Growing potatoes in a more regenerative way

Ed Brown is an agronomist and head of agroecology at Hutchinson’s, spending his time consulting and advising growers on implementing regenerative systems. He has been working with John Bubb, a grower from East Shropshire.

Trading as J M Bubb & Son, Mr Bubb grows 400 acres of potatoes for McCain on a sandy loam soil on a six-year rotation across a total of 2,000 acres, which includes wheat and oilseed rape. He also has a diversified business – Shropshire Petals – growing flowers for drying. Mr Bubb has had an interest in sustainable and regenerative farming for many years, but it’s only been in the last two or three that he has really started to look into it into more detail.

Cover crops

The use of cover crops is one area that has shown promising results on Mr Bubb’s farm. Ed Brown explained: “We have the opportunity to use cover crops twice in the six-year rotation – cover crops have been grown before potatoes, and they’re also grown before spring-sown flowers. Then we usually try and get a catch crop in between oilseed rape and wheat as well.

“A huge part of growing a potato crop regeneratively is what happens in the rest of the rotation. We’re trying to use as diverse a cover crop mix as we can, with as many species in there as is practically possible and affordable to do so.”

The mix being used currently includes linseed, buckwheat, phacelia, vetch, clover and oats. Mr Brown has moved away from a brassica cover crop, primarily due to regrowth within the potato crop, as well as to help combat slug issues.

Before potatoes, the mix will include spring oats due to the soil stretching benefits – although they are omitted prior to spring flowers as an allelopathic effect has been noted on the following flower crop.

Whole farm approach to cultivations

Mr Bubb explained that he takes a whole farm approach to cultivations. “We’re trying to use a spade as much as possible in order to work out what we really need to do within each field, instead of running a blanket operation across the whole farm regardless of the crop.

“When it comes to the potatoes, we’re certainly seeing the benefits of the cover crops, and the soil is definitely more friable than it used to be – so we’re starting to reduce the depth of cultivations, trying to eliminate passes and resisting the urge to plough.”

Mr Bubb uses a Kverneland DTX for potatoes instead of ploughing and then, in an effort to reduce the depth of the de-stoner, he uses share tines which help to get rid of any pan.

He’s undertaking a lot less bed tilling than previously, which helps to reduce the number of passes and therefore assist in improving the soil health.

In fact, making a move to strip tillage for the OSR and flowers means that within the whole rotation there’s a lot fewer passes than previously.

With such stony ground, Mr Bubb’s particular concern is bruising at the point of harvest; so while in some of his fields he could get away without de-stoning, on the whole he feels de-stoners still have an important place.

Nutrient management: Feed the need

Ian Robertson runs independent soil testing business Sustainable Soil Management, and said: “Soil testing allows us to make more informed decisions on what we’re doing. We conducted soil testing with John 20 years ago, but we didn’t do an awful lot with it. More recently, we’ve begun using the gold soil test to really drive the regenerative programme forward.

“We’re measuring what is in the soil, and then rather than just applying more nutrients the whole time, we look at what we can do in the rotation to cycle those nutrients to the crop. It’s all about management practices. For example, if you’ve got 1,228kg of total phosphorus in the soil but only 85kg is cycling, there’s a problem with the soil in that something’s not letting the nutrients cycle.

“What we’re achieving with the cover crops is less cultivational biological disturbance, which allows a lot more of the nutrients to cycle with less chemical additives to the soil. This is allowing that soil to become much more native, which again will improve all the nutrient cycling.

“Of course, nitrogen is a massive input for growing potatoes and cover crops will capture nitrogen in the soil profile which allows us to reduce the amount needing to be applied.”

Pest control

According to Ed Brown, when it comes to pest control, he is trying to enable Mr Bubb to go back to older methods like re-ridging to potentially move away from herbicide use.

He recognises that getting away from that routine ‘prophylactic every seven-days’ blight spray programme is quite difficult, because when it goes wrong, it can go spectacularly wrong. “So, what we’re trying to do is put in the groundwork now to build our healthy soil, to build our healthy plant by managing its nutrition, so that we have a plant that should hopefully be much more robust and resistant to plant pathogens like blight.

“Bringing diversity into the field is another critical element of that, and we’ve seen in other crops where you can grow different plant species together within the field it has this uplift of plant health, and as such disease becomes less of an issue.”

Plant diversity is one of the key principles of soil health or regenerative agriculture for Mr Brown. “It’s so critical– not just across the rotation in terms of crops you grow, but within specific crops and within the field and around the field.

“John is fitting diversity in via stewardship schemes; for example, he now has wildflower margins around lots of his fields which are building up the beneficial insect numbers, pollinators, and natural predators.

“We’re also then looking at putting in cover crop mixes within the potato field on the headlands and the corners of fields again to try and build up the levels of beneficials within the crop and bring that level of diversity to try and help with plant health.

“Lately, we’ve been looking at companion planting with potatoes, using peas and beans – because most of the potato herbicides that we use are safe to use in peas and beans as well. This way, we can try to find a happy balance where we can let the companions do their thing but still get our weed control and hopefully we can get some form of nitrogen benefit to the crop as well.”

Mr Bubb also uses a living mulch, seeding clover in the late spring between 50cm rows of wheat, which remains for up to five years before the potatoes go in. He feels the clover mulch will provide a real benefit to his system going forward.

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