27 May 2020
Chris Duller, Soils and Grassland Specialist
Normally in late May, grass would be approaching peak growth, with growth rates of over 100kgDM/ha/day being achieved and concerns would be about grass getting away from stock. The reality this year for many parts of Wales is that a prolonged dry spell has seen growth rates plummet to less than 30kgDM/ha/day.
Before panic sets in about forage shortages, it should be pointed out that we still have half the growing season left, so there are plenty of opportunities to ‘right the boat’. But action taken over the next couple of weeks could have big impacts if this dry spell extends into July.
1) Managing grazing
Be careful not to chase grass. As growth rates decline, there is a danger that rotation lengths shorten and farm grass covers crash which will slow down recovery when rain does finally come.
Buffer feeding should start now to keep rotations beyond 16 days.
Back fence to prevent stock from grazing any new leaf growth. If they graze that new growth too soon it will reduce root mass; the last thing you want to do in a dry spell.
Hit your residual targets by not grazing too tightly as you will increase soil moisture loss and slow regrowth. But at this time of year with grass heading, you still need to graze to 1,500kgDM/ha to ensure quality in the following grazing rounds.
Adding more ground to the grazing platform by grazing silage fields is only really an option with covers below 3,500kgDM/ha. Once covers get too strong the level of wastage will rocket upwards; the last thing needed in a forage shortage is lots of wastage.
Don’t forget that grazed grass is half the price of silage. Don’t be tempted to feed bales whilst there is an option to graze a light silage crop (as long as wastage is kept low).
2) Silage issues
Those that cut decent crops in early May can feel suitably smug, although, re-growths are very slow, second cuts may be delayed and grass is heading strongly in many aftermaths.
Be careful with fertiliser on these aftermaths. With dry cracked ground there is always the risk that a dry spell ends with a heavy thunderstorm and nitrogen can be lost quickly through run-off and by-pass flow (down the cracks and into the drains), therefore, keep any rates low (<40kgN/ha). Ideally, wait until there is some chance of some steady rain in the forecast, soil nitrogen supplies won’t be low so there’s no urgency to rush out with the spinner.
Similar advice applies for those that would normally shut out in May for late June/July cuts. If there’s a few millimetres of rain in the forecast then take the opportunity to get some fertiliser out – if not, then sit tight.
Although it’s been dry, soil nitrogen mineralisation has still been happening, therefore, soil N levels will be fairly high. There is the potential for a bit of a nitrogen surge into crops when the rain does come, therefore, I’d be inclined to drop your standard rate back by 20-30kgN/ha (16-24 units/acre).
Be careful with any slurry/dirty water going out. The irrigation value is minimal and nitrogen losses are significant in dry weather. Also, the risk of leaf contamination is high. A dribble bar/trailing shoe would be essential.
3) Reseeds and crop management
For crops in the ground, there isn’t a lot we can do but sit it out. Most crops that went in in early/mid-April are advanced enough to survive but any crops drilled within the last couple of weeks may struggle.
If you are thinking of reseeding or getting crops such as swedes in the ground in the next few weeks, then seed bed preparation should be all about keeping moisture in the soil. Avoid overworking the soil, roll and roll again. There is a danger that seed can go too deep in a dry fine seed bed and soils worked in dry conditions can easily cap or move when rain does come. If you are yet to decide which field to plant with swedes…don’t pick the one with the steep slope and the light soils.
There is time left to establish swedes. In 2018, we saw late drilled crops emerge in August and still made decent yields.
If you are thinking that silage stocks may be in short supply then Italian/Westerwold crops may be an option to boost your forage supplies and save the permanent reseed for next year. There may also be opportunity over the next few months to establish forage crops for winter grazing; so reducing demands for silage. Make your plans now and buy the seed early as plenty of other farmers will be having the same idea.
Oversowing is just a nonstarter in dry weather. There is no chance of keeping the shallow tilth layer moist enough for the seeds and drill slots will tend to open up and leave the seedlings hanging in the air. Leave the seed in the barn for a few more weeks.
4) Stock management
Impending forage shortages should immediately trigger decisions about how to reduce demands on the farm.
- Sell the barrens now, take the hit on the price and get rid.
- Wean early and tighten up the dry stock.
- Condition score everything and identify anything that can go onto poorer ground.
- Creep feed and get stock away early. Whilst animals are young their feed conversion makes it economic to creep but less so by the time we get to late summer.
Natural water supplies are low in many areas and grass dry matters are well over 25%, therefore, stock will be looking for water and this can have a huge hit on milk production. Make sure all troughs are running and clean.
Many farms will already be 10-20% down on forage growth due to low soil moisture levels and it may get a little worse for some. Take action now to safeguard what forage you do have and make plans for boosting forage supplies later in the year.