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Power Stations and Black Spot

Date Added: 16/03/2016

Blog: by Richard Elsdon, Technical Consultant, United Oilseeds

As I drove home recently, I suddenly realised that throughout most of my life the plume of steam from the cooling towers of coal fired power stations, something I had taken for granted since a small child, had disappeared from the landscape.

This thought was reinforced by a recent article in the Guardian explaining that three out of the four Fidlers Ferry coal fired power stations at Widnes are to be closed. These power stations, like so many of the older models, have been closed by edict from the EU. My understanding is that whilst their emissions had been reduced  - they had not been reduced enough.

Industrial emissions have been reducing since the 1970s and are now at about 7% of the start level. This cleaner air may be good news for forests in Europe that had suffered badly from acid rain, but surprisingly, this cleaner air does have a down side as well.

You may have noticed that roses get black spot much quicker and more seriously than ever before. The sulphur in the atmosphere - and more particularly in the rain - acted as a mild fungicide keeping the disease at bay. Lack of sulphur has also meant that oilseed rape and most cereals now need an application of sulphur bearing fertilizer in the spring, something that was unheard of when I became involved in oilseed rape in 1980.

In my innocence, I thought that all oilseed rape crops received an application of sulphur fertilizer. Wrong! The fertilizer usage survey tells us that that the figure is nearer 75%. Would this go some way to explain some of the lower yields that are reported every year?

Information released by ADAS reminds us that the optimum amount of SO3 to be applied in any season is about 75kgs per hectare. The way in which sulphur is applied is also important.  Animal manures that have been applied need to be taken into account -  both the amount applied and the speed of breakdown and therefore the amount available in the growing season. There is also the perception that sulphur based fertilizer needs to be applied early in the season. This is not the case. It needs to have been applied by the time the crop is in green bud, so time is not pressing just yet.

The form of sulphur has created some debate. I have been told that while ammonium sulphate is one of the cheapest sources of sulphur. it can lead to short term acidification of the soil. My preferred source would be Kieserite as it supplies both sulphur and magnesium, which is very helpful in some high pH soils and in addition it avoids the acidification issue.

The demise of sulphur belching power stations and rise in black spot on your roses should serve to remind us all that the oilseed rape crop needs the appropriate amount of sulphur. Please ensure that it is applied, as not doing so will seriously reduce your yield.

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