CLIMATE CHANGE AND VARIABILITY: SMALLHOLDER FARMING COMMUNITIES IN ZIMBABWE PORTRAY A VARIED UNDERSTANDING

Increasing awareness of risks associated with climate change and variability among smallholder farmers is critical in building their capacity to develop the necessary adaptive measures. Using farmer participatory research approaches and formal questionnaire surveys, interaction has been made with >800 farmers in two distinct smallholder farming systems of Makoni and Wedza Districts in eastern Zimbabwe to determine the current level of understanding of climate change and variability, current responses to perceived changes, as well as identify sources of agro-meteorological information. The results indicated that farmers portrayed a varied understanding both within and across the study sites. While poor rainfall distribution was seen as the major indicator for climate change by over two-thirds of the respondents in both sites, more farmers in Makoni attributed delay in onset of rains, high incidences of flush floods and unpredictable \u2018wind movements\u2019 yielding cyclones to climate change. In Wedza, it was recurrent droughts, winter and summer temperature extremes, and increased pest and disease incidences for both crops and livestock that indicated climate change. Perceived changes were linked more to natural and human forces (Makoni), unknown forces as well as breakdown in cultural norms and beliefs and rise of Christianity (Wedza). Disparities between the two sites could be attributed to the inherent differences of the communities in terms to their social settings. The national extension, Agritex, was ranked first by 50-60% of the farmers as major source of weather information. Electronic media (radio and television) ranked second with 47% of farmers in Makoni and 35% in Wedza. Concerns were raised over inadequacies of such information, apparent lack of reliability, timing and frequency of dissemination that directly influenced the utilisation of the information. Common coping strategies included early planting which was the more prevalent in Makoni, while combinations of cereals and legumes were a preferred solution in Wedza. We concluded that farmers\u2019 interaction with various information sources and knowledge sharing platforms needs to be enhanced in order to deepen their understanding as well as increase their capacity to respond to pressures of climate variability and change.L\u2019am\ue9lioration des connaissances des petits fermiers sur les risques lies au changement du climat et sa variabilit\ue9 est un fait important pour l\u2019\ue9dification de leur capacit\ue9 de d\ue9velopper des mesures n\ue9cessaires d\u2019adaptation. En utilisant des m\ue9thodes de recherche participative et un questionnaire d\u2019enqu\ueate formelle, l\u2019interaction a \ue9t\ue9 faite avec plus de 800 fermiers de deux syst\ue8mes d\u2019exploitation distincts de districts de Makoni et Wedza \ue0 l\u2019Est du Zimbabwe, afin de d\ue9terminer le niveau actuel de compr\ue9hension du changement du climat et sa variabilit\ue9, les m\ue9canismes d\u2019adaptation aux changements per\ue7us, ainsi qu\u2019identifier les sources d\u2019information agro m\ue9t\ue9orologique. Les r\ue9sultats ont indiqu\ue9 que les fermiers avaient un niveau vari\ue9 de compr\ue9hension dans les deux sites d\u2019\ue9tude.Alors qu\u2019une faible distribution des pr\ue9cipitations \ue9tait consid\ue9r\ue9e comme \ue9tant l\u2019indicateur majeur du changement du climat par plus de 2/3 des r\ue9pondants dans les deux sites, la plupart des fermiers de Makoni ont affirm\ue9 que le retard dans l\u2019apparition des pluies, incidence \ue9lev\ue9e des inondations et mouvement du vent impr\ue9dictible r\ue9sultant du cyclone par le changement du climat. En Wedza, le changement du climat \ue9tait manifest\ue9 \ue0 travers les s\ue9cheresses r\ue9currentes, des temp\ue9ratures extr\ueames pendant l\u2019hiver et l\u2019\ue9t\ue9 ainsi que l\u2019accroissement d\u2019incidences de pestes et maladies affectant des cultures et le b\ue9tail. Les changements per\ue7us \ue9taient plus li\ue9s aux forces naturelles et humaines (Makoni), des forces inconnues aussi bien que la non-observance des normes culturales et les croyances et le d\ue9veloppement de la chr\ue9tient\ue9 (Wedza). Les disparit\ue9s entre les deux sites pourraient \ueatre attribu\ue9es aux diff\ue9rences inh\ue9rentes des deux communaut\ue9s en termes de leurs environnements sociaux. La vulgarisation nationale, Agritex, \ue9tait rang\ue9e la premi\ue8re par 50-60% des fermiers comme source majeur de l\u2019information sur le climat suivi du media \ue9lectronique (radio et t\ue9l\ue9vision) avec 47% des fermiers dans Makoni et 35% dans Wedza. Les probl\ue8mes \ue9voqu\ue9s \ue9taient li\ue9s au manque de consistance de l\u2019information, manque apparent de fiabilit\ue9, le temps et la fr\ue9quence de diss\ue9mination qui directement influencent l\u2019utilisation de l\u2019information. Les strat\ue9gies communes d\u2019adaptation consistaient en la plantation \ue0 temps sp\ue9cialement dans Makoni, pendant que les combinaisons des c\ue9r\ue9ales et des l\ue9gumes \ue9taient une solution pr\ue9f\ue9r\ue9e en Wedza. En conclusion, l\u2019interaction des fermiers avec des sources vari\ue9es d\u2019information et les plateformes de partage de connaissance ont besoin d\u2019\ueatre d\ue9velopp\ue9e afin d\u2019am\ue9liorer leur niveau de compr\ue9hension aussi bien renforcer leur capacit\ue9 \ue0 r\ue9pondre aux pressions du changement du climat et sa variabilit\ue9

