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BIOLOGICAL Farming, with the help of natural soil bacteria and Fungi, is growing rapidly and in the current crazy
climate there is more and more interest – after all, we can now use these little bugs to provide Nitrogen, Phosphate
and now Potassium. There are also products that will stimulate root growth and help to reduce disease pressure.
Written by Robert Plumb

I have been working on the Biological side of farming for 20+ years; before that, I was a fertiliser blender in mainstream agriculture, so over the years I have seen a few changes, not least the demise of companies like ICI, Fisons, Albright &Wilson and lots of others. In those early days when fertilisers were made more commonly available, many fertiliser companies took soil samples and simply recommended their products. It was very confusing for farmers as the soil results given used a range of different laboratories many using different extraction methods, this meant the farmer could not easily compare results.

In the early 70’s the ADAS (then based at Cambridge), asked for a meeting with these fertiliser companies that included ICI, Fisons (now Norsk Hydro) and about15 other companies plus advisors; they then worked on an extraction method for a common soil analysis.

Now bear in mind these people were there to sell fertiliser. The idea of replacing what you take off came later and sounds very good but is it really necessary? Little notice was made for the use of manure, and compost was unheard of. At that time fertilisers were quite cheap and a rule of thumb was a tonne of Nitrogen was about the same price as a tonne of Wheat, ie about £20.In fact, most compounds were at a similar price and Phosphate even qualified for a subsidy, as did all lime materials. It was a pretty simple system and it certainly sold a lot of fertiliser. But was it really necessary? Many of our long term friends have not applied any P or K fertilisers – other than a bit of compost, for a very long time (20 years plus) and their soil levels are pretty much the same as when we started, and yields have been OK. They are not trying to grow maximum yields but do they actually make a profit?

Levels of K go from low to high

Potassium (K) is extremely important for crop health and yield and at Soil Fertility Services we like to monitor the plant response with regular plant samples. We found that last season’s K levels – in all crops, were extremely low. No surprise from a dry soil. With plants unable to pull it off the clay particles and exchange sites, we are now being told that straw K levels were high! Potassium is important as it helps a plant to regulate water uptake and the opening and closing of the stomata; it is also critical in producing proteins and most wheat protein levels have been low. 

Plants actually need similar amounts of Potassium as they do Nitrogen. This could be up to 200kg. I have never seen one with that level of Potassium at the main stem extension period, but now we may be able to help. We have developed a K fixing product. Similar to the N Fixing product Bio-N, the beneficial K fixing micro-organisms will release around 50kg of K from your soil’s “locked” up reserves, directly into the rhizosphere where your plant system can easily take it up. It may take two applications of 10 litres to provide all your crop’s needs, but it will surely help to overcome the problem of Potassium shortages.

We have been measuring ‘total Soil K reserves’ and find between 6,000 and10,000 kg/ha in the top 10cm (4”) of your soil. Most of this K is in the lattice of the clay particles and is considered ‘unavailable’, but we can easily find200 – 300 kg on the surface of the clay fraction that can be made available to your crop with the help of the Bio-K.

Transitioning to more regenerative regimes hasn’t been entirely plain sailing for three growers with very different soils and situations who shared their experiences at a packed Agrii Green Horizons seminar at this year’s Groundswell.

All three no-till novices have found their journey over the past 6-8 years very positive and are increasingly profiting from moving less soil, protecting its surface, keeping roots in the ground and diversifying their cropping. While their goals are very similar, the way the growers have gone about achieving them reflect clear differences in the balance each has to strike between long-term sustainability gain and short term profitability need. On his mostly light 160ha at Hawkmill Farm just to the east of Cambridge, David White’s principal stakeholders are his family. This and his determination to‘ wean himself off the comfort blanket of cultivation as soon as possible’ led him to switch from full to no-till in a single, bold step in 2015.

Since then, he has been experimenting at scale with a whole host of regenerative opportunities, including a vast range of cover cropping mixes and management methods; early drilling and a variety of OSR companion crops to combat cabbage stem flea beetle; and, most recently, bi-cropped beans and oats –both winter and spring. At Revesby Estate near Horncastle in Lincolnshire, farms manager Peter Cartwright has been moving more steadily but very deliberately towards no-till across the Wiggins-Davies family’s1100 cropped hectares since 2014.Getting the basics working correctly, keeping things simple at the start and building on carefully trialled experience with a firm goal in mind has been his recipe for success to meet the business’ need for parallel improvements in profitability and sustainability. 

