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Climate Actions for August

Climate Actions for August

  1. Catch Crops are a very useful tool to catch any residual nutrients following a cereal crop
  2. Apply Lime to low pH grassland crop soils
  3. Extra grazing days in the Autumn are achieved by building grass cover during August.
  4. Milk Recording
  5. If feeding ration with grass only -
  6. Empty your slurry tanks

Catch Crops are a useful tool to catch any residual nutrients following a cereal crops

 Maintaining a green cover over the winter period has many environmental, agronomic and economic benefits including:

  1. To take up any remaining nutrients after harvest especially nitrogen and reduce potential nitrate leaching over the winter period.
  2. To improve soil structure, soil drainage,
  3. To protect soils from winter rainfall and
  4. To add valuable soil organic matter over time. 

Read more here Early Establishment of Green Covers

Apply Lime to low pH grassland crop soils

Don’t leave all your liming until the end of the year, weather conditions may not allow you to get it out.

Once fields have been grazed-off and grass covers are low, it is an ideal time to apply lime. Identify blocks of land that require lime, for example this could require ordering a load of lime (20t) after each grazing rotation to correct soil pH (covers approx. 10 ac @ 2t/ac lime application rate). Aim to avoid high grass covers > 800kg DM/ha.

  1. Paddock Availability - Once fields have been grazed-off and grass covers are low, it is an ideal time to apply lime
  2. Lime Residue on Grass - Ideally apply lime to low grass covers to reduce the risk of lime residues. 
  3. Softening of the Ground / Sod - Soil types where a relatively thick (5-10cm) organic layer has formed above the top soil may be more prone to poaching during wetter period of the year.
  4. Silage Fields - Leave sufficient time (up to 3 months in dry weather) between applying lime and closing for grass silage for the lime to be fully washed into the soil.
  5. Lime & Slurry - Spreading cattle slurry on fields that have received lime recently or freshly limed land.
  6. Lime & Urea - For urea, a similar situation to cattle slurry where increased N loss (ammonia-N volatilisation) may occur where straight urea fertiliser is applied on recently limed land.
  7. Lime & High Molybdenum Soils - Soils with high Mo status may increase the risk of inducing a copper deficiency in grazing animals.
  8. Speed of Reactivity - Once lime is applied and is washed in it starts to adjust soil pH.
  9. Return on Investment (ROI) - Research shows that liming acidic soils increases grass production by 1.0t DM/ha.
  10. Lime Type - There are two main types of ground limestone that are available nationally – Calcium & Magnesium. 

For further information on liming, check out the full factsheet here: The Facts on Applying Lime (PDF)

Extra grazing days in the Autumn are achieved by building grass cover during August.

Extra days at grass will result in less silage in the diet reducing methane emissions; less slurry management required and improved efficiency. Keys tips for building grass in Autumn include:

  1. Establishing stocking rate and what targets you need to hit;
  2. Aiming to extend rotation from the 10th August;
  3. Remove last of surplus bales by early August to all sufficient regrowth;
  4. Control demand by introducing supplement or reducing stocking rate;
  5. Apply protected N + K protected, in line with your NMP.

Here Fergus Bogue, Teagasc Grass10 joins Stuart Childs on Let's Talk Dairy to discuss Autumn Grazing Targets

To build Autumn grass, spread 20-25 kg N / ha using protected urea in the last 2 weeks of August when you get the best response in grass growth.  Matching N application to grass growth optimises the efficiency of N and reduces GHG emissions

Every effort should be made to apply nitrogen (N) where required sooner rather than later.  As we move from August to September to October the response to applied fertiliser N will decline.  

Late Season N Response Studies

 Fertiliser N studies conducted over the last 3 years at four sites in Wexford, Cork, Louth & Mayo within the Agricultural Catchments show the average response to per kilo of N applied during August, September and October were 27kg, 19kg and 10kg respectively (figure 1).

Response to applied late N fertiliser

  • Average grass growth in August was 27kg DM per kilo of N applied. Grass dry matter yield response to applied N reduces by 30% in September and 63% in October
  • Currently N costs ~€1/kg. The N cost for growing a kg of grass DM in August and early September is ~ 3 to 5 cent per kilo. Grass grown from N fertiliser applied in later September costs approximately 10c per kilo 
  • Earlier applied N results in greater grass growth & more efficient use of each kilo of N

Nutrient Advice

  • Apply cattle slurry to meet grass fertiliser demands & empty slurry tanks before winter
  • Apply 30 kg N/ha on grazing ground to build grass covers
  • Where grass will be cut for silage apply 60kgN /ha depending on grass yield potential

Milk recording

Check milk recording & bulk milk health screening reports or faecal egg count reports for issues that need to be resolved.  Healthy animals means increased animal performance, reduced replacement rate and fewer non-milking animals, reducing GHG emissions per kg of milk produced. 

These reports provide valuable information on your herd and are an important decision support tool for making health decisions on your farm. 

If feeding ration with grass only - feed maximum 14% CP

Less excess protein in the diet means less N excreted and less GHG emissions.  The protein content of Autumn grass is high, greater than 20%.  The requirements for protein of mid/late lactation animals or finishing animals for protein is met by grass only.  Energy is the most limiting nutrient in this type of grass, supplement with energy and low protein. 

 Empty your slurry tanks

Managing your slurry over the winter to be able to spread the slurry when you will get the maximum value from it in Spring and reduce the quantity of chemical fertiliser needed, starts now. 

In an environment, where chemical fertilisers are expensive and where their use is going to be subject to increased regulation, farmers must use slurry as the Number 1 source of nutrients on the farm.  Only then should you top up with chemical fertiliser to meet your crop requirements.

Spreading slurry in mid January when there is no grass growth and soil temperatures are very low is a waste of nutrients.  The correct time of the year to spread slurry is when grass is actually growing.  For most soils this is when soil temperature is greater than 5-6o Celsius.  So for dry soils, this could be late January in a warm dry spring.  But for heavy or peat soils, this could be the early to mid-March. 

Emptying your tanks now will reduce the risk of storage issues over the winter where storage is an issue, allowing you to optimise the value of this nutrient in Spring.