Maize Farmers in Tanzania

Rainfall Variability

The most important factor in sustaining crop productivity is water availability. Rainfall variability from season to season largely impacts soil water availability to crops, and therefore face crop production risks. Ideally, crop cultivations should be situated in areas with high rainfall and low variability. However, as shown in figure 1, in SSA about 37% of maize- growing areas are located in areas where there is high seasonal rainfall variability- coefficient of variation (C.V.) >0.2 (HarvestChoice, 2010).

Figure 1: Map of sub- Saharan Africa showing the coefficient of variation (C.V.) of seasonal rainfall at major maize growing areas during 1955-2004.

Source http://harvestchoice.org/labs/rainfall-variability-and-crop-yield-potential

As shown in the previous posts, with climate change will come increased rainfall variability, and this will have further implications for Maize farmers.

Maize in Tanzania

In Tanzania, up to 95% of food production depends on rainfall, which is highly affected by climate variability, and this will likely change due to global warming (Sixbert, 2016).  In Tanzania Maize is the 'staple food'. According to the (FAO, 2015), 80% of maize in Tanzania is produced by small-scale farmers and is usually grown under low input, rain-fed conditions. Maize is grown for both substance (65-80%) and cash crop (20-35%).

Hai District 

In a study on the 'Decline in maize and Beans production in the face of climate change at Hai District in Kilimanjaro Region, Tanzania', it was found in the Hai district that in the non- drought years, Maize has the highest yield in comparison to other crops (Figure 2). However, in the years 2003 and 2009- where there was lower annual rainfall- almost 98% of maize crops failed, but the same extreme impact was not felt in low rainfall years of 2005 and 2007.  The study found that there is a strong and significant association between climate change and high variability in yield patterns of maize in the Hai District. The reductions in maize yield are primarily due not only to the increases in temperature and decreases in rainfall amount, but also the distribution during the growing season (rainfall variability).

Figure 2: Annual maize and rainfall/ temperature patterns in Hair District from 2000 to 2010 

source:http://search.proquest.com.libproxy.ucl.ac.uk/docview/1655266955/fulltextPDF/5E7207F4328C4936PQ/1?accountid=14511

Wami Ruvu Basin

Adaptation is the only way rain-fed farmers can survive the threat of climate change, and this is on the agenda of many countries around the world. However, before this can properly be thought out and implemented, it is important to know and fully understand the impacts of climate change at smaller scales. In a study on the 'Assessment of the impacts of climate change on maize production in the Wami Ruvu basin of Tanzania', they sought to do exactly this. Using detailed field and household survey information, data of current climate conditions and future climate projections (RCP 4.5 and RCP 8.5), they created a model. They assessed the impacts of climate change of maize production by analysing the changes in simulated maize yields (2010-2099) and compared them to the baseline period (1971-2000).

Results showed that due to climate change future maize yields over the Wami Ruvu basin will slightly increase relative to the baseline during the current century. However, maize yields will decline in the mid and end centuries. The report also highlights how different parts of the basin will be affected differently: The eastern parts of the basin will experience decreased yields, while part of the central region and the Western side of the basin will experience increased maize yields. They also show a high decline projected over lower altitude regions due to projected increase in temperatures.

It is important to note that different models provided different estimates of future maize yields, highlighting the uncertainties associated with the projections.

Manyoni District

Many Farmers have already adapted their farming practices due to changing rainfall patterns and amounts, and other land changes. Based on a study of two villages in Manyoni District in Singida region, Tanzania, the table below summarises how maize farmers have adapted their practices:

Table 1: Impacts of changes in rainfall pattern on maize cropping practices in Kamenyanga and Kintinku Villages

 Source: https://assets.publishing.service.gov.uk/media/57a08b47e5274a27b2000a75/Majule-and-Mary.pdf

This paper is highly reliant on data collected from local people and their perception on how the climate has changed. Results showed that this region has presented increased temperatures and a delay in the rainy season. Although the annual quantity of rainfall is reported to not have changed, rainfall variability has increased, seeing more droughts and floods. This has meant that local farmers, in particular maize farmers, have changed their farming practices, to suit the new changing climate. Thornton (2007) has shown that some farmers may even completely change the crop they grow, for example, due to a reduction in the growth period, maize might be substituted by sorghum and millet since they are more suited to their drier environments. Inclusion or change to drought resistant crops such as Casava or sweet potatoes may also be an option  (Munishi, 2015).

Concluding thoughts

High rainfall variation, is increasing the risk of short- run crop failures and long- run production declines, therefore with further projected changes, adaptation methods need to be strengthened, on a case by case basis.  Maize specifically has been shown to be very vulnerable, and receptive to changes in temperature and rainfall, and therefore continued reliance on this crop will be a high risk to farmers, especially in the face of climate change.

Next week's blog will look at how farmers can adapt to changes in rainfall, by using irrigation.