The challenge of HIV/AIDS: Where does agroforestry fit in? - World ...

58World Agroforestry into the FutureCumulative maize grain yield (t ha —1 )252015105baaaa0No P MPR MPR TSP TSP0 50 x 5 250 x 1 50 x 5 250 x 1P source and rateFigure 3. Cumulative maize yields over 5 years (five crops, ‘long rains’ cropping season only) in western Kenya. Nitrogen (N) andpotassium (K) were supplied. Minjingu phosphate rock (MPR) or triple superphosphate (TSP) fertilizer were added, either once at 250 kgP ha –1 , or at a rate of 50 kg ha –1 each year for 5 years. There was also a control plot with no added P.Source: Sanchez and Jama (2002).Conclusion and way forwardImproved fallows of leguminous speciesand biomass transfer are both promisingagroforestry techniques that can contributeto integrated soil fertility managementpractices in smallholder farms. They canalso provide other benefits such as controlof pests and diseases, and in the case ofimprove fallows, provide fuelwood that isin short supply in many rural settings. Toenhance the impact of these technologies,there are a few remaining challenges thatneed to be addressed. These include:1. Determining the recommendation domains(geographic areas and householdtypes where the technologies are feasibleand profitable), something that is necessarygiven the large biophysical and socioeconomicvariability that exists within andbetween farms. 2. Developing strategies tomake fertilizers affordable, especially thosecontaining P that organic produce cannotsupply adequately. 3. Promoting widelysynergistic technologies such as biologicalsoil and water conservation measures.4. Promoting the keeping of livestock toproduce manure, and developing bestmanagement practices for its use. 5. Developingstrategies for wide-scale disseminationof the options available, particularlythose that deal with overcoming the prevailingconstraints of germplasm supplyand information on their use. 6. Assessingecological benefits of fallow plant specieswhile mitigating potential problems ofthem becoming invasive weeds. 7. Determiningways in which high-value trees,crops and livestock can be more intensivelyfarmed, providing a natural progressionout of poverty.ReferencesBarrios, E., F. Kwesiga, R.J. Buresh, and J.I.Sprent 1997. Light fraction soil organicmatter and available nitrogen followingtrees and maize. Soil Science Society ofAmerica Journal 61: 826−831.Barrios, E., F. Kwesiga, R.J. Buresh, J.I. Sprentand R. Coe 1998. Relating preseason soilnitrogen to maize yield in tree legumemaizerotations. Soil Science Society ofAmerica Journal 62: 1604–1609.Buresh, R.J., P.C. Smithson and D.T. Hellums1997. Building soil capital in Africa. Pp.111–149 in: Replenishing Soil Fertility inAfrica. American Society of Agronomyand Soil Science Society of America. SSSASpecial Publication No. 51.Buresh, R.J. and G. Tian 1997. Soil improvementby trees in sub-Saharan Africa. AgroforestrySystems 38: 51–76.