EVEN under the most sympathetic management, the structure of soil can pose a limiting factor to crop performance.
The benefits which soil conditioner products can bring in these cases are well documented. The trouble has been finding one which works well and fits into an arable budget, explains Dr Keith Dawson of CSC Cropcare.
"Most are intended either for the amenity sector or for high value vegetable crops."
But about five years ago he brought back a product, Agri SC, from the US which seems to deliver results and, at about £17.50/ha (£7/acre), fits into a broadacre context.
Based on ammonium laureth sulphate, a derivative of lauryl alcohol, Agri SC mimics naturally occurring humic compounds such as sugars which arise from the decomposition of organic matter in the soil.
A qualified soil scientist, Dr Dawson is by nature very sceptical of products that "claim the earth".
But as technical director of a company which has the biggest potato consultancy in the north of the UK, he also feels obliged to try them, as much to find out which products he should advise against – and which he can advocate.
After four years of replicated trials by the company and field scale trials by growers the results are very encouraging, says Dr Dawson, with yield increases up to 10% recorded.
"This soil conditioner can also form a useful part in an integrated programme to control powdery scab in potatoes," he states.
"Though we have no truly heavy soils in Scotland, the surprise is that Agri SC works on both light and heavier soils."
In loamy soils, he explains, it acts as a glue, sticking small particles together to form larger aggregates, and therefore improving the drainage.
Conversely, in coarser sandy soils it attracts water to the soil particles and water retention is improved.
This dual phenomenon has also been witnessed by Jimmie Simpson, farm manager at Rose Farm in Cromarty and a CSC Cropcare customer.
"Where you have hollows and humps across the field, Agri SC helps drainage in the areas where water tends to gather, while the places prone to dry out hang on to moisture better."
Mr Simpson first used the product on a trial basis five years ago. The results were so convincing that, after just two years, its use was extended across all 51ha (127 acres) of seed potatoes.
Using the farm sprayer, Agri SC is applied in the second part of February, weather permitting, giving the product time to start working before planting begins in Cromarty, generally at the end of April.
While Mr Simpson enjoys the sight of healthy looking potatoes growing uniformly across the field, the main benefit for him comes right at the end of the growing season.
Firstly the unmanned Richard Pearson harvester runs along, like the proverbial knife through butter, lifting at rates of about an acre per hour.
But secondly and more importantly, he says, the potatoes come out beautifully clean, despite Rose Farms silty loam soils being quite tacky.
Because soil doesnt stick to the skin, imazalil (Fungazil 100 SL) applications give better coverage and, therefore, better keeping in store.
This fits the Tibre (Targeted inputs for a better rural environment) guidelines which Mr Simpson follows.
It also means the farm stays one step ahead of specifications laid down by Tesco, whose Natures Choice contract growers are the destination for the seed it produces.
Some of the potato production takes place on rented land and Mr Simpson finds that he has acquired preferred tenant status.
The effects of Agri SC seem to last at least a year and the landowner invariably benefits from a fine cereal crop after the potato harvester has moved out.
While Mr Simpson uses Agri SC wholesale across the potato crop, somebody using it to crack a very specific problem is Tony Ponder, who manages Dammerwick Farm at Burnham on Crouch in Essex for Strutt and Parker.
Ever since he took on the farm, one particular field has vexed him.
Originally two fields with the dividing ditch filled about eight years ago, one half repeatedly yields significantly less than the other, most noticeably in sugar beet, but also cereals.
Finally this year, on the recommendation of a neighbour, he has tried the soil conditioner approach. Agri SC was supplied by Kings Lynn-based Bio-Fertilisers, whose K-Komplex plant stimulant and microbial activator he was already familiar with.
Applied in March soon after drilling peas, Agri SC appeared to be taking effect already by the time of a test dig at the end of May.
This was despite the interim two months being extremely dry – the product is said to work faster where rain or light irrigation follows application.
While Mr Ponder stresses that he can only judge the product on what he saw on that one day, he admits that the soil structure definitely seemed better and more friable.
"We dug in several places and the ground wasnt as hard as before. It did rather surprise me.
"I was amazed to think that half a litre per hectare could make a difference," he adds.
If the good results are borne out through to harvest then he will consider continuing the treatment at the reduced rate of 0.33 litre/ha.
However, Dr Dawson cautions against cutting the soil conditioner rate as trials have shown that efficacy drops off rapidly as rate is cut.
When traditional cultivations fail to achieve
the desired results, consider adding a soil
conditioner, suggests Tia Rund.