Soil moisture deficit (SMD) are really impacting on grass growth in many areas of the country, however it is variable across the country and even within farms. Heavier ground is growing more grass than drier ground, newer ryegrass swards are growing more grass than old pasture and farms with higher soil fertility are growing more grass in general than those with poorer soil fertility. Demand is also very variable; some drystock farms have low demand and will only need a few tweaks while others have very high demand so each farm needs to look at their own individual situation.
Nevertheless from PastureBase Ireland we can see everywhere is growing some grass and this need to be encouraged with the application of fertiliser while the SMD remains below 60mm. Tailor fertiliser applications based on current soil moisture deficits in your region depending on weather conditions and grass growth rates. Where conditions are suitable (Good grass growth rates) apply 20 units N/ac , use a compound if possible (18-6-12+S) to maintain grass growth. However, if drought conditions persist to > 60mm soil moisture deficit it is advised to delay N until rain is forecast especially on bare swards. Research shows that protected urea will give a similar grass growth response to CAN under the current dry conditions.
Maintaining covers, sticking to a rotation, reducing demand if necessary and acting now are the key management practices to getting through this period. With an average growth rate of 60 kg/ha, a 23 day rotation is required to achieve 1400 kg DM/ha pre-grazing cover (i.e. 1400 / 60 = 23 days). However as the dry weather continues it is unlikely that a growth of 60 kg Dm/ha/day will be achieved going forward, if we look at the east and 54kg DM/ha/day a 25-26 day rotation is required. A lower pre-grazing cover may have to be accepted in some cases but every effort must be made to try to hold a 25 day rotation.
|Current Growth rate kgDM/ha/day||Rotation Length needed||Pre-grazing Cover target kgDM|
To try and keep at least 1200kg DM/Ha growth will have to stay at ~ 50kg dm/ha/day, the
rotation at 25 days (grazing 4% of the available grazing area per day, or 28% per week) if growth falls below 50, the rotation will have to be lengthened in accordance to 30 days. Demand will have to equal or be lower than growth to maintain covers, the old adage it take grass to grow grass still applies, this may require supplementary feeding with hay/silage/concentrate. The introduction of supplementation should be done before grass supply on the farm declines to a serious extent. Below are some tips that can be used on farm to achieve your targets.
- Rotation length must be maintained at 24-25 days approximately. Effectively this means grazing no more than 4% of the grazing area daily. On a 100 acre farm that’s 4 acres per day.
- Keep in mind the dry matter of grass is high, so you will get longer out of paddocks.
- Graze down tight to 4cm, otherwise feed is being wasted
- Assess the grass available on this area and if you are grazing more than 4% per day you should supplement with forage/concentrate to balance herd demand
- For example, on 100 acres graze 4 acres per day, 28 acres per week, if you see you are grazing down to 4cm or less and exceeding the 4 acres per day you will need to supplement with silage, hay or concentrate.
- Reduce daily grass demand if necessary 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
- Strip graze strong paddocks
- Increasing rotation length beyond 30 days may lead to much reduced grass quality in current conditions (>50 kg dm/ha/day grass growth).
- Maintain fertilizer N applications after grazing apply 20 units of Nitrogen, use a compound if possible e.g. 18-6-12. Risk of N losses are low at present. However, if drought conditions persist to >60mm soil moisture deficit it is advised to delay N until rain is forecast. Do not use straight urea, Research shows that protected urea will give a similar grass growth response to CAN under the current dry conditions.
Applying slurry currently under the very dry weather conditions increases the risk of N loss through volatilization. It also presents a possible risk of burning of re-emerging grass under very hot & dry conditions. It is possibly best to hold slurry applications until rain is forecast to increase N recovery and reduce losses.
To reduce demand if required:
- Wean autumn calved cows and restrict, they are already in calf
- Prioritise spring calved cows, you need to get them back in calf
- Pay particular attention to heifers going to the bull to calve at 2 years of age
- Cull unproductive cows
- Look at supplementing cattle near finish, 5+ kg meal for 60 days
- Can you sell any stock?
- Graze paddocks meant for second cut silage if < 2,500kg dm/ha
- On sheep farms consider weaning lambs early and prioritise the grass on the farm to them, some steps that could be taken include:
- For lambs supplement with concentrates ad-lib where grass supply is below 7 days ahead, consider reducing for lighter lambs as covers exceed 10 days ahead
- Draft lambs 38kg +
- Consider establishing a finishing lamb group – most forward lambs (34kg+) separated and supplemented with 0.5kg meal at grass. This will maintain a steady drafting pattern and increase grass availability to the rest of the flock
- If ewes need to be restricted in the longer term some forage supplementation will be required to prevent excess body condition loss, hold rotation length at 25 to 30 days. Supplement until covers have increased to provide 15+ days grazing ahead with favourable growing conditions
- Sell off cull ewes
Feeding out tips for forage supplements in dry weather
- Dry conditions should make the task of feeding out much easier compared to spring. Each farm will have its own preference (based on facilities/machinery/labour) but the main aim remains to reduce total daily grass intake to the level of daily growth or below. Once available daily grass is known, some options for feeding are:
- Offer silage/hay to all cows in the grazing paddock. Silage allocation should be calculated to balance available grass on the paddock daily. Forage should be spread along a long linear distance (1m per cow) to reduce bullying.
- Baled silage can be fed at ANY stage after wrapping.
- Bales need to be consumed quickly so as not to heat, so feed a little and often. A typical bale made from surplus grass has about 200kg DM. Therefore 2 bales will provide 100 animals with 4 kg DM/head per day. Expected intakes of baled silage would be 3-4 kg DM for a 3-4 hour feeding period (mature animals) provided all animals have equal access.
- Do not open pit silage within 3 weeks of ensiling
- High fibre straights can be offered PKE/hulls/pulp at a rate of 3 kg per cow. Some farms choose to feed these in mobile feed troughs in the field. Note that citrus pulp does not work well in this situation due to its lower NDF fibre content.
- Ensure full access to clean water.
Take your first cut silage
- If rain is forecast apply slurry - Unlikely
- Do not apply slurry of there is no rain coming as you will get a crust and scorching
- Alternatively apply a compound fertiliser
Second Cut Silage
- Learn from 2018 - Only apply a max 30 units of Nitrogen per acre
- Preferably in the form of a compound like 15-3-20
- This will give the grass enough fertiliser to push on growth, if rain comes you can top up to the recommended rates (see table below); if rain does not come you can graze it and not waste fertiliser.
- You won’t lose the P&K, it will be there later when growth starts again
Whichever actions are chosen, it is vital to act now to ensure that grass supply is rationed out as early as possible. Plan to supplement until 3-4 days after growth exceeds demand.
Suckler to Beef farmer Sean Roddy from Kildare has had to make a lot of decisions to hold grass on his farm due to poor grass growth from high soil moisture deficits