Soil Fertility Consortium For Southern Africa Sofecsa

Harare, Zimbabwe

Soil Fertility Consortium For Southern Africa Sofecsa

Harare, Zimbabwe
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Nezomba H.,Soil Fertility Consortium For Southern Africa Sofecsa | Mtambanengwe F.,Soil Fertility Consortium For Southern Africa Sofecsa | Tittonell P.,Instituto Nacional de Tecnologia Agropecuaria | Mapfumo P.,Soil Fertility Consortium For Southern Africa Sofecsa
Catena | Year: 2017

Crop production on smallholder farms in Southern Africa is increasingly being constrained by deteriorating land quality. Assessing soil degradation at farm-level is therefore important to enable formulation and better targeting of rehabilitation options. In this study, farmers' local indicators and scientific diagnostic parameters were combined to develop criteria for assessing soil degradation on croplands in Hwedza smallholder farming area in Eastern Zimbabwe. Farmers used common weed species, crop performance aspects and soil physical attributes to categorize arable soils into four main productivity classes: productive, moderately productive, degraded and severely degraded. Broad-leafed weeds, that included Commelina benghalensis L., Bidens pilosa L. and Leucas martinicensis (Jacq.) Ait. f., were considered as main indicators of productive soils, while grass weeds, Melinis repens (Willd.) Zizka and Eragrostis minor Host, were perceived as typifying severely degraded soils. Maize grain yields of 6 to 8 scotch carts ha−1 (3 to 4 tha−1) and < 2 scotch carts ha− 1 (< 1 tha− 1) were indicative of productive and degraded soils, respectively. Consistent with farmer criteria, broad-leafed weeds contributed most of the weed biomass on productive soils, with diversity higher on productive and moderately productive than on degraded soils. Properties of soils sampled from field productivity classes differed significantly (p <0.05) and the magnitude of the differences was also influenced by farmer resource endowment. Soil organic carbon (SOC), mineralizable nitrogen (N), available phosphorus (P), exchangeable calcium (Ca) and effective cation exchange capacity (ECEC) decreased from productive to severely degraded soils, and from resource-endowed (RG1) to resource-constrained (RG3) farms. Most of the soil properties showed a decline (negative degradation indices) when compared with uncultivated lands. Exchangeable Ca and mineralizable N showed a strong relationship with SOC (R2 > 0.5) across the soil productivity classes and farmer resource groups. Principal components analysis of 16 soil physico-chemical and biological properties revealed mineralizable N, microbial biomass N, exchangeable bases and available P as the most important parameters influencing soil productivity. Drawing on the relationship between weed species populations and soil properties observed in this study, a soil degradation assessment scheme is proposed for enhancing decision-making on options for rehabilitation of croplands by smallholder farmers in similar agro-ecologies in Southern Africa. © 2017 Elsevier B.V.

Mtangadura T.J.,Soil Fertility Consortium For Southern Africa Sofecsa | Mtambanengwe F.,Soil Fertility Consortium For Southern Africa Sofecsa | Nezomba H.,Soil Fertility Consortium For Southern Africa Sofecsa | Rurinda J.,International Plant Nutrition Institute IPNI | Mapfumo P.,Soil Fertility Consortium For Southern Africa Sofecsa
PLoS ONE | Year: 2017

