Case study: Insecticide-free arable farming

Author: Martin Lines
Farm: Papley Grove Farm, Cambridgeshire: 160 ha farmed in-house plus 360 ha contract farmed

Aims:

In 2013, my agronomist recommended that I spray for black bean aphid, but conditions were too wet and windy for a period of ten days, after which aphid numbers had dropped and ladybirds were eating them, so I decided not to spray and saw no detrimental impact on my gross margin. This got me thinking about the pros and cons of insecticide use, as insecticides were becoming less beneficial due to resistance and were taking out the beneficials that were doing the natural pest control. Prior to this, I had already stopped using Dursban to control Orange Wheat Blossom Midge (OWBM) about 15 years ago because of the damage I could see this did to the insect life as a whole in the field. Also, my experience of contract farming an area of organic farmland for ten years led me to realise that insecticides were not necessary for yields in this system: the reduced yield of the organic land seemed to be more down to crop nutrition and weed pressure than pests or diseases. So I took the decision to do everything I could to control pests without insecticides and monitor the impacts on my yields and profit margins.

I took advice from my Frontier agronomist, who is very understanding of where I am coming from and where I want to get to. I also get ideas from events and social media.

Management:

Prior to 2013, insecticide spray decisions were based on a combination of thresholds and convenience. As the products cost £1.60 / ha and the operation cost £5 or £6 / ha, I would occasionally add an insecticide to a fungicide or herbicide application if its use was likely to be necessary, to save the money of running two operations. After 2013, the convenience use of insecticides stopped and I monitored against thresholds for the first few years and did not find a single justifiable case to spray. There were anxious moments in the early years when I would see signs of Barley Yellow Dwarf Virus (BYDV) on small areas, but in experience this did not result in a net economic loss. Pest numbers seem to have been suppressed from exceeding thresholds from year one. Subsequently, I keep an eye out on forecasts and look for visible signs of an issue but am more relaxed that I have built up the resilience of my soil, crops and beneficials to have confidence that I may never need an insecticide again. I am not saying that I will never use them, but as yet, I have not had a need to. I occasionally see OWBM, but timing of control for these is so critical, and the use of a summer insecticide is so damaging that I have resisted the urge I would have previously had to resort to the can. Cabbage Stem Flea Beetle (CSFB) problems seem to occur whether I use insecticides or not and the way I look at it now is that the more you use the chemical, the greater the risk of resistance build up.

I have broadened the range of crops I grow. Previously, I stuck to a rigid two wheats, oilseed rape, one or two wheats, beans, all winter-sown, and the ratio of crops in the ground would be roughly 70% wheat, 20% oilseed rape, 10% beans. Now I have added winter and spring barley and have no fixed rotation, tailoring the cropping in each field to weed pressure and soil health. So, for example, if I have a black-grass problem then I will not go with a 2nd wheat, even though this gives a better return than a break crop. In general, I grow less wheat, more barley, less oilseed rape and more beans than previously. I now average about 40% wheat, 30% barley, 20% beans and 10% oilseed rape. The reduction in area of oilseed rape is more due to the challenges of dry August / September than issues with CSFB. On paper this would seem like a less profitable rotation, but in reality, I have slashed my cost of production, which has more than made up for loss of yields and crop values and my net profits have increased. Books also say that incorporation of spring crops to reduce black-grass levels results in a net loss in profits, but in reality, incorporation of the full range of Integrated Pest Management (IPM) techniques more than makes up for this through reducing costs of production.

I use pest resistant varieties where possible, but take decisions based on the best contracts that I can get, so this is not a major consideration. I have moved back towards traditional recommended cropping intervals, but this is a balance to have full IPM and maintaining a balanced rotation, so unlike virtually all farmers, I am moving back towards five to six years between oilseed rape crops.

I drill cereals after mid-October if weather allows, rather than September to reduce black-grass and autumn aphid pressure. I avoid over-feeding crops with nitrogen fertiliser in one application to prevent rapid growth, making the crop more prone to pest and disease pressure.

Making the habitats to enable the beneficial insects and spiders to thrive is key to the success of this system. I started off with flower-rich margins around the outside of the fields, and now have been adding flower-rich strips every 4th tramline (120m) to improve natural pest control and insect pollination. I am forever increasing my habitat areas voluntarily until my agri-environment agreements expire and allow me to top up the payments based on the areas I am taking out of production. I see the benefits of the in-field strips on the yield maps of my oilseed rape and beans, with yields being 5-20% greater next to the strip and tailing off further into the field: this also reflects my observation of the number of bumblebees I see across the fields. The yield response is probably a combination of the effects of increased insect pollination and increased natural pest control. I have not looked at whether the enhanced pest control next to the flower strips shows any benefits in my cereals yields yet.

What area/% of cropped land is now out of production for AES / voluntary habitats compared with pre-2013?

I have around 9% on rented land and 12% at home. I also see increasing soil organic matter and, where soil structure allows, direct drilling of crops as measures that benefit the natural pest predators in providing a more functional soil ecosystem within which they can thrive. Many of the measures I have adopted in the transition to regenerative agriculture have multiple benefits, and it is difficult to tease out individual cause and effect impacts.

As well as stopping the use of insecticides, I have also cut down on the use of herbicides, fungicides and molluscicides. I put this down to improved soil health, crop health and better rotations – a consequence of the holistic regenerative agricultural system. I am conscious that pesticides as a whole do damage to the functional ecosystem that boost my yields, and I am looking to reduce use across the board. I monitor slug levels, but if I see lots of beetles in the field, I see if they can do the job first and only treat areas that seem to be struggling. I am not looking to eliminate slugs from the field, but keep them at manageable levels, whilst maintaining a thriving food chain for the beneficials.

This year, I have tried a few new ideas to further benefit from the IPM approach. I have sown a mix of wheat varieties in my wheat field to avoid the pest and disease risks that can arise from a single variety monoculture. I have also undersown my beans with clovers and tried intercropping my oilseed rape with phacelia and clovers to see if these measures will disguise the crop from pests and boost beneficial numbers further.

Achievements:

Overall, crop yields are a little lower, but I think this is more because of the switch to direct drilling than the loss of insecticides. The yield losses are more than made up for by the reduction in costs of production and the net margins are up, despite reducing the areas of wheat, our most profitable crop. Last year, cost of production of my wheat was c.£72 per tonne, about half of the average across my peers. Prior to 2013, profit margins had stagnated, but the trend is now definitely upwards. The total farm profit is so variable from year to year, it is not possible to put an average percentage figure on it yet. I do feel my business is more resilient to the market and weather pressures.

There are visibly more beneficial insects and spiders. I don’t know what they are, but the ground is alive with them. There is noticeably more wildlife overall, especially the birds. The incidence of pest levels exceeding economic thresholds has declined to zero. This was apparent from year one, but probably accrued over the first few years. Prior to 2013, I might spray a cereal crop with insecticides in the autumn against BYDV, at ear emergence and potentially again for OWBM. In oilseed rape, I would spray between two and four times in the autumn for CSFB.

I also believe there are benefits in this approach to my personal health, with fewer potentially harmful chemicals to deal with.

There is no blueprint to IPM and I feel it has to be a whole farm and landscape approach as it is not as easy as conventional farming with pesticides. Farmers need support through Knowledge Transfer platforms to help them to reduce pesticide use – this is not readily available beyond organic farming.