GrowthWatch: Chemical fertiliser deadline approaching
By Teagasc’s Seán Cummins and James Fitzgerald
The chemical fertiliser spreading closed period begins on September 15 for the entire country and so – from this date onwards – the spreading of chemical fertiliser containing phosphorus (P) or nitrogen (N) is prohibited.
The response you can expect from N fertiliser is lower now than what it would have been earlier in the grazing season and – in general – grass growth rates are quite good at present, resulting in most farms not requiring a split of N for the rest of the year.
However, there can be farm-to-farm variations in grass growth and availability, and so decisions should be made based on knowledge of what is happening on your own farm.
If you have a Nutrient Management Plan completed for your farm, now is your last chance to go back and calculate the amount of units/ac of P you have spread to date and top it up to what is required with chemical fertilisers where needs be before the deadline date.
Alternatively, slurry or dung can be used to top up the P needed by your soil up until the organic fertiliser spreading closing date specific to your region.
On peaty soils, do not aim to build up the soil P index if it is low, but instead just spread maintenance levels of P as peaty soils have a far lower ability to retain P than mineral soils.
Having an accurate Nutrient Management Plan in place for your farm will inform you on the quantities of P, K and lime needed by the soils to reach optimum soil fertility.
Remember that correcting soil pH through spreading ground limestone is by far the cheapest and most important step in improving soil fertility and can be done at any time of the year.
The wet and stormy weather that was experienced over the last couple of weeks has really slowed growth and we’re looking for some level of kindness going forward to boost grass growth rates and to help under-foot conditions.
Over the past seven days, the farm recorded a growth rate of just 23kg DM/ha, which is back significantly from the 62kg DM/ha average we’ve recorded over the previous four weeks.
Although we’ve got a lot of rain, we’re still managing away with grazing, but we have to be selective of where we move cattle as some parts of the farm are still quite wet and it will take a good spell of weather to get them back grazing.
I currently have the yearling cattle split into three groups; one group of Friesian stores are being supplemented with 4kg/head/day of concentrates and the target for these animals is to produce a 290-300kg carcass in November.
The calves are also being supplemented with 1kg of ration/head/day and this level of feeding will continue until housing in October or November – depending on what way the weather plays out.
I also have to be selective on where I am applying fertiliser at the minute, as some of the paddocks are too wet to travel.
Where I can travel and ground conditions allow, I am applying 30un/ac of protected urea to help build grass for the backend of the year.
Good grass growth rates over the late summer have resulted in areas of surplus grass still being baled up to as late as August 29.
While I already had enough silage in the yard to do this winter, I feel that the best course of action was to bale what I knew I wouldn’t be able to graze while the ground conditions allowed. And also to get the ground back to growing better-quality, shorter grass to graze later in the autumn.
As well as that, you can never tell when the extra silage is going to be needed going on the fodder crises of the recent past.
In mid-August, 1.5t/ac of ground limestone was spread on the entire home block bar the fields that were earmarked for cutting surplus bales and those being grazed at the time.
Now that the bales have been cleared from this remaining ground, I have a chance to spread the same rate of lime on the remaining ground to complete the job.
A couple of heavy nights’ rain helped greatly in washing the lime off the grass that was to be grazed and the cattle seemed not to suffer any ill effects of grazing this ground shortly after.