Cabinet recently approved the revised Agro-Ecological Zones, in a major milestone that largely aims to strengthen the capacity of farmers to plan for climate risks and boost agricultural production and food security. In this report, Sifelani Tsiko (ST), our Agric & Environment Editor speaks to Professor Desmond Manatsa (DM), lead coordinator and climate science expert from Bindura University of Science Education to help the nation understand more about the reclassified zones.
ST: Can you tell us more about what Agro-Ecological Zones are all about?
DM: By definition an Agro-Ecological Zone is an area of land which has similar characteristics related to land suitability, potential production and environmental impact. Limits to productive capacity of these land resources are set by climate, soil and landform conditions as modified by the use and management of the land. In this regard, climate change in addition to such factors as competition with industrial and urban demands, degradation and pollution are causing a decline in both quantity and quality of essential natural resources, such as land and water. The resulting problem is one of the mounting pressures on our existing natural resources. Thus the initial step requires that the zones themselves be accurately defined and so that they become climate change compliant as the defining input parameters such as temperature and rainfall characteristics change. The zones are a prerequisite for the achievement of sustainable food security as well as acting as a major driving force towards the attainment of Vision 2030 for our agro-based economy.
ST: What was the main reason for reclassifying Zimbabwe’s Agro-Ecological Zones?
DM: Despite the observed changes in the climatic pattern which directly affects crop and livestock production, agricultural practice in the country is still being planned based on the traditional Agro-ecological Zones which were developed by Vincent and Thomas in the early 1960s. There is now a growing consensus among researchers, farmers and development practitioners that it has outlived its usefulness. Such calls have become increasingly relevant due to increased crop failure emanating from changes in rainfall patterns and recurrent droughts thereby affecting agricultural production systems — the backbone of the country’s development. In fact, farmers have continued to follow the traditional way of practising agriculture as there has been no revision in the pattern of agricultural practice. As such, the continued utilisation of this seemingly outdated map to inform agro-economic national planning is severely affecting its full revenue generation potential. However, although these old zones provided an adequate basis on which agricultural practice in the country was based, the changes induced by climate change has made the applicability of these zones difficult or rather misguided. Climate change has altered temperature and rainfall regimes thereby affecting patterns of agricultural practice relevant for different regions in the country. This has threatened the sustainability of the national agricultural sector due to deployment of unsustainable agricultural practices which are incongruent with prevailing climatic conditions. The resulting mismatch between land capability and agricultural practice has led to a number of undesirable outcomes such as land degradation, loss of biodiversity and ecosystem services and consequently results in poor performance of the sector, which is key to our economy of Zimbabwe. It is evident that poor agricultural yields reduce economic growth hence the need to restructure the zone boundaries so as to reflect current trends in the climate.
ST: How are farmers and all other economic sectors likely to benefit from the revised Agro-Ecological Zones?
DM: Let me provide the likely benefits of the revised Agro-Ecological Zones from a sectorial point of view — in land use planning and policy the revised agro-ecological zones: makes it possible to use land according to its biophysical potential and limitations in order to protect soil resources from degradation and at the same time to meet farmers’ demands for optimal crop production. It also provides the basis for policy formulation and land-use planning through revealing answers to the following questions — How is land with different potentials and constraints distributed within the country and in component provinces or districts? What uses can be recommended on different types of land in different locations? How do potential yields vary among locations, years and seasons? What is the balance between population density, land availability and food production in specified areas? And, what is the impact of improvements in inputs or management? It will also act as an enabler for agricultural strategies including land-use policies through easily accessible essential farming information for an individual farmer, provision of appropriate, area-specific, agricultural information, national agricultural inputs, relief programmes, setting of agricultural research priorities and the establishment of networks for agro-technology transfer. Benefits are vast and cover the formulation of legislation or guidelines to regulate and minimize environmental damage and the identification of appropriate development programmes or projects per province. In agriculture, the Agro-Ecological Zones can be used to predict potential productivity for a specific crop in a particular location and other factors related to production, crop water requirements, land management, optimum seed variety use, fertiliser use and policy guidance for agricultural research and climate proofing. In disaster risk reduction the AEZ map can be used in land-use planning to identify suitable agricultural, flood-prone and drought-susceptible and ecologically sensitive areas that may be prone to degradation. It can be used to design appropriate agricultural adaptations to reduce vulnerability. It can also complement the development of long-term drought mitigation measures like irrigation potential.
