Sustainable Land Management Practices are one of the key pillars of Agricultural productivity. Following is a review of the history, challenges and current SLM practices in Kenya
The history of land and soil conservation measures in Kenya dates back to the colonial era with the incorporation mandatory soil and water conservation activities for all local administrators and agricultural technicians. At the time, the main soil and water conservation interventions included contour farming, tree planting, terraces, strips and destocking. All these gains were lost after Kenya gained independence. The period between 1963 and 1972 saw people destroy previous soil and water conservation structures in a bid to revenge against the colonialists. Soil and water conservation became untenable as they were viewed as symbols of oppression.
The Stockholm Conference on Human environment in 1972 changed things a bit, more so with the formation of United Nations Environment Program in Nairobi. The government formed the National Soil and Water Conservation Company in 1974 to implement the agreements of the conference and to spear heard conservation efforts in the country.
The years between 1988 and 1998 ushered in a new era in soil and water conservation in the country as a new management approach was introduced in all national programs. The catchment/watershed management approach would be used by all subsequent agricultural programs in the country including the National Agriculture and Livestock Extension Program (NALEP) of 2000. Today, approaches to land, soil and water conservation are largely fragmented but there are plans to form a national policy on the same.
Sustainable land management interventions are broadly classified into Agronomic/vegetative and structural interventions. Agronomic/vegetative interventions rely on soil and water balance systems to guide agricultural activities aimed at reducing land degradation. Water harvesting, crop and soil management, conservation agriculture, mixed cropping, mulching, contour farming, agro-forestry are some of these agronomic interventions.
Structural interventions to land degradation entail the construction of human made structures to reduce land degradation. Principally, structural interventions should only be implemented once all agronomic and vegetative interventions have been exhausted. For best results, the structural measures should strive to complement agronomic interventions, with the latter taking priority in soil and water conservation compared to the former. Important to note is that all structural interventions have to be designed. Here, due consideration should be given to the catchment, rainfall, slope and other physical variables important in design. Some of the common structural interventions in Kenya include terraces, retention ditches, cutoff drains and semi-circular bunds.
Gulleys are one of the most problematic outcomes of land degradation in Kenya. They are formed when runoff erodes channels, which expand into gulleys. Measures to address gulleys should stick to the principles of SLM and the design of such structures. In that regard, they should first adopt a catchment/water shed management approach to ensure they have the desired impact. Secondly, vegetative interventions towards gulley control should take priority over structural interventions or to the extent possible, the two should complement each other.
Lastly, when treating gulleys, it is advisable to start where the gulley begins-where the runoff starts eroding the land. Taking this approach is much cheaper and may eliminate the need for structural interventions. Besides, structural interventions at the gulley that fail to ignore the source of runoff will often be washed away. This has been the experience with the use of gabions in Kenya. Most have been washed away since they were installed at the gulleys with no supporting interventions upstream.