“We have been surprised at how quickly soil biology can start working much better when you look after it and encourage it to proliferate. Working with nature rather than trying to force the soil with big, heavy machines has seen our soil structure and health come on by leaps and bounds. “Amongst other things, both shallow working and deep burrowing earthworm numbers have built-up really rapidly. Keeping the land green the year round with catch and cover crops has been very useful in capturing nutrition. And drilling directly into them with the least possible soil disturbance has also helped capture carbon.

“We are finding many ways to farm both more sustainably and profitably. The bi-crop of spring oats and spring beans we tried last year, for instance, performed handsomely with no in-crop herbicides, fungicides or fertiliser at all. The two species complemented each other extremely well, generating a much higher margin than the traditional beancrop we grew alongside it. “Higher seed rates and the right soil structure mean we are increasingly able to employ crop competition in place of herbicides to deal with weeds,” David added. “We need much less tractor horsepower these days, and work our tractors for around a quarter the time we used to. This means they last longer and we at least halve our diesel usage. “Our soils are far more resilient to both drought and heavy rainfall too. At the same time, the amount and diversity of wildlife we have on the farm these days is a joy to see.”

Since moving from minimum tillage with rotational ploughing to almost entirely no-till cropping over the past eight years, Peter Cartwright has also seen huge improvements in the workability, resilience and health of soils with up to 40% clay and 40% silt at Revesby Farms. Over this time, he has almost halved diesel usage and substantially reduced labour needs while increasing average wheat yields by 1t/ha; not to mention getting to grips with horrendous blackgrass problems. “Our transition was actually prompted by the need to deal with levels of blackgrass that made some of our land almost uncroppable,” he explained. “Following the Stow Longa recipe, we introduced up to three consecutive years of spring cropping, concentrated on moving as little soil as possible at drilling and employed the most competitive wheat varieties at high seed rates drilled as late as possible in the autumn.

“The rotational change led us to trial a range of cover cropping options and we now grow around 450ha of winter covers a year. We first ventured into direct drilling with a tined Horsch Sprinter, to which we have just added an Avatar drill now our soils are in good enough condition. We trialled the prototype Avatar back in 2016 and knew this would be ideal for our needs once we were in a position to make the most of its disc coulter system.”

Two different types of direct drill these days gives the Revesby team the flexibility they need to deal with different soil conditions, trash levels and the weather. Over 90% of their crops are now drilled without cultivation, and the capacity to drill all their winter wheat in5-6 days reduces both their weather risk and need to travel when the conditions aren’t right. Alongside moving the least possible soil under the most favourable ground conditions, moving to their own version of Controlled Traffic Farming has made a big difference to the physical as well as biological health of their soils. “Everything is coming together so well now that I think we should be able to push our wheat yields up another 1t/ha over the coming four years,” suggested Peter Cartwright.

“With hindsight, we should have been braver and cut down our cultivations sooner. And we certainly shouldn’t have invested in the Horsch Cruiser cultivator we have hardly needed to use since the day it arrived because our soil condition improved so much.. “Getting the basics of both drainage and black-grass management right before moving too wholeheartedly into no-till have been essential to our success. A shave been attention to detail, working towards a clear goal, and careful trialling under our own conditions in a scientific way as an Agrii Technology Centre.”

Improving drainage and soil structure to enable the most successful direct drilling have been as important in the Fraser family’s transition from traditional plough and min till cropping to the regenerative regime they now employ on more than 80% of their farmed l and. They are also being able to successfully extend this experience to their contracting operations to provide the resource and experience needed to help more West Country growers benefit from soil-first management. “We have found digging soil pits everywhere to assess soil condition and carefully targeted low disturbance subsoiling and mole-ploughing to sort out any inadequacies a crucial first step,” George Fraser stressed. “With our agronomist, we also plan everything on the basis of full soil testing, repeated every four years to monitor changes.

“We really benefit from being large enough to run several different types– including a Weaving GD, Amazone Cayena and Weaving Sabre Tine – so we can match the kit we use closely to soil needs and condition. The substantial slurry, muck and digestate service that is part of our family business has been great fit with our organic matter-building focus too. “Contract farming means we can’t afford to be evangelical about our system. So, where ground needs subsoiling it gets it; where trash causes slug problems we stubble rake; and everything we put into our cover crops is there for a particular economic as well as environmental reason. “Like David and Peter, we have seen great improvements in the health, vitality and workability of our soils in a relatively short time without compromising crop performance,” he reported.

