Charlie--chalk
Member
- Location
- Hampshire
Just wondered on the question above. Cheers
It's the first time growing winter osr for me so I've not had any experience with it hence the question. My index's range from 1.7 to 2.6. Seeing the agronomist next week so wanted half an idea. Cheers, Charlie
Went out and cut and weighed a few m2 yesterday and have between 55 and 75 kg/ha of N in the crop. According to the formula in the Strategies 3 NIAB document, that means applied spring nitrogen requirements of between 105 and 155 kg/ha. Then again we bought our Nitram at £170/t which equates to 50 p/kg which, combined with OSR where it is now, would mandate, according to RB209, roughly another 50 kg/ha of N. I'm not sure though whether that formula is that sensitive to N vs OSR price though.
I note the strategy document say 160 kg/ha for exceptionally large canopies and 200kg/ha for large (average) canopies. So my view would be you should just aim to apply the 155kg/ha or somewhere between that and 200 kg/ha (that would get you to the RB209 amount) - not more complicated than that, but split the timings to put more of it on towards the later usual timing - ie green bud / latest time spreader will get through crop. But you do need some sulphur on early and thus your choice of S N fert will drive the decision process as well. Examining the dose response curves can be 50 kg/ha either side of the optimum and be correct. Hey ho
So your timing of the second dose will be determined by the canopy size? Are you using liquid or solid?