Overall nitrogen rates applied to arable crops saw a 5kg/hectare decrease in 2019 compared with the previous year. The total nitrogen use of 137kg/ha on these crops remained near the typical 140-150kg/ha range seen over most of the previous 30 years of the recently published British Survey of Fertiliser Practice.
The overall nitrogen rate for winter wheat and spring barley fell by 1kg/ha (to 185kg/ha) and 6kg/ha (to 95kg/ha), respectively. The overall rate for winter barley was unchanged at 143kg/ha, whereas the overall application rate for total nitrogen on oilseed rape decreased 8kg/ha to 180kg/ha, compared with 2018.
Commenting on the drop in N use on spring barley and OSR, Professor Roger Sylvester-Bradley, ADAS head of crop performance says: “Possibly the most logical explanation is that the winter [2018/19] was dry and warm, so there was less leaching of N before spring barley crops and better overwinter growth and N capture by OSR crops.
“If so, growers should be complimented for taking the conditions into account and saving costs to themselves and the environment.”
Overall, fertiliser phosphate and potash use on all crops and grass has varied little over the last five years with rates on arable crops about three times higher than those used on grassland. For arable crops in 2019, P use was 26kg/ha compared with a five-year average of 28.2kg/ha. K use in 2019 was 34kg/ha compared with a five-year average of 36.6kg/ha.
But Prof Sylvester-Bradley says it is important to take account of long term trends. According to the survey, overall phosphate usage on arable crops declined gradually between 1984 and 1996. Thereafter the decline in rates became more marked until 2009, after which there was some recovery and relative stability until 2018, when a 3kg/ha decrease to 27kg/ha was recorded.
Prof Sylvester-Bradley says: “The downward trend in P applications for arable crops is of some concern, given that we are finding P deficiencies are quite common. However, this may be mitigated somewhat by the increasing use of organic manures.”
In 2019, 62 per cent of arable crops received a dressing of sulphur, unchanged from 2018. Overall applications of sulphur on arable crops remained at 35kg/ha in 2019, the same as for 2018 and 2kg/ha above the five-year average.
In 2019, organic manure was applied to 26 per cent of the area of arable crops compared to 35 per cent for grass of five years old and over and 47 per cent for grass under five years old.
The Defra Farm Business Survey 2018/19, also recently published, revealed that 24 per cent of farm businesses carried out precision farming techniques to guide fertiliser application. Usage was more likely on cereal and general cropping farms and on farms with at least some of their land within a Nitrate Vulnerable Zone (NVZ).
Just over a quarter (27 per cent) of farms used soil nutrient software packages to help determine fertiliser applications. Again, usage was most common on cereal and general cropping farms and on farms with at least some of their land within an NVZ.
Nearly half of farm businesses (46 per cent) relied on their own non-FACTS qualified advice for nutrient planning, 26 per cent relied on independently supplied FACTS advice, and 23 per cent received advice from their FACTS-qualified fertiliser supplier.