Silvohorticulture - a systems approach

A third of my production area is under agroforestry. We have a 5-acre field which I established 3 years ago - I put in the agroforestry for all the horticultural benefits to my crops i.e. wind protection, predator habitat, creating microclimates, increasing three dimensional cropping, reducing inputs... So the trees are part of my whole system approach to horticultural veg production. The benefit of having other crops from my trees was secondary. With a lot of agroforestry, the crop from the trees tends to be the driving decision and then there are secondary benefits, for me it has been very much the other way round. The veg system is designed around the trees being in it and the trees are fitted around the irrigation system, the size of the cropping areas and the rotation areas, and around our crop protection and weeding practices. All the trees are underplanted with wildflower strips - their main purpose is for attracting predatory and pollinating insects, we don’t harvest any of the wildflowers.

We are a big very old farm, so there were already alot of trees and planned forestry on the farm. We already produced woodchip for the biomass boiler that runs the farm shop and cafe for hot water, timber for new buildings, and we already had a managed sustainable firewood setup... so we didn't really need any of the classic timber products. With it being a systems approach, the thought process behind our decisions were we looked at what, within our existing horticultural operation supplying the shop and the café, we could bring in-house that we had been buying in... The two obvious areas were compost propagation material and we had also been buying in a lot of UK top fruit.

Once we decided we wanted some trees in the system, it was then a case of deciding on timber, biomass, or cropping trees like nuts and fruit... I don’t see it as some charitable thing, I see it as making my production far more competitive, producing inputs, so a serious tool for my horticultural production.

System layout & species

We now have intercrops of apples and coppice (hazel, willow and alder) - made into woodchip which is spread directly onto cover crops (ramial woodchip) but also made into compost for propagation, and we have top fruit - apples, pears, plums, with woodchip from coppicing made into compost to boost on-site fertility. We also have biodiversity species - elder, spindle and wild cherry.

There have been mainly three governing factors in the layout:

1. Mathematical - to match existing equipment like irrigation and crop meshes
2. Ecological - to provide predatory insect cover over the whole of the cropping area
3. Wind protection - to give us full wind protection over each cropping area we took the height of the intended trees into account - the height has to be 10 times higher than the crops to make an effective windbreak.

The lines of trees are 50m apart and 100m long. The 50m apart is basically 3 times the width of our irrigation boom and is also perfectly divisible by the width of our crop protection meshes. 100m is also the length of all of our existing crop protection meshes, so everything is mathematically based around existing equipment. From an ecology point of view, 50m is the maximum productive range of beneficial insects from a permanent habitat - so by having the strips of trees and wildflowers 50m apart, that gave us more than enough full coverage of insects over the whole of each rotational cropping area.

Management

We probably devote about 60 hours a year labour to agroforestry. The main management requirements are related to establishment, maintenance and production. January and February are very much 'tree time' - mulching and pruning… One thing I'm doing right now (mid July) in this hot weather is running an irrigation boom down the youngest trees I’ve got and the fruit trees with fruit on them. This year, we have had rain often enough for it not to be too much of an issue for trees, but the first 2 years after we planted, we had proper April droughts which I think are going to become more and more of an issue. A lot of people will look at planting trees February and March time when it is pouring with rain, but then will be hit by these very early droughts. We are lucky - we were set up for irrigation because we are a horticultural business, but if you were planting out across a 1,000 acre arable field, it could be a big challenge. With the climate getting hotter and droughts coming earlier in the year, it’s important to remember trees can be affected hugely.

Deciding on what, where and how to plant

I learnt the most from talking to other farmers (particularly Tolly and Ben Raskin) - speaking to people who have done it already and learning from their mistakes is probably the best way. I did deliberately sit a couple of years behind Tolly and Ben's plantings and just watched and learned from their mistakes - positives and negatives! In silvohorticulture there was not much to copy in this country. There was a bit that had been done at Wakelyns around potatoes etc. (Wakelyns has been a massive trail blazer), but the main country I was getting information from was France. What's fascinating is how much more information is now 'out there' than there was 5 years ago.

With the top fruit trees - apples, pears and plums, we picked two experts in the field. One was based at an organic fruit tree nursery in Evesham called Walcot Nursery - he's a genius on organic apple tree production so from a variety and planting perspective we referred to him - we already has an existing relationship so got him round for a bit of consultancy (this was purely in relation to local apple tree knowledge). Then, because we are commercial and wanted to grow competitive yields in an organic system (which is tricky with top fruit), we also visited a successful established organic top fruit business in Hereford and spent the day there speaking to them about best varieties and best succession for a full season of apples i.e. August all the way through to March (with storage). They weren't doing agroforestry but they knew their apples and pears! Particularly in an organic system you have to be very careful about your variety selection in relation to resistance etc., and also the successional need for continuous supply - because we're a farm shop, it is not about doing one massive crop of apples and selling it, it's about spreading out that production full season. The storage varieties are a bit of an art form.

