Repairing damaged paddocks a priority

“Reseeding can be expensive but younger swards are definitely responding to fertilizer at the moment compared with my older swards. Damaged swards from last year need to be repaired. There is no point sowing fertilizer on them as they are no longer productive,” said Charlie Crawford, who farms 48.5ha of grassland outside Castlefin, Co Donegal.

Like all farmers, the lack of grass growth in 2013 has hit Charlie hard. Silage has now finished and forage is being purchased locally to feed livestock. In addition to his 40 cow suckler to weanling enterprise, Charlie runs 150 lowland ewes which have finished lambing and taken grazing priority over the cows due to poor ground conditions. While suckler cows have remained housed since autumn, calves and weanlings have been given access to grazing to reduce silage demand.

Sward damage

Last year, managing grazing ground to prevent poaching was difficult, but having a paddock system in place meant Charlie minimised damage to most of his grassland. However, some older swards became poached from cows grazing, but Charlie believes it is better to have damaged an old sward than reseeded ground.

At present, Charlie is working closely with his programme adviser Shane McHugh, as well as his local Teagasc adviser Gary Fisher, to discuss reseeding options and repairing damaged swards. The cost of reseeding is going to be a major hurdle for the farm this year as cashflow has been severely hindered by purchasing additional feed. Table 1 outlines some of the options and the typical associated costs for sward improvement. Six acres have been earmarked for reseeding immediately, with additional ground to be improved depending on weather, grass growth and finances.

Ploughing

For Charlie, ploughing is the preferred choice for repairing swards in a normal year as it alleviates drainage issues on land that has been poached, especially where there is soil compaction from livestock and machinery. Ploughing will also level ground again, but it comes at a price.

Taking a field out of production by ploughing means that there is period of approximately 10 to 11 weeks before it is able to carry livestock again. Unless weather and ground conditions improve, it is unlikely that suckler cows will be able to graze a ploughed reseed until autumn as the soil is too soft to carry the animal.

As the grass plant has not tillered properly, the open sward can become easily damaged. As such, post emergence management is crucial. At approximately €280/acre for a full reseed, it is an expensive option to bring ground back into full production again.

Min Till

Reseeding using minimum tillage is limited in its uptake by farmers but is something that should be considered.

The process usually involves burning off the existing sward with glyphosphate and then sowing with a seed drill, or with a machine such as an Einbock or Gruttler which combines a grass harrow with an air seed drill. It offers advantages over ploughing, such as:

Land is out of production for a shorter period of time.

Ground is not disturbed, so heavier livestock can graze if required.

Lower cost than conventional reseeding at €200 to €210/acre.

Stitching

Where swards have become open through grazing damage, the option of stitching grass seed directly into the existing sward offers an opportunity to repair ground and introduce younger grass. If managed correctly, the new grass will displace the older varities and weed grasses through competition for soil nutrients.

Using machines, such as an Einbock with the grass harrow, will remove dead grass and older grass from the sward, increasing the chance of successful germination, while at the same time levelling the field.

For both min-till and stitching options, it is crucial that swards are grazed tight after seed establishment

Soil contact

The stitching method is a better way to rejuvenate open swards than spreading grass seed in a fertilizer spreader, although it is obviously more expensive. There is a better germination where grass seed is incorporated directly into the soil. When broadcasting, grass seed has less soil contact which can only be improved through rolling. Rolling damaged grassland is to be avoided as it only magnifies the soil compaction problems.

Drainage

Problems with surface water have become an issue for Charlie, especially where concrete drains have replaced open sheughs over the years. Blocked drains are becoming a problem so Charlie intends to open a few drains to improve soakage in the short term.

Digging back clay and stoning to the surface is an expensive undertaking and as it would place too large a burden on cashflow, it will not be carried out this year.

Soil Compaction

Alleviating soil compaction is something that Charlie is considering as an alternative to drainage. In wet conditions, the top few inches of soil can become compacted from the weight of grazing livestock. This inhibits the drainage of surface water and can prevent chemical fertilizer getting to the plant root. Local contractors have soil spikers or aerators for hire at €25 to €30/acre, but Charlie would prefer a machine such as a pan lifter, or sub-soiler that will open the ground more and help drainage. If cashflow permits, Charlie hopes to use such a method to improve soil structure and drainage this year.

Under-sowing grass

“I was reluctant to undersow my reseed with spring barley last year, but with the advice from Shane on managing the crop, it proved successful and I am glad I did it as the feed was invaluable. It made great use of reseeded ground with higher yields than a straightforward grass reseed,” Charlie explained.

Twelve acres of old grass was ploughed in May 2012 with the intention to reseed and cut along with the second cut silage. However, to boost silage yields, the decision was taken to under sow with spring barley and then cut as whole crop silage.

Grass seed was sown at 12kg/acre consisting of Twymax, Aston Princess, Delphin, Stefani and Mezquita. Spring barley was sown at four stone/acre on 25 May along with two bags/acre of 10-10-20. A further bag of CAN was applied in late June.

Whole crop was harvested in early September and yielded approximately 10 tonnes/acre. The yield of ryegrass was lower than anticipated. The whole crop was ensiled and covered with second cut grass silage to prevent birds and vermin eating the grain. Silage analysis was 63 DMD and the whole crop was fed to cows before calving, replacing purchased straw from their diet.

After cutting, one bag of 18-6-12 was applied to the silage aftermath and then grazed with sheep to encourage the sward to tiller. As the grass seed contained mainly tetraploid grass varieties, the sward has a very open base. With tight grazing and good management, Charlie is confident that it will thicken out and prevent weeds from entering the sward.