Maintaining a 21-day rotation
The rain over the past few weeks has resulted in difficult grazing conditions on some farms, with rotation length under pressure. Those grazing heavier covers would have been most affected owing to animals grazing on a smaller area.
In early May, we took out three paddocks which had gone too strong to graze, a further two paddocks were cut on Tuesday along with the remaining first cut. Taking out the surplus paddocks in early May prevented pre grazing covers going above 1,600kg, this has allowed us to easily maintain a 21-day round (170kg/cow). The main benefit of grazing covers of 1,300-1,500 is the regrowths. The higher the pre grazing cover, the greater the nutrient off take and root death which leads to slower recovery post grazing. It is easy to maintain a 21-day round if covers are at the desired level – lower covers mean rapid regrowths and therefore a shorter rotation is needed.
Options for surpluses:
– Bales (taken off as soon as a surplus is identified);
– Introduce more stock onto platform;
– If lowly stocked, spread more fert on this area and allow build for silage. Demand/ha should be >60kgs to maintain grass quality in June; and,
– Reseed poorest performing paddocks.
Now is a great opportunity to increase the growth potential of the poorest performing paddocks. Soil sample paddock(s) to identify ph status (and p/k if no slurry applied to date). The soil type in the paddock will have a bearing on the grass varieties used, i.e. Diploid : Tetraploid ratio. On very heavy land, no tetraploids should be used as they have a lower density than diploids and therefore more soil exposure – leading to damage in the shoulders of the year. Lighter soils or paddocks with good roadway access should have 30-40% tetraploids and the remainder diploids (if including clover, 0.5kg/acre is sufficient of ‘chieftain’/’crusader’ varieties – do not use large leaf clover). I would use three grass varieties max, usually one tetraploid and two diploids.
The subsequent management of a reseeded paddock is much more important than the varieties used.
Soil fertility, pre grazing covers and grazing intensity are the three main factors affecting the longevity of a reseed. Rotation length should not exceed 18-20 days until autumn, when PGC’s can increase to 1500kgs max.
On some reseeded paddocks where animals have been outwintered in the previous year, cows may dislike the paddock and refuse to graze out fully/may drop in milk. This is usually due to chemical compaction and so an indepth soil sample is required.
Resseding is only expensive if it is done/managed badly! The value of growing more grass and increasing feed quality are two major benefits of reseeding.
Cathal McAleer is a grassland consultant working with individual farmers and facilitating discussion groups throughout Ireland.
087 160 2491 / 0044 7749 531679 [email protected]