How much effort — and money — should we put into establishing cover crops, asks Terrafarmer’s Anthony Ellis
Our first foray here at the family farm into the veritable rabbit warren that is cover crops began in 2016 with a simple oats and radish mix to fulfil the greening requirements for BPS.
Since then, we have trialled various cover crop mixes – including a 7-way mix. However, we now seem to have settled on a 5-way mix that suits our system and is also appealing to our sheep’s oh-so-refined pallet!
The Pensipple Farm cover crop mix: tillage radish, forage rape, phacelia, spring oats (home-saved), and vetch
The 5-way mix we aim for here at Pensipple Farm is tillage radish, forage rape, phacelia, spring oats (home-saved), and vetch. This year, depending on the earliness of harvest, I would quite like to throw a small amount of buckwheat in as a late source of food for pollinators and to mobilise some more phosphorus.
In principle, it’s about introducing diversity to the soil
Each species in our cover crop mix is selected to perform a different function in terms of rooting depth and root structure, as well as adding different physical positives for the soil (see below). But, in principle, it’s about introducing diversity to the soil.
Cover crop species and their function
Spring oats – Relatively shallow rooting, oats have quite an acidic rhizosphere which helps mobilise P. Also act as the “grass” portion of the sheep ration.
Forage rape – Soaks up any excess N left over from the previous crop and is a high protein feed for the sheep.
Tillage radish – Busts through compaction layers in the soil and improves the water infiltration and water-holding capacity of the soil.
Vetch – As a legume, it fixes atmospheric N for the next crop, as well as providing a good protein source for sheep.
Phacelia – Shallow, fibrous root system conditions the top 2 or 3 inches of soil and is a good scavenger of excess P left over from the previous crop.
Introducing diversity
On our conventionally farmed system, the soil has had a monoculture of, in this case, wheat for the entire 2022/23 growing season. This means the soil biology has had to survive off the root exudates of just one species during all that time. It’s like asking you to eat nothing but bread: it’s not a very wholesome or balanced diet. Different plant species mean different root exudates feeding different forms of soil biology and, in turn, affecting different soil nutrients.
The Pensipple Farm cover crop in action.
The big question for me (and others) now is, “How much effort should we put into establishing cover crops?” Bearing in mind they don’t provide any direct income as a cash crop, should we keep establishment time and costs to an absolute minimum and just throw the seed on, walk away, and let it fend for itself?
Should we keep establishment time and costs to an absolute minimum and just throw the seed on, walk away, and let it fend for itself?
Or should we treat it like any other crop? In other words, cultivate and sow it “properly” to give it the best chance of survival. I suspect the answer lies somewhere in the middle and, as is so often the case in farming, includes the phrase “it depends”. On our farm, we’re definitely expecting a positive return for the next crop from the benefits of sowing these cover crops. But I appreciate that it can sometimes be harder to quantify.
The Guttler Greenmaster: great for over-seeding on stubble… in the right conditions!
For the past six or so years, we have used a Guttler GreenMaster to sow the crop direct onto stubble, which has worked reasonably well. But after a very difficult season a couple of years ago, we introduced a light cultivation with an old Bomford Dyna Drive ahead of the Gutler to produce a tilth. This seems to have improved establishment considerably during the more ‘challenging’ seasons we’ve recently experienced!
All this for a cover crop, you might ask?! Well, yes…
As noted above, it’s hard to put exact figures on the benefits we’re going to get from this. But the proof of the pudding for us so far lies in the condition of our soils.
The combination of cover cropping and strip tillage has resulted in a noticeable improvement in water-holding capacity and drainage over the last four years. Not that we’re finished tweaking yet though! Our system is constantly evolving and there are always lessons to be learnt in farming. But cover crops have a definite place in our rotation, that’s for sure.
About the author
Anthony Ellis graduated from Harper Adams in 2004 with a BSc (Hons) in Agriculture with Environmental Management and went on to become a commercial agronomist. Over the years, Anthony has built up extensive knowledge and experience of a range of different crops, both organically and conventionally. He has gained numerous BASIS qualifications, including Crop Protection, Soil and Water Management and Biodiversity and Ecological Training for Advisors.
About the author
Anthony Ellis graduated from Harper Adams in 2004 with a BSc (Hons) in Agriculture with Environmental Management and went on to become a commercial agronomist. Over the years, Anthony has built up extensive knowledge and experience of a range of different crops, both organically and conventionally. He has gained numerous BASIS qualifications, including Crop Protection, Soil and Water Management and Biodiversity and Ecological Training for Advisors.