Role of soil texture, clay mineralogy, location, and temperature in coarse wood decomposition—a mesocosm experiment

Of all the major pools of terrestrial carbon (C), the dynamics of coarse woody debris (CWD) are the least understood. In contrast to soils and living vegetation, the study of CWD has rarely relied on ex situ methods for elaborating controls on decomposition rates. In this study, we report on a mesocosm incubation experiment examining how clay amount (8%, 16%, and 24% clay), clay type (soil reconstructed with kaolinite vs. montmorillonite), wood placement (on litter layer surface, at the litter layer–soil interface, buried in the mineral soil), and laboratory incubation temperature (10°, 20°, or 30°C) control decomposition rates of highly standardized stakes and blocks of coarse aspen wood. Clay type effect was pronounced, with wood decomposing more quickly in kaolinite- than in montmorillonite-amended soils, perhaps due to a combined effect of moisture and microbial access to the substrate. Clay amount had only very limited effect on wood decomposition, which was a function of contact with the mineral soil (Surface \u3c Interface \u3c Mineral), perhaps due to greater contact with the decomposer community. Temperature effects were significant and dependent on interactions with clay type and wood placement. Effects of temperature on wood decomposition declined as the effects of soil variables increased, suggesting a hierarchy of controls on wood decomposition rates. Both water content and temperature had a strong effect on wood decomposition. Our results highlight that multiple interacting factors likely regulate wood decomposition processes. Multifactorial field experiments are needed to examine the physical, chemical, and biological factors controlling wood decompositio

Eliciting experts’ tacit models for the interpretation of soil information, an example from the evaluation of potential benefits from conservation agriculture

