The 2007 Grazing Season – Anything but Simple!
With the 2007 grazing season nearing an end, now is a good time to reflect on results of the GrassCheck project.
The 2007 grass growing season began slowly on many farms following a very wet winter period. Poor ground conditions impacted on fertiliser applications and made grazing very difficult for many. However, this was to be a good indicator of the challenges that lay ahead for every grassland manager. The Agri-Search and the Department of Agriculture and Rural Development (DARD) funded GrassCheck project monitored grass growth throughout the season, with measurements taken at sites in Antrim, Hillsborough, Loughgall, Portaferry and Fintona.
The wet start to the season led to below average growth in March across most sites, with Portaferry being the only site to perform just above average. Weather conditions improved through March, and this continued into April and May with below average monthly rainfall recorded at AFBI Crossnacreevy for these three months.
April was particularly dry, with monthly rainfall being 80% lower than the 16 year average. This improvement in the weather caused grass growth to increase quickly. However, at the Fintona site, grass growth continued to remain below average through April and into early May. Growth at the Hillsborough, Portaferry and Antrim sites increased rapidly throughout April, with growth increasing from around 60% below average on the 5th April at the Hillsborough and Antrim sites, to over 60% above average by the 30th April on all three sites. This dramatic change in growth caused grassland management problems on many farms, with grazing platforms quickly accumulating surpluses. This was further exaggerated where turnout had been delayed.
A settled period of weather in early May provided ideal silage harvesting conditions for those prepared to cut early, but the weather turned more showery from the middle of the month. Grass growth declined at the Antrim, Portaferry and Hillsborough sites in late May, but this was expected given the very high peak growth rate achieved. The Fintona site failed to reach average levels in mid-May, but growth did increase to above average levels in late May.
Figure 1. Grass growth throughout 2007 at sites in Portaferry and Fintona, the average growth of the five sites through 2007 and the average growth from the previous three years (2003-2006).
The increasing grass growth at Fintona continued into June and early July, with growth reaching a peak in mid-June, when growth was 49% higher than average. Grass growth was above average through most of June and early July at Antrim, Portaferry and Fintona. However, wet weather from the middle of June impacted on ground conditions, and eventually grass growth.
At AFBI Crossnacreevy, June rainfall was over 2.5 times the monthly average, with daily rainfall reaching almost 2 inches (47mm) on one particular day. Monthly rainfall totals continued well above average through July and August, with rainfall figures being 70% and 48% higher than the 16 year average for these two months. This period of weather made the harvesting of second cut silage very difficult for many farmers and contractors, with much silage cutting restricted to small areas only. At this stage many milk producers began to buffer feed silage, with some housing cows overnight and on occasions both day and night.
Growth at Fintona fell from 49% above average to 52% below average in the period from late June to early August with growth rates at this stage declining to 24kgDM per ha per day. On the drier sites, the above average summer rainfall encouraged above average grass growth. The Portaferry site in particular maintained above average growth throughout July and August. In early August, whenever growth was very poor in Fintona, growth in Portaferry was actually 65% above average.
Following the very wet summer, the weather improved during the autumn with mild temperatures and dry weather across the province. Monthly rainfall totals for September and October at Crossnacreevy reflect this, with the monthly averages being 59% and 47% below average for these months. Growth remained above average in Portaferry until mid-September.
In Fintona, grass growth in early September reached above average levels, and remained above average until the end of the month. This settled period of weather allowed most producers to graze paddocks out well in preparation for the winter period, with every grazing day greatly appreciated given the silage already fed out during the unsettled conditions in summer.
Total herbage production varied greatly across the five sites this year. The above average mid season rainfall benefited grass growth at the normally dry Portaferry site with total grass yields 27% above average at 13.62tDM per ha, compared to the three year average of 10.70tDM/ha. In contrast, wet weather severely affected growth on the heavier soils, particularly in Fintona where total herbage production was restricted to 9.08tDM per ha.
As another grazing season ends, it is clear that 2007 has provided the grassland manager with a variety of challenges. Looking forward, the short and medium term prospects for the dairy industry in Northern Ireland are looking very strong. However, do not allow the current euphoria around milk price to alter the focus on the importance of maximising milk from forage, particularly milk from grazed grass. The GrassCheck project has highlighted the variability that this season has provided, and will be back in the spring to assist with grassland management planning through the 2008 season.
by Dr Andrew Dale, AFBI, Hillsborough, and Dr David Mackey College of Agriculture, Food and Rural Enterprise, Greenmount Campus