Many Kenyan farmers harvest five to seven tonnes from an acre, according to available statistics. This is by far short of the optimal yield of between 16 and  20 tonnes or up to 400 sacks of 50 kilos. At a cost of Ksh1,500 per bag, one is sure of Ksh600,000 per acre within only  three months of planting. This can only be achieved when you plant the right  seed, use the right inputs and follow apt agronomic practices
To realise maximum yields, several factors should be considered.  They include:
Soil testing:
this is done to determine ph, which  confirms availability of micronutrients; mineral and nutrient content of  the soil before planting. Seeds Use certified seeds; Plant one variety only or separate  them if more than one; a large-sized potato is ideal for  planting, contrary to popular practice where farmers select the small  ones.
Only plant seeds after they have sprouted, with the sprouts facing upwards. this ensures uniform  growth; always plant a potato seed deep  enough on a ridge and ensure there  is a heap of soil; Prepare the soil before planting to  give you 15cm of loose ground. To do this mechanically, use a horizontal working rotovator;
To have a nice and equal field with plants, grade the seeds into several sizes; Spraying programme Potato blight is the most devastating  disease capable of wiping out an entire plantation within a day. To guard  against this, a farmer should get the  right fungicide;  Monitor the crop on a daily basis; stick to a spraying programme.
If it is a 10-day interval, it should remain so whether the disease has been detected or not. Farmers should seek advice from Ministry of Agriculture on the right programme; there is more risk of attack during the wet season; spraying should commence when the plant attains a height of three inches.
Crop rotation
do a good crop-rotation, plant potatoes once in four years in the same  field, otherwise nematodes will in- crease and you will never get rid of  bacteria wilt.