Sustainability of maize-based cropping systems is a major challenge for southern Africa, yet the demand for maize as staple food and animal feed in the region continues to increase. A study was conducted on a sandy clay loam (220 g clay kg-1 soil) at Domboshawa in Zimbabwe to investigate the long-term effects of organic resource quality and application rate, and nitrogen (N) fertilization on soil chemical properties and maize (Zea mays L.) productivity. Crotalaria juncea (high quality), Calliandra calothyrsus (medium quality), cattle manure (variable quality), maize stover and Pinus patula sawdust (both low quality) were incorporated into soil at 4.0 t C ha-1 (high rate) and 1.2 t C ha-1 (low rate) at the start of each cropping season for nine consecutive years. At both high and low application rates, each of the five organic resources was applied in combination with or without mineral nitrogen (N) fertilizer at 120 kg N ha-1. The nine-year period saw maize grain yields declining by 22% to 84% across treatments despite increases in soil organic carbon, total N and available P from 6% to 80%. Crotalaria, Calliandra and manure led to a less steep yield decline. Exchangeable calcium (Ca), magnesium (Mg) and potassium (K), and soil pH explained much of the variation in yield patterns observed under the different organic resource applications. Maize grain yield was positively correlated with exchangeable Ca (r = 0.51), Mg (r = 0.62) and K (r = 0.53), and soil pH (r = 0.49), but negatively correlated with other soil properties over the 9-year period. We concluded that declining soil exchangeable basic cations were the underlying causes of decreasing maize productivity, and was aggravated by use of low rates of organic resource inputs, particularly with N fertilization. Current nutrient management and fertilizer recommendations that emphasize inorganic N, P and K significantly undervalue the role played by organic resources in sustainability of maize cropping systems in southern Africa. © 2017 Mtangadura et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Woittiez L.S.,Wageningen University | Rufino M.C.,Wageningen University | Rufino M.C.,Center for International Forestry Research | Giller K.E.,Wageningen University | And 2 more authors.
Ecology and Society | Year: 2013

Common lands provide smallholder farmers in Africa with firewood, timber, and feed for livestock, and they are used to complement human diets through the collection of edible nontimber forest products (NTFPs). Farmers have developed coping mechanisms, which they deploy at times of climatic shocks. We aimed to analyze the importance of NTFPs in times of drought and to identify options that could increase the capacity to adapt to climate change. We used participatory techniques, livelihood analysis, observations, and measurements to quantify the use of NTFPs. Communities recognized NTFPs as a mechanism to cope with crop failure. We estimated that indigenous fruits contributed to approximately 20% of the energy intake of wealthier farmers and to approximately 40% of the energy intake of poor farmers in years of inadequate rainfall. Farmers needed to invest a considerable share of their time to collect wild fruits from deforested areas. They recognized that the effectiveness of NTFPs as an adaptation option had become threatened by severe deforestation and by illegal harvesting of fruits by urban traders. Farmers indicated the need to plan future land use to (1) intensify crop production, (2) cultivate trees for firewood, (3) keep orchards of indigenous fruit trees, and (4) improve the quality of grazing lands. Farmers were willing to cultivate trees and to organize communal conservation of indigenous fruits trees. Through participatory exercises, farmers elaborated maps, which were used during land use discussions. The process led to prioritization of pressing land use problems and identification of the support needed: fast-growing trees for firewood, inputs for crop production, knowledge on the cultivation of indigenous fruit trees, and clear regulations and compliance with rules for extraction of NTFPs. Important issues that remain to be addressed are best practices for regeneration and conservation, access rules and implementation, and the understanding and management of competing claims on the common lands. Well-managed communal resources can provide a strong tool to maintain and increase the rural communities' ability to cope with an increasingly variable climate. © 2013 by the author(s).

Rufino M.C.,Wageningen University | Dury J.,Wageningen University | Tittonell P.,Wageningen University | van Wijk M.T.,Wageningen University | And 5 more authors.
Agricultural Systems | Year: 2011

