Water management

Climate change impact

Rainfall is expected to become more erratic and extreme events like droughts and floods are likely to become more common in the future. Parts of West Africa are becoming dryer over time (Medina and Laliberte, 2017), and cocoa seedlings are particularly vulnerable to extended drought periods (Carr and Lockwood, 2011). Moreover, many regions in Central and South America are already experiencing flooding and the incidence of floods in West Africa is also expected to increase. Farms affected by floods are more vulnerable to pests and diseases. A climate resilient water management approach is required to maintain plantations in the establishment phase and along maturity.

Description of practices

Water harvesting (rainfall water collection in large tanks for use during extended dry periods) and irrigation are useful to reduce water stress. Low-cost irrigation systems using bamboo or plastic bottles increase the accessibility of this practice. Polymers and biopolymers can be used on the farm for increased soil water retention. (Maghchiche, et al. 2009). Drip irrigation refers to controlled irrigation where water is input at low rates through a network of plastic pipes increasing water use efficiency (FAO, n.d.).

When close to a water body, buffer zones should be prepared to avoid flooding (WCF, 2017). Cocoa varieties well adapted to floods have been used in Brazil and the Amazon floodplain and could be promising for other flood-prone regions. Cover crops, some tree species, and contour planting have also been reported to decrease the effects of extreme weather including droughts and flooding. Additional options include the installment of drainage systems (e.g. trenches to reduce the effects of soil erosion caused by flooding (WCF, 2017).

Outlook

Limited capital is one of the main barriers to adoption of drip irrigation, a problem that will be made worse by decreasing yields from more erratic rainfall (Abdulai, et al. 2011). Accessibility problems are persistent, and many farmers consider irrigation systems a luxury (Carr and Lockwood, 2011). As part of climate adaptation plans in West Africa, irrigation infrastructures should be built, they will be valuable in periods of reduced rainfall (Ofori, et al. 2014).

Productivity: The climate change effects on water could be considered the most crucial factor in crop productivity loss and food security (Okoffo, et al. 2016). Rainfall variability reduces the planning capacity of farmers (Hutchins, et al. 2015). CSC promotes the adoption of management that makes yields less reliant on rainfall. 

Adaptation: The effect of climate change on water availability is twofold: lower and more erratic patterns of rainfall, and increased evapotranspiration as a consequence of increasing temperatures (Schroth, et al. 2016). Water management practices will aid in sustaining yields as rainfall variability increases. In regions where extended and regular droughts are expected to occur, irrigation could be a possible solution, however, its costs may make shifting cultivation or other income sources more profitable (Abdulai, et al. 2017). 

Mitigation: Irrigation positively affects the growth of shade trees and cocoa thereby increasing their capacity as carbon sinks. GHG emission increases are assumed to be small for drip irrigation using bamboo or recycled plastic bottles. For machinery intensive systems of irrigation, emission increases should be taken into account.

As rainfall becomes more erratic farming management decisions will be better informed by weather forecasts instead of calendars. The literature on increasing resilience to drought has largely been focused on the development of drought-tolerant cocoa varieties (Medina and Laliberte, 2017). Higher temperatures lead to higher rates of evapotranspiration which could be countered by greater shade cover or the planting of cover crops and mulching. Species that increase soil structure (to reduce nutrient leaching due to heavy rainfall or flooding) and/or increase the water retention capacity of the soil should be planted. For agroforests, species with roots at a different depth than cocoa should be selected to reduce water competition (Abdulai, et al. 2017). Water management affects the rate of canopy expansion and, in turn, pruning costs (Carr and Lockwood, 2011). Moreover, incorrect (indiscriminate) irrigation and floods may increase the risk of production losses due to pests and diseases.