The National Cereals and Produce Board (NCPB) has blamed extensive land subdivision in South Rift for reduced maize production.
Addressing media in Kericho town on Thursday, Managing Director Newton Terer said the agency might not reach its target of buying two million bags this year.
Mr Terer also said that few farmers had delivered their crop to NCPB depots in Kericho County despite a 90-kg bag going for Sh3,000 - which is the highest price ever offered by the State.
He said Sh1 million was allocated to each of the four depots in Fort Ternan, Kedowa, Kipkelion and Londiani in Kericho County for maize purchases.
"A combination of factors have affected maize production in the South Rift including the maize necrosis disease, which hit the region hard in 2014 and 2015; and the shift to mixed farming.
"There is less maize in this region because farms have become too small," Mr Terer said.
He noted that NCPB - which buys and stores maize on behalf of the Strategic Food Reserve - has been forced to rent out some of its stores in Kericho to other businesses.
The managing director added that the board has so far bought 800,000 maize bags from North Rift farmers, its prime region.
"The government has given us an allocation of Sh6 billion for the purchase of two million bags of maize this season.
"But the question is whether we will be able to achieve this target. We want to urge farmers to continue growing maize which remains a staple food this country," he added.
NCPB has stocked close to 1.3 million bags (117,000 tons), which Mr Terer said will be adequate to feed Kenyans.