Deep N Case Study

December 12, 2007

Farm manager, Malcolm Brown, has historically used coffee residue as a base for his nitrogen applications across 220 hectares of his arable land near Banbury in Oxfordshire. His soils vary from light loam over ironstone at the top of the farm down through loamy clays to river clay alluvium along the River Cherwell. The farm is also in an NVZ.

The coffee residue has a slow release (over three years) and Malcolm uses the Deep Nitrogen Testing service each year across every field on the farm to quantify the available nitrogen that the coffee is releasing. The sampling points are GPS logged on a W-pattern sampling regime so that each year's testing is comparable from season to season.

The soils are taken from the three distinct depths at each logged point and the field samples are batched before being sent in a chilled box to the laboratory. The results are then available within 3 to 4 days.

The analysis is used as a base for each field's application and as a justification for the balance of nitrogen to be applied. This is monitored through the season and the planned dose adjusted to meet with the expected yield requirement.

In the 2007 season the results ranged from a Soil Nitrogen Supply (SNS) index of zero (48.8 kgs/ha of available N including a
10 kg/ha in crop allowance) up to an SNS index of 5 (173.2 kg/ha of available N including a 20 kg/ha in crop allowance).

As a result of this Malcolm has been able to cut his bagged nitrogen by 50 tonnes across the farm and has applied specifically to each field's requirement.

Read more about the Deep N service

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