Nitrogen test is major part of winners plan
Closer attention to nitrogen inputs can pay dividends when
growing malting barley. Andrew Blake relays the plans of
last years LIncs-based winner of the DuPont/farmers
weekly Barley-to-Beer competition
SOIL mineral nitrogen tests will probably have a much bigger influence on Lincs-based Mark Irelands future fertiliser policy. But until the concept of using measured available N reserves to drive applications is fully proven on his own land he intends to rely mostly on experience-backed dressings.
Limited yield potential on the unirrigated 1008ha (2490 acres) of mainly light land at Heath Farm, North Rauceby, Sleaford, means malting barley rather than wheat is the dominant cereal.
This year Mr Irelands 210ha (519 acres) of winter varieties are Rifle, grown for the first time under contract, and Halcyon. Optic and Cooper, as last year, account for the 251ha (620-acre) spring area, Cooper having provided the competition winning sample.
"We have reverted to Halcyon from Fanfare, Regina and Puffin to try to make sure we get a good premium to offset our lowish yields," he says. Too many producers growing the high-yielding newcomers could further erode their relatively small premiums, he reasons.
N test worked
Last years first time soil mineral N tests, carried out by ADAS, highlighted scope to optimise nitrogen inputs. A small trial showed that where Mr Ireland used a higher fertiliser rate recommended on the strength of the tests, he gained an extra 0.27t/ha (2.2cwt/acre) without compromising malting quality.
This year he has opted for a much cheaper sampling and advisory service conducted by Boston-based Ian Scard using Anglian Soils Analysis and the HRI, Wellesbourne WellN recommendation programme.
WellN takes account of a wide range of factors including winter rainfall, planting and harvest dates, previous cropping, yield and residue disposal.
"We have done four complete fields chosen entirely at random, three of spring barley and one winter," says Mr Ireland. "The samples were taken on Feb 5 and we had the results back on the 14th. Last year it cost us £87.50 a sample. This time we are getting the same information for £32.50 which swung it Ians way.
"We shall do very much as last year, using our normal dressing on most of the area and running small trial strips on the basis of what WellN is telling us.
"I particularly like the look of it because its recommendations are not too far away from what we have applied in the past." Last years advice from ADAS was to use nearly one-and-a-half times his normal rate, he notes.
"Another point I like about Ians system is that it tells me that if I put on 125kg/ha on one field I should get 6t/ha; but if I use only 100kg/ha, to make sure of low grain N, the yield should only drop to 5.9t/ha. That is just the sort of information I want."
"I am also interested to see that the recommendation shows straw as well as grain yields. It seems a bit more detailed than the ADAS system."
He has slight reservations over using the WellN model because it was originally designed for vegetable growers and does not cater for barley. But Mr Scard is confident its wheat recommendation can be extrapolated to cover the malting crop.
The advice, based on sampling to a maximum depth of 60cm (2ft), offers a range of applications including an optimum, defined as the level where a further 10kg/ha of fertiliser N increases yield by less than 1%.
In the past ADAS monitoring of the Nitrate Sensitive Area on part of the farm has provided useful guidance on N needs. But Paddy Johnson, in change of the porous cup exercise, says analysis of the results for MAFF is currently carried out only at the end of the season to detect the effects of different cropping regimes.
The farms usual N dressing for winter barleys, whose average yield is 6.05t/ha (2.4t/acre), is about 120kg/ha (96 units/acre) in two splits, mid February and early March to avoid leaching.
Spring barleys, averaging 5.7t/ha (2.3t/acre), get at most 100kg/ha (80 units/acre) as third cereals. "We drop to 90-93kg/ha for spring barley after sugar beet," says Mr Ireland. Beside a small amount as seed-bed compound the bulk goes on in a single shot at the 1.5-2 leaf stage. Any later dressing could risk high grain N, he explains.
Apart from one slightly odd result on a field tested last year, this seasons sampling suggests heavy January rain, 84mm (3.3in) on top of 164mm (6.5in) in Oct, Nov and Dec, has leached most of what might have been available to crops this spring. The bottom line is that WellN advised rates are slightly higher than Mr Irelands own plans.
Top quality, solid fertiliser, now SP5 rated, is used to avoid uneven top-dressing jeopardising malting quality. "We use a Lely Superbowl spreader working on 24m tramlines and wont use anything other than top grade UK products. For the past 10 years that has meant Nitram or ExtraN. Personally I prefer the latter because not being a prill it spreads sightly better. But Nitram has won on price for two years."
Mr Ireland acknowledges the potential of using soil mineral N testing, but is in no hurry to abandon his tried and tested approach.
"What we need to do is build up a database using both methods. It would take three to four years of consistent results in favour of soil testing to get us to drop what we have done in the past." *
Careful dosing of N maximises yield and protects spring barley quality – a key element of Mark Irelands 1997 Barley to Beer success.
Heath Farm soil mineral N test results and recommendations (kg/ha)
Crop Reserves* Ireland WellN
Spring barley (after beet) 28 93 125
Spring barley (after beet) 18 93 100-125
Spring barley (3rd cereal) 63 98 100-125
Winter barley (2nd cereal) 10 120 125
* All equate to soil N index of zero.