In communal areas of NE Zimbabwe, feed resources are collectively managed, with herds grazing on grasslands during the rainy season and mainly on crop residues during the dry season, which creates interactions between farmers and competition for organic resources. Addition of crop residues or animal manure is needed to sustain agricultural production on inherently poor soils. Objectives of this study were to assess the effect of village-level interactions on carbon and nutrient flows, and to explore their impact on the long-term productivity of different farm types under climate variability. Crop and cattle management data collected in Murewa Communal area, NE Zimbabwe was used together with a dynamic farm-scale simulation model (NUANCES-FARMSIM) to simulate village-level interactions. Simulations showed that grasslands support most cattle feed intake (c. 75%), and that crop residues produced by non-cattle farmers sustain about 30% of the dry season feed intake. Removal of crop residues (0.3-0.4tCha-1yr-1) from fields of non-cattle farmers resulted in a long-term decrease in crop yields. No-access to crop residues of non-cattle farmers increased soil C modestly and improved yields in the long-term, but not enough to meet household energy requirements. Harvest of grain and removal of most crop residues by grazing cattle caused a long-term decline in soil C stocks for all farm types. The smallest decrease (-0.5tCha-1) was observed for most fertile fields of cattle farmers, who manure their fields. Cattle farmers needed to access 4-10ha of grassland to apply 3t of manure ha-1yr-1. Rainfall variability intensifies crop-livestock interactions increasing competition for biomass to feed livestock (short-term effect) or to rehabilitate soils (long-term effect). Prolonged dry seasons and low availability of crop residues may lead to cattle losses, with negative impact in turn on availability of draught power, affecting area under cultivation in consecutive seasons until farmers re-stock. Increasing mineral fertiliser use concurrently with keeping crop residues in fertile fields and allocating manure to poor fields appears to be a promising strategy to boost crop and cattle productivity at village level. The likelihood of this scenario being implemented depends on availability of fertilisers and decision of farmers to invest in rehabilitating soils to obtain benefits in the long-term. Adaptation options cannot be blind to what occurs beyond field and farm level, because otherwise recommendations from research and development do not fit the local conditions and farmers tend to ignore them. © 2010 Elsevier Ltd.

Mapfumo P.,Soil Fertility Consortium For Southern Africa Sofecsa | Mapfumo P.,University of Zimbabwe | Adjei-Nsiah S.,University of Ghana | Mtambanengwe F.,University of Zimbabwe | And 2 more authors.
Environmental Development | Year: 2013

Emerging trends of a changing and increasingly variable climate have introduced new livelihood challenges in rain-fed smallholder agricultural systems that predominate in Sub-Saharan Africa (SSA). The capacity of local farming communities and their institutions to respond to the new and emerging impacts of climate change is often constrained by lack of access to information and improved technologies, as well as poor support mechanisms to promote assimilation of new knowledge. This threatens to heighten vulnerability of the majority of SSA's rural communities who are already facing severe problems of food insecurity and a declining soil resource base. In this paper we use two case studies from Wenchi district in Ghana and Makoni in Zimbabwe to communicate how participatory action research (PAR) methodology, characterised by iterative planning-action-reflection cycles, was coupled with a new concept of field-based farmer learning centres to build adaptive capacity of smallholder farmers to climate change. The study was part of a University of Zimbabwe-led project supported under the Climate Change Adaptation in Africa (CCAA) programme to explore the state of resilience in African smallholder farming. The PAR and learning centre processes enabled communities, local leaders, and extension agents and researchers to establish the, hither to, imperceptible link between poor soil fertility and rising institutional challenges within communities. Institutional conflicts related to land tenure and sharecropping arrangements between migrant farmers and native landowners were addressed in Ghana, while local institutions supporting traditional social safety net mechanisms were revitalized in Zimbabwe. In both cases, it was apparent that farmers faced multiple stresses, at the core of which were poor and declining soil fertility and weakening local institutions. The worsening rainfall distribution and increasing cases of drought are broadening the scope for vulnerability, often driving competing claims and conflicts. PAR was successfully used as an entry point, empowering communities to self-mobilize and self-organize to co-learn and experiment with integrated soil fertility management (ISFM) technologies and other improved farming practices. They realised opportunities for achieving high crop yields and generate surpluses in good years. Strengthening local institutional capacity to revitalise community safety nets proved an essential ingredient for enhancing adaptive capacity of smallholders to climatic shocks. The PAR process was a major driver of effective partnerships among community members, extension, policy makers and researchers, but ensuing success generated a new set of social challenges that could not be addressed within the short timescale of the project. We conclude that PAR was a suitable mechanism for supporting self-organization and co-learning processes among smallholder farmers and their service providers, enabling them to use ISFM technologies and strengthen their local institutions around natural resource management. This revealed the scope for building adaptive capacity of these communities against climate change and variability. © 2012 Elsevier B.V.

