Take out paddocks for silage if your rotation exceeds 30 days
Published 21/08/2013 | 05:00
After a dry summer there often follows a good and growthy autumn and many farms have recently seen grass growth rates that have matched or exceeded this spring.
Paddocks are a lush rich green and cows are settled and content. This is after having suffered notable falls and rises in milk production, especially milk protein percentage, which was most likely due to the hot weather and heat stress of the summer.
August is a time in the grassland management calendar when ideally we finish up making silage, reseed and start to lengthen the grazing rotation. The aim of this is to push grass forward into the autumn in an attempt to extend the grazing season.
Due to late first cuts and attempts to make third cuts in places, I have no doubt that there will be plenty of silage made this September, but on a milking platform, August is a tricky month to manage. While one may be happy that there is an increase in the pasture cover, August can often see surpluses quietly grow to a level that requires action.
If you see your grass cover increasing substantially and rotation lengths already exceeding 30 days, it is better to cut paddocks for silage in mid-August than at the start of September.
Therefore, it's crucial to do a weekly pasture walk during this time to manage the grass supply and demand. Others have questioned management decisions with respect to the possibility of another period of dry conditions. But with the day-length closing in, I feel that if this was to happen, then the impact would be short-lived.
While it's farm specific and influenced by stocking rate, I find that holding a grazing rotation of 22-26 days up until around August 20 works well. From that date it's then ideal to start increasing the rotation length to roughly 30 days by September 1, 35 days by September 15, and 40 days by October 1.
This should coincide with an increase in the pasture cover up to or exceeding 1,000kg DM/ha by October 1.
Avoid increasing this above 1,200kg DM/ha by October 1 if you want to maximise October and November grass growth rates, tillering, grass quality and grazing residuals. The last grazing rotation then commences in and around the first week of October.
For those of you on the wetter, heavier soils, considering the present ground conditions and the soil's ability to take deluges of rain, this may be the first chance in a few years to play out a normal autumn management plan. When I considered preparing for the autumn, the first thing that occurred to me was that there was a maximum of three grazings left per paddock until the end of the year.
Including these three potential grazings, on average this year we will have grazed the paddocks 7.8 times. In 2012, on average, each paddock was grazed 7.2 times, while in 2011 each paddock was grazed an average of 9.6 times – ranging from 12 grazings to seven.
Grass measurement results indicate that in 2011 we grew on average 13.78t DM/ha, with paddocks ranging from 17t to 11t DM/ha. In 2012, the average fell to 9.02t DM/ha and ranged from 13.7t to 5t DM/ha. In 2013, total growth to date sits at 5.53t DM/ha and it's likely the remainder of the year will grow no more than 4t DM/ha.
We have a heavy farm in a high rainfall area with 1,511ml of rain in 2012. This year, 640ml had fallen by July 31, compared with the 820ml that had fallen by the same date in 2012.
High rainfall levels and heavy soil type have hindered grass growth and pose substantial grazing challenges.
Using grazing management, minimising poaching, having the optimal soil pH, P and K status and a sward with a high perennial ryegrass content are key factors in this quest.
While it's nice to finally see the pastures recovering and perennial ryegrass starting to dominate as it did in 2011, it will be important this autumn to optimise tillering during September and October. Measurement and management are key this autumn. Therefore avoid grazing covers of greater than 2,200kg DM/ha.
Finally, weeds including buttercup, ragwort, rushes, docks and thistles have noticeably increased on heavy ground and competed with ryegrass over the last two years. This autumn may also be a good time to hit these. Also, don't forget to lime where soil pH is less than six and use compound fertiliser including P and K in the last rounds of spreading where it's required.
Mary Kinston is a discussion group facilitator and consultant, and farms with her husband in Co Kerry. She can be contacted at firstname.lastname@example.org
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