The current rural broadband roll-out is 'not sufficient' to meet the needs of most farmers, according to a new report.
The government has said it is committed to making the UK the best connected country in the world but farmers are already being held back by poor connections.
The report, published by the NFU, said it was vital for connections to be improved.
850 members responded to the NFU Digital Technology Survey, carried out during the summer of 2015.
"I employ four people and in 50% of the farm we can’t get in contact with each other over the mobile," said one farmer.
"We sometimes have no connection, but on average have between 0.3 and 0.6 Mbps.
"Our biggest hurdle is not being able to attract potential tenants to our converted sheds to offices, as the connection is too weak," said another respondent.
Current levels of broadband and mobile phone provision in rural areas are not catering for demand and are stifling innovation, the report says.
'Social, economic and environmental benefits'
There are social, economic and environmental benefits' of connecting the final 5%, especially for the delivery of a sustainable and productive agricultural sector, the report states.
"We need to be able to use the technology to farm more efficiently to meet the needs of our growing population and compete in the international markets.
"Farmers with poor connectivity cannot use the full range of agricultural technology.
"They spend time traveling back and forth to signal hot-spots and have to outsource their management of online finance and regulatory systems.
"Online compliance can cuts costs for both the government and farmers", the report highlighted.
In July, another report by an influential group of MPs said poor customer service and an overrealiance on a copper network were not meeting the needs of rural homes.
CLA Deputy President Tim Breitmeyer said: "The Government’s commitment to a broadband universal service obligation was a major breakthrough for those of us who have campaigned for an end to the discrimination felt by those that live and work in the countryside.
"The day this legal right to a superfast broadband connection becomes law cannot come a day too soon and we support the MPs’ challenge to government to see if it can be brought in earlier than the current target of end of 2020."
