And now, the Lands and Agriculture ministries are exploring ways of controlling such settlements in a campaign to tackle the twin problems of population growth and hunger.
The ministries are seeking ways to tighten rules for changing land use from agricultural to residential in both towns and rural areas.
In rural areas, population growth has exerted pressure on farm land as settlements eat into farms, while an upsurge of urban dwellers has led to increased demand for housing. This has fuelled a real estate boom in the suburbs.
All these activities have been at the expense of food production, a situation that has Agriculture minister William Ruto worried, calling land subdivision a threat to productivity.
“For example, in another 15 years, the whole of Kisii District might become a rural slum, yet it is highly productive agricultural land,” he said.
He also said productive areas in the outskirts of Nairobi were being taken over by settlements.
The minister was speaking at a workshop attended by scientists to “look below the surface” and discuss how farmers can tap soil organisms to improve fertility.
The experts, who concluded research on how land overuse influences soil organisms, urged farmers to “pay attention to what is underneath” if they were to cut fertiliser use and increase yields.
The scientists said they conducted research in Embu and Taita, where they studied organisms in uncultivated forest land and those in over-used farm land.
Dr Sheila Okoth, the research coordinator, said the project came up with an “integrated basket” to encourage farmers to add organic materials to the soil alongside other practices like use of fertiliser to enable soil organisms to thrive.
Separately, one million bags of fertiliser have arrived at the Mombasa port and 1,000 tractors are expected from China in three months, Mr Ruto said.
With the onset of the long rains, the government has been distributing inputs to farmers to boost yields.