© 2020 The Authors We examined a procedure to elicit the tacit models underlying expert opinions on environmental factors that affect the absolute yield benefits expected from the adoption of conservation agriculture (CA) practices in southern Africa. The procedure is based on expert evaluation of the expected improvement in crop yield on adoption of CA in a particular scenario or ‘state’, a state being a specified set of soil conditions captured by a standard soil profile description from a specified agroecological zone (AEZ) of Zambia. Mixed groups of scientists including soil scientists, agronomists, agricultural economists and other environmental scientists, facilitated by experienced senior researchers, were presented with multiple subsets each of three states, and asked to rank the states in each subset with respect to expected yield improvement under CA. The groups of scientists could be divided into two sets. Each set comprised two groups, and the agreement on ranking between groups within each set was larger than would be expected if the ranking were done at random. For both sets of groups the ranking could be modelled with respect to properties of the soil, and the contrast between AEZ. The models revealed two contrasting groups of conceptual assumptions. One group broadly expected larger absolute yield improvements from conservation agriculture in settings where water is most likely to be limiting and the carbon status of the soil is poor. By contrast, the other group expected larger improvements where water was less likely to be limiting. These contrasting views are relevant to current discussions as to whether conservation agriculture, which is promoted as a ‘climate smart’ strategy for cropping, is sufficiently attractive for smallholder producers in conditions where crop production is already challenging, and whether the potential benefits in areas where water availability is not of itself a common limitation should be considered. The elicited models could be translated directly into competing hypotheses to be tested, perhaps in on-farm trials of conservation agriculture practices over contrasting soils in the different AEZ. The method, based on modelling the ranking process, could be of more general interest for the elicitation of expert opinion about complex soil, crop and environmental systems

Zimbabwe : mobilizing local safety nets for enhanced adaptive capacity to climate change and variability in Zimbabwe

French version available in IDRC Digital Library: Zimbabwe : mobiliser les filets de sécurité locaux pour améliorer la capacité d'adaptation à la variabilité et aux changements climatiques au ZimbabweThis bulletin outlines participatory action research (PAR) used in revitalizing traditional safety nets. Eighteen villages participated in the project in Zimbabwe. Community members mobilized organic nutrient inputs and draught power, prepared common land and cultivated maize, soya and cowpea following integrated soil fertility management (ISFM) guidelines developed by a team of technical experts including lead farmers. By integrating knowledge sharing platforms with technical services, opportunities were generated for the Nyahava community to revitalize “Zunde raMambo,” a traditional social safety net. This further strengthened community cohesion for collective action in safeguarding vulnerable households

Organic matter quality and management effects on enrichment of soil organic matter fractions in contrasting soils in Zimbabwe

Maintenance of soil organic matter (SOM) at levels that sustain optimal supply of soil nutrients and enhance efficiency of externally added fertilizers is a major challenge for smallholder farming systems of southern Africa. A study was conducted to quantify the interactive effects of organic resource quality and management on SOM formation and subsequent maize yields under contrasting soil types. Crotalaria juncea L., Calliandra calothyrsus Meissn., cattle manure, maize (Zea mays L.) stover and Pinus patula Schiede and Schltdl. and Cham. sawdust were applied at 1.2 and 4 t C ha?1 at Domboshawa and Makoholi Experimental Stations, simulating some of the soil amendments commonly available on smallholder farms. Soils at Domboshawa are sandy clay loams with 220 g clay kg?1 while the sandy soils at Makoholi had <100 g clay kg?1. At 12 14 weeks after incorporation, organic resource quality effects on particulate organic matter (POM) C enrichment were most significant (p < 0.01) in the macro-POM (250 2,000 ?m diameter) fraction of both soil types constituting 15 30% of total soil C on coarse sand soil and 5 10% on sandy clay loam soils. The highest increases were under C. calothyrsus, manure and sawdust treatments. There was evidence of sub-soil enrichment under these two treatments on sandy soils at different sites. While no significant treatment effects were observed on the size of organo-mineral fraction, there was a significant (p < 0.05) separation of treatments in terms of potential mineralizable N from the same fraction. On coarse sands, organo-mineral fraction under medium to high-quality materials such as manure and C. juncea released ?50 mg N kg?1, compared to 8 18 mg N kg?1 from sawdust and maize stover, suggesting that such materials enhanced the N-supply capacity of this fraction without necessarily increasing its size. The same trends were observed under sandy clay loams although, in contrast to coarse sands, the high-quality materials released no more than 25 mg N kg?1, suggesting that the added C was protected against short-term mineralization. These contrasting properties were also reflected in maize yield patterns. On sandy clay loams, a significant linear relationship between maize yield and the amount of mineralizable N in the macro-POM fraction (R 2 = 0.50; p < 0.01) was evident, while the best predictor for maize yield on coarse sands was the amount of mineralizable N from the organo-mineral fraction (R 2 = 0.86). We concluded that maize productivity on contrasting soil types hinges on different soil organic fractions and therefore require different management strategies. Sustainability of cropping on sandy soils is likely to depend on a regular supply of high-quality C materials, which enhance the nutrient supply capacity of the small organo-mineral fraction. Under the relatively C protective sandy clay loams, it is apparently the size of the macro-POM fraction which largely determines crop yields in the short-term

