Climate and rotation

13 Aug 2014

My final pre-harvest prediction of wheat yields was superseded by the actual harvest! As expected, yields are exceptionally high in some areas. The reported variable yields must in part be explained by the variation in June rainfall, which was a result of localised storms rather than frontal rain. Solar radiation in June and July was well above average and temperatures were not too high until the very end of ripening.

It was on a recent and beautiful sunny Sunday morning that I noticed that my neighbour’s leylandii hedge appeared to be dying. The Cambridge Council tree officer was kind enough to visit and said it was due to the high number of aphids that had survived the exceptionally warm winter. Apparently, this is the worst year in living memory for such damage. So, my neighbour and I have sprayed thrice with a legal neonicitinoid, but there may be lasting damage to the hedge.

Is this a result of a warming climate? There are other clues in our garden. For instance, this is also the first year that I have had to spray my zonal pelargoniums (geraniums) against rust. From a personal point of view, after a shower my hair now dries three or four time more quickly than when I was a teenager, but my wife diplomatically points out that there could possibly be less of it.

The mild winter has had its impact on UK agriculture. The challenge from yellow rust in wheat has been exceptionally high. The only compensation is that there appears to be no resistance in yellow rust to the major groups of fungicide used on wheat. The mild winter and early drilling may also have contributed to the difficulty in controlling triazole-resistant septoria in wheat. All this has resulted in more flexible and expensive fungicide programmes, banging a further nail in the coffin of the old (T0), T1, T2 and T3 approach.

One problem with the exceptionally mild winter was that there was little or no frost tilth present on the heavy soils when the spring crops were sown. This problem was magnified by the fact that it was extremely wet in the early spring and, in many areas, when it eventually turned dry there was little further rain in the following two months to support crop establishment. In the ‘old days’ this could have been disastrous because the seedbed cultivations would have dried out the soil resulting in poor and slow crop germination. In fact, this is what happened in some cases this year when a combi-drill was used. However, where the crops were established into autumn cultivated land with a single-pass disc or with a disc direct drill the germination, establishment and initial growth was superb despite the very dry March and April.

This experience is great in order to convince those farmers who are knee deep in black-grass to consider adopting spring cereals in order to break its life cycle. Possibly one of the reasons for their reluctance is the memory of trying to establish a spring cereal crop in conditions similar to this year. The thing is that equipment has changed dramatically since they may last have tried to do it, and now we have better machines for the job. These make spring-sown cereals a much more resilient and sustainable cultural control option. I must admit that I am not a ‘tyre-kicker’ and this is perhaps the full extent of my knowledge on drills, but I think that I have made my point.

Talking of difficulties with drilling and crop establishment, we’ve just had a visit from a NZ farmer who reports the trauma they have recently been going through whilst trying to establish autumn-sown cereals and small-seeded crops.

They have had exceptionally wet and dull conditions for months. Lack of sun resulted in disappointing wheat yields and the rain meant a difficult and delayed harvest. In the main area on the Canterbury Plains, especially on heavy soils, there have been few small-seeded seed crops and winter wheat crops established in their autumn. Some crops that were sown have failed. The only realistic option for many farmers in this part of the world is now spring barley.  

It is their worst late summer and autumn for arable farming in living memory and confirms that we are not the only ones who suffer from prolonged periods of extreme weather.  Such events plus that of pesticide resistance and pesticide withdrawals mean that farming and the supply industries must adjust to a more flexible approach.  In the UK, sowing spring crops on heavy soil is now part of that desired flexibility. The old certainties seem to be disappearing.

NZ Canterbury Plain - autumn drilling 2014

June on the Canterbury Plains in New Zealand. This is a time of year when fields should be green with vegetable seed crops, grass seed crops or winter wheat. The grass margins provide a firm base for the passage of linear boom irrigation equipment along the field (when needed!!!).