Grass10: Managing through the current dry period

With high temperatures and very little rainfall expected for the next 10 days, this week’s Grass10 newsletter focuses on managing through the current dry spell.

In parts of the east and south east, soil moisture deficits of >40mm are present. Growth rates, however, have remained strong on average with surplus grass on many farms. On dairy farms, an average growth rate of 75kg DM/ha/day was recorded, while growth rates of 62kg DM/ha/day were recorded on drystock farms using PastureBase Ireland.

On drier farms for the past week, growth rates above 55kg DM/ha/day were recorded, so don’t assume your grass growth and supply have reduced. It is now essential to measure grass to identify growth, surplus and deficits. Hold a reasonable demand on your farm (50-60kg DM/ha) and remove any surplus stock, replacement heifers or non-priority animals from the main grazing platform.

Measure

Measuring grass supply once per week is not enough in these conditions. At least three grass measures in two weeks or ideally twice per week is recommended. For all enterprises, target an average farm cover of 600-700kg DM/ha and rotation length of 18-21 days. If the farm is getting quite dry, push this out to 25 days. In terms of cover per livestock unit, 160-180kg DM/LU is the target on dairy farms, with 12-15 days grass ahead.

Plan to correct grass quality

Although dry farms in the south and east will start to face grass supply challenges given the current predicted weather pattern, other farms in the north of the country or on heavier soils will continue to experience strong growth. Where pre-grazing covers are above 1,600kg DM/ha on these farms, grass quality should continue to be corrected. Grazing paddocks at lower covers (1,100-1,200kg DM/ha) will help sort some of the problem.

Fertiliser for grazing and silage

With growth rates still being good, the Grass10 team recommends applying 15-16 units of nitrogen per acre, especially on heavier soils. In addition, using collecting yard or watery slurry spread using LESS will give a better response during the current weather conditions.

For second cut silage, consider splitting the application given the current weather patterns. The below table from Mark Plunkett, Teagasc Johnstown Castle, outlines the options for fertiliser second cut. Remember not to forget sulphur as it plays a key role in increasing sward dry matter yield. For second cut grass silage swards, apply 8-15kg of sulphur/ha (6-12 units/ac).

This article first appeared as part of the Grass10 Campaign's weekly newsletter. For more information on the Grass10 Campaign or to sign up to future newsletters, visit its webpage.