When writing this column it’s either a feast or a famine when it comes to topics to ponder over; this month it’s a feast. Although we have thought spring was with us when daytime temperatures hit the high teens, a day later we have a frost.
Where we needed to apply Atlantis (iodosulfuron+mesosulfuron) it caused quite a bit of (transient – so our agronomist says) yellowing. Also the product has been very slow to work in one or two cases, but overall it has worked much better than last year. We still have black-grass even after two spring crops in one particular field, whereas land literally over the hedge sprayed with the same tank load half an hour later is squeaky clean.
With only 6mm of rainfall throughout April I doubt if much of the fertiliser applied to wheat reached its target. By the end of the month we had applied just over 200kg/hectare of N; this was a combination of 18:46:0 (DAP-combine drilled), 46% urea, 26:0:0:36S (N/S compound), and in addition to this we put on 87kg/ha of potash. Less nitrogen than we would have used in the past, but more sulphur and potash to help overall nutrient uptake on our hi-mag soils.
The spring wheat will have similar fertiliser inputs, with the exception of nitrogen which will be reduced by about 20%.
Disease-wise all winter wheat (JB Diego, Relay and Evolution) has remained clean, so we took the risk and omitted the T0 spray and have gone in with a more robust T1. This might be a mistake, but weather conditions are different from last year and the gap between T1 and T2 will be only 14 to 21 days.
Locally there was a lot of concern about pea and bean weevil attacking the spring beans which were slow to emerge due to the cool, dry conditions. To date we have not had to treat any crops, but the recent rain and warmer conditions might just change the situation. What is more of a concern is the level of emerging black grass in some of the crops, despite two hits this spring with glyphosate pre-drilling.
We were able to go in with an additional post-drilling/pre-em glyphosate on one or two fields, but that might not be enough, so it looks as if we will be applying quite a bit of Laser (cycloxydim). We have found angled jets (30 degrees forward and backwards) have really helped getting Laser into winter beans where the canopy was beginning to close up.
The spring beans drilled into cover crops were not planted until the middle of April as the soil did not dry out as quickly as it did where we had just bare stubbles. But soil temperatures were much higher (12degC) at the time of drilling. This combined with the no loss of soil moisture, meant the beans were through within 10 days, catching up those planted into cultivated seedbeds.
We still have a lot to learn when it comes to matching the cover crop to the following cash crop. This year our cover crop mixtures which contained deep-rooting brassicas, such as oil radish, left the soil in the most friable state and virtually weed free. Mixtures dominated by shallow rooting species, such as oats and forage rye were less successful and it was difficult to close the slot after the drill.
Much has been talked about companion cropping and oilseed rape, but very little work has been done in the UK with cereals. Purely an observation while top dressing winter wheat after beans – we had some spring bean volunteers which made it through the winter, only sprayed off in early April, the wheat around the decaying bean plant looked as if it had received another 100kg of nitrogen. It might just be the association between the two plants (mycorrhiza) which I was observing, not necessarily extra nitrogen.