Abstract
The effects of green manures, sorghum residues and farmyard manure on N dynamics and crop yields were studied during three dry and wet seasons on a Typic Sombriudox in South Rwanda. In addition, a resin core study was conducted within a 4-year green manure field experiment to follow the seasonal pattern of N mineralization and leaching after application of residues from Tephrosia vogelii, Sorghum bicolor, a mixture of both materials, and farmyard manure.
During the dry season, topsoil (0–20 cm) mineral N remained constant. At the beginning of the wet season, the rainfall pattern determined N availability. With low rainfall intensities a mineralization flush occurred, doubling topsoil mineral N concentrations within 5 days after wetting. In contrast, under heavy rains at the onset of the rainy season, topsoil mineral N decreased by 50–70% within the first two weeks.
The application of organic fertilizers has a strong influence on N availability, but the effects can be negated by heavy rainfall. Incorporation of leaves from Tephrosia vogelii (2.7 t dm ha-1) and farmyard manure (7 t dm ha-1) doubled the mineralization flush after the first rains. During the rest of the wet season, N release by the green manure was small, whereas the farmyard manure was found to mobilize N after a period of N immobilization. Incorporation of sorghum residues had only a small effect, while mixing the straw with green and farmyard manure immobilized N temporarily.
Nitrogen leaching, measured by exchange resins at a depth of 20 cm, was increased up to 50% by the incorporation of green and farmyard manure. This points to rapid N translocation of easily mineralizable N. The additional incorporation of sorghum residues reduced N leaching of both materials significantly. Since rainfall is often unpredictable, the synchronization of N released from crop residues with crop N demand may require additional management practices.
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References
Aoyama M and Nozawa T 1993 Microbial biomass nitrogen and mineralization-immobilization of nitrogen in soils incubated with various organic materials. Soil Sci. Plant Nutr. 39(11), 23–32.
Birch H F 1960 Nitrification after periods of dryness. Plant Soil 12, 81–96.
Bushway R J, Angela Y and Al-Yamany A 1988 Analysis of rotenone in Cubé and Derris root powders and formulations by liquid chromatography. J. Assoc. Off. Anal. Chem. 71(2), 323–324.
Christensen S, Simkens S and Tiedje J M 1990 Spatial variation in denitrification: Dependence of activity centers on the soil environment. Soil Sci. Soc. Am. J. 54, 1608–1613.
Constantinides M and Fownes J H 1993 Nitrogen mineralization patterns of leaf-twig mixtures from tropical leguminous trees. Agroforestry Systems 24, 223–231.
Copper W P, Ewel K C and Raich J 1985 The measurement of soil CO2 evolution in situ. Pedobiologica 28, 35–40.
De Bruin B, Penning de Vries FWT, Van Broekhoven LW, Vertregt N and Van de Geijn S C 1989 Net nitrogen mineralization, nitri-fication and CO2 production in altering moisture conditions in an unfertilized low humus sandy soil from the Sahel. Plant Soil 113, 69–78.
Dorich R A and Nelson DW 1982 Direct colorimetric measurement of ammonium in potassium chloride extracts in soil. Soil Sci. Soc. Am. J. 47, 833–836.
Drechsel P, Steiner K G and Hagedorn F 1996 A review on the potential of improved fallow and green manure in Rwanda. Agroforestry Systems 33, 109–136.
Drechsel P, Mutwewingabo B, Hagedorn F and Wortmann C S 1996 Soil and foliar phosphorus determination in Rwanda: Procedures and Interpretations. African Crop Sci. J. 4(2), 167–175.
Holland E A and Coleman D C 1987 Litter placement effects on microbial and organic matter dynamics in an agroecosystem. Ecology 682, 425–453.
Hübner C, Redl G and Wurst F 1991 In situmethodology for studying N-mineralization in soils using anion exchange resins. Soil Biol. Biochem. 23(7), 701–702.
Kieft T L, Soroker E and Firestone M K 1987 Microbial biomass response to a rapid increase in water potential when dry soil is rewetted. Soil Biol. Biochem. 19(2), 119–126.
