S. Zingore

Managing soil fertility diversity to enhance resource use efficiencies in smallholder farming systems: a case from Murewa District, Zimbabwe

Smallholder farms in sub-Saharan African exhibit substantial heterogeneity in soil fertility, and nutrient resource allocation strategies that address this variability are required to increase nutrient use efficiencies. We applied the Field-scale resource Interactions, use Efficiencies and Long-term soil fertility Development (FIELD) model to explore consequences of various manure and fertilizer application strategies on crop productivity and soil organic carbon (SOC) dynamics on farms varying in resource endowment in a case study village in Murewa District, Zimbabwe. FIELD simulated a rapid decline in SOC and maize yields when native woodlands were cleared for maize cultivation without fertilizer inputs coupled with removal of crop residues. Applications of 10 t manure ha−1 year−1 for 10xa0years were required to restore maize productivity to the yields attainable under native woodland. Long-term application of manure at 5 and 3 t ha−1 resulted in SOC contents comparable to zones of high and medium soil fertility observed on farms of wealthy cattle owners. Targeting manure application to restore SOC to 50–60% of contents under native woodlands was sufficient to increase productivity to 90% of attainable yields. Short-term increases in crop productivity achieved by reallocating manure to less fertile fields were short-lived on sandy soils. Preventing degradation of the soils under intensive cultivation is difficult, particularly in low input farming systems, and attention should be paid to judicious use of the limited nutrient resources to maintain a degree of soil fertility that supports good crop response to fertilizer application.

Performance of bucket drip irrigation powered by treadle pump on tomato and maize/bean production in Malawi

The performance of a bucket drip irrigation system (BDI) powered by treadle pump was evaluated on tomato and intercropped maize/bean crops, between 2005 and 2007 in Malawi. It was a split plot experiment with three replicates. The BDI system consisted of a 1,300-l tank mounted 1.5xa0m above ground and connected with a 32-mm mainline and 15-mm lateral lines spaced at 1xa0m by 0.6xa0m. A treadle pump was used to uplift water to the tank. Tomato and intercropped maize/bean were irrigated every 4xa0days. The system reduced labour and water by >25% and it showed high uniform application depth and wetted diameter. Yields were significantly different between tomato varieties (Pxa0<xa00.05). Maize/bean yields were highly significantly different between monoculture, intercropping system and bean varieties (Pxa0<xa00.001). Consequently, an economic analysis shows that there is a significant difference, in terms of net income, between the various crop enterprises. Tomato was more valuable with BDI, compared to maize and beans. It can be concluded that BDI, powered by a treadle pump, saves labour and time and it provides uniform irrigation for crop production. Therefore, tomato is recommended for use with this system, compared to maize and bean.

Determinants of Fertiliser Use by Smallholder Maize Farmers in the Chinyanja Triangle in Malawi, Mozambique and Zambia

Abstract Farm surveys in Malawi, Zambia and Mozambique were carried out to assess the determinants of fertiliser use given continued low yields, low organic matter and general poor soil health in southern African soils. Regression modelling showed that fertiliser use was influenced by household and farm characteristics. In addition, it was also influenced by social and human capital and farmers’ perceptions of the effect of fertilisers on soil fertility. Farmers who perceived fertilisers as bad for their soil were less likely to adopt their use. This is a key result, as the emerging discussions on a green revolution for Africa, as well as the continued food crisis discussion, are prompting increased fertiliser use as an immediate intervention for increasing nutrient inputs into agriculture in the developing world. Increased policy efforts should be placed not only on increasing access to fertilisers but also on evolving farmers’ perceptions and attitudes towards fertiliser use.