Nyikahadzoi K.,University of Zimbabwe | Siziba S.,University of Zimbabwe | Mango N.,International Center for Tropical Agriculture | Mapfumo P.,Soil Fertility Consortium For Southern Africa Sofecsa | And 2 more authors.
Food Security | Year: 2012

The failure of the linear and non-participatory Agricultural Research and Development (ARD) approaches to increase food security among smallholder farmers in sub-Saharan Africa has prompted researchers to introduce an Integrated Agricultural Research for Development (IAR4D) concept. The IAR4D concept uses Innovation Platforms (IPs) to embed agricultural research and development organizations in a network to undertake multidisciplinary and participatory research. This paper uses Zimbabwe as a case study to analyze the relevance of the technologies and innovations that are being promoted by IPs in Zimbabwe to improve food security. Using data collected through the Sub-Saharan Africa Challenge Programme, the paper shows that access to inputs, social capital, productivity enhancing technologies and market information are critical in addressing food security issues among smallholder farmers. The multi-stakeholder partnership forged through IPs should adopt a coordinated approach to provide smallholders with access to these prerequisites for food security. The paper argues that more emphasis should be put on these issues rather than on farm research initiatives whose contribution to food security appears to be less significant. © 2012 Springer Science+Business Media Dordrecht and International Society for Plant Pathology.

Manzeke G.M.,University of Zimbabwe | Mapfumo P.,University of Zimbabwe | Mapfumo P.,Soil Fertility Consortium For Southern Africa Sofecsa | Mtambanengwe F.,University of Zimbabwe | And 3 more authors.
Plant and Soil | Year: 2012

Background and aims: Low soil zinc (Zn) threatens crop production and food nutrition in most cereal-based cropping systems in Africa. Agronomic management options that include farmers' locally available organic nutrient resources need to be evaluated in the context of Zn nutrition in staple cereals. A three-year study (2008-11) was conducted in two smallholder farming areas of eastern Zimbabwe to evaluate the influence of farmers' diverse soil fertility management practices on soil Zn status and effect on uptake patterns and nutritional value in maize (Zea mays L.). Methods: Participatory research approaches and formal surveys enabled identification of farmers' diverse soil fertility management practices, which were then classified into five main domains: manure or woodland litter + mineral fertilizer; sole mineral fertilizer; legume - maize rotation; and a non-fertilized control. Over 60 randomly selected farms in each study area were then surveyed for influence of identified practices on soil Zn status across the domains. Maize growth, yield and Zn uptake patterns were monitored on a sub-sample of 20 farms covering the five management domains in each study area. Results: Ethylenediaminetetraacetic acid (EDTA) extractable soil Zn ranged from 0. 50 to 2. 43 mg kg-1. Different farmer management practices significantly influenced Zn uptake (p < 0. 01). Combined use of organic and inorganic fertilizer yielded >2. 1 t ha-1 maize grain, against <;0. 8 t ha-1 in the non-fertilized control. Maize grain Zn concentrations increased by 46-64 % over the control. Regardless of management practice, resultant phytic acid to Zn (PA: Zn) ratios were above the critical value of 15 suggesting inadequacies in current farmer management options. Conclusions: We conclude that the current farmer soil fertility management regimes are insufficient to influence Zn nutrition in maize grown without external Zn fertilization on Zimbabwean sandy soils. © 2012 Springer Science+Business Media B.V.

