Apply nitrogen to fresh grass
At this time in a normal year, or at least in more recent years, I would be telling farmers to start gearing up to apply early nitrogen. As I look at pastures today, they are a mixture of pale green to light brown in colour, with no sign of fresh growth.
Average soil temperatures are up to 1°C below normal and most soils are saturated. Soil temperature is the main factor that determines the start of spring growth. Grass needs a soil temperature of 6°C for growth and, over much of the country, this does not occur until early March.
Recent winters have been exceptionally mild, with periods of several weeks when the average temperatures were in the range of 6-8°C. This gave a good accumulation of grass over the winter months where land was closed from late October.
The provision for early grazing in February and March comes from grass grown between October/November and February, rather than any substantial response to early nitrogen. Where there is good soil fertility there is adequate background nitrogen to provide for the low-level growth that occurs during the closed period.
Unfortunately, to date this year, not only has there been no growth but the pasture covers that were there in December have diminished by around 200kg DM/ha, or 60-70pc of what we might currently expect to be available. Still, a couple of mild weeks would get growth started and we could end up with 'normal' grass covers on rested land by mid-March.
Apart from southern counties and coastal regions, growth rates in February are likely to be low or non-existent due to prevailing temperatures. Therefore, the yield response to applied nitrogen will be low.
Over most of the country, temperatures rise steadily from early March and so does the response to nitrogen. Because early grass is valuable there is an advantage in going out with a small amount in advance of when growth takes off. Also, there is a lag of a week or so between the spreading of nitrogen and its effect on growth. Even if temperatures are lower than that required for growth, it takes a while for the nitrogen to get through the soil and into the plant roots, and this occurs at 1-2°C lower than that for growth.
If weather conditions are suitable from next week onwards, then start spreading nitrogen where there is a reasonable cover of fresh grass. A reasonable cover might be a grass height of 3-6cm of fresh growth -- not a decayed stubble.