ST: What is the accuracy levels of the reclassified Agro-Ecological Zones? What are the new tools and technology that were used to draw the latest agro-ecological zonations?
DM: The accuracy of the redefined Agro-ecological Zones of Zimbabwe was determined using validation data from several ground truth GPS coordinates obtained during field surveys. These were selected based on their proximity to zone boundaries as well as to cover the whole country’s regions and to detect intra-class variabilities. The results of GPS-based field validation across different Agro-Ecological Zones showed that the final zones map had relatively high overall accuracy of more than 95 percent. The accuracy of each region was as follows; Region I: 98 percent, Region II: 92 percent; Region III: 95 percent, Region IV: 97 percent and Region V: 100 percent. These results imply that the newly-delineated AEZ can be used with confidence as it has been validated. Geospatial technologies combined with rigorous statistical analysis of climatic data, field validation and stakeholder consultations were predominantly applied to redefine the AEZs of Zimbabwe.
ST: Scientific tools have a downside too. What do you think are the main shortcomings of the reclassified Agro-Ecological Zones? How can these weaknesses be addressed to help farmers to plan their activities?
DM: The observed climate data that we received was either not spatially adequate for our purpose or had a resolution too course. As a result, boundaries in some places may not be exactly where they are supposed to be, we have to consider these boundaries as transitional zones rather than proper line demarcations. My advice is for farmers to rely more on the zones interpretation of AGRITEX extension officers whom we worked very closely with in redefining these zones. There should also be an improvement in climate data observations by the Meteorological Services so that more accurate zonation can be achieved.
ST: What are some of the factors that were incorporated in the reclassified Agro-Ecological Zones?
DM: Agriculture is strongly dependent on climate in Zimbabwe hence agricultural practice was delineated based on productivity potential and constraints. In addition to climate factors, soil also influences agricultural activities. As a result the viability of crop and livestock production at any given point is determined by proportional contribution of the different factors. In this regard, all factors considered important in determining agricultural practice were considered in the mapping exercise. In this exercise, conditional statements were applied in a GIS to delineate the new zones using in-situ measurements and remotely sensed data. The approach was similar to the one followed by Vincent and Thomas to allow for comparison in the regions delineated under different climatic regimes. Different ranges of values of precipitation attributes, that is, dry spells, length of season, probability of annual rainfall exceeding certain thresholds and total annual precipitation, temperature and elevation were considered to separate the country into homogeneous regions.
ST: What are the major differences of factors used between those that were used between 1945 and 1960 and the latest reclassified Agro-Ecological Zones?
DM: During the 1950s and 1960s, the time of the development of Vincent and Thomas agro-ecological maps there were no computers used hence they manually overlaid isolines of climate parameters superimposed on soil resource maps and vegetation to delineate five agro-climatic zones (Region I to V), a process that was less accurate, overly generalised, time consuming and rather too costly. Advances in technology in areas such as Geo -technologies -Geographical Information Systems (GIS) and Remote Sensing have provided unlimited opportunities to integrate various spatial datasets that are important in the delineation of homogeneous regions that constitute Agro-Ecological Zones. The provision of these datasets by modern technology therefore becomes a key motivating factor for this work. Geo-technologies have now and will continue to revolutionise the way data is collected, analysed and archived.
Thus relative to the 1960s’, these research techniques have become not only more efficient and accurate, but also cost effective. They have also drastically reduced data processing time. Hence, when employed in the context of agro-ecological zoning, they can rapidly provide novel approaches to effectively monitor and manage land resources in an integrated manner.
ST: Did the reclassification process include all stakeholders? Shed light on the composition of the teams.