Rurinda J.,Wageningen University | Rurinda J.,University of Zimbabwe | Mapfumo P.,University of Zimbabwe | Mapfumo P.,Soil Fertility Consortium For Southern Africa Sofecsa | And 7 more authors.
European Journal of Agronomy | Year: 2014

Questions as to which crop to grow, where, when and with what management, will be increasingly challenging for farmers in the face of a changing climate. The objective of this study was to evaluate emergence, yield and financial benefits of maize, finger millet and sorghum, planted at different dates and managed with variable soil nutrient inputs in order to develop adaptation options for stabilizing food production and income for smallholder households in the face of climate change and variability. Field experiments with maize, finger millet and sorghum were conducted in farmers' fields in Makoni and Hwedza districts in eastern Zimbabwe for three seasons: 2009/10, 2010/11 and 2011/12. Three fertilization rates: high (90kgNha-1, 26kgPha-1, 7tha-1 manure), low (35kgNha-1, 14kgPha-1, 3tha-1 manure) and a control (zero fertilization); and three planting dates: early, normal and late, were compared. Crop emergence for the unfertilized finger millet and sorghum was <15% compared with >70% for the fertilized treatments. In contrast, the emergence for maize (a medium-maturity hybrid cultivar, SC635), was >80% regardless of the amount of fertilizer applied. Maize yield was greater than that of finger millet and sorghum, also in the season (2010/11) which had poor rainfall distribution. Maize yielded 5.4tha-1 compared with 3.1tha-1 for finger millet and 3.3tha-1 for sorghum for the early plantings in the 2009/10 rainfall season in Makoni, a site with relatively fertile soils. In the poorer 2010/11 season, early planted maize yielded 2.4tha-1, against 1.6tha-1 for finger millet and 0.4tha-1 for sorghum in Makoni. Similar yield trends were observed on the nutrient-depleted soils in Hwedza, although yields were less than those observed in Makoni. All crops yielded significantly more with increasing rates of fertilization when planting was done early or in what farmers considered the 'normal window'. Crops planted early or during the normal planting window gave comparable yields that were greater than yields of late-planted crops. Water productivity for each crop planted early or during the normal window increased with increase in the amount of fertilizer applied, but differed between crop type. Maize had the highest water productivity (8.0kgdrymattermm-1ha-1) followed by sorghum (4.9kgmm-1ha-1) and then finger millet (4.6kgmm-1ha-1) when a high fertilizer rate was applied to the early-planted crop. Marginal rates of return for maize production were greater for the high fertilization rate (>50%) than for the low rate (<50%). However, the financial returns for finger millet were more attractive for the low fertilization rate (>100%) than for the high rate (<100%). Although maize yield was greater compared with finger millet, the latter had a higher content of calcium and can be stored for up to five years. The superiority of maize, in terms of yields, over finger millet and sorghum, suggests that the recommendation to substitute maize with small grains may not be a robust option for adaptation to increased temperatures and more frequent droughts likely to be experienced in Zimbabwe and other parts of southern Africa. © 2014 Elsevier B.V.

Nezomba H.,University of Zimbabwe | Tauro T.P.,University of Zimbabwe | Tauro T.P.,Chemistry and Soil Research Institute | Mtambanengwe F.,University of Zimbabwe | And 2 more authors.
Field Crops Research | Year: 2010

