Maize production in Malawi is limited mainly by low soil N and P. Improved fallows of N-fixing legumes such as Tephrosia and Sesbania offer options for improving soil fertility particularly N supply. The interactions of Tephrosia fallows and inorganic fertilizers on soil properties, N uptake, and maize yields were evaluated at Chitedze Research Station in Malawi. The results indicated that the level of organic matter and pH increased in all the treatments except for the control. Total N remained almost unchanged while available P decreased in all plots amended with T. vogelii but increased in T. candida plots where inorganic P was applied. Exchangeable K increased in all the plots irrespective of the type of amendment. The interaction of N and P fertilizers with T. vogelii fallows significantly increased the grain yield. The treatment that received 45？kg？N？ha？1 and 20？kg？P？ha？1 produced significantly higher grain yields (6.8？t？ha？1) than all the other treatments except where 68？kg？N？ha？1 and 30？kg？P？ha？1 were applied which gave 6.5？t？ha？1 of maize grain. T. candida fallows alone or in combination with N and P fertilizers did not significantly affect grain yield. However, T. candida fallows alone can raise maize grain yield by 300% over the no-input control. Based on these results we conclude that high quality residues such as T. candida and T. vogelii can be used as sources of nutrients to improve crop yields and soil fertility in N-limited soils. However, inorganic P fertilizer is needed due to the low soil available P levels. 1. Introduction Land degradation and depletion of soil nutrients are widespread in sub-Saharan Africa (SSA) and especially in Malawi. In small-scale farming systems, continuous cropping of cereals without rotation with legumes and inappropriate soil conservation practices have depleted soil fertility [1]. Recent analyses [2] show that N limitation is widespread in Africa. This is specially so due to depletion as a result of soil erosion. According to Stoorvogel et al. [3] and Smaling [4] the annual net nutrient depletion exceeds 30？kg？N of arable land in Malawi. The inability of most farmers to practice fallowing due to land shortage and reduced inorganic fertilizer use due to high prices of inorganic fertilizer are some of the major causes of decline in crop productivity in Malawi [5] and sub-Saharan Africa at large. Many options have been explored to address land degradation and declining soil fertility in Malawi [6–8]. Because organic sources such as animal and plant manure are often in short supply, governments and
References
[1]
J. N. Chianu, J. N. Chianu, and F. Mairura, “Mineral fertilizers in the farming systems of sub-Saharan Africa. A review,” Agronomy for Sustainable Development, vol. 32, pp. 545–566, 2012.
[2]
J. Liu, L. You, M. Amini et al., “A high-resolution assessment on global nitrogen flows in cropland,” Proceedings of the National Academy of Sciences of the United States of America, vol. 107, no. 17, pp. 8035–8040, 2010.
[3]
J. J. Stoorvogel, E. M. A. Smaling, and B. H. Janssen, “Calculating soil nutrient balances in Africa at different scales—I supranational scale,” Fertilizer Research, vol. 35, no. 3, pp. 227–235, 1993.
[4]
E. M. A. Smaling, “Nutrient flows and balances as indicators of productivity and sustainability in sub-Saharan African agroecosystems,” Agriculture, Ecosystems and Environment, vol. 71, pp. 1–346, 1998.
[5]
M. Smale and T. Jayne, “Maize in eastern and southern Africa: “Seeds” of success in retrospect,” Environment and Production Technology Division Discussion Paper 97, International Food Policy Research Institute, Washington, DC, USA, 2003.
[6]
F. K. Akinnifesi, W. Makumba, and F. R. Kwesiga, “Sustainable maize production using gliricidia/maize intercropping in southern Malawi,” Experimental Agriculture, vol. 42, no. 4, pp. 441–457, 2006.
[7]
G. Denning, P. Kabambe, P. Sanchez et al., “Input subsidies to improve smallholder maize productivity in Malawi: toward an African green revolution,” PLoS Biology, vol. 7, no. 1, Article ID e1000023, 2009.
[8]
J. D. Glover, J. P. Reganold, and C. M. Cox, “Plant perennials to save Africa's soils,” Nature, vol. 489, pp. 359–361, 2012.
[9]
G. W. Sileshi, L. K. Debusho, and F. K. Akinnifesi, “Can integration of legume trees increase yield stability in rain-fed maize cropping systems in southern Africa?” Agronomy Journal, vol. 104, pp. 1392–1398, 2012.
[10]
D. Djumaeva, J. P. A. Lamers, C. Martius, A. Khamzina, N. Ibragimov, and P. L. G. Vlek, “Quantification of symbiotic nitrogen fixation by Elaeagnus angustifolia L. on salt-affected irrigated croplands using two 15N isotopic methods,” Nutrient Cycling in Agroecosystems, vol. 88, no. 3, pp. 329–339, 2010.
[11]
P. L. Mafongoya, R. Chintu, T. S. Chirwa, J. Matibini, and S. Chikale, “Tephrosia species and provenances for improved fallows in southern Africa,” Agroforestry Systems, vol. 59, no. 3, pp. 279–288, 2003.
[12]
M. P. Gichuru, “Regeneration of a degraded ultisol with Tephrosia candida in the humid zone of southeastern Nigeria,” Interciencia, vol. 19, pp. 382–386, 1994.
[13]
M. A. Huancheng and Z. Jueiming, “Effect of Tephrosia candida on soil,” Nitrogen Fixing Tree Research Reports, vol. 11, pp. 127–128, 1993.
[14]
P. C. Stevenson, G. C. Kite, G. P. Lewis et al., “Distinct chemotypes of Tephrosia vogelii and implications for their use in pest control and soil enrichment,” Phytochemistry, vol. 78, pp. 135–146, 2012.
