Pasture Project update SPRING 2018 - Understanding and managing grass growth alongside varying weather conditions

26 June 2018

If ever a period demonstrated a perfect definition of the effects of extreme weather conditions, it will be the complete metrological u-turn during the spring of 2018 and its effect on grassland management on Welsh livestock farms. Steady rainfall and cool conditions in March and April would not allow for early turnout or the efficient utilisation of grass covers with many farmers buying in extra forage to feed stock indoors. The welcome dry spell from mid May has continued well into June to the extent that growth on silaged lighter land is beginning to wane and even on some heavier soils that retained much of the spring’s moisture. Where once farmers were wishing the rain to stop they are now doing the exact opposite, highlighting the potential difficulties and the need to implement management practices that will help ensure grass is grown and utilised efficiently during such contrasting conditions. Table 1 below shows clearly a huge difference in the weather between March and May with more than two and a half times more sunshine and more than 58% less rainfall.

Table 1. Average Met office weather data for Wales during March, April and May 2018

(Source: Met office)

Soil temperature is one key driver of early grass growth and table 2 below explains again how slow the growth in March 2018 would have been compared to 2017, with soil temperatures around 3.5-4  ^oC less than during the same period last year. Therefore not only there are these swings in environmental conditions within a year, it will vary dramatically from year to year too. Good grassland farmers therefore need to be flexible when it comes to managing stock against the backdrop of the various weather elements that drive grass growth.

Table 2. Soil temperatures at three participating Farming Connect Soil temperature map sites

(Source: Farming Connect Soil temperature project)

Often this flexibility will manifest itself as a compromise, with seasonal calving and lambing occurring within a pre-determined period with a need to match the animals demand with adequate energy and protein, whatever the external factors. It is crucial that farmers take into account the specific conditions on their farms and gather as much information as possible to help them decide when their start and average date of calving or lambing is best suited to ensure sufficient nutrition can be delivered to lactating animals, ideally as grazed grass and for optimum profitability. Table 3 shows spring 2018 growth rates for 3 spring seasonal calvers who start calving at the beginning of February, understanding the likely impact of weather on grass growth is key in ensuring cows that reach peak production 6 weeks post calving are supplied with enough quality grazing or at least supplement during known periods of slow growth.

Table 3. Growth rate during March, April and May 2018 on 3 Participating Pasture Project Dairy farms

(Source: Welsh Pasture Project)

Predicting grass growth is never easy and we have seen first-hand how no one year is the same, however having a good grasp of the potential grass growth on your farm and the likely impact of varying weather conditions will assist planning for such aspects as optimum stocking and Nitrogen application rates, start of breeding period, early spring grazing, securing surplus silage and adopting other contingencies if there is ever a repeat of this years spring.