The Pearson’s correlation coefficient was used to run and examine the relationship between rainfall and maize production for 14 years
The Pearson’s correlation coefficient was used to run and examine the relationship between rainfall and maize production for 14 years (2002-2016). However, it was noted that there was a negative relationship between rainfall and maize production because as the rainfall increased production, decreased and vice versa. Such results assume presence of negative correlations between the two variables, although the relation is not significant as indicated by P=0.092 (P ;0.05) (Table 4.6).
Table 4.6: Coefficient Correlations between rainfall and maize production
Rainfall Maize production
Rainfall Pearson Correlation 1 -.468
Sig. (2-tailed) .092
N 14 14
Maize production Pearson Correlation -.468 1
Sig. (2-tailed) .092
N 14 14
Source: Field Survey (2018)
Also from secondary data proved that increase in rainfall also led to decrease in maize production and vice versa. Rainfall has significant impact on maize production, but it seems that in those years with high rainfall (2004, 2011, and 2016), they received high rains with decreased production compared to years with optimum rains (2003, 2007, and 2010) with high production. Such variation might be caused by different factors like occurrences of rains in 2004, 2008, 2015 and 2016 that were very erratic and destroyed crops. Also respondents explained that in these years, erratic rains were associated with crop pests, crop diseases, use of unimproved seed and unwillingness of people to cultivate maize because others have shifted to grow drought tolerant crops. All of these might affect trend of maize production.
4.5 Discussions on Climate Change Impacts in the Study Area
4.5.1 Household Heads’ Perceptions on Climate Change
Findings from this study showed that farmers perceived climate change in their local environment compared to the past 20 years. The main six prominent changes from this study (Table 4.4) were also reported by the study by Elum and colleagues (2016) in South Africa. Elum and his colleagues (2016) revealed that the element of climate mainly extreme weather conditions such as drought, rainfall, temperature and floods have considerably changed over time. The mainly prominent cited changes were also supported by the study by Frida (2016) in Kilimanjaro region whereby farmers referred to Kilimanjaro Mountain when explaining how their local climate had changed, especially decreased glacier due to increased temperatures. Also the study by Pauline and Grab (2018) in south-western Tanzania revealed that farmers perceived climate change mostly changes in terms of weather patterns, intensity and consistent precipitation, drought and prolonged dry spells. These findings indicate that climate changes have deeply affected the agricultural sector, which employs majority of the population in the study area.
4.5.2 Changes in rainfall and temperature
This study found that based on knowledge and experiences of local community on the perceived changes of climate, it implies that the local climate in the study area has changed and contributed to shifts in farming activities. Such shifts include sowing dates by cultivating during one season only (long rainy season) compared to the past that they cultivated during two seasons (short rains and long rains). In most cases, precipitation has been starting later than normal (Table 4.4). In line with results from this study, other studies done in the country and other parts of Africa have documented this fact that local people have already perceived climate change. The study by Kangalawe and co-workers. (2016) in Western Tanzania revealed that farmers have perceived CC by explaining that there is decline in precipitation and temperatures have increased. The study by Haque and colleagues (2012) in Bangladesh found that most households perceived on increased heat, overall warmer winters, reduced rainfall and fewer floods.
In Sub-Saharan Africa, similar results have been documented in Sekyedumase and Wa West District of Ghana (Kusakari et. al., 2014) and Uganda (Okonya et. al., 2013) whereby both have shown that local people perceived increasing temperature while rainfall declined. Other studies have also shown that in the last 100 years, there has been an average global temperature increase of 0.74 °C (IPCC, 2001). In a study conducted in the transition zone of Ghana by Derkyi and colleagues (2018), it was found that there were increasing and intense temperatures, delayed rain onsets, short raining periods, windstorms and impulsive rain periods. Also these findings supported those by Nyanga and co-workers (2011) as well as Apata and co-authors (2009) who disclosed that farmers have perceived delay in precipitation and short as well as extreme rains and strong storm.
