Farm Ireland
Independent.ie

Wednesday 21 November 2018

Tool up now to measure grass growth - or rue it in spring

 

Mary Kinston

What an exceptional autumn. Ground conditions are superb and not what we're used to dealing with in Kerry at this time of year, but it's a welcome change.

Grass growth has also been remarkable, especially when you see an average of greater than 30kg DM/day for Munster at the end of October as summarised by Pasturebase. Cows are also milking very well, with many herds doing in excess of 1.4kg MS/cow/day in late lactation.

However, not all farms are equal and it's essential to use measurement to assess the weekly position and make a series of correct decisions which optimise the spring 2019 position.

Whilst the present cashflow position and feed debt issues associated with 2018 is maybe to the forefront of farmers' minds, 2019 should now be our number one priority.

But, unfortunately, is there a risk that farmers will graze on too long and have too little grass for spring? In some farms, the answer is 'yes'.

Is there a risk that covers are so high this autumn that this will impact tillering, re-growth and spring growth? In some farms, yes, depending on the winter.

Our only resolve to the differing circumstances of every farm in every region will be the weekly grass round.

For example, some farms still have big grass covers and will easily see grazing well into November. This is especially the case if a farm was late to recover from the dry and drought situation. Here I suspect the residual nitrogen is giving a boost to grass growth, which farms to the west saw in August and September.

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However, rejection is common and it has been challenging to get a good clean-out in places. Note if your average cover still exceeds 1,000kgDM/ha at November 1, it may be important to increase demand with other stock to get very heavy covers off before the grass plant stops actively growing and for recovery of the sward.

In other extremes, whilst grass growth has remained high, some farms may need to close in excess of 75pc of the milking platform by November 1, especially where the stocking rate is high or farmers have struggled to extend the grazing rotation above 35 days.

Cow demand has been notable this year. It's as if grass just didn't have the eating power that we're used to.

Personally I suspect that exceptional grass growth has coincided with lower sugar levels because of decreasing day lengths.

It's no surprise that it's been difficult in many herds to remove the higher-than-usual levels of concentrates without severely plummeting milk solids.

Another indicator of this is that the difference between growth and demand has not tallied with changes in the average pasture cover from week to week, where covers have remained or declined even though growth exceeded demand.

So the present decision is whether to continue to graze on or to increase supplementary feeding and reduce grazing demand, ultimately leaving ground closed for spring.

Whether you've closed 60pc or not by now is not important - what you need to determine, is how much grass you need in spring.

High stocking rates of greater than 3 cows/ha and/or earlier calving/compact calving herds need more grass in spring. Starting with an average pasture cover of plus 800kg DM/ha at February 1 is a massive feed saving in these circumstances and promotes milk production.

From this point we can back-calculate what's needed at closing in autumn. If we back-calculate to December 1, assuming a growth rate of 3kg DM/day will see the need for a closing cover of around 620kg DM. If you've less than this at November 1, you need to question grazing decisions in November.

For example if we consider the potential for the accumulation of cover in November, assuming a growth rate of 10kg DM/day will see 300kg/ha growth accumulate onto the average cover if grazing stops and cows are housed.

Therefore, all things being equal, we can then state that if your average pasture cover is less than 320kg DM/ha on November 1 that you would need to cease grazing and close up 100pc to achieve your spring targets.

Obviously grass growth varies in November and often will range from 15kg to 5kg DM/ha/day from start to end. Here the same principles can apply that the last 10 days will accumulate 50kg DM/ha and the cover must be at least 570kg DM/ha at November 20 or grazing should have ceased prior to this point.

Feed budgets are an excellent tool when weather conditions and thus grass growth are an exception to the norm.

If used it will help you determine when to close up grazing this November. Avoid the temptation to graze on too long. In essence you will only be robbing Peter to pay Paul. Ultimately the benefits of having grass in the diet in spring are greater.

Mary Kinston is a discussion group facilitator and consultant, and farms with her husband in Co Kerry

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