Grass management in dry weather conditions

Soil moisture and high daily temperatures are beginning to impact on daily grass growth in many parts of the country. While fields and paddocks remain green growth is impaired. Teagasc specialist, Joe Patton has advice and tips for managing grass in the current prolonged spell of dry weather.

Information from PastureBase indicates that growth rates on many farms are falling below 50kg DM per day. As a result, average farm covers are beginning to drop below the target 160-170kg DM per cow. In most cases paddocks remain green but with impaired growth.

Managing grass in dry weather

Given the risk of sustained dry weather, it is important that prompt actions are taken to manage the situation. 

• The priority now is to reduce daily grass demand to below daily growth rate. This will help to hold grass cover on the farm, protecting current growth and speeding up recovery when rain arrives.
• Rotation length must be maintained at 20-25 days approximately. This means grazing no more than 4-5% of the grazing platform daily. Assess the grass available on this area and supplement with forage/concentrate to balance herd demand.
• Keep AFC cover 500 kg/ha.
• Increasing rotation length beyond 28-30 days can lead to much reduced grass quality in very dry conditions. Visibly drought stressed covers should be grazed to allow recovery of green leaf after rain.
• Post grazing residuals of 4 to 4.5cm must be maintained, otherwise feed is being wasted
• Maintain fertilizer N at ±20kg per ha after grazing if average growth is 45kg or higher. Risk of N loss is low with protected urea products.
• However if drought conditions persist to >60mm soil moisture deficit and growth slows it is advised delay N until rain is forecast.

Hints and tips on feeding out supplements in dry weather

• Feeding supplementary forage will be necessary for some farms. Dry field conditions should make the task of feeding out forage much easier compared to spring. Each farm will have its own preference based on facilities/machinery/labour. The main point is to reduce total daily grass intake to the level of daily growth or below. Act early based on average farm cover to ensure that grass supply is stretched out.
• Parlour-fed concentrate will form a major part of daily feed allowance in drought conditions. Feeding up to 5kg of parlour concentrate per day in the short term is a relatively safe level when adequate forage and water are provided.
• Reduce meal feeding rates after 2-3 days when growth recovers
• A high energy low protein ration (14%) is adequate where grass provides at least half of the forage in the diet.
• Ensure full access to clean water.
• Areas closed for silage and accessible for grazing with <2200kg DM covers may be grazed as a ‘standing supplement’.
• If silage swards have surpassed ideal pre-grazing herbage masses and are nearing cutting stage then it is preferable to leave for silage cutting at this stage.

Further Information

You might also like to read Water requirements for beef cattle  and  Dry Weather & Fertiliser Nitrogen

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