Participatory research in Ikulwe-Iganga District, Uganda

A participatory approach to research on system improvement was initiated in five communities around Ikulwe District Farm Institute in Iganga District, Uganda. The site is located in the southeastern tall grassland zone, where perennial and annual crops are produced in mixed farming systems. Farmers identified and prioritized 15 problems related to crop production using a PRA approach. Crop pests and diseases predominated; soil-related problems included low soil fertility and soil erosion. Other problems included low crop yields and unreliable rainfall. However, the priorities change as new problems are identified during regular semi-annual planning and evaluation meetings. Farmers and researchers agreed to focus research on Africa cassava mosaic virus, groundnut rosette virus, bean diseases, banana weevil, soil erosion control and soil fertility management. Several crop varieties have been evaluated for either tolerance or resistance and farmers have adopted Nanse 2 and SS4 cassava varieties; K131, K132, MCM 2001, MCM 3030, OBA 1, UBR (92) 32 bean varieties; some sweet potato varieties; and two upland rice varieties. Farmers are paring corms to control banana weevils, and researchers have promised a cheaper alternative to the hot water treatment with which farmers had experimented. Canavalia, Mucuna, Crotolaria, and lablab were evaluated as either green manure or improved fallow for soil fertility improvement, and for their incorporation into the farming systems. Information obtained from FPR and on-station research was used to develop a decision guide to the use of these species in Eastern and Central Uganda. Living barriers of vetiver grass were evaluated and are now being used for controlling soil erosion. Through independent experimentation farmers have found Tephrosia effective in controlling root rats (Tachyoryctes splendens)

Plant materials for soil fertility management in subhumid tropical areas

Lantana camara L., Senna hirsuta (L.) Irwin & Barneby, Tithonia diversifolia (Hemsl.) A. Gray, and Aspilia kotschyi du Petit-Thouars occur naturally in eastern and central Uganda. Trimmings of these species were evaluated for effectiveness in improving soil productivity. The plant trimmings varied for N (13 30 g kg?1), P (1.1 1.8 g kg?1), lignin (11 16%), and polyphenol (1.3 2.5%) concentration. Decomposition rates were higher for incorporation than for surface placement, but placement did not affect maize (Zea mays L.) and bean (Phaseolus vulgaris L.) yield. Decomposition rates were similar for all species with the same placement method. Potassium and Mg were generally mineralized most and least rapidly, respectively, with intermediate rates for N, P, and Ca. Maize and bean yield increased with application of 4 Mg ha?1 dry wt. trimmings of L. camara, S. hirsuta, and T. diversifolia, but only maize eventually responded to A. kotschyi Yields per units of N and P applied were more and less, respectively, with inorganic than with organic treatments, but plant trimmings supplied less P than fertilizer. At the end of the trial period, available soil P was more for the full rate of fertilizer than for the mean of the plant materials. Combining L. camara and fertilizer, at 50% rates, resulted in an average of 0.22 Mg ha?1 more yield than expected from mere additive effects of the organic and inorganic resources. The value of plant materials may be enhanced by balancing nutrient supply with inorganic fertilizers