In the past, fertiliser nitrogen (N) was so cheap relative to its potential for increasing pasture production that there was very little interest in getting free N from clover. Also, the feeding value of the clover plant itself was undervalued.
The big breakthrough with clover came with the trials at the Teagasc Solohead farm over a decade ago, carried out by researcher James Humphreys and colleagues. These trials indicated that with very high-level clover based pastures, it was possible to support over 2.1 cows per hectare (higher than the national average) producing almost 3,000 gallons per hectare (more than double the national average) with only 72 units of N per hectare (including silage) and moderate levels of concentrates.
James Humphreys’ work with clover and N has not only convinced many farmers of the value of clover, but also convinced Teagasc personnel who traditionally were sceptical about the benefits of clover.
As a result, there have been many trials in recent years with clover in normal grass mixtures. Moorepark trials indicate that including around 2kg of clover seed per hectare significantly increase pastures and milk production, using normal levels of N. Last year, a five-year trial, including clover with a tetraploids and a diploid variety of grass, began at Clonakilty Agricultural College.
The pastures receiving 200 units of N per acre are stocked at 2.75 cows per hectare and are grazed as per normal recommended management practices. It is early in the trial, but data from last year, and so far this year, shows a very significant benefit from including clover in the sward. Pasture production, milk yields and milks solids were significantly higher on the pastures containing clover.
Of course there are questions, because some farmers had poor experiences from clover in the past. Most of the questions have been answered in trial results, and we look forward to further answers and information from the Clonakilty trial over the next five years. Based on trials and farm experience to date, there is no doubt that clover has a major role to play in the future in improving milk and beef production from pasture.
Every farmer should include clover seed in seed mixes. Most seed merchants offer mixes with high levels of clover seed, to suit lower stocking rates and low fertiliser N applications.
One of the biggest fears of clover in the past was bloat, but to the best of my knowledge, it has never been a problem in clover trials, even in Solohead with extremely high levels of clover, and no precautionary measures being taken. Perhaps animals getting used to clover and not entering paddocks containing very high levels of clover when too hungry helps to prevent problems.
Another problem often questioned is persistency, especially with normal fertiliser N applications. Improved grassland management, such as tighter grazing, has also helped clover to persist longer. Clover can die out in one year with unsuitable management. In the Solohead Teagasc trials, over-seeding after silage every four or five years helped to maintain very high-clover based pastures indefinitely.
Over-seeding with clover seed on clean, bare stubble after silage, or after tight grazing in the spring, should help to boost clover content where necessary, and maintain satisfactory levels of clover in the pasture.
Don’t forget that clover can provide up to 150 unit of N per acre from the air, with proper management.