Reseeding is a profit-making tool – but which approach works best?
Reseeding old pastures increases grass production and increases profit. Newer swards are 25pc more responsive to nitrogen fertiliser and can produce up to 40pc more grass compared to old permanent pasture.
This additional grass yield is particularly noticeable in spring and autumn. New ryegrass varieties have a higher sugar content, which leads to enhanced animal performance and improved ensilability.
Despite the obvious benefits, a recent Teagasc survey found that up to a quarter of farmers said they never reseed.
Nationally there is huge potential to increase output of beef, lamb and milk from cheap grass, which can be grown more efficiently from reseeded pastures.
Once the decision is taken to reseed, the next question is – which method of reseeding is best?
Some farmers choose to plough when reseeding because it provides an opportunity to level fields, especially after land reclamation work.
Farmers in some parts of the country will plough and establish a tillage crop for two seasons before returning the field to grass.
Ploughing can also help to improve land drainage.
A fine-firm seedbed is essential in establishing a good reseed, and ploughing will help achieve this, together with burying older grasses and weeds.
Ploughing reduces the risk of a reseed failing to establish, due to a high level of soil to seed contact in a fine seedbed, more available moisture and the natural release of nitrogen from the soil.
There are many circumstances where ploughing is not suitable, and this is where the alternative minimum cultivation methods have a role.
This is particularly the case in ground that contains a lot of stone or where there is rock near the surface.
One of the other benefits of minimum cultivation is the minimal ground disturbance created, which allows a return to grazing within 60 days in ideal conditions. It is also generally cheaper than ploughing, and the most fertile soil remains at the surface where nutrients are needed.
Reseeding Methods Demonstration in Kilbeggan
Farmers have a wide range of establishment methods to choose from, whether they be plough-based or minimum cultivation.
A Teagasc demonstration in Kilbeggan examined a range of reseeding methods, using machines which were available to local farmers in the area.
The field chosen had been cut for hay continuously over the past years, with the sward containing old grasses, plantain and buttercup. The field had not been reseeded for decades.
The field was soil-sampled to establish the P, K and lime status. The field was sprayed with 2l/ac of glyphosate. Two weeks later, half of the field was ploughed.
All plots were sown in mid-June using seven different treatments, as outlined in Table 1, above left (Reseeding demonstration site lauout).
All plots were sown with 14kg/ac of 'Sweet tooth' grass seed mix from Germinal seeds. In addition, three bags per acre of 10:10:20 was applied to all plots at sowing together with two bags per acre of granulated lime.
The entire site was ring-rolled after sowing to consolidate and level the seedbed. A post-emergence spray was applied six weeks after sowing.
The new sward was closely monitored for slugs and frit fly, but no issues were noted.
The material costs of the reseed are outlined in Table 2, Material reseedinng costs per acre (below right), while the machinery costs associated with each method are outlined in Table 3, Costs of machinery used in the reseeding demonstration per acre (top right).
Ploughed Plots Amazone One-Pass
* Created an excellent seedbed with one pass.
* Grass was sown with the tilling operation and avoided further tracking.
* The machine was easily and accurately calibrated.
* Grass established in rows, similar to a cereal crop. However, this can be addressed with good post-grazing management to promote tillering and improve ground cover.
Einbock Grass Harrow
* Very evenly-distributed seed and the tines gave seed sufficient cover to aid germination.
* The seedbed has to be fully prepared prior to using this machine. This means that there is an additional sowing cost and there is additional driving over tilled seedbed which may lead to tracking.
Grass Seed Barrow:
* The grass seed barrow is available free of charge to farmers from local merchants.
* We found it very difficult to calibrate the seed barrow for even seed distribution.
* We had to use a ring roller to give sufficient soil to seed contact.
Power Harrow & Fiona Grass Seed Box
* It is a specialised one-pass machine for sowing grass. We used this machine on both ploughed and unploughed plots. We found that best results were seen where this machine was used on the ploughed area, but grass establishment was also quite satisfactory on unploughed plots.
* We found it easy to set the seeding rate and calibration was accurate.
* We had to use a ring roller on the ploughed area to give sufficient seed cover for better germination.
Unploughed Plots Aitchison Grass Stitcher
* This was the cheapest reseeding method we had on demonstration.
* We found it to be a very simple grass seed-sowing machine with limited ground disturbance.
* The grass established in lines and could potentially be slow to establish full ground cover. Good, tight grazing after establishment is key to success of this method.
Guttler Grass Seeder:
* We observed that this pneumatic seed distribution machine sowed a ley that established evenly.
* It was the second cheapest method of reseeding at our demo.
* Post sowing there was quite a lot of dry weather which did not suit this method. We therefore concluded that this method requires plenty of moisture after sowing as there is minimal soil to seed contact for germination.
Reseeding is an expensive exercise, however a properly managed reseed will pay for itself in three to four years, making reseeding one of the most cost-effective on-farm investments money can buy.
Every field and farm situation is different, so there is no one-size-fits-all in terms of methods of reseeding.
All methods have their advantages and disadvantages, as outlined above, but the key is choosing the right method for your own farm situation.
Good practice in terms of soil fertility, correcting pH, seedbed preparation, variety selection and sowing the correct rate of seed is just as important as the method chosen.
Finally, a step often forgotten is the post emergence herbicide, which should be applied from five to eight weeks post- establishment.
The target weed in this spray is seedling docks, so ensure the weed spray chosen is excellent in this regard.
Correct management (tight grazing, avoid poaching, sufficient nutrients) of the sward into the future is critical to fully reap the benefits of your reseed.