Climate Smart Agriculture (CSA) is agriculture that sustainably increases productivity, resilience (adaptation), reduces/removes greenhouse gases (mitigation), and enhances achievement of national food security and development goals (UN-FAO). CSA includes proven practical techniques such as mulching, intercropping, conservation agriculture, crop rotation, integrated crop-livestock management, agroforestry, improved grazing, and improved water management. Involves the introduction of innovative practices such as more dependable weather forecasting, early-warning systems, and climate-risk insurance.
The three pillars of CSA are productivity, adaptation, and mitigation. Climate change will have direct impacts on agriculture and food security of a growing population. World’s population will increase by one-third by 2050. FAO estimates that agricultural production will have to increase by 60%. However, climate change is estimated to have reduced global yields of maize and wheat by 3.8 % and 5.5 % since 1980. Agriculture (including land use change and deforestation) contributes to 20–30 % of the anthropogenic Green House Gas (GHG) emissions. GHG emissions from agriculture grew 1.1 % per year during 2000–2010.
Its main effects on agricultural production are increased variability of production, decrease of production in certain areas and changes in the geography of productions. Climatologically, Zimbabwe has an extremely variable rainfall distribution, which will be exacerbated by climate change. These future climate change impacts are likely to aggravate the harmful effects of poor landuse practices, especially deforestation, soil degradation, and water pollution. Communities that have been made vulnerable by economic hardship and disease will find it even harder to cope.
Several studies by the Intergovernmental Panel on Climate Change (IPCC) on the impacts of climate change in southern Africa (Zimbabwe included) show that from 2050 until the end of the century the following phenomena are likely to be observed. A modest decrease in the total amount of rainfall predicted and changes in the onset and cessation of rainy seasons more frequent and prolonged mid-season droughts, reduced groundwater recharge, erratic spatial rainfall distribution across Zimbabwe.
Temperature increase between 1°C and 3°C, which is greater than the global average increases. The consequences likely to arise include reduced water supply for domestic and agriculture uses, the expansion and contraction of Natural Regions V and I respectively, degradation of natural resources, especially soil, water, natural vegetation, crops, and livestock and reduced food security because of negative impacts on agriculture.
Access to irrigation provides the means to cultivate an additional crop and is one of the most effective strategies to boost the productivity of small-scale, dry land farming systems. In the face of climate change, irrigation will be required to counter the predicted increase in evapotranspiration rates and decreases in rainfall in the future. CSA, however, farmers are encouraged to use localised irrigation methods (e.g., drip or subsurface irrigation) that have higher field-level application efficiencies of 70 % to 90 % as surface runoff and deep percolation losses are minimised. Resources permitting, farmers could also use hydro-culture technologies, e.g., hydroponics with very high water-use efficiencies.
In-situ rainwater harvesting refers to the method of diverting, inducing, collecting, storing, and conserving local surface runoff for agricultural production. Researchers in Zimbabwe have focused on options that prolong periods of soil moisture availability, e.g., tied-ridges, no-till-tied-ridges, off-season weeding, winter tillage, contour planting and mulching and promote the infiltration of water into the soil, e.g., potholing, retention of crop residues, ridging/furrowing, terracing, trash lines, vegetative barriers, stone lines, and planting basins.
The practices that are promoted include those that decrease the erodibility of runoff and of the soil. Contour ridges and storm-water drains should be established, rehabilitated, or maintained, depending on the area. Off-field practices are beneficial in catchments and reduce erosion, siltation, and sedimentation. The practices should reduce wind, rain and sleet, as well as gully and fluvial erosion. Some of the methods used in Zimbabwe include gabion blocks, establishing vegetation on bare steep slopes.
Methods for carbon sequestration that have been suggested include cover and catch crops, e.g., grasses and weeds as temporary cover between planting seasons. Concentrate livestock in small paddocks for days at a time so they graze lightly but evenly to encourage roots to grow more deeply into the soil; and restore degraded land, which slows carbon release, while returning the land to agriculture or other use.
Mulching and residue management can be defined as a technology whereby, at the time of crop emergence, at least 30% of the soil surface is covered by organic residues from the previous crop. Crop residues are utilised for soil and water conservation, as well as for soil organic inputs and livestock feed, and are critical in smallholders building and maintaining soil nutrient stocks. Mulching improves infiltration, and the soil cover provides effective protection against rain splash erosion and surface runoff.
Climate smart agricultural practices applicable to livestock and rangeland management in Zimbabwe include but are not limited to; application of science and advanced technology in feeding and nutrition through appropriate feed formulation and precision feeding; over-sowing legumes in grazing paddocks, especially in the high veld (high rainfall region). Bio-fortification of livestock forage; application of science and advanced technology in genetics and reproduction; improved animal herd or flock health control programming; and general improvements in animal husbandry.
Feed supplementation is traditionally meant to correct nutrient deficiencies, but of late it has been discovered that the practice can be used to reduce net greenhouse emissions from livestock. Six strategic techniques to decrease methane emissions from ruminants have been proved through applied research include improved forage quality: feeding ruminants with good-quality roughage increases the activity of rumen cellulolytic bacteria at the expense of the methanogens that produces methane gas. A larger proportion of concentrates in the diet that are well-balanced to meet animal requirements promotes rumen fermentation that suppresses methane production. Feeding at least 55% forage and up to 45% concentrates in high-producing dairy cows decreases methane production significantly. Up to 8.5% of the dietary energy intake can be lost as methane.
More rumen-resistant starch in the ruminant diet results in lower methane production in the rumen. Adding fats and oils when it is economic and at levels that do not affect digestion has been shown to lower dietary energy losses in the form of methane by up to 37%. Secondary plant metabolites improve feed conversion efficiency and in the process reduce methane production. Feed additives boost feed utilisation efficiency and reduce pollutants in manure. Novel mitigation opportunities consist of adding feed additives like prebiotics, probiotics, acetogens, ionophores, bacteriocins, organic acids and plant extracts like condensed tannins. Many enzymes like phytases are already in use by commercial feed companies.
Bolton Kudzai Kakava is a Plant Pathologist/Agronomist/Food and Agriculture Standards Consultant: Email address email@example.com Cell number +263779579803