DM: The project was State initiated and funded. We only came in as implementers of the State project. The project was developed in response to the urgent need of aligning agricultural practice with the changing climatic patterns which I have already alluded to. The Government of Zimbabwe through the Ministry of Higher and Tertiary Education, Innovation, Science and Technology Development initiated a revision of the country’s Agro-Ecological Zones. Minister Professor Amon Murwira was very supportive and enthusiastic about the project. We are very grateful for his invaluable support, including our university vice chancellors. The project included scientists from Bindura University of Science Education, which was the lead institution through myself as the team leader, University of Zimbabwe, Midlands State University, Chinhoyi University of Technology and Zimbabwe Meteorological Services. The main source of observed data for crop and livestock was AGRITEX since they have this data from ward level and is the main Government institution which uses the map in its day to day activities in its agriculture extension services. These AGRITEX officers were also used to validate the automatically generated first draft agro-ecological map. The Zimbabwe Meteorological Services provided the observed climate data and had two members who were incorporated into the map development team.
ST: There have been major technological advances over the years. What are some of the new methods and techniques that were utilised in the reclassification of the Agro-Ecological Zones?
DM: All geospatial layers important in determining agricultural practice together with rainfall and temperature were overlaid in a GIS environment in order to define homogeneous zones where different land-use practices were recommended. The main advantage of the current zone definition is that it goes beyond the conventional approach and includes an interactive Android based software that is not only user friendly, but freely available. The Agro Zim App allows stakeholders to obtain information on the different farming activities in each zones. This application was developed after the realisation that access to climate information and advisory services is key in enhancing agricultural productivity. The ease of information accessibility ensures that the marginalised and vulnerable small-scale farmers make more informed and timely decisions at the click of a button on their mobile phones. The redefined zones were validated through stakeholder consultation in all the provinces of Zimbabwe, where user needs for the mobile application were also collected.
ST: What are the main features of the revised Agro-ecological Zones?
DM: The revision of the Agro-ecological Zones indicates that there have been significant shifts in the boundaries. In particular, though the distribution of zones have been relatively stable, several regions have contracted owing to shortening of the rainfall season of some stations in a particular zone. This shortening of season is attributed to a reduction in rainfall coupled with increase in increased evaporation, which have not been uniform for stations (areas) in a given zone. On the overall, results show that Region III, IV and V, expanded at the expense of Region I, IIa and IIb. An important development is that Region V, the driest region in the country, has been sub-divided into Region Va and Vb, indicating further worsening rainfall patterns in this region. It is through the realisation that Region Vb can no longer sustain any form rain-fed agriculture without being complemented with irrigation, even the drought tolerant crops which used to flourish there.
ST: What are your future hopes on the development of the classification systems of Agro-Ecological Zones in the wake of climate change?
DM: Being mindful of the fact that these newly-derived boundaries were even going to shift at a much faster rate than before, efforts have been made in ensuring that the map updates automatically the moment more parameters that factor in climate change becomes available. In-order to ensure effective use of modern technologies, information on the map which includes point data such as fertiliser use, rainfall and temperature characteristics as well as recommended land use can easily be accessed through a mobile application that is installed on a smartphone with specified minimum requirements. Consequently, accessibility of information on the map through the smartphone will ensure efficient and effective management of land and water resources culminating in enhanced agricultural productivity. This is an ongoing process, though some of the aspects are already being addressed. I envisage the revised Agro-ecological Zones map and accompanying mobile application to provide accurate, relevant and easily available information about the target environments. These should become standard tools to be reliably employed as enablers for agricultural research and investment. Since agricultural determinants such as rainfall, temperature, cropping patterns and agriculture management are highly dynamic, the pattern of Agro-ecological Zones may change significantly under the background of global climate changes. As such, an assessment of shifting patterns of Agro-Ecological Zones in Zimbabwe has been pivotal in guiding the nation’s current and future agricultural development that guarantees national sustainable food and nutritional security through meaningful investment in agriculture. The central issue in agricultural development is increasing productivity, creating employment, and increasing income for the agricultural population. Hence we deliberately designed this product to assist farmers achieve increased productivity at reduced costs by enabling better management, including protection of natural resources. Most importantly, the ease of information accessibility ensures that the marginalised and vulnerable small-scale farmers are able to make more informed and timely decisions with great potential to sustainably boost productivity while reducing the environmental degradation footprints of agriculture.