King, H G C and Heath G W 1967 The chemical analysis of small samples of leaf material and the relationship between the disappearance and decomposition of leaves. Pedobiologica 7, 192– 197.
Kolberg R L, Rouppet B, Westfall D G and Peterson G A 1997 Evaluation of an in situ net nitrogen mineralization method in dryland agroecosystems. Soil Sci. Soc. Am. J. 61, 504–508.
König D 1992 Erosionsschutz in Agroforstsystemen. Mainzer Geographische Studien, Heft 37. Geographisches Institut, Universit ät Mainz, Germany. 212 p.
Kotschi J, Neumann I, Pietrowicz P and Haas J 1991 Standortgerechte Landwirtschaft in den Ruanda. Zehn Jahre Forschung and Entwicklung in Nyabisindu. Schriftenreihe der GTZ Nr. 223, 174 p.
McIntire J 1986 Constraints to fertilizer use in sub-Saharan Africa. In Management of Nitrogen and Phosphorus Fertilizers in Sub-Saharan Africa. Eds. A U Mokwunye and P L G Vlek. pp 33–57. Martin Nijhoff Publishers, Dordrecht.
Nelson D W and Sommers L E 1975 A rapid and accurate method for estimating organic carbon in soil. Proc. Indiana Academy of Science 84, 456–462.
Palm C A and Sanchez P A 1991 Nitrogen release from the leaves of some tropical legumes as affected by their lignin and polyphenolic content. Soil Biol. Biochem. 23(1), 83–88.
Reuter D J and Robinson J B (Eds.) 1986 Plant Analysis – An Interpretation Manual. Inkata Press, Melbourne, 151–153.
Semb G and Robinson J B D 1969 The natural nitrogen flush in different arable soils and climates in east Africa. East African Agric. For. J. 350–370.
Steiner K G, Drechsel P, Sekayange L and Nzabonihankuye G 1995 Chances et limites des engrais verts pour la gestion de la fértilité des sols du Centre-sud du Rwanda. Les essais de l'ISAR/Rubona 1988-1993. ISAR Note technique. Rubona, Rwanda. 116 p.
Soil Survey Staff 1990 Keys to soil taxonomy. SMSS Technical Monograph No.19, Fourth Edition. SMSS Technical Monogragh No. 19. Blacksburn, V.A. 422 p.
Tian G, Kang B T and Brussard L 1992 Biological effects of plant residues with contrasting chemical compositions under humid tropical conditions: decomposition and nutrient release. Soil Biol. Biochem. 24(10), 1051–1060.
Vallis I and Jones R J 1973 Net mineralization of nitrogen in leaves and leaf litter of Desmodium intortum and Phaseolus atropureus mixed with soil. Soil Biol. Biochem. 5, 391–398.
Van Gestel M, Ladd J N and Amato M 1991 Carbon and nitrogen mineralization from two soils of contrasting texture and microaggregate stability: Influence of sequential fumigation, drying and storage. Soil Biol. Biochem. 23(4), 313–322.
Vanlauwe B, Vanlangenhove G, Merckx R and Vlassak K 1995 Impact of rainfall regime on the decomposition of leaf litter with contrasting quality under subhumid tropical conditions.Biol. Fert. Soils 20, 8–16.
Van Soest PJ and Wine RH 1968 Determination of lignin and cellulose in acid-detergent fiber with permanganate. J. A.O.A.C. 51(4), 780–785.
Yadvindher-Singh, Bijay-Singh, Maskina m S and Meelu O P 1988 Effect of organic manures, crop residues and green manure on nitrogen and phosphorus transformations in a sandy loam at field capacity and under waterlogged conditions. Biol. Fert. Soils 6, 183–187.
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Hagedorn, F., Steiner, K., Sekayange, L. et al. Effect of rainfall pattern on nitrogen mineralization and leaching in a green manure experiment in South Rwanda. Plant and Soil 195, 365–375 (1997). https://doi.org/10.1023/A:1004266205502
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DOI: https://doi.org/10.1023/A:1004266205502