By Marianne Curtis
SOIL sampling and making the most of slurry and manure are likely to be more important than ever this spring, as producers aim to reduce input costs.
That is the view of ADAS Gleadthorpe adviser Brian Chambers.
“Slurry and manure have never been valued particularly highly.
“But as the economic climate worsens, they can provide a useful source of nitrogen and particularly phosphorous and potash.”
Ideally, slurry should be analysed. However, book values can provide a useful guide, says Fieldfare Associates consultant Mike Dewhurst.
“Total nitrogen loading should be less than 250kg/ha a year – equivalent to no more than 80t/ha of cow slurry a year.
“A sensible slurry dressing in spring of 50t/ha delivers about 50kg/ha of nitrogen, 30kg phosphorus and 160kg of potassium, a good starter dose for silage.
“These slurry values should always be deducted from a crops total needs before applying fertiliser.”
Savings of 30-70/ha (12-28/acre) are possible through making better use of slurry and manure, says Dr Chambers.
“ADASs computer program MANNER takes account of nitrogen availability from manure and slurry, rainfall and method of application.
“This allows replacement rates for slurry and manure to be worked out and fertiliser rates to be calculated for individual farm situations.”
But Dr Chambers advises delaying fertiliser applications after recent rain.
“Although many areas are reaching T°-sum 200, recent wet weather means care is needed.
“Delaying fertiliser applications for a week or two until ground dries up wont make much difference to grass growth.”
But getting the balance of nutrients correct is critical to get the most from pasture, says Dr Chambers.
“Now is a good time to do soil testing: Increasing numbers of producers are taking samples themselves, as many fertiliser companies no longer offer the service free.”
Soil analyses collected by Hydro just before Christmas showed residual nitrogen levels similar to last year, according to its head of agronomy Jim Lewis.
“High rainfall since Christmas may have pushed residual nitrogen levels lower than last year.
“But the recent warm spell means mineralisation and nitrogen release will boost levels.
“The overall effect is likely to mean similar residual levels to last year.
“But making better use of slurry and manure is likely to have a far more significant effect on reducing fertiliser cost than considering residual nitrogen levels,” says Mr Lewis.
Another element that must not be forgotten is sulphur, says Dr Chambers.
“Sulphur deficiency can be a problem in high rainfall areas away from urban areas or power stations.
“Response to sulphur is generally seen for second and third cut silages.
“A plant test for sulphur should be carried out after first cut in areas where it is likely to be low.”
- The MANNER program is suitable for all PCs and can be obtained from ADAS free of charge. Call 01623-844331 for further details.