride extracts of soil. Soil Sci. Soc. Am. J. 48, 72-75.
Franzluebbers A J, Hons F M and Zuberer D A 1995 Tillage and crop effects on seasonal soil carbon and nitrogen dynamics. Soil Sci. Soc. Am. J. 59, 1618-1624.
Greenland D J 1958 Nitrate fluctuations in tropical soils. J. Agric. Sci. 50, 82-92.
Hartemink A E, Buresh R J, Jama B and Janssen B H 1996 Soil nitrate and water dynamics in sesbania fallows, weed fallows, and maize. Soil Sci. Soc. Am. J. 60, 568-574.
Jones R B, Snapp S S and Phombeya S K 1996 Management of leguminous leaf residues to improve nutrient use efficiency in the sub humid tropics. In Driven by Nature. Plant Litter Quality and Decomposition. Eds G Cadisch and K E Giller. pp 239-250. CAB International, Wallingford, UK.
Kumwenda J D T, Waddington S R, Snapp S S, Jones R B and Blackie M J 1995 Soil fertility management in the smallholder maize based cropping systems of Africa. In The Emerging Maize Revolution in Africa: The Role of Technology, Institutions and Policy. Michigan State University, USA, 9-12 July, 1995.
ICRAF 1998 ICRAF Annual Report for 1997. International Centre for Research in Agroforestry, Nairobi, Kenya.
Maroko J B, Buresh R J and Smithson P C 1998. Soil nitrogen availability as affected by fallow-maize systems on two soils in Kenya. Biol. Fertil. Soils 26, 229-234.
Mwiinga R D, Kwesiga F R and Kamara C S 1994 Decomposition of leaves of six multipurpose tree species in Chipata, Zambia. For. Ecol. Manage. 64, 209-216.
Palm C A and Sanchez P A 1991 Nitrogen release from the leaves of some tropical legumes as affected by their lignin and polyphenolic contents. Soil Biol. Biochem. 23, 83-88.
Robinson J B D 1957 The critical relationship between soil moisture content in the region of wilting point and mineralization of natural soil nitrogen. J. Agric. Sci. 49, 100-105.
Sanchez P A 1976 Properties and management of soils in the tropics. John Wiley and Sons, New York.
Sanginga N B, Vanlauwe B and Danso S K A 1995 Themanagement of biological N fixation in alley cropping systems, estimation and contribution to nitrogen balance. Plant Soil 174, 119-141.
SAS Institute 1990. SAS/STAT User's Guide, Vol. 2. Version 6.1. SAS Institute, Cary, NC, USA.
Semb G and Robinson J B D 1969 The natural nitrogen flush in different arable soils and climates in East Africa. E. African Agric. For. J. 34, 350-370.
Stephen D 1967 Effects of grass fallow treatments in restoring soil fertility of Buganda clay loam in South Uganda. J. Agric. Sci. (Cambridge) 63, 391-403.
Warren G P, Atwal S S and Irungu J W 1997 Soil nitrate variations under grass, sorghum and bare fallow in semi-arid Kenya. Exp. Agric. 33, 321-333.
Weber G, Chude V, Pleysier J and Oiketh S 1995 On farm evaluation of nitrate nitrogen dynamics under maize in the northern guinea savanna of Nigeria. Expl. Agric. 31, 333-344.
Wetselaar R 1968 Soil organic nitrogen mineralization as affected by low soil water potential. Plant Soil 29, 9-17.
Wild A 1972 Nitrate leaching under bare fallow at a site in northern Nigeria. J. Soil Sci. 23, 315-324.
Wong M T F and Nortcliff S 1995 Seasonal fluctuations of native available N and soil management implications. Fert. Res. 42, 3-26.
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Ikerra, S.T., Maghembe, J.A., Smithson, P.C. et al. Soil nitrogen dynamics and relationships with maize yields in a gliricidia–maize intercrop in Malawi. Plant and Soil 211, 155–164 (1999). https://doi.org/10.1023/A:1004636501488
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DOI: https://doi.org/10.1023/A:1004636501488