I used to be a coppice worker before I was a farmer, so could apply my knowledge of alders, willows and hazels for coppice from my previous career, and for the wildlife trees, I used to do quite alot of woodland management for conservation... but I also looked at the trees we had on the farm that grew well and were obviously a really good habitat for birds, insects etc

Outputs & benefits - environmental, ecological, economic…

The primary purpose has been to bring horticultural benefits but also very much to offset the challenges of climate change - winds, heavy rain and drought are the big three. The impact of trees on wind was the number one reason I became interested in agroforestry. All climate change forecasts show that weather will get more extreme - trees essentially offer mitigation against climate change. The tree lines bring great wind protection, alleviating wind speeds across my cropping area. Reducing wind speeds mean I get less evaporation of water in the cropping area which means I don’t need to irrigate so much. Their roots allow extreme rain events to percolate through the soil quicker, and soak up the water quicker after a big summer rainstorm.

We planted wildflowers the year before we put in the alley cropping, so planted the trees into the flower strips, and always think of that as being a part of the system. 4 years in, the biggest benefit is biodiversity - I can see the wildflower strips underneath are absolutely heaving in predatory insects. Although 2021 has been quite a bad aphid year in the veg world, there have been swarms of hoverflies everywhere - giving us a massive competitive advantage. Yes, I’ve given up a wide strip of my cropping area, but that is far outweighed by increasing sustainable yield - I deem it as making me much more competitive and effective as a veg grower.

Carbon capture is also a big benefit and underground, I suspect fungal networks are fast establishing under the crops.

The pandemic has shown how important short supply chains are, so being more self-sufficient in cropping will also make me more resilient in extreme economic events.

We have a very well established and diverse education setup on the farm. We have a preschool nursery and primary school kids come down from London and stay on the farm for a week - some have never been to the countryside before. They learn about the countryside and the trees fit into that, so there is the educational benefits of trees in the landscape that we can bring into the education side - this is probably the most important benefit of all - it’s the future!

Lessons learned

The wildflower strips can be an area where creeping thistle and couch grass can creep out from into the field. We manage this by leaving a blank strip either side which we cultivate.

It’s really important to take your time. We were lucky, we got delayed in the Woodland Trust grant application so we should have started a year earlier than we did, but that year's delay turned what was essentially for me three or four months of intense learning and priming into a year and three months, and I pretty much changed everything! So it is really important to allow a proper amount of time to think things through. Although it is all the rage at the moment, proper planning and preparation is vital. Trees can be in the ground for hundreds of years so you really have to put them in the right place.

There is too much emphasis on number of trees in the ground and not enough on aftercare. I am very lucky, I have water everywhere so can water my trees, but with serious droughts it is becoming a bigger and bigger challenge.

Costs

Costs incurred have been for planting and we had to reorientate a field - we had to take the field out and put it back into production, so there have been ongoing labour maintenance costs. We got funding from the Woodland Trust via the PUR project (now called 'Trees for your farm' - find out more and register an enquiry here). The Woodland Trust grant covered the cost of trees and protection. All the labour and mulching costs since have come out of the farm pocket. Because we’re a veg farm we were already set up with rabbit fencing, but if you're an arable or pasture farmer, you probably won't be, and that cost of protection from both wildlife and livestock can spiral out of control.

Future plans

We would like to expand silvohorticulture across further areas of the cropping and plan to have protected cropping silvohorticulture - we're already going to do fan trained peaches in between the rotation areas in our 1,000m square glass house. Most people with a glasshouse that big put in really expensive shading systems - we want to try and do the same with plants. When we need light in the winter, none of the peaches or climbers will have leaves so we will get maximum light on the crops. In the summer, when it's too hot and sunny in the glasshouse, if we had peaches in there out in full leaf, they would be casting shade on the ground and cooling the glasshouse and improving my tomato production around them. So we have already ordered the trees...

Wider scale adoption of agroforestry

Help towards establishment and maintenance costs would encourage more farmers to adopt agroforestry. We got a grant straight away, it was quite quick to do. Start-up costs without a grant though would be a big stumbling block, for a farmer to put in trees now, there needs to be an upfront incentive. With what I planted, apple trees will be in production within 10 years, and we'll probably be getting good amounts of coppice within 20, but then with a lot of other areas of agroforestry ie. nut production, it can take a good many more years... so many farmers wouldn't be planting those crops for their own income. If you’re talking timber, that's for your great grandchild. The start up costs are really important to skip over that generational gap - where there may be no advantage to the current tenant in key timber crops.

Farm-by-farm, everyone always has different reasons for doing things, but on a country wide approach, climate change mitigation is the really important one.

This profile was created by Janie Caldbeck as part of A National Network of Agroforestry Farms project. Find out about it here.

Andy is also part of a group of growers sharing knowledge and experience of increasing diversity in protected cropping as part of the DiverIMPACTS project. This year (2021) the group are trying out Caliente Mustard as a biofumigant and looking to increase wildflowers in the polytunnels to attract beneficial insects.

Photos and video footage courtesy of Andy Dibben