Farmers keen on keeping pests at bay while reducing chemicals on their farms are now courting a low cost practice of trapping the sun's energy into plastic bags and directing it to soils, ending over reliance on chemicals that have been blamed for rising soil infertility in the country which currently stands at a staggering 40 percent.
Known as solarization the practice involves farmers covering their already prepared nursery beds with clear plastic papers for four to six weeks before they can start planting. The sun’s energy is trapped beneath the plastic, killing off a wide range of soilborne pests, including weeds, pathogens, nematodes, and insects. Though laborious, the practise guarantee no pest attack on the beds for upto five successive planting seasons. The top 6 inches of the soil heats up to as high as 52 degrees celsius which is hot enough to kill a wide range of soil inhabiting pests such as; wilt and root rot fungi, root knot nematodes and noxious weed seed.
Over several weeks, that's hot enough to kill a wide range of soil inhabiting pests such as; wilt and root rot fungi, root knot nematodes and noxious weed seed. In Kiambu where the practise is entrenched especially among vegetable farmers, the farmers argue that the process also has the additional benefits of leaving no chemical residues while improving the overall structure of the soil through increasing the availability of nitrogen and other essential nutrients necessary for the health of the crops.
“It is especially important in the seed germination period where the seeds are very susceptible to pests since they are forming and are weak. Use of pesticides on the soil at that time also mean that toxic chemicals weaken the soil and are absorbed by the seeds which may affect its growth,”says Silas Kinyua a vegetable farmer in Kiambu who has been an agricultural extension officer for the last ten years. He has mobilized over 200 farmers into solarization, arguing that it is the only way to reclaim the dwindling fertility of the area's soil.
The majority of the eliminated pathogens are the nematodes that cause crop wilts such as potato and banana wilt, which are some of the biggest diseases facing farmers. A 2011 survey by regional farmers' NGO Bridgenet Africa found that potato blight was among the major causes of the potato shortage in the country last year, which saw a 60 per cent increase in potato prices as farmers turned to pesticides that did nothing to improve the situation.
Another contraption invented by a local agricultural economist has also played a key role in the country 's pursuit of fighting pests without relying on the pesticides. The contraption uses mirrors to concentrate the sun onto soils to clean out pathogens and diseases ending the practice of soil roasting.