My last update began with the expectation of high growth after a period of rain. Indeed, growth rates did take off at the beginning of last week with many farms recording figures >100 kgDM/ha/day. However as the week progressed these growths declined again as the lack of soil moisture began to take its toal with levels reducing to circa 60 kgDM/ha/day. Mid-day soil temperatures range from 19 degrees plus in the South and South-West, to 16 degrees in the remainder of the country. At these levels, it is indicative of a long period of warm dry weather which can effect nitrogen utilisation and growth. However it seems that we have come a full circle again and I find myself preparing farmers for another surge in growth after the recent rain. The weather forecast for the coming week suggest a welcomed balance of rain and heat - ideal for continued high growths. The recommendations at this time are echoes of the past two updates, so have a quick read of them to refresh your self – with one addition – first cut cutting date is now closer than before (if not already cut), therefore, with the expected high growth rates, it should be possible to increase demand higher (70-75 kgDM/ha/day in some cases) for the short period until first cut aftergrass returns.
Back to Urea?
The heading raises the question and I think the answer is yes - temporarily at least. There is no doubt that the drought curtailed the utilisation of CAN in the past 2-3 weeks, and from what I have seen the problem was exasperated when Urea was used. There has been enough of recent rainfall to allow for the efficient use of urea - so why not take this opportunity to make a saving until dryer conditions prevail again. Lighter stock farms may have their first cut silage already cut and are now in a position to close ground for second cut - apply Urea instead of CAN now in these areas.
While on the subject of fertiliser, it is well worth to mention Sulphar. It is recognised that many counties in Ireland, especially those dominated by lighter sandy soils with low organic matter, would benefit from Sulphar application. Such soils can experience a significant increase in DM production when Sulphar is applied especially during the Summer - approximately 20 units/ac should suffice. A quick word of caution for those in low copper/high molybdenum areas - sulphar is antagonistic and can cause copper deficiency.
Dry matter % and aftergrass
Aftergrass from the first cut will be returning to the grazing platform very soon. Your weekly farm walk will tell you how quickly it is recovering - generally it should return to the farm cover calculations when it is in the range of 400-600 kgDM/ha. - introducing a large area it at this range prevents a big jump in the average farm cover. It is best to clip and weigh some of the aftergrass paddocks to help to calibrate your eye - often aftergrass looks strong from a distance but is thin on the ground. It is also prudent to lower the suggested % dry matter of the aftergrass
by 1-2 units compared to the grass on the platform when measuring. The lower % DM in aftergrass is often an reason for a slight drop in cow performance especially if grazed in the wet weather. If this is the case it is advisable to alternate grazings between aftergrass paddocks and existing grass on the platform - however be mindful to keep residency in each paddock below 3 grazings if possible.
Reproductive tillers in the sward
The drive of perennial ryegrass to reproduce was also evident in the past week with flag leafs and some seed heads emerging. it is almost inevitable that this will happen and that some stem is part of the grazing horizon at this time of the year. It is critical not to relax the grazing pressure at this time - the grazing height must be below the emerging seed heads to remove them for good. If you continue to graze to 3.5-4cm then you guarantee a leafy vegetative sward in subsequent rotations. If you are grazing more laxly, be prepared for continued stem in the grazing horizon. Which do you think is more beneficial? Topping is an option, only if the "toplink" is tightened up and the topping height is consistently <4cm.