The observed shifts in the onset of rainfall and ending earlier than average could have affected farmers’ shortening of the growing season, which does not suit maize crop grown in the study villages that requires three months to mature. This is similar to results from the study by Pauline and Grab (2018) in south-western Tanzania who found delayed onset of rainy seasons and rains ending earlier than normal affected maize and rice crops because the crops normally require a minimum of three months to mature.
4.5.3 Reasons for the Changes of the Perceived Climate
Results from this study revealed that the perceived climate changes in the study area are caused by anthropogenic factors (deforestation, timber, population growth and bushfire) Figure 4.4. On the other hand, the same conditions have been expressed by farmers in similar studies. For example, a study by Croon and co-workers (1984) in Southern highland of Tanzania revealed that rapid migration into the area, deforestation, bush clearing and burning, which resulted in an extensive farming contributed to climate change in dry intermediate zone of Iringa region. The same was also commented by Odame and co-authors (2018) in rural Ghana who disclosed that exclusion of vegetation has accounted for changes in the local climate. This is in line with Syampungani and colleagues’ (2010) findings that deforestation, forest land degradation and agricultural activities increase the amount of carbon dioxide and other greenhouse gases, which lead to CC. Furthermore, a study conducted at Mkomazi in Same district, Kilimanjaro region reported that changes of local climate are influenced by global warming and environmental degradation, mostly deforestation and forest degradation (Ndaki, 2014).
Results from the study by European Commission (2015) found that climate change is contributed by cutting down trees that leads to release of carbon dioxide into the atmosphere. Also the study by Frida (2016) in Moshi District reported that population increase and deforestation have contributed to CC in Kilimanjaro region. That was the same pattern like results from the study conducted in Tanzania that disclosed that CC is mainly caused by human activities (Adeline, 2010). Additionally, some previous studies carried out in Tanzania and other parts in the African continent have recognized this fact (for example, Kangalawe and Lyimo 2013; Legesse et. al., 2013; Teka et. al., 2012; Acquah and Frempong, 2011; Acquah, 2011; Mongi et. al., 2010; Agrawal et. al., 2003).
4.5.4 Rainfall trend for Nduli Meteorological Station
Results showed that there was a slight increase in annual rainfall at the rate of 3.02 mm (Figure 4.10) as supported by minority respondents (8.5%) from Mkungugu and 2.5 percent from Mkulula (Table 4.4). This contrasts majority of households’ perceptions on decreasing amounts and it becomes intense. This finding is related to the study results by Pauline and Grab (2018) in South-Western Tanzania who held that 59 percent of households in Ruaha Mbuyuni village and majority (93%) in Ibohora village perceived decline in rainfall, while 30 percent of farmers in Ikuvala village reported having increased rainfall over 40 to 54 years. The statistical data from Iringa Meteorological Station showed that the rainfall trend increased by 0.01 mm over the period of 40 to 54 years, which was contrary to majority of local community members’ perceptions. Such increase might be related to intense precipitation events such as the El Niño in 1997 and 1998 whereby most parts of the country experienced heavy precipitation (Pauline and Grab, 2018; Kangalawe et. al., 2017). This was supported by Ovuka and Lindqvist (2000) who argued that household perceptions and rainfall records sometimes are unmatched in terms of space and time.
On the other side, the study findings showed variability in terms of rainfall onset. Majority (94.6%) of respondents household (Table 4.4) reported rainfall starting later than normal times (November) and that had negative impacts on farming operations. Pauline and Grab (2018) supported that farmers’ explanations whereby the average onset of rainfall seasons in Iringa has changed from November to mid-December, and it has imposed negative effects on farming activities.
4.5.5 Temperature trend for Nduli Meteorological Station
The results showed there was an increase in temperature trend at the rate of 0.020C per year (Figure 4.11). This observation were supported by 96.6 percent of respondents in the study area (Table 4.4) that temperature has been increasing in the past twenty years as exhibited