Cambrigeshire arable farmer, David Walston is actively seeking ways of making best use of his number one resource, his soil.
After completing a Nuffield scholarship on ‘Improving yield and profits through improving soil’ he is now implementing best practice on his 800 hectare family farm, Thriplow Farm.
Mr Walston began his education studying biology at university and dipped his toe into the photography industry before becoming gripped by the farming way of life in 2009.
During his time on the farm, he has noticed differences in performance between neighbouring fields with those recently in pasture yielding up to 25 per cent more across all crops. It was clear the characteristics associated with pasture were beneficial to soil and ultimately crop performance, he says.
A desire to harness the characteristics of these fields in order to improve the whole farm led him to set about traveling the world for solutions. He visited New Zealand, the USA, Australia, Denmark and beyond, with no-till, cover and companion cropping and livestock integration being his key areas of interest.
Mr Walston says: “I visited farmers who had decades of soil improvement experience and claimed they could increase organic matter levels by 1 per cent every year, as well as researchers who said this was not possible.
“One thing I learnt is that you can’t just take ideas from places and use them on your farm because everywhere is so different. You have to pay attention to your local area and find what works for you.”
In an attempt to optimise soil health on his farm, Mr Walston is restricting farm traffic to tramlines to avoid widespread compaction. He has moved from a min-till based system to a no-till approach. Cover and companion cropping are now being extensively adopted. Despite selling his last few cows, other livestock still graze on-farm so the benefits of grassland can be harnessed within the arable rotation.
Currently, crops grown include winter wheat, spring barley, peas, beans and oilseed rape however Mr Walston is keen on experimenting with more minor crops.
This year, Mr Walston is reducing machine size and reducing distance between tram lines from 32m to 30m so the combine (10m header) and sprayer (30m boom) will match up.
Therefore, the combine will be on the tramlines 33 per cent of the time and trailers can unload on tramlines reducing traffic and compaction.
Mr Walston hopes this system will reduce the chance of compaction layers developing and the need for whole-field cultivation, increasing the viability of a no-till approach.
Choice of cultivation method is partially dependent on soil type. At Thriplow Farm, the soil type is predominantly light sandy loam over chalk with some heavier areas, which Mr Walston feels requires no rolling and lends itself to direct drilling.
While in the past the focus has been on shallow cultivations, when experimenting with direct drilling, Mr Walston found the soil was in great condition. This made him question why you would want to cultivate soil which was well structured and full of life and incur extra cost in doing so?
“I prefer to have as little soil disturbance as possible as it reduces weed germination and reduces destruction of soil organic matter. It does not destroy habitat for living organisms and it saves time and money. Most of all, if the soil is already in a suitable condition, so why change it?
“Soil dries out very quickly, we are nearly always limited by lack of water and so lighter ground yields 20-30 per cent less than heavier ground.
“Direct drilling helps retain water at establishment, but when we really want water is nine months after drilling, in the spring. In theory, by leaving residue on the soil surface, more water is retained.
“Many modern farming methods are contributing to a decrease in productivity and soil health. Cultivations carried out by heavy machinery are causing structural damage and organic matter loss at the same time,” he says.
During his travels Mr Walston became interested in the benefits of cover cropping, primarily in terms of increasing soil organic matter which aids water retention and feeds soil micro-organisms, but also in terms of improving soil structure and providing nutrients. Including legumes in cover crop mixes, for example, captures nitrogen, which potentially saves on fertiliser inputs, he says.
As a result the use of cover crops is extensive with around 250ha sown on the farm this year. However, the cover crops grown on the farm are not part of ‘greening’ requirements under the basic payment scheme as this does not allow for extensive seed mixes or grazing. Instead, they are let to a sheep farmer in the autumn for grazing, which generates further income.
The cover crop used for sheep grazing includes stubble turnips, sunflower, oats and vetch. The field has been no-tilled for four years and the soil benefits are noticeable, says Mr Walston. Wormholes are present throughout, some up to the size of a five pence piece.
“Lots of worms give you drainage, generate structure, help combat compaction and encourage rooting,” he says.
The low price of seed and low cultivation costs means sowing cover crops is a viable option for increasing soil fertility, he adds.
“When the crop is good, grazing makes money but more importantly there are long-term benefits.”
As well as this, he is experimenting with sowing lucerne alongside oilseed rape with the intention of increasing soil nitrogen for the following wheat crop, as well as improving soil biodiversity and suppressing weeds.
The trend in developed countries to move towards arable production and away from integrated livestock systems, is causing a reduction in soil health as plant diversity is diminished, Mr Walston believes.
"The lack of perennial pasture means soil organic matter levels are significantly lower than their potential,” he says.
So, despite having few livestock of his own, he has incorporated a two to three year grass ley into his arable rotation, which is rented out and mob grazed by cattle.
“We don’t get muck from anywhere as there is nowhere nearby that could supply it. Therefore it is important we use grass to gain organic matter and to help increase soil nitrogen instead.”
Fields which have previously been in grass have seen elevated soil organic matter levels. For example an arable field which has been taken out of long-term pasture has an average soil organic matter content of around 4.5 per cent while other fields are likely to be around 3 per cent.
“Actively changing practices to improve soil is challenging because it is hard to prove better soil characteristics improves profitability. I’ve decided, if I can do it with little or no cost, then I will do it and we will see what it looks like in five year’s time,” says Mr Walston
“Actively changing practices to improve soil is challenging because it is hard to prove better soil characteristics improve profitability. I have decided, if I can do it with little or no cost, then I will do it and we will see what it looks like in five year’s time,” Says Mr Walston
- Reduce (ideally eliminate) cultivations and soil disturbance
- Grow as many different plant types as possible as either cash, companion or cover crops
- Try to integrate livestock where economically (and socially) feasible
- Be proactive rather than reactive with our farm’s soil health
- Experiment with as many new ideas as possible and increase the chances of finding something which works
- Do not give up when an idea does not work at first, but try to learn from what went wrong and fix it
Source: David Walston, Nuffield scholarship report