Agroforestry has the potential to contribute to climate change adaptation, mitigation and food security (Mbow, Smith, Skole, Duguma, & Bustamante, 2014; Mbow, Van Noordwijk, et al., 2014; Verchot et al., 2007). Regarding adaptation of Kenyan horticulture to changes in climate, agroforestry has the potential reduce the impact of climate extremes on crop growth. The shade providing tree canopy can create a suitable micro climate for crops to be grown. However, this shading effect could also hamper crop growth if solar radiation is blocked too much. Research could be performed to explore agroforestry options that would serve the local circumstances best (Mbow, Van Noordwijk, et al., 2014), in terms of biophysical (hydraulics, soil fertility) and financial (diversification, income risk) impact (Verchot et al., 2007).
Major side benefit of the technology is that it can be performed in degraded areas, where it increases soil fertility (Mbow, Van Noordwijk, et al., 2014). Besides, trees sequester carbon in the soil and their woody products, serving climate change mitigation. The trees’ products (being both fruits and wood) could be sold as an extra source of income, making the farmer less dependent on his/her horticultural crops (Mbow, Van Noordwijk, et al., 2014). Three examples of agroforestry practices are briefly presented below.
Eggplant mango intercrop
Eggplants covered by straw mulch interact beneficially with mango trees. In the dry season, the trees provide shade to the annual crops while the mulch retains soil moisture in the root zones. The soil is prevented from eroding by the annual crop and mulch cover, and its quality will improve when the mulch is decaying. On top of this, mulch could provide co-benefit of weed control on the parcel.
To overcome the lack of income when the mango trees are not yet producing fruits (in the first three years, depending on the variety), extra eggplant can be cultivated in the free space between the trees. To avoid nutrient exploitation and disease outbreaks, the farmer should consider adopt a rotation of the annual crop. (WOCAT SLM Technologies, 2018d)
Banana coffee intercrop
As in the previous system, the bigger tree crop in this intercrop (banana) providing shade to the smaller crop (coffee) is one of the major benefits of this practice. The right amount of shade (less than 50%) reduces the stress on coffee, without hampering its growth. Moreover, shade even can even improve bean quality. The banana tree can provide mulch to the system, which supports root development for both crops and improves the availability of nutrients (especially K, potassium) in the soil. The mulch also minimizes soil erosion and retains soil moisture. (Wairegi, van Asten, Giller, & Fairhurst, 2014)
Establishing optimal conditions for both crops requires careful management of soil and canopies (image). Besides, it takes longer for the system to become productive since coffee is not an annual crop.
Banana Pea intercrop
Combined with cowpea cultivation, timely irrigation and fertilization, banana yields increase. Besides, intercropping the two crops suffers less from weed infestation compared to a banana monoculture.
Adjust cropping calendar
To avoid crops being exposed to extreme temperatures, a farmer could explore opportunities to adjust his cropping calendar according to the expected changes in climate. Key would be to avoid exposing the crop to extremely high temperatures in its most vulnerable stage (seedling).
Switch to climate tolerant varietiesTo support previous measure of adjusting one’s cropping calendar, a farmer might need his/her crop to mature earlier. A crop variety with a shorter growing cycle could still deliver the same yield as his/her current variety. Another option would be to use heat tolerant varieties. This measure is highly depending on farmer’s access to the seed market.
Crop change/diversification(Partly) changing to a climate resilient crop could be an option to deal with the effects of climate change. Examples of crops that grow well under high temperatures are tomatoes, beans, pumpkin & zucchini (Nekesa & Meso, n.d.), corn, sweet potato, cowpea, eggplant, okra, Armenian cucumber, peppers, broccoli, millet-groundnut, mushroom, passionfruit, carrots and parsnips. While some of these crops need a lot of water, this could be overcome by irrigation. Diversifying one’s farm to cultivation of multiple crop species is a way to avoid years without any income.
Bucket cultivation is a low-tech technology that allows for full control of soil circumstances. Besides preventing leakage of nutrients and water, bucket cultivation prevents soil erosion in extreme events. Especially for farmers who’s soil quality is a main limiting factor for crop growth, bucket cultivation might be an appropriate solution. In a previous project in Kenya, cabbage was planted to grow in buckets. Sprouting occurred multiple times, compared to the one time sprouting under conventional tillage.