As featured in previous newsletters, five Scottish farmers are working together to find and share answers to some challenging questions around enhancing farm soils and the wider benefits this can have for both the farm business and environment.

During the last five months, on-farm working trials have continued, with Ross Mitchell at Castleton Farm trialling a stripper header at harvest, James Hopkinson and Cloud Farming taking the plunge and buying a strip till drill and Hugh Black at Backboath going large on his organic manure applications while the weather allowed. Ben Baron at Leitfie Farms continued to build on his wheat variety mixes, taking his total up to 4 varieties in the same field and Douglas Ruxton at Moss-side of Esslie has joined in with the rest of the group to give cover crops another look. Read on for more details.

Trialling a stripper header

A Stripper header is a type of combine header which removes the grain from the plant, leaving the stem standing in the field.   Although this implement can increase harvest efficiency, one of the main reasons for trialling this machine is to look at new ways to deal with the straw residue.

Chopping the straw can provide a significant mat on the soil surface which is beneficial for soil protection. It can also create ideal conditions for slugs and provide a large quantity of carbon into the soil very quickly, potentially resulting in nitrogen lock up for the following crop. A stripper header, which leaves the straw standing, may therefore make it easier to manage subsequent crops due to reduced slug pressure. Furthermore, stripper headers can also harvest in wetter conditions as the straw is not processed, providing more opportunities to harvest.  The photo shows harvested wheat using the stripper header on the left hand side of the picture, showing the standing straw.

Getting to grips with grain analysis  

Ben Barron and Hugh Black have been investigating grain analysis and considering how this can influence their nutrient management on farm.  Alongside soil testing and in-season tissue testing, grain analysis can offer a post-mortem ‘look back’ on plant health, potentially identifying nutrient shortfalls which can be addressed for the coming season.

Although grain analysis is usually used to assess quality, research has identified critical levels to highlight nutrient deficiencies within a crop. Focusing on phosphorus (P) offtakes, it was found that P removal can vary from 4kg/t to 9kg/t of grain. Furthermore, if P is below 0.32% of the grain dry matter weight, it has likely created a yield limitation. Alongside P, nitrogen, sulphur and manganese also have well defined critical limits. Hugh analysed wheat and spring barley crops, finding that the phosphorus in both was less than required, indicating that the plant has not been able to access the P it needs. Although Hugh’s soil analysis indicates that there is adequate soil P, the plant is not currently able to uptake that nutrient. This suggests that we need to look at the plants rooting and take another look at that soil!

Working with wheat varieties

Ben Barron has been investigating the use of mixed varieties in his wheat crop at Leitfie.  After successfully mixing varieties in his oilseed rape in 2019, Ben established three varieties of wheat (Istabraq, Spotlight and Sundance - as shown in the photo) by mixing the seed as he put it into his seed drill.

Mixing varieties has the potential to reduce the disease burden within a crop as each variety has a different tolerance to different diseases. Ben has taken this approach a step further by mixing four species for his 2020/21 crop. We will keep you posted!

Costing out cover crops

The group has been taking a serious look at how to integrate cover crops into their farming enterprises. Cover crops have the potential to be a key to unlock the regen-ag principles by providing soil cover, maximising diversity, maintaining a living root and even integrating livestock. However, they aren’t as simple as they might seem!

The challenges of growing cover crops include the additional cost of seed, extra work in their establishment and the potential for damage by slugs. Adding these challenges with a later and cooler harvest often means that their growth is limited and disappointing. However, for the second year running, Ross has established his cover crops into standing crops two weeks prior to harvest, and other members of the group including James, Douglas and Hugh have followed suit and given it a go.  Establishing covers in this way gives cover crops the best possible start while the weather is still warm and in most cases there is still moisture in the base of the crop. Here's what has been grown by the group:

The group are all growing diverse mixes at varying costs.  Along with benefits such as permanent soil cover and increasing crop diversity, one of the main deciding factors on what to grow is the existing crop rotation.

Ross and Douglas have chosen to include mustard, as they do not grow oilseed rape and therefore club root is not an issue. Hugh is growing fenugreek, a plant with high nitrogen content which is attractive for grazing animals. The key is finding a mix that works on your farm and establishing it while there is still warmth in the soil. Furthermore, if the mix can be grazed it can assist in recouping some of the cost associated with establishment and introduce livestock back into an arable rotation.

There are situations where cover crops may not be necessary, Ben thinks that his natural seed bank should provide enough winter cover to protect his soils and he is actively encouraging volunteers to germinate. A study in NE Scotland by Baggs, Watson and Rees (2000) found that nitrogen uptake did not differ between sown cover crops and weeds growing naturally. This study states that this result is a reflection of short-day length and colder weather, limiting growth. Perhaps the groups ambition to obtain early establishment is along the right lines, to ensure maximum nutrient uptake while the weather is suitable for growth.

Visit our Soil Regenerative Agriculture Group page to keep up to date with what's happening on the farms.

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