Lime – The Starting Point of Soil Fertility
Soil pH is the foundation for soil fertility and pasture performance. To achieve a target pH of 6.3-6.5, lime needs to be applied; however national figures indicate that we are only spreading approx. 50% of the lime that we need to. Any field that is operating at a low pH is not working to its full potential.
When a soil becomes acidic, the availability of major nutrients (N, P & K) are dramatically reduced. Nitrogen availability can be reduced by 30% and phosphorous can be inhibited by up to 60%. If one bag of 18.6.12 is applied only 12 units of N and 2-3 units of P will be available to the plant for uptake.
Lime is one of the best on farm investments available. It is predicted an extra 1 ton/ha grass production response from lime alone. This is valued at €181/ha/yr of extra grass production. At farm level this equates to a return on investment of 1:6. Every €1 spent on lime equates to €6 worth of extra grass produced.
Lime and high molybdenum soils can reduce copper uptake in grazing animals. This will result in higher risks of copper deficiency occurring. To avoid this it is recommended to keep pH on high molybdenum soils between pH 6.0-6.2.
CAN and NPK fertilizer are all ok to spread any time before or after lime.
Urea and slurry are different, wait 7 – 10 days after applying slurry/urea before applying lime and avoid spreading slurry/urea to any land that received lime in the previous 3-6 months. Land that receives lime in the next month will have no issue receiving urea/ slurry next spring.
Lime can be spread at any time of the year. In grazing ground lime is not harmful to cows but in a worst case scenario it may cause some slight scouring, however once the lime is washed off the grass there is no risk.
For silage ground it is always best to apply lime in the autumn, this will ensure that lime is well washed in before saving for silage next year.
Any fields known to have low pH should be targeted with lime now, if pH is unknown it is recommended to soil test over the Winter and put a lime plan in place for your farm.
Reseeding Demonstration and Family Day
The recent Reseeding Demonstration and Family Fun Day took place on the farm of Denis and Fiona Harnedy. The large attendance on the day were able to get first hand experience of the different methods of soil cultivation and seedbed preparation. In addition to this, expert guest speakers from the Irish farming industry were present to give advice on all the key topics around grassland reseeding.
There was a common theme from the guest speakers on the importance of getting the basics right at reseeding. Dr. Stan Lalor of Grassland AGRO focused on soil structure, Stan stressed that the cultivation method selected must address any soil structure issues. Soil fertility is key and should be determined from a soil test. Apply lime and appropriate nutrients as required.
Dr. Michael O’Donovan Teagasc discussed the influence that proper seedbed preparation has on seed establishment. A fine, firm seedbed is always the best approach to achieve optimum seed establishment.
Dr. Mary McEvoy of Germinal Seeds spoke on the importance of choosing the correct grass seed varieties. Mary stated that the future use of the reseed will determine the mix of grass seed varieties to use. In order to maximize return from the new sward, only the best performing varieties on the Teagasc Pasture Profit Index and Department of Agriculture recommended list should be considered.
Dave Barry of Goldcrop discussed the importance of weed control in reseeds - post emergence spraying is one of the most important parts of reseeding. The best time to control weeds in a field is after reseeding when the roots of the weed have not developed properly. Timing of post emergence spraying is very important, especially when using clover safe sprays. The reseed can be sprayed once the grass is at the 3 leaf stage.
A group discussion took place around direct seeding and pasture rejuvenation. When direct seeding critical points include removing all the dying grass from the surface of the field by grazing or baling and applying lime to neutralize any acidity from the dying grass. When stitching in to established grassland to rejuvenate an older pasture, ensure good seed to soil contact. Grass seed variety is key - only tetraploid varieties should be used. Grazing management is also a critical point, ensure the field is grazed at light covers after seeding to allow the new grass seed establish and not to get smothered by the existing grass.
Don Crowley of Teagasc emphasized the increased grass growth capacity of farms through more productive reseeded swards compared to older pastures.
A special thank you to the Harnedy family for generously providing such an ideal site for the event.The three contractors on the day: Robert Ellis, Brian Lawlor and Martin Coakley must also be acknowledged for taking time out of their busy schedules to show the reseeding options available in the area.