The benefits of sward renewal

Philip Creightonl, Michael O'Donovan2 and Laurence Sha11002 Grassland Science Research Department Animal ; Grassland Research and Innovation Centre Teagasc Athenry and Moorepark2 Introduction Grassland in Ireland including rough grazing accounts for over 90% of agricultural land use. Lolium perenne (Perennial ryegrass) is by far the most widely sown grass species accounting for over 95% of forage grass seed sold each year. It produces a dense sward, highly acceptable to livestock with the ability to produce high dry atter yields, especially in spring and autumn reducing the seasonality of production.Achieving good performance from grass is dependent on having high quality perennial ryegrass/clover swards. This paper will outline the important aspects of reseeding pasture, what's happening at farm level, why and when reseeding should be completed, its benefits and costs. What is happening at farm level? A recent survey of a proportion of co-op suppliers from Kerry, Connaught Gold and Glanbia (Creighton et al. , 2011) found a number of significant findings from a eseeding perspective, these are listed below. i. v'. ‘x.Regular reseeding took place on 50% of participants farms, 25% reseed infrequently, 25% never reseed. Of those reseeding, 50% of participants reseed 2-4ha/year, 20% 8. 0 Soil K Index 2 3 4 Soil K ranges (mg/ 0-50 51-100 101-150 > 150 K application rate (kg/ha) 110 75 50 Slurry is a good option to maintain nutrient status. With the increased cost of compounds (P and K) slurry should be used in reseeding, 1000 gallons of slurry at 7% DM is equivalent to 4kg N, 3kg P and 19. 5kg K. At soil index 3, slurry (3000gals/ac) is sufficient to supply the P and K nutrients.Weed control The best time to control docks and all other weeds is after reseeding. By using a post emergence spray seedling weeds can be destroyed before they properly develop and establish root stocks. Established weeds can seriously reduce the yield potential and economic lifetime of the reseeded sward. From the survey information it is clear that only 50% of farmers are applying a post emergence spray, resulting in over 90% of surveyed farms having problems with dock infestations.To ensure that a post emergence spray can be applied reseeding should be targeted for the spring or early autumn when establishment conditions are much more suitable and the opportunity for weed control is guaranteed. The post emergence spray should be applied approximately 6 weeks after establishment Just before the first grazing takes place. With weed control it pays to be proactive, spraying when grass is at the two leaf stage works well. Grazing management of reseeded swards Care needs to be taken when grazing newly reseeded swards.The sward should be razed as soon as the new grass plants roots are strong enough to withstand grazing (root stays anchored in the ground when pulled). Early grazing is important to allow light to the base of the plant to encourage tillering. Light graz ing by animals such as calves, weanlings or sheep is preferred as ground conditions may still be somewhat fragile depending on establishment method used. Grazing new reseeds with larger animals can create high levels of tiller pulling. The first grazing of a new reseed can be completed at pre grazing yields of 600-1000kg DM/ha. Frequent grazing of the reseeds at light covers (