A picture worth a thousand words

The aim is to have the wedge follow the slope of the target line. A feed wedge can show three situations – feed deficit, feed surplus, or just right. Deviations from the target line signal some management decisions are on the horizon.
“Humps and hollows indicate a deficit or surplus of pasture, which means you have to manage those in order to best utilise your pasture. If there’s a hollow coming up, maybe you need to put some nitrogen on or bring in supplement. If there’s a hump then you know you can conserve grass for supplement later on.”
Rather than going off a gut feel, feed wedges allow more informed decisions to be made in a timely manner. They are not simply a note of average cover or the longest and shortest paddocks. They can add value by starting conversations about pasture management, and to communicate decisions to staff and plan ahead. Contractors can be booked earlier if in surplus, nitrogen use can be managed more effectively, and the use of brought-in supplement can be controlled and planned.
“Feed wedges have a lot of uses,” Glassey said. “Most of all it’s a great conversation starter – having something visual is easier to explain than a bunch of numbers. In practical terms pasture management and quality can be improved. Plotting a weekly feed wedge was been a key tool for Lincoln University Dairy Farm in Canterbury lifting ME from an average 11 to 12.2 over three years.”
Although average pasture covers are important, they can’t be solely relied on as a pasture management tool.
“They are a little misleading, they don’t provide enough information to make any informed decisions from. You can have the same average pasture cover on three farms, but have completely different feed wedges that require different management. Feed wedges allow you to apply management decisions to individual paddocks, so it’s more accurate and effective.”
Feed wedges are best used when there is a consistent rotation length, which is usually from balance date to the end of autumn.
“The challenge comes when rotation lengths are changing more frequently, then your target line on the feed wedge needs to be changed as well, so using a feed wedge is more complex over the calving period for example.”
At other times, particularly in late autumn and early spring when pasture covers and stocking rates are rapidly changing, feed wedges need to be used with other tools such as feed budgets, spring rotation planners and average pasture covers.
There are some considerations to take into account when doing feed wedges. Larger paddocks might need to be split into two to give a more accurate representation in the wedge. When the round length changes, so too must the feed wedge.
But Glassey said the most important thing was not to get too hung up on pasture assessment accuracy.
“Don’t get hung up on getting every paddock accurate to the last decimal point. Just having an estimate to be able to rank paddocks from longest to shortest is the main objective, and the fact you are actually looking at your pasture to obtain this is a step in the right direction.”