Dealing with drought on the grazing platform

Piers Badnell, consultant at Pasture to Profit, shares his advice on dealing with the effects of drought on grazing platforms and grass growth.

A couple of days ago I received an email from someone who has had no significant rain since the end of February and whose growth is in single figures. So, some notes for those of you that have been without rain.

I will split these into what you can do today, what could be done when entering a dry period in the future and some wider long-term comments.

What can you do today

• Protect the grass plant – don’t over graze or chase what little there is; grazing one leaf grass will stress the plant further
• At single-figure growth, average cover will most likely have been depleted, so it may be best to sacrifice a paddock due for reseed and feed cows in there. Camping cows on a paddock and feeding there will reduce costs of slurry, but take into consideration soil indices. If the paddock is low on phosphorous (P) and potassium (K), then camping cows on it will raise indices as a small bonus. However, if the paddock is P & K 3+, find another paddock
• Have you done a feed budget for winter, i.e. do you have enough? If you do not have enough or if it is close, then feeding a product like palm kernel can help, and will most likely raise fat %
• Do cull calculations early to reduce feed demand; there is no point feeding a cull in this situation
• Be ready for rain – the first rain will start grass growth, but it will likely be more than two weeks before you have sufficient growth to start grazing properly again. Never graze below two leaves as it slows recovery. The first leaf is 15% of plant yield, the second 40% of yield and the third makes up 45%. So, wait a little until the platform is ready to perform – go too early and you prolong the scarcity
• Be ready with fertiliser, but do not apply it too quickly after a long dry period. There will probably be some residual nitrogen from previous applications and there will be nutrients from dead leaf and root material. Hold off until you have grazed the new regrowth before applying more nitrogen

Tips for entering a dry period in future

• Review your Agrinet data. What does historical data tell you? Look at growth versus demand and plan accordingly. Lengthen rotation to match growth. Sub 25 to 30 growth will be a rotation of around 40 days; there is probably not much benefit of going beyond this
• Do not forget the third leaf is 45% of plant yield. Lengthening the rotation early to allow the third leaf to grow fully will maximise plant growth potential. This may mean higher entry covers than 3000 kg DM/ha, but it will be dry, and if you are accurate with allocation, you should utilise it all. I am not talking about 3500 kg+ covers here
• You should plate meter weekly so you have three or four opportunities to assess what you think growth rates will be over the coming weeks
• What is soil moisture like?  What temperatures are forecast? 20°C makes for good growing conditions, whereas at 28°C the rye-grass plant will struggle. What is average cover? How does growth compare to demand, and should you make any early modifications?
• One of my clients on medium land fed grazed grass through the whole of 2022 summer with a minimum of half the diet from grazed grass. He did this by acting early, lengthening the round, adding supplement early, culling early and looking after the plant. Others had to fully feed for weeks
• You will not have enough dirty water to irrigate, but it can act as a plant tonic to keep it healthy. It is a limited resource, so apply to paddocks that will give you the best return on your investment
• Prilled nitrogen needs moisture for a plant to take it up, so if it has not rained for a couple of weeks and there is no rain forecast, then there is not much point applying it. One thing to consider for the future is foliar-applied nutrient; this is absorbed by the leaves and can be applied after the point that prilled fertiliser application should stop. This will not beat the drought, but it will mean nutrient is available further into the dry period and will help your cover last longer
• Reduce demand by getting culls gone. While this will not reduce demand hugely, when done early enough it will mean more grass on the platform and in the diet longer
• Grass utilisation drives profit, so the longer we keep grass in the diet, the better. Supplementing the diet increases total cost of production through additional labour, machinery, cows on yards and greater slurry to store

Long term – dealing with climate change and blocks of wet or dry weather

• Drainage – optimise this for wet weather, but it is equally important for dry weather too. Wet soils suffer damage to structure, becoming compacted. Damaged soils do not perform as well in any conditions, so improving drainage in wet weather will help you in dry periods
• Lime soils to keep paddocks above pH 6. A farm average of 6 means that some paddocks are below 6 and under performing, so aim for an average higher than 6
• Consider soil structure, chemistry and biology. A healthy soil will grow more and is more resilient, be that wet or dry. We can all do with widening our knowledge on soils; see GREATsoils | AHDB or attend events like RABDF Down to Earth or Groundswell
• Reseeds perform better in dry conditions. Are you reseeding 10–15% of your platform?
• Consider mixed species swards. Clover tolerates dry conditions and heat longer than rye-grass. Modern cocksfoot is worth considering, as is festulolium, but do your research and talk to an agronomist. In 2018, a Teagasc study showed a six-species sward outperformed two rye-grass plots by 1.3 t and 3.1 t DM/ha
• If growth and tonnes produced has changed, review your stocking rate. Look at the rolling average over last five years, and check how growth compares to your demand

After rain arrives

• Take a spade out and check how much moisture is in the soil. Is it just in the top layer? How long will that last without further rain?
• If there is rain in the forecast and you are confident in above-60 growth continuing over the next few weeks, then maintain a 21-day round. Take off surplus if there is any, and drive milk from vegetative swards