Nitrogen effciency matters
Rapeseed needs large amounts of nitrogen.
Choosing a readily available nitrogen form therefore makes a difference. What are these differences?
Yield, oil yield and nitrogen uptake
Recent field trials in France revealed significantly higher performance of ammonium nitrate when compared to urea and UAN. Better results were recorded in all three areas of interest: uptake efficiency, yield and oil yield (figures 7). Lower efficacy of urea and UAN reduces the N uptake by 15 and 30 kg N/ha respectively as compared to AN and causes therefore avoidable nitrogen losses through volatilization and leaching.
Rapeseed yield (top), oil yield (middle) and nitrogen uptake (bottom) with ammonium nitrate, urea and UAN at identical application rates of 180 kg N/ha. Ammonium nitrate produced 1,4 dt/ha more yield than urea and 2,2 dt/ha more yield than UAN, 3,2 % more oil than urea and 4,6 % more oil than UAN as well as a higher uptake of nitrogen compared to urea (+16 kg/ha) and UAN (+35 kg/ha) [6].
Figure 8 compares GHG emissions for biofuel production from rapeseed, using different nitrogen forms from different origins. Nitrate fertilizers from European plants are the best allies to meet the GHG savings imposed by the European biofuel directive in 2017 and 2018.
