Q&A: slurry and fertiliser webinar

You can watch the webinar back here.

What’s the plan for fertiliser on Tullamore Farm this spring?

Adam Woods: We’ve no chemical nitrogen spread yet but we intend to go with some this week or next week, depending on the weather and ground conditions.

We’ve divided the farm into three sections based on grass covers.

The low covers that have been grazed out well will be spread with 3,000 gallons/acre of slurry and closed for silage.

Some of the medium covers have received 2,000 gallons per acre of slurry and the rest of these medium covers will get 23 units/acre of urea when the weather improves. In terms of the higher covers, some of them will get nothing until after they are grazed and then get slurry or urea and others will get 23 units/acre of urebefore grazing.

Does urea work as well as CAN on silage ground?

Mark Plunkett: Any differences could be down to conditions at the time of spreading. Protected urea is better from an emissions point of view and it also helps to protect against ammonia losses.

Can I spread lime on silage ground now? It will be getting slurry in April.

Mark Plunkett: At this stage, I’d be inclined to hold off on the lime and go with it after the first cut of silage is taken. There is a risk you could bring some of the lime back in on the grass when cutting the silage.

Should I continue on my P and K buildup programme this year?

Aidan Brennan: With the cost of P and K this year, I think it would be better to just focus on feeding the crop and pressing pause on correcting the soil fertility. This doesn’t mean not spreading any P and K this year.

It just means you are spreading what the grazing or silage crop needs.

I’ve no nitrogen spread yet. I was going to spread 23 units/acre in February but now the weather has turned bad. Should I just wait and go with a full bag of urea (46 units/acre) in mid-March?

Aidan Brennan: It depends on the demand for grass but it’s a long time to wait until mid-March to get nitrogen applied and on a highly stocked farm it’s a lost opportunity to grow valuable grass, so I’d be inclined to go with the 23 units/acre as soon as conditions allow and spread the same amount in March.

Mark Plunkett: Grass growth rates are low at 7kg to 8kg/day which have a requirement of 2kg of nitrogen per week, which the soil can provide.

I’m hearing a lot about protected urea but my merchant doesn’t stock it. What can I do?

Siobhán Walsh: Urea is scarce and stocks are low but if farmers put in their orders for protected urea, the merchant should be able to get it for them. The fear for the merchant is they will get the stock and not be able to sell it, so if you plan ahead you should be able to get it.

Where can I get my slurry tested and is it expensive?

Siobhán Walsh: Most companies that test soils will also test slurry. It takes about 10 days for the results to come back and it costs between €60 and €80 per sample.

I was accepted into the soil sampling scheme but have heard no word yet on when the samples will be taken. What can I expect to happen?

Adam Woods: There were about 7,000 applicants to the scheme and 1,600 have been sampled so far. We understand that they have ramped up sampling in the last few weeks but the chances are that a lot of those farmers won’t get sampled this spring and they’ll be held over to next autumn or winter.

Is urea still the product of choice in spring?

Mark Plunkett: Yes, urea is still the product of choice. Unlike CAN-based or nitrate-based fertiliser, it will bind to the soil.

My fertiliser spreader manual doesn’t give machine settings for low rates. What can I do?

Aidan Brennan: This is a common problem because most machines have been calibrated for use at higher rates. In this instance, I recommend farmers to estimate the machine setting for a particular rate by deducting the increment between the rates that are in the spreading chart. It should be close to the target spreading rate. To double-check, take off the spreading disk and calibrate the machine or apply a small amount and measure the area it was applied to, to work out the exact rate.

What’s the best strategy for fertilising a traditional hay meadow?

Adam Woods: We sometimes miss a trick on drystock farms by spreading more of our slurry in summer or after first-cut silage. However, by making more use of slurry in spring, we can offset most of the fertiliser that’s required. In this instance, spreading 2,500 gallons/acre of slurry before closing will provide all the P and K requirements and most of the nitrogen, save for perhaps around a half bag of urea or 23 units/acre of nitrogen.

What grass varieties would you include in a multispecies sward?

Siobhán Walsh: Perennial ryegrass is fine in it, you can make up your multispecies mix or purchase an off-the-shelf mix.

Aidan Brennan: It’s important to pick good perennial ryegrass varieties that are high on the PPI list because it constitutes a lot of the sward, particularly after the herbs fade after a few years.

What is the maximum grass cover you can spread lime on?

Mark Plunkett: As low as possible, ideally after a paddock has been grazed out, but a maximum of 500kg to 600kg per hectare of a cover.

Is there any merit to slurry additives?

Mark Plunkett: The slurry additives are questionable. There has been work done in Johnstown Castle where they looked at four additives. From an emissions point of view, they couldn’t find any real benefit. There was one that reduced methane by 10%, but the jury is still out on the slurry additives.

I applied slurry using the dribble bar on 29 January at 2,300 gallons/acre. Field is greening up and has grown compared to fields that have not got slurry. Should I apply more slurry or fertiliser in March as it is for first-cut silage in May?

Mark Plunkett: I’d be asking the question, is it Index 1, 2 or 3? If it’s Index 3, all it requires is straight nitrogen for silage. If it’s Index 1 or 2, I’d be inclined to top it up with something like 24:2.5:10 or similar to give it that little bit more P and K.

Could I go with pig slurry after grazing instead of chemical nitrogen?

Aidan Brennan: Yes, you could, but you need to watch the P and K levels because too much phosphorus will be bad for water quality while too much potash could upset magnesium uptake and cause grass tetany.

Siobhán Walsh: Pig slurry is variable so get it tested to know what dry matter and N, P and K levels are.

Is it more economical to reduce stocking rate on suckler farms than to purchase fertiliser?

Adam Woods: Maybe if you had non-priority stock or if there were cows that you were thinking of culling anyway, of course you could offload them before you go to grass. I wouldn’t be offloading breeding stock but at the moment the cattle trade is hot and you could use it as an opportunity to lower stocking rate.

What’s the best time to apply farmyard manure and where is best to spread it?

Siobhán Walsh: The best time to spread farmyard manure is in the autumn because it will be broken down by then. It’s high in P and K but they are released slowly, so I wouldn’t be reducing chemical P and K in the first year it’s applied. It’s also very high in organic matter.

Does protected urea grow more grass than ordinary urea?

Mark Plunkett: The thing to remember is you’re reducing the nitrogen losses when using protected urea. In long-term simulated grazing studies at Johnstown Castle in six out of seven years’ protected urea grew an average of 13% more grass than ordinary urea. In effect, you can spread 10% less nitrogen if using protected urea.