[15]
N. Sanginga and P. L. Woomer, Eds., Integrated Soil Fertility Management in Africa: Principles, Practices and Developmental Process. Tropical Soil Biology and Fertility, Institute of the International Centre for Tropical agriculture, Nairobi, Kenya, 2009.
[16]
Government of Malawi, Chitedze Agricultural Research: Station Guide 1999, Ministry of Agriculture and Irrigation, Lilongwe, Malawi, 1999.
[17]
C. Chilimba, “Methods of analysis of soil, plants, animal feed & fertilizers: working manual for use in soils and plants laboratories at Chitedze and Bvumbwe research stations Department of Agricultural Research and Technical Services,” 1997.
[18]
A. Walkley and I. A. Black, “An examination of the Degtjareff method for determining soil organic matter,and a proposed modification of the chromic acid titration method,” Soil Science, vol. 37, pp. 29–38, 1934.
[19]
M. L. Jackson, Soil Chemical Analysis, Prentice-Hall, Englewood Cliffs, NJ, USA, 1958.
[20]
J. Murphy and J. P. Riley, “A modified single solution method for the determination of phosphate in natural waters,” Analytica Chimica Acta, vol. 27, pp. 31–36, 1962.
[21]
P. Mutuo, A. E. Marandu, R. Rabeson, and M. Mwale, “N fertilizer equivalency values of organic materials of differing quality: network trial results from East and southern Africa, season 1,” in Proceedings of the 24th East Africa Soil Science Society Annual General Meeting, pp. 13–19, Tanga, Tanzania, December 1998.
[22]
F. Hagedorn, K. G. Steiner, L. Sekayange, and W. Zech, “Effect of rainfall pattern on nitrogen mineralization and leaching in a green manure experiment in South Rwanda,” Plant and Soil, vol. 195, no. 2, pp. 365–375, 1997.
[23]
N. L. Nabahungu, J. G. Mowo, A. Uwiragiye, and E. Nsengumuremyi, “Use of Tithonia biomass, maize residues and inorganic phosphate in climbing bean yield and soil properties in Rwanda,” in Innovations as Key to the Green Revolution in Africa, A. Batiano, B. Waswa, J. M. Okeyo, F. Maina, and J. M. Kihara, Eds., pp. 335–341, Springer, Dordrecht, The Netherlands, 2011.
[24]
J. J. Mbonigaba, Ess4aie de compostage de dechets verts et evaluation des effects des composts obtenus sur des soils acides [M.S. thesis], Rwanda Universite de Gembloux, 2002.
[25]
C. A. Palm, R. J. K. Myers, and S. M. Nandwa, “Combined use of organic and inorganic nutrient sources for soil fertility maintenance and replenishment,” in Replenishing Soil Fertility in Africa, R. J. Buresh, P. A. Sanchez, and F. Calhoun, Eds., SSSA Publication no. 51, pp. 193–217, Soil Science Society of America, Madison, Wis, USA, 1997.
[26]
F. Kwesiga and R. Coe, “The effect of short rotation Sesbania sesban planted fallows on maize yield,” Forest Ecology and Management, vol. 64, no. 2-3, pp. 199–208, 1994.
[27]
J. B. Maroko, R. J. Buresh, and P. C. Smithson, “Soil nitrogen availability as affected by fallow-maize systems on two soils in Kenya,” Biology and Fertility of Soils, vol. 26, no. 3, pp. 229–234, 1998.
[28]
V. Rutunga, N. K. Karanja, and C. K. K. Gachene, “Six month-duration Tephrosia vogelii Hookf and Tithonia diversifolia (Hemsl) a gray planted-fallows for improving maize production in Kenya,” Biotechnology, Agronomy, Society and Environment, vol. 12, no. 3, pp. 267–278, 2007.
[29]
C. N. Gachengo, Phosphorus release and availability on addition of organic materials to phosphorus fixing soils [M.S. thesis], Moi University, Eldoret, Kenya, 1996.
[30]
R. Chikowo, P. Mapfumo, P. Nyamugafata, and K. E. Giller, “Woody legume fallow productivity, biological N2-fixation and residual benefits to two successive maize crops in Zimbabwe,” Plant and Soil, vol. 262, no. 1-2, pp. 303–315, 2004.
[31]
P. A. Sanchez, Properties and Management of Soils in the Tropics, Wiley, New York, NY, USA, 1976.
[32]
D. L. Karlen, L. A. Kramer, and S. D. Logsdon, “Field-scale nitrogen balances associated with long-term continuous corn production,” Agronomy Journal, vol. 90, no. 5, pp. 644–650, 1998.
[33]
F. M. Kihanda, “Effect of composted manures with high quality organic manures on dry matter accumulation, nitrogen uptake and grain yield,” East African Agricultural and Forestry Journal, vol. 69, pp. 63–68, 2003.
[34]
W. Makumba, B. Janssen, O. Oenema, and F. K. Akinnifesi, “Influence of time of application on the performance of gliricidia prunings as a source of N for maize,” Experimental Agriculture, vol. 42, no. 1, pp. 51–63, 2006.
[35]
R. Harawa, J. Lehmann, F. Akinnifesi, E. Fernandes, and G. Kanyama-Phiri, “Nitrogen dynamics in maize-based agroforestry systems as affected by landscape position in southern Malawi,” Nutrient Cycling in Agroecosystems, vol. 75, no. 1–3, pp. 271–284, 2006.
[36]
A. W. Kramer, T. A. Doane, W. R. Horwath, and C. V. Kessel, “Combining fertilizer and organic inputs to synchronize N supply in alternative cropping systems in California,” Agriculture, Ecosystems and Environment, vol. 91, no. 1–3, pp. 233–243, 2002.
