Grassland management if dry conditions continue

Thursday, 8 June 2023

With the lack of rain in the forecast for many areas, now is the time to adapt management. Especially on the thinner and lighter soils, as soil moisture might be limited over the next 2–3 weeks if we don’t get any rain.

Top tips on managing grass and feedstocks

  1. Don’t overgraze and protect regrowth by not grazing below the 1,500 kg DM/ha (4cm) residuals.
  2. Consider having a sacrifice field to avoid overgrazing paddocks.
  3. Slow down the rotation by providing supplementary forage and keep stock in one paddock for a few days longer to allow other paddocks on the farm to recover.
  4. Be careful of carrying fields with high cover as these might go backwards.
  5. Introduce more paddocks to extend the rotation and allow covers to recover (these could be extra grazing fields or fields which have been silaged).
  6. Don’t apply nitrogen fertiliser if no rain is in the forecast, as the plants will have little ability to utilise this into growth in dry conditions.
  7. If the sward height is under 4 cm (1,500 kg DM/ha), provide ewes and lambs with supplementation. If sward height is less than 3 cm (1,200 kg DM/ha), extra forage is required as well to maintain lactation and lamb growth rates.

How to fill a possible deficit gap

  1. Bales are a good option in a dry period as they can be opened almost immediately after bailing. Ideally, clamp silage needs to be left for eight weeks after harvesting to reduce the risk of aerobic deterioration. If you require forage soon, leaving clamps closed for four weeks before feeding would be good.
  2. Fill the forage shortage as economically as possible while protecting and monitoring winter forage stocks.
  3. Dig deeper to see how certain feed options stack up in terms of relative cost per unit of energy and protein.
  4. Reduce the cost of bought-in feeds and forage by buying in bulk and locating local sources were possible to keep transport costs down.
  5. Don’t carry any passengers; cull empty cows/ewes or poor doers to help reduce the stocking rate if you can.
  6. Monitor body condition scores for dairy cows, beef cattle and ewes.

Water requirements

  1. Water requirements for milking cows is 120–140 L per day, 70 kg ewe at peak lactation requires more than 7 L per day, and a lactating suckler cow will drink 40–70 L.
  2. Trough capacity and pipe size must be correct to supply water rapidly and provide enough space so all those that want to drink at any one time can do so.
  3. Consider placing extra troughs in the fields or near the parlour. If it does not restrict cow flow, it can take the pressure off the trough in the field.
  4. Check regularly – algal growth and contamination will reduce water consumption.

Managing seed heads

Seed heads will always happen, but correctly managing them can reduce the impact they have on cow intakes, milk production and the rest of the grazing season.

However, moisture becoming a limiting factor puts pressure on the grass plant, and it will head earlier. To avoid this, make sure you enter the correct covers and accurate allocation to hit target residuals to ensure you get the leafy regrowth.

In mid-season, a well-managed sward should still be on 80% leaf, whereas a poorly managed one will achieve only 60% within the sward.

Ideally, cows should graze pre-emerging seed heads. If you know your platform heading dates, this will be about 5–6 days pre-emergence, when the seed head is still leafy and digestible.

Once the grass has produced a seed, it becomes stemmy, fibrous and quality drops – as do intakes.

Think ahead when reseeding: set up the platform correctly by selecting varieties with heading dates as close together as possible.

The heading date is when 50% of the varieties' tillers head – the rest being within a week on either side of this date.

Making sure that heading dates are as close as possible limits the overall time that the paddocks head, thus minimising the drop in quality.

Further information

Planning grazing strategies for better returns

Is it too dry to apply bag nitrogen?

Forage For Knowledge (interactive grass growth dashboard)