Widening the range of organic nutrient resources, especially N sources, is a major challenge for improving crop productivity of smallholder farms in southern Africa. A study was conducted over three seasons to evaluate different species of indigenous legumes for their biomass productivity, N2-fixation and residual effects on subsequent maize crops on nutrient-depleted fields belonging to smallholder farmers under contrasting rainfall zones in Zimbabwe. Under high rainfall (>800 mm yr-1), 1-year indigenous legume fallows (indifallows), comprising mostly species of the genera Crotalaria, Indigofera and Tephrosia, yielded 8.6 t ha-1 of biomass within 6 months, out-performing sunnhemp (Crotalaria juncea L.) green manure and grass (natural) fallows by 41% and 74%, respectively. A similar trend was observed under medium (650-750 mm yr-1) rainfall in Chinyika, where the indifallow attained a biomass yield of 6.6 t ha-1 compared with 2.2 t ha-1 for natural fallows. Cumulatively, over two growing seasons, the indifallow treatment under high rainfall at Domboshawa produced biomass as high as 28 t ha-1 compared with ∼7 t ha-1 under natural fallow. The mean total N2 fixed under indifallows ranged from 125 kg ha-1 under soils exhibiting severe nutrient depletion in Chikwaka, to 205 kg ha-1 at Domboshawa. Indifallow biomass accumulated up to 210 kg N ha-1, eleven-fold higher than the N contained in corresponding natural fallow biomass at time of incorporation. Application of P to indifallows significantly increased both biomass productivity and N2-fixation, translating into positive yield responses by subsequent maize. Differences in maize biomass productivity between indifallow and natural fallow treatments were already apparent at 2 weeks after maize emergence, with the former yielding significantly (P < 0.05) more maize biomass than the latter. The first maize crop following termination of 1-year indifallows yielded grain averaging 2.3 t ha-1, significantly out-yielding 1-year natural fallows by >1 t ha-1. In the second season, maize yields were consistently better under indifallows compared with natural fallows in terms of both grain and total biomass. The first maize crop following 2-year indifallows yielded ∼3 t ha-1 of grain, significantly higher than the second maize crop after 1-year indifallows and natural fallows. The study demonstrated that indigenous legumes can generate N-rich biomass in sufficient quantities to make a significant influence on maize productivity for more than a single season. Maize yield gains under indifallow systems on low fertility sandy soils exceeded the yields attained with either mineral fertilizer alone or traditional green manure crop of sunnhemp. © 2009 Elsevier B.V. All rights reserved.

Rurinda J.,Wageningen University | Rurinda J.,University of Zimbabwe | Mapfumo P.,University of Zimbabwe | Mapfumo P.,Soil Fertility Consortium For Southern Africa Sofecsa | And 6 more authors.
Field Crops Research | Year: 2013

Adaptation options that address short-term climate variability are likely to lead to short-term benefits and will help to deal with future changes in climate in smallholder cropping systems in Sub-Saharan Africa (SSA). In this study we combined field experimentation and long-term rainfall analyses in Makoni and Hwedza districts in eastern Zimbabwe to evaluate cropping adaptation options to climate variability. Analyses of long-term rainfall data closely supports farmers' perceptions that the mean annual total rainfall has not changed, but the pattern of rainfall within-season has changed: the number of rainfall days has decreased, and the frequency of dry spells has increased at the critical flowering stage of maize. On-farm experiments were conducted over two cropping seasons, 2009/10 and 2010/11 to assess the effects of planting date, fertilization and cultivar on maize production. Three maize cultivars were sown in each of the early, normal and late planting windows defined by farmers. Each of the nine cultivar-planting date combinations received N, P, K and manure combinations at either zero, low or high fertilization rates. Overall, there were no significant differences in maize development or grain yield among cultivars. Maize grain yield was increased by increasing the amount of nutrients applied. Average yield was 2.5tha-1 for the low rate and 5.0tha-1 for the high rate on early planted cultivars on relatively fertile soils in Makoni in 2009/10 season. Yields on poorer soils in Hwedza were small, averaging 1.5tha-1 for the low rate and 2.5tha-1 for the high rate. Maize grain yields for the early and normal planted cultivars were similar for each fertilization rate, suggesting there is a wide planting window for successful establishment of crops in response to increased rainfall variability. Yield reduction of >50% was observed when planting was delayed by 4 weeks (late planting) regardless of the amount of fertilizer applied. Soil nutrient management had an overriding effect on crop production, suggesting that although the quality of within-season rainfall is decreasing, nutrient management is the priority option for adaptation in rain-fed smallholder cropping systems. © 2013 Elsevier B.V.

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