Zimbabwe : mobiliser les filets de sécurité locaux pour améliorer la capacité d'adaptation à la variabilité et aux changements climatiques au Zimbabwe

Version anglaise disponible dans la Bibliothèque numérique du CRDI : Zimbabwe : mobilizing local safety nets for enhanced adaptive capacity to climate change and variability in Zimbabw

Comparative short-term effects of different quality organic resources on maize productivity under two different environments in Zimbabwe

Major challenges for combined use of organic and mineral nutrient sources in smallholder agriculture include variable type and quality of the resources, their limited availability, timing of their relative application and the proportions at which the two should be combined. Short-term nutrient supply capacity of five different quality organic resources ranging from high to low quality, namely Crotalaria juncea, Calliandra calothyrsus, cattle manure, maize stover and Pinus patula sawdust were tested in the field using maize as a test crop. The study was conducted on two contrasting soil types at Makoholi and Domboshawa, which fall under different agro-ecological regions of Zimbabwe. Makoholi is a semi-arid area (750 mm yr?1) soils are sandy-clay loams with 220 g kg?1 clay. Each organic resource treatment was applied at low (2.5 t C ha?1) and high (7.5 t C ha?1) biomass rates at each site. Each plot was sub-divided into two with one half receiving 120 kg N ha?1 against zero in the other. At Makoholi, there was a nine-fold increase in maize grain yield under high application rates of C. juncea over the unfertilized control, which yielded only 0.4 t ha?1. Combinations of mineral N fertilizer with the leguminous resources and manure resulted in between 24% and 104% increase in grain yield against sole fertilizer, implying an increased nutrient recovery by maize under organic–mineral combinations. Maize biomass measured at 2 weeks after crop emergence already showed treatment differences, with biomass yields increasing linearly with soil mineral N availability (R 2 = 0.75). This 2-week maize biomass in turn gave a positive linear relationship (R 2 = 0.82) with grain yield suggesting that early season soil mineral N availability largely determined final yield. For low quality resources of maize stover and sawdust, application of mineral N fertilizer resulted in at least a seven-fold grain yield increase compared with sole application of the organic resources. Such nutrient combinations resulted in grain harvest indices of between 44% and 48%, up from a mean of 35% for sole application, suggesting the potential of increasing maize productivity from combinations of low quality resources with mineral fertilizer under depleted sandy soils. At Domboshawa, grain yields averaged 7 t ha?1 and did not show any significant treatment differences. This was attributed to relatively high levels of fertility under the sandy-clay loams during this first year of the trial implementation. Differences in N supply by different resources were only revealed in grain and stover uptake. Grain N concentration from the high quality leguminous resources averaged 2% against 1.5% from sawdust treatments. We conclude that early season soil mineral N availability is the primary regulatory factor for maize productivity obtainable under poor sandy soils. Maize biomass at 2 weeks is a potential tool for early season assessment of potential yields under constrained environments. However, the likely impact on system productivity following repeated application of high N-containing organic materials on different soil types remains poorly understood