Agronomy Advice

Low rainfall impacting grass growth in many areas

The continued dry weather is putting huge pressure on grass supply, in those mainly affected in the east and south east of both the UK and Ireland.

Spreader in a field
Spreader in a field

Soil moisture deficits are already very low in many places and with this latest increase in temperatures many more areas will start feeling the pinch. In areas where drought is affecting grass growth, there is a need to reduce daily grass demand. This will help to hold grass cover on the farm through supplemental feeding.

Teagasc point out that grass DM is higher during drought periods and grass supply tends to be underestimated. Post grazing residuals should be maintained at 4 to 4.5cm. Higher residuals means scarce grass is being wasted. Average farm covers (AFC) should be kept above 2,000kg/ha (500kg/ha in Irish terms) and try and keep rotation length to 25 days. By going below this it begins to negatively affect overall farm growth rates. It takes grass to grow grass, so maintain a grass wedge to allow for a quick recovery in grass growth once we receive some rain.

As for fertiliser, if there is dirty water available then apply this in the evening time, otherwise if grass growth rates are less than 35kg DM/ha, nitrogen applications should stop. Soil N is released after a drought so don’t over fertilise with nitrogen. After rain arrives and growth rates return to >45kg/ha then apply 15-20kg/ha of N after grazing.

On those farms that grass growth rates are in a healthier position, the focus should switch from a week to week approach to a longer term outlook and start building farm covers over August and September for feeding in October and November, and providing enough time for a proportion of the farm to recover to provide grazing in the early spring. We can start this by extending the rotation length out to 30 days by early September and increasing pre-grazing yields up to 3,700kg DM/ha (2,200kg DM/ha in Irish terms) by mid-September.

P & K review

Reconcile how much P & K has been applied in fertiliser and slurry to date on paddocks and silage fields, so that you can calculate the shortfall if offtakes exceed inputs. Now is a good time to top up those fields or paddocks that haven’t received their full maintenance requirements.

Read about improving nutrient efficiency

Wheat agronomy and fertiliser advice
Wheat agronomy and fertiliser advice

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