To contact one of our “Forage for Profit” team, call the Seed Office on 01769 576232
or Graham Ragg on 07798 583667 or email firstname.lastname@example.org.
Measuring Grazed Grass
We have talked a lot about measuring grazed grass and setting targets to achieve the best grazing utilisation, but what is the best way to do this?
There are various methods for measuring grass and all can work, although some are a bit crude, these are:
- Sward sticks
- Marks on wellies
- Notches on a stick
- A beer bottle (standing up = pre grazing, lying down = post grazing)
There is no doubt, though, that the best way to measure grass quantity is with a rising plate metre which measures kg DM/ha. It gives the most accurate measurement and from an investment of around £350 will help to improve animal performance from grazing. It has been described as a feeder wagon equivalent for the grazing system, this describes it perfectly.
Feeder wagons have provided us with good information on DM intakes and plate metres can do the same with grazed grass. There are some terms we need to be familiar with and understand to make best use of the information provided and these are:
This is the average grass DM cover of the whole farm taken by adding up the total of each field and dividing by the hectares available i.e. 165,000kgDM total, 75 hectares available = 2,200kgDM average farm cover per hectare.
As above, but just for each individual field i.e. 6,250kgDM total for the field, 2.5 hectares available = 2,500kgDM/Ha cover.
This is the kgDM cover of the next field to be grazed. The aim is to be at 2800kgDM/Ha. If the cover is above this there is a potential for wastage, and if the cover is less, animal performance could suffer unless other feeds are made available.
This is the kgDM cover of the field after the cows have come out. The aim here is for 1500kgDM/Ha in the early part of the season and 1800-2000kgDM/Ha later in the season. If the cover is above this, then grazing potential is being lost and later grazing will be compromised by the amount of stem remaining, if the cover is less, then cows have been restricted too much and productivity will be lower.
Available Grazing Cover (AGC)
This is the difference between the pre-grazing and the postgrazing cover that is available for the cows i.e. 2800kg – 1500kg = 1300kgDM/Ha available grazing. If we have a 15kgDM per cow target then 1300 ÷ 15 = 86 cows/Ha for one day. Daily cover growth This is to work out what the daily grass cover growth rate is for the whole grazing area farm cover).
Take last week’s measurement away from this weeks and divide by the number of days in between, i.e. 2650kg – 2335 = 315 ÷ 7 = 45 so the daily cover growth rate is 45kgDM/day for that particular week.
There is a strong correlation between grass digestibility and intake, high quality grass translates into better animal performance. Regular re-seeding goes a long way to maintaining quality grass.
This is the measurement of grass cover on each field across the farm and how each fields growth is matching expectation (see graph below). When fields fall below the target line then there is a likelihood of grass shortage, so action needs to be taken to get back on target by additional buffer feed, adding more grass, or increase nitrogen rate ahead. If fields are above the line then they need to be grazed sooner or shut up for silage. It is a good way of monitoring how grass growth is progressing and where to focus attention.
Once you come to terms with these descriptions, start using use the plate metre to really
monitor weekly grass growth and availability, then you will soon see improvements in grass utilisation and animal performance. Your Mole Valley Feed Solutions specialist can help you to use plate metre and then set some realistic M+ from grazing targets.
How much grass have you got?
Plate meters, used weekly through the grazing season, provide information for you to make grassland and stock management decisions.
Plate meters can be ordered from Mole Valley Plus on 01769 576201.