CHAPTER ONE
INTRODUCTION
Background
Agriculture in Ghana is predominantly on a smallholder basis contributing to about 90% of farm holdings. Maize (Zea mays L.) production in Ghana is mainly by small-scale agriculture, contributing 70 percent of the total domestic production in the country (FAO, 2010). Maize (Zea mays L.) is a major cereal crop in West Africa, accounting for slightly over 20% of the domestic production in the sub-region (IITA, 2000). In Ghana, it is one of the most important cereals cultivated in all the agro-ecological zones (Fening et al., 2011). However, yields presently obtainable in Ghana fall around 1.7t ha-1 (MoFA, 2011). Farming is mainly dependent on rainfall in Africa, providing employment for over 70 percent of the labour force (Fleshman, 2007), with associated low level of food production.
The Intergovernmental Panel on Climate Change (IPCC, 2004) studied the inter-annual variability in climate of West African countries and pointed to the fact that one undisputable cause of hunger in the Guinea Savanna and Sudan savanna zones of Africa is crop failure emanating from either inadequate or untimely rainfall. Farmers in these regions are faced with erratic and unreliable rainfall. Climate variability therefore poses one of the biggest limitations to the achievement of food security and poverty reduction in Africa.
The News Highlight Report of the Food and Agriculture Organization (FAO, 2001) reported that in sub-Sahara Africa, long term climate change would negatively affect agriculture, as well as threaten food security among the world‘s most vulnerable people. In addition, climate change extremes, which are very difficult to plan for, may put further burden on the already weak
farming system. The implication is that the current imbalances in food production between sub- Saharan Africa and the rest of the world could be worsened. Climate change impact is the noticeable effects that come with the seasonal climate variability posing major production risks in agriculture. This variability includes extreme rainfall, flooding, or low rainfall resulting in increased temperatures and subsequent drought stress leading to crop failure. To assess the impact of climate change on the yield of maize, 30 years‘ historical (1980 to 2009) weather data were used to run simulations and compared with those from projected weather data. If the difference is positive is an indication that climate change may lead to an increase in yield; thus positive impact. On the other hand, negative result is an indication that climate change could result in yield reduction; negative impact. Climate change impacts on agriculture can be handled at various levels such as crop yields, farm and village level outputs and income, regional and national production, and global production and prices (Motha, 2011).
Agricultural systems in Ghana are generally grouped as low in productivity, caused by uncertainty in the rainfall patterns, obsolete agricultural practices and low application of inputs. Apart from negative effects of climate change, it has been observed that low soil fertility particularly nitrogen (N) and phosphorus (P) deficiencies have negatively influence agricultural productivity in sub- Saharan Africa (Sanchez et al., 1997). In developed countries, nitrogen deficiency is efficiently lessened by inorganic fertilizer applications. On the other hand this is impossible in developing nations due to either unavailability of fertilizer or where available being too expensive for small holder farmers (Gerner et al., 1995; Mkhabela and Pali- Shikhulu, 2001; Yeboah et al., 2009). Soil fertility decline is reported as a major biophysical factor posing great challenge to crop production in Ghana (Logah et al., 2010). The way out of this cycle in the face of climate change is to intensify agricultural production in a sustainable way, which will
require nutrient inputs (soil amendment), either from organic or mineral sources as part of a solution to soil fertility decline and rising global food demands. Biochar has been in use for several decades as an alternative soil improvement input. According to Moses et al. (2011) biochar production and application in soils have a very high potential for the expansion of sustainable agricultural systems in Ghana, and also for global climate change mitigation.
The life cycle of maize crop depends much upon water availability and water deficit at any phenological stage has a different response and can reduce grain yield (Cakir, 2004). Although maize is regarded as a plant that is quite hardy and adaptable to reasonable environmental stresses, any increases in temperature and reduction in rainfall at important growth stages could have serious implications on yields, which could contribute to increased food insecurity in the country. Good understanding of climate change and its impacts on maize crop performance is essential for taking proactive actions to mitigate adverse climate effects and for long-term policy making.
    Problem statement
Climate variability and change have direct, and most often adverse, influence on the quantity and quality of agricultural production. Temperature, rainfall, humidity, sunshine (day length) are the important climatic elements that influence crop production. Changes in the amounts of rainfall and temperature are the most important contributing factors to maize yields. Maize is the primary food staple in Ghana. Basically, almost all Ghanaians consume maize, either fresh or processed and it is a major ingredient for both the brewery and poultry feed industries. The gradual decline in the productivity of soil in Sub-Saharan Africa has been identified as one of the major causes of food insecurity and poverty due to continuous cultivation resulting in nutrient
loss. Crop yields on smaller holder fields continue to decline resulting in a huge gap between potential crop yields and actual crop yield. The average yield of 3.1 t ha-1 (Pixley et al., 2009) of maize in the developing world still lags behind the world‘s average of 4.9 t ha-1 (Edgerton, 2009). The imbalances could be due to continuous soil fertility decline coupled with the impacts of climate change on food productivity in Sub-Sahara Africa (SSA). In order to close the huge gap created in food supply chain there is the need for the adoption of efficient soil fertility management strategy that overrides the impacts of climate change on maize production. Unfortunately, research works on the effects of climate change on maize in the coastal savannah of Ghana is limited. It is within this context that this study was initiated using modern tools to assess the impact of climate change on maize productivity in the coastal savannah in order to recommend for adoption of appropriate crop management options for maize production in the coastal savannah zone. The Decision Support System for Agro-technology transfer (DSSAT) model was used in this study.
Aim
The main objective of this study was to use DSSAT model to analyze the impact of climate change on maize production in the coastal savanna of Ghana.
Specific objectives
The specific objectives of the study were:
- To calibrate and evaluate DSSAT Crop Simulation Model for 3 maize varieties.
- Assess the impact of different crop management options on maize production.
- Assess impact of climate change on maize production.
