Losing flexibility

6 Jun 2014

The level of risk management in arable cropping in many parts of Australia is awe-inspiring. Choosing the correct crop to grow and the level of inputs that will be required in relation to current (and future) weather conditions is critical. There are severe penalties for getting it wrong. Applying nitrogen in a dry year will reduce yields whilst there are enormous benefits from its use in a ‘wet’ year. Our decision-making over the last few decades has been by comparison straight-forward as witnessed by our relatively stable year-to-year yields.NIAB TAG Blackgrass Research Centre

However, things are changing for many UK farmers and the catalyst is black-grass resistance. No longer can herbicides be used to negate the risks involved with a totally autumn-sown rotation. This year many September sowings of wheat are severely infested with black-grass despite the huge use of herbicides. As every farmer knows, delaying sowings significantly increases the risks to crop establishment and yields.  

I gave a paper to the 1995 BCPC Brighton Conference entitled ‘crop technology; a flexible friend for the farmer and the environment’. In it I argued that the challenges of future food production whilst still protecting the environment would be best served by having technology that would give us the flexibility to manage crop production effectively. I did mention the possibility of pesticide resistance reducing this flexibility but the paper was written before the birth of another threat namely the EU Drinking Water Directive. This is putting the growing of oilseed rape at risk because the key herbicides can move to water in quantities that exceed the 0.1 parts per billion specified in the Directive.

So the question must be how do we react to the current situation? We discussed this when my colleagues in TAG Consultants visited the NIAB TAG Black-grass Research Centre last week. The bulk of the time was spent on the current difficulties in controlling black-grass and its impact on farming systems. All the alternative strategies put forward would result in a lower bottom line.NIAB TAG's John Cussans at the Blackgrass Research Centre Open Day

There are a few different approaches that may be taken but all of them must take into account the need to reduce background black-grass numbers. Lower background numbers would ensure greater flexibility because one would be further away from the cliff-edge of disaster.

Everyone is aware of the relative benefits of the different cultural control measures and the days are gone when many considered a mere tinkering with crop management was the solution. A major problem is that the full economic impact of the different approaches is almost impossible to predict accurately. There are not many heavy land farmers who have had a disaster from growing spring barley over the last few years, despite their own sometimes severe misgivings before they re-adopted the crop in order to reduce black-grass numbers. However, they may have a bad year or two in the future. On the other hand, there are many farmers who have regretted adopting later autumn sowing. One possible response to this is to choose varieties of wheat and barley that can be either late-autumn or spring sown.

A variation of this approach, straight out of the Australian ‘rule-book’, is to store home-grown undressed but tested seed of autumn and spring crops and/or varieties and to take advantage of any weather window that presents itself. Perhaps it is not necessary to look to the other side of the world for an example of this option. In parts of France farmers will grow sunflowers when the previous autumn has been too dry to establish oilseed rape.

An attractive option for many is to set out a rotation that contains sufficient spring sown crops in order that when winter wheat is grown it can be sown sufficiently early to optimise yields whilst reducing the risk of wet weather delaying or affecting the quality of establishment. The issue of winter oilseed rape is perhaps another debate; it is not easy to design an effective weed control programme that does not risk pesticide movement to water at a level that exceeds that specified by the Drinking Water Directive. Water Companies can generally deal with small exceedances but not the major peaks of concentrations that can occur.

This is the time of year to look at the level of black-grass infestations and to mull over the future. One thing is certain, there are no immediate prospects of miracle herbicides and so things will not get any easier.