Rapid urban growth and the environmental, social and political consequencies are major issues in Africa, especially in the major Sahelian cities. Using remote sensing technologies it has been established that between 1980-2000, the rate of urbanization more than doubled in the capital city of Burkina Faso (118% increase) and nearly doubled in capitals of Mali (62%) and Niger (63% increase). There has been the drastic conversion of vegetated and open lands to urban and residential use. Population in these cities also grew significantly, clearly outpacing the overall population growth of the countries. Data obtained will be useful in policy issues related to sustainable urban planning and will also serve as input into urban growth models to predict patterns of future urban expansion.

Sole cropped pearl millet and intercropped pearl millet with cowpea are the dominant cropping systems in the Sahelien agroecological zone of Burkina Faso with low and stagnant pearl millet and cowpea yields. Two experiments were conducted in randomized complete block designs with split plot arrangements and three replications. The main plot was tillage method in both experiments and the sub-plot was soil amendment (compost, fertilizer, and crop residues). The objective was to identify the best combination of tillage method, cropping system, and soil amendment to optimize sole and intercropped millet and intercropped cowpea yields. In Exp. 1, sole crop millet grain yield was increased by soil amendment application from 238 kg ha-1 to 450 to 768 kg ha-1 , and stover yields from 551 kg ha-1 to 1075 to 1813 kg ha-1. In Exp. 2, zaï tillage increased sole cropped millet grain yield by 348 to 495 kg ha-1 , and intercropped millet by 194 to 202 kg ha-1 over use of no till and scarify. Combined zaï with C + F application increased sole cropped millet grain yield from 288 to 777 kg ha-1 and intercropped millet from 114 to 502 kg ha-1 over zaï without soil amendment. Similar trends were observed for millet stover and intercropped cowpea grain and stover yields. Influence of soil amendment application on grain and stover yields was greatest for sole cropped millet with use of zaï in high rainfall years. This first documentation of differential soil amendment response of sole and intercropped pearl millet with zaï, scarify, and no till systems indicates that the greatest pearl millet grain and stover yield is obtained with application of plough or zaï in combination with C + F, F + CR or C + F + CR soil amendment.

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Sorghum [Sorghum bicolor (L) Moench) is a major grain crop in Burkina Faso. Two three-year experiments were conducted in the Sudanian and Sudano-Sahelian zones to determine how plant nutrient concentrations are affected by tillage methods (T) and soil amendments (SA). In both locations, T and SA had little effect on grain and stover nutrient concentrations with some cases of inconsistency across years. Some nutrient concentrations differed by year. The grain nutrient concentrations of N, P, Mg, S, Zn, and Fe were adequate for human nutrition at both locations, but deficient for K, Ca, Mn and Cu. Sorghum nutrient concentrations for feeding cattle were adequate for K, Ca, Mg, S, Mn, and Zn in most cases at both locations but low for N, P, and Cu. The stover N and P concentrations also appeared to be deficient for optimal plant growth. In both agroecological zones, nutrient applications or genetic enhancement to improve deficient nutrient concentrations, or use of diverse foodstuffs, or biofortified sorghum to provide deficient nutrients in human and cattle diets is needed to meet dietary requirements. In addition to grain and stover yield, studies need to evaluate grain nutrient and stover nutrient concentrations to meet human and cattle dietary requirements.

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