1) Better understand which type of crops may respond most to foliar N
2) Assess whether the Yara N sensor can be used to identify the areas of field which respond most to foliar N
3) Identify the optimum timing of foliar N
4) Quantify the effect of foliar N on the nutritional value of the rape-meal
Twenty two experiments by ADAS & Yara over 8 seasons have shown that 40 to 50 kg/ha of foliar Nitrogen applied to oilseed rape at the end of flowering increased seed yield by an average of 0.35 t/ha where applied in optimal conditions. ADAS experiments also found that foliar N decreased seed oil concentration and increased seed protein concentration by 1%. Timing experiments indicated that similar sized yield responses could be achieved from applications between mid-flowering and 2 weeks after the end of flowering which indicates there may be potential to apply foliar N with Sclerotinia fungicides.
2012-13 Experiments
In the cropping season 2012-2013, experiments were set up near ADAS High Mowthorpe with variety Catana on a shallow silty clay loam over chalk and near ADAS Terrington Excalibur was grown on a deep silty clay loam. The work was to investigate how different plant populations and soil applied N fertiliser rates affected the yield response to foliar N. Both experimental sites were established by Oyjard drill, at 125 mm row widths at ADAS High Mowthorpe and 180 mm row widths at ADAS Terrington.The matrix of trials utilised seed rates of 20, 60 and 120 seeds/m2, then over treated with soil applied N fertiliser rates (AN) of 50, 250, 380 kg N/ha and then followed by foliar applied N fertiliser rates (Chafer Nufol 20) at 0, 20, 50, 120 kg N/ha
In February at both sites the soil mineral N was 37-41 kg N/ha and the crop N was small (<20 kg N/ha). This gave an estimated optimum fertiliser N requirement of 250 kg N/ha at both sites.
At the ADAS Terrington site a timing experiment was set up in which 50 kg foliar N/ha was applied to the crop weekly from GS3,3 (green bud) for nine weeks. This was a replicate of a similar experiment hosted by Yara in 2011-2012.
Results for seed yield 2013
At High Mowthorpe (Figure 1): The average yield at 250 kg soil applied N/ha was 3.49 t/ha. The average yield response to 50 kg/ha foliar N/ha over 50 and 250 kg/ha was 0.17 t/ha. Yield responses to foliar N were larger at the lower soil applied N rates. At 50 kg Soil applied N, foliar N at 20, 50 and 120 kg N/ha increased yield by 0.18, 0.24 and 0.26 t/ha. However yield responses to foliar N also occurred at the super-optimal soil applied N rates, for example at 350 kg soil applied N/ha 50 kg foliar N resulted in a yield increase of 0.18 t/ha. The high soil applied N rate resulted in yield reductions compared to the medium soil applied N rate due to lodging. The seed rate had no effect on how foliar N affected yield.At Terrington (Figure 2): The average yield at 250 kg soil applied N/ha was 5.18 t/ha. The average yield response to 50 kg/ha foliar N/ha over 50 and 250 kg/ha was 0.18 t/ha. At 50 kg soil applied N/ha, foliar N at 20, 50 and 120 kg/ha increased yield by 0, 0.22 and 0.19 t/ha. Effects were smaller at the higher soil applied N rates with an average yield response to 50 kg foliar N/ha of 0.06 t/ha. There was no lodging at Terrington. The seed rate had no effect on how foliar N affected yield.
On the Terrington timing experiment (Figure 3): The average yield for this experiment was 3.03 t/ha. The greatest yield increases to 50 kg foliar N/ha were from the early applications at yellow bud and late green bud (0.19 t/ha). Applying foliar N after yellow bud had no substantial effect on yield.
The Yara timing experiment (Figure 4): The average yield for this experiment was 4.06 t/ha. The greatest yield increase to 50 kg foliar N/ha were from the application four weeks after green bud (0.27 t/ha). Application at GS3,3 also resulted in a relatively high yield increase of 0.2 t/ha.
For more information
Dr Pete Berry
01944 738646
Dr Charlotte White
01623 844331