We all know that grass grows seasonally. It starts to grow as the weather warms the soil in spring, grows fast until it seeds in early summer, then growth slows down as the availability of water reduces (hopefully) over summer. There is often a flush of grass around September as rainfall increases but the soil is still warm, then growth slows and stops or almost stops during winter. However, as our climate changes, so will patterns of grass growth.
If you are keeping grazing livestock all year, this growth pattern can present a problem – what are you going to feed the livestock in the winter when there is no grass? Generally, the answer is some sort of forage crop and usually one made from conserved grass – hay, haylage or silage.
Silage can also be made from other crops like whole crop barley or maize, but for the purposes of this article, silage will mean grass silage. Other non-grass based forage crops include swedes, turnips, fodder beet, cabbages and kale.
Calculating grazing requirements
Using Livestock Units, you can roughly calculate how much grass you will need for summer grazing and therefore how much grass is available for conservation. One LU needs approximately one acre for grazing and one conserved for forage.
Productive grassland to which some fertiliser has been applied will produce around 5 tonnes of hay per hectare (slightly more than 2 tonne per acre); species rich meadow with no fertiliser applied may yield half of that.
|Forage type||Weight of large round bale (1.3m diameter)||Equivalent small bales per large round||Weight of large square bale (2.5x0.9x1.2m)||Equivalent small bales per large square|
|Wheat straw unchopped||220kg||15||250kg||17|
Assumes silage dry matter of 22-25%; if DM is 18%, add 150kg per large bale. Barley straw produces a denser bale then wheat straw, so will weigh more.
Improved Grassland Management John Frame