Uasin Gishu County Farmers Association Director Kipkorir Arap Menjo has said the use of "substandard fertilizers" provided by the national government will lead to food insecurity.
He said most farmers had been affected after their crops got malnourished and turned yellow.
"This year's maize harvest will reduce by over 4 million bags due to the use if substandard fertilizers," he said.
Speaking to journalists after meeting with farmers from the region on Wednesday, Menjo said last year, 21 million bags of maize were harvested but this year they are expecting 17 million bags of maize.
"I am calling upon the national government through the Ministry of Agriculture to conduct tests on the affected crops for us to know what caused yellowing of maize plants," he said.
Areas most affected include Ziwa, Turbo, Soy and Moiben.