Question 1

What is a grass wedge?

Accepted Answer

A grass wedge is a bar chart showing all your paddocks ranked from highest to lowest cover (kg DM/ha). When it forms a wedge shape — highest covers on the left tapering down to the right — your rotation is working well. Paddocks above the pre-grazing target line are surplus; paddocks below the post-grazing line are in deficit and need grazing immediately.

Question 2

What is Average Farm Cover (AFC)?

Accepted Answer

AFC is the weighted average dry matter cover across all open paddocks in your rotation, measured in kg DM/ha. It is calculated as the sum of (paddock cover × paddock area) divided by total open area. AFC is the key metric for managing a rotational grazing system — AHDB recommend a target AFC of 2,000–2,400 kg DM/ha entering spring, rising with grass growth.

Question 3

What are typical target covers for UK dairy farms?

Accepted Answer

For UK dairy using the AHDB system: pre-grazing target 2,500–3,000 kg DM/ha (enter a paddock when cover reaches this level), post-grazing target 1,400–1,600 kg DM/ha (leave when grazed to this level). For ROI/Teagasc system: pre-grazing 1,300–1,600 kg DM/ha, post-grazing 50–100 kg DM/ha. The ROI system uses different measurement methods (plate meter) and lower post-grazing targets.

Question 4

How do I measure paddock cover?

Accepted Answer

The most common methods are: (1) Rising plate meter — a calibrated plate resting on the sward gives a reading that is converted to kg DM/ha using a regional calibration. (2) Visual assessment — experienced farmers can estimate cover reasonably accurately. (3) Walk and average — take readings at multiple points across the paddock and average. (4) Electronic sensors — some farms use drones or satellite NDVI to estimate cover. For this planner, enter your best estimate for each paddock in kg DM/ha (UK system) or kg DM/ha (ROI system uses the same units despite lower target values).

Question 5

What is days ahead?

Accepted Answer

Days ahead is how many days of grazing your current farm cover provides at current demand. It is calculated as (AFC − post-grazing target) ÷ daily demand per hectare. AHDB recommend maintaining 8–12 days ahead during the main grazing season. Below 7 days ahead means you are running short and may need to buffer feed; above 14 days ahead means you have surplus to close for silage.

Question 6

How do I calculate daily DM demand?

Accepted Answer

Daily DM demand = herd size × DM intake per cow per day. A 600 kg dairy cow in mid-lactation typically eats 18–22 kg DM/day from all sources — but when calculating grazing demand for the wedge, use only the portion from grass, typically 13–15 kg DM/cow/day (adjusting for any buffer feed). For beef cattle, use 2.5% of bodyweight as a starting point.

Question 7

What does the ±ha balance mean?

Accepted Answer

The ha balance shows whether you have surplus or deficit area relative to your target rotation. Surplus ha (amber) means paddocks above the pre-grazing target that could be closed for silage without affecting the rotation. Deficit (red) means you do not have enough grass to complete the target rotation — you need to reduce demand, buffer feed, or extend the rotation temporarily.

Grass Wedge Planner

Paddocks

Frequently Asked Questions — Grass Wedge & Rotational Grazing