|Agro-ecological map of Tanzania|
Agro-ecological zones are geographical areas exhibiting similar climatic conditions that determine their ability to support rained agriculture.
FAO on the other hand defines Agro-ecological zone (AEZ) as: a land resource mapping unit, defined in terms of climate, landform and soils, and/or land cover, and having a specific range of potentials and constraints for land use.
According to FAO the essential elements of the core applications of agro-ecological zone comprise of: (i) land resources inventory (ii) inventory of land utilization types and crop requirement and (iii) land suitability evaluation.
However our interest is on crop requirements and land suitability for crop production
Now, let’s begin this way.
Agro-ecological zones (AEZ) are influenced by a number of factors. The key factors being:
- Rainfall amounts
- Distribution during growing season and
- Latitudes at a regional scale
|The agro-ecological map of African Region|
If we assume all the socio-economic factors to be constant, agriculture is majorly affected by environmental factors which are: climate, topography/relief (high lands, sloping lands or lower lands) and soil fertility. However climate is made up of, among others; temperature, humidity and rainfall which are also the major factors influencing agro-ecological zones (AEZ) as shortlisted above. If you review the factors influencing crop growth and development you will find out that it is temperature, moisture/water/rain, light and soil fertility (plant nutrients).
What actually I’m a trying to say?
My point is “the performance of the crops depend on the agro-ecological zone”, and that “not all crops can do better in all agro-ecological zones”. So you must choose carefully either the crops to cultivate in your agro-ecological zone or the agro-ecological zone for the crops you want to produce.
You understand now, right?
The knowledge of agro-ecological zone is essential to crop growing period, and provides a way of including seasonality in land resource appraisal. In many tropical areas, conditions are too dry during part of the year for crop growth to occur without irrigation, while in temperate climatic regimes crop production in winter is limited by cold temperatures. The growing period defines the period of the year when both moisture and temperature conditions are suitable for crop production in that particular zone.
The growing period provides a framework for summarizing temporally variable elements of climate (in a particular agro-ecological zone), which can then be compared with the requirements and estimated responses of the plant. Such parameters as temperature regime, total rainfall and evapotranspiration and the incidence of climatic hazards are more relevant when calculated for the growing period, when they may influence crop growth, rather than averaged over the whole year.
Do you understand now how important it’s to choose a suitable zone? If you mistake, you are done!
Now back to our home land;
Division of Tanzania into Agro-ecological zones (See the map on top of this post)
The research done by Mlingano Agricultural Research Institute (ARI Mlingano) divided Tanzania into seven Agro-ecological zones. These are
- Central zone which covers the central regions of Tanzania; Dodoma and Singida.
- Eastern zone which covers Morogoro, Dar es salaam, Tanga, Coastal region, Unguja and Pemba islands.
- Western zone: covers Kigoma and Tabora regions.
- Lake zone: includes Mara, Shinyanga, Mwanza and Kagera
- Northern zone covers Arusha, and Kilimanjaro regions
- Southern zone has two regions: Lindi and Mtwara
- Southern highlands zone which includes Mbeya, Iringa, Njombe, Ruvuma, and Rukwa regions.
Keep in mind:
“the performance of the crops depend on the agro-ecological zone, and that “not all crops can perform better in all agro-ecological zones”. So you must choose carefully either the crops to cultivate in your agro-ecological zone or the agro-ecological zone for the crops you want to produce.”
I hope that helps you.
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This article was prepared by Mtalula Mohamed, a final year student at Sokoine University of Agriculture.
1. Tanzania, MALF. Agricultural maps. Available at http://www.kilimo.go.tz/agricultural%20maps/Tanzania%20Soil%20Maps/Soil%20maps.htm
2. FAO, Agro-ecological zoning. Available at http://www.fao.org/docrep/w2962e/w2962e-03.htm
3. HarvestChoice/International Food Policy Research Institute (IFPRI), 2010. Agro-ecological Zones of sub-Saharan Africa. Available at http://harvestchoice.org/maps/agro-ecological-zones-sub-saharan-africa