Most livestock farmers will be faced with wet, compacted soils this spring, but what needs to be done to ensure productivity is not compromised? Aly Balsom finds out
Many will say chemistry is at the heart of a long-term relationship, while others will say it’s all about the physical stuff – most will agree it’s a bit of both.
However, when it comes to soils, many farmers could be paying too much attention to the physical side and neglecting the chemistry – something which could be compromising their long-term relationship with their land.
Independent consultant Josephine Scamell of Ground Level Nutrition, says failure to address soil mineral balance and biology, along with physical structure will only result in a short-term fix and cause ground to become structureless and unproductive.
“Ensuring soils are healthy with the correct physical and biochemical balance will also mean ground is more likely to cope with weather extremes and recover more quickly,” she says.
Mrs Scamell suggests the following areas for attention:
As soon as possible, go out and dig a hole. Only then will the extent of any problems become clear. Remember to evaluate earth worm activity – they are a valuable indication of soil health.
Many farms will have waterlogged soils which will have suffered from long-term anaerobic conditions.
This may have caused “slumping” – a term used to describe a structureless soil which no longer has a desirable “crumb like” structure.
If this happens at the same time as machinery or livestock traffic, compaction will be a problem.
1) Surface compaction
• Caused by livestock traffic
• A tight, compact, slumped layer will be formed on the first 4-6in
• There may be an open crumb structure below.
• Surface slit aerate soils when ground has dried out enough (March-April)
• A vehicle should not create track marks and the slits should not cause smearing
• Carry out a full, detailed soil analysis to assess what’s going on at a chemical level.
2) Machinery/deep wheel compaction
• Likely to be more extreme on maize ground after last year’s wet harvest
• Could be at significant depth, possibly in excess of 18in
• Failure to address will result in soils remaining in an anaerobic state for several years and becoming unproductive
• If there is compaction down to 12 inches, deep flat-lift 1-2 inches below the compaction layer
• Only deep flat lift when ground is dry enough. If ground has not dried out enough this Spring, it may be worth waiting until Autumn.
• Compaction must be addressed before putting in an expensive crop.
• Depending on farm situation, a grass seed mix could be power-harrowed in in the interim
• If you need to put maize back into damaged ground, it’s important to rejuvenate soils first.
• If ground is too wet to deep-flat lift it is worth considering moving maize to another field – viability will need to be assessed on a field by field basis
• Some farmers may need to question the acreage of maize they grow – Can you grow quality grass instead of maize? Soil recovery and crop productivity needs to be factored in to the cost of growing maize.
Many ditches will be clogged up with silt and debris following extended wet weather. Ground compaction will have exacerbated the problem with greater surface run off as a result.
• Clear ditches and waterways to encourage drainage
• Improving soil structure and chemistry will also encourage water to percolate through soils and reduce run-off
CHEMISTRY AND BIOLOGY
1) Carry out a full detailed soil analysis
What is it?
A detailed soil analysis includes regular analysis for N, P, K and pH, but also tests for organic matter, physical soil character, major elemental balance (for example, calcium, magnesium, sodium and potassium) and trace element availability (eg. Sulphur, copper, selenium and zinc)
Test fields with the highest commercial value that are worth investing in, for example those which will reward the farm with profit.
• Actions will be farm specific
• In some, but not all cases, gypsum (calcium sulphate) may have a role to play in opening up soils, particularly on land that has been flooding for long periods
• High rainfall means many elements, including salt are likely to have been washed out of soils. Most farms will benefit from salt application this year. This will improve forage palatability and sward production.
2) Slurry additives
• Consider using additives made up of friendly bacteria and enzymes, to enhance the slurry’s biological benefit to soils and reduce its noxious toxicity
• These are typically applied to slurry when it is being stored for eight weeks or more.
BOX; Ed and John Frost, Melsbury Farm, Polsham, Wells
By addressing soil chemistry and structure, one Somerset dairy farm has been able to maintain exceptional milk from forage figures even in the monsoon year of 2012.
A whole farm soil improvement programme at Melsbury Farm, which borders the Somerset Levels, has resulted in better soil drainage. Consequently, cows were only housed for one week during last year’s grazing season.
“We did house three weeks earlier than usual, but this is a lot better than some surrounding farms,” says Ed Frost, who runs the 140-cow herd with his brother John.
Last year the 7,500 litre herd achieved 49% milk from forage- an improved figure from 2011. Cows also yielded 2,589 litres from grazed grass, compared with 2,529 litres in 2011.
In fact, the focus on soil management and forage quality started about three years ago when the farm decided to move towards this more grass-based system.
The Frosts started by deep flat lifting and re-seeding 40 acres of wet FBT land. However, when the changes made no difference, they turned to consultant Josephine Scamell.
Only then were they made aware of the need to address soil mineral imbalance. “We went down the physical route of addressing soils, but it made no difference. We were surprised it was the mineral aspect that needed addressing,” says Ed.
In-depth soil analysis on the farm, which is primarily heavy clay loam or peat land, showed high levels of magnesium relative to calcium which was causing the soil to slump. As a result, Mrs Scamell recommended application of gypsum (calcium sulphate) at 1t/acre for three years, along with farmyard manure and spring and autumn slit aeration.
Mrs Scamell explains: “The sulphate in gypsum is attracted to magnesium to form magnesium sulphate or Epsom salts. This is readily drained out of the soil, removing magnesium and leaving calcium behind,”
“The calcium ‘fluffs up’ the soil so there is more ‘pore space’ and added crumb structure. This improves soil drainage and water-holding capacity, while providing more air pockets for aerobic microbial function.”
To address sodium and potash levels, Silvernite (a natural potash salt rock) was also applied to ground. This year this will be replaced with salt (sodium) on some ground where potash levels are sufficient. This will help improve forage palatability and productivity.
As a result of improved soil management, John says grass yields have increased by 10-15%, something Mrs Scamell attributes to improved soil biofunction because ground has been opened up.
“We’ve also seen improved cow fertility,” says John. “We now have conception rates of more than 48% compared with 30-35% two years ago.” The brothers link this with working closely with their vet, as well as improved forage quality and less maize in the ration.
In fact this year, the farm will be reducing the amount of maize in response to a starling problem and increased risks associated with growing the crop. Consequently the focus will be on growing a more reliable and better value crop of quality grass.
“Good quality forage and getting cows out earlier will allow the Frosts to get the most from forage and also gives them the confidence to stop growing maize,” Mrs Scamell says.
Case study: Clyde Jones, Brixeys Farm, Bistern Estates, Ringwood, Hampshire
Herbal leys could enhance nutrient capture in ground prone to both waterlogging and drought.
As an alternative to a conventional grass mix, Hampshire dairy farmer Clyde Jones will be planting 17ha of a herbal mix on sandy ground coming out of an arable rotation this year.
In this case, the decision to grow ryegrass, timothy and white clover, with a selection of herbal varieties has been made in attempt to get more from drought prone land.
“The deep rooting of chicory and cocksfoot for example means these plants are more able to cope with lack of moisture,” Mr Jones explains.
On light soils where it is difficult to maintain nutrient levels (both in wet and dry conditions), deep rooting will also help retain organic matter. This is particularly important at Brixeys Farm where a programme of slit aeration and intelligent use of slurry has helped improve organic matter from 2.5- 3% over three years.
The mix will be planted in March-April and is likely to be grazed in a rotation or mob grazed at waste height.