“Wider rotations are giving us more flexibility to adapt to conditions as well as greater biodiversity. Cover crops are helping condition soils and build organic matter while providing late-season wildlife food and shelter. And better plant health through healthier soils and more balanced nutrition is taking the pressure off sprays programmes at just the time we need it with the loss of so much chemistry. “Moving to no-till is far from a panacea and it’s all too easy to make mistakes; especially where them likes of bromeas well as blackgrass are problematic. But we have no doubt that integrating the most appropriate regenerative techniques into our business with attention to detail and the best-informed advice has to be the way ahead.”

Martin Lole of Springfield Farm and Mzuri, reflects on drilling into stubble and his recipe for successful
straw management.

As farming systems become more productive, arable enterprises are faced with increasing levels of straw to manage post-harvest. For many this provides a valuable secondary income source when baled, but for others, whether through environmental objectives or simply not having the demand for it, straw management forms part of the preparation for next year’s crop. Some growers may see leaving straw in the field as a luxury or perhaps a nuisance depending on their system, but when managed well, there are a number of advantages with wide ranging benefits from soil health to better establishment.

Advantages of drilling into
stubble:

• Provides nutrition for soil microorganisms, supporting healthy populations

• Increases soil organic matter

• Reduces risk of wind and water erosion by protecting with a straw thatch the upmost field surface from harsh weather

• Supports good soil structure and promotes better machinery travel

• In dry seasons, stubble can help to preserve moisture by retaining it in the soil

Talking predominantly about direct establishment systems, drilling into stubble can be a very effective and efficient way to establish a range of crops, but success in doing so can depend on several key management factors which are important to consider before heading in with the drill.

1. Assess your straw

“You’ve had a bumper harvest and with that comes a bumper crop of straw. You recognise the benefits of leaving the straw on the surface but what next? ”The most important factor relating to successful direct drilling into straw is ensuring an even spread and a chopped to a consistent length. By far the easiest and most cost-effective way to achieve this is to start with the combine. Watching to see if straw is chopped and distributed evenly will highlight whether the combine is operating as it should, or whether further preparation is required prior to drilling.

Uneven straw distribution will cause problems with variable germination and can cause drills to block if not managed correctly, something which can cause unnecessary downtime and frustration. This leads onto considering what type of drill will be used and what the operator wants to achieve by drilling into stubble. For farmers wanting to drill into a lot of surface residue, strip tillage has the advantage with wide row spacing and sufficient clearance for trash flow, something which the Pro-Til range has been specifically designed for. For those growers who still want to drill into stubble but want a hybrid system that gives a more conventional row spacing, covering large areas quickly, good straw management is particularly important. The iPass sits in this category, offering conventional row spacings into stubble, min till or cultivated land whilst maintaining high forward speed and accurate seeding which makes the iPass range a versatile solution for a range of drilling situations.

2. Manage uneven straw

“Your combine wasn’t what it was and refuses to chop and spread straw consistently, what now? ”For effective drilling, chopped straw should be short in length and evenly spread across the field. This not only provides a smooth canvas for direct drills to operate in, but it also starts the process of decomposition and returning those nutrients back into the soil. There are a number of methods of pre-drilling field preparation that can be used to manage uneven straw levels including raking with a stubble rake such as the Mzuri Rezult. Fitted with discs and five banks of stiff tines, a pass of this surface cultivator can help to chop surface straw, spread it evenly across the field and also generate a small level of tilth mixing it with the straw to aid decomposition. 

For growers who want to maximise the incorporation of chopped straw with the top layer of soil, there are various surface cultivators for example the Vaderstad carrier which will produce more tilth than a stubble rake, but will leave a very even finish of mixed soil and straw –accelerating straw decomposition which can be an ideal canvas to drill into with a direct drill, particularly if there is a large amount of surface straw to deal with.

Not only does lightly incorporating the straw prepare the field for drilling, but it can also act as an important step in minimising slug and weed pressures for the next crop. The Mzuri Rezult rake can be used in the heat of the day post combining of OSR stubbles to disrupt slug habitats and expose slug eggs to the midday sun reducing slug pressure for the following crop. Raking can also encourage volunteers and weed seeds to chit by mixing them with a slight tilth which creates a stale seed bed that can either be harrowed again for cultural control or receive chemistry both providing a blank canvas ahead of drilling.

3. Success with straw

“You’ve taken the time to assess your straw and carried out light surface cultivation in fields that need it, giving the direct drill operator the perfect recipe for success. ”When managed effectively, working with surface straw can yield great benefits over traditional establishment methods. Not only does it provide a weatherproof finish which helps mitigate erosion and run off in high rainfall, it can also provide a sheltered microclimate for young seedlings when drilled between stubble rows. Stubble acts as a mulch to preserve soil moisture and prevent it drying out in dry seasons, reducing stress to the crop and protecting long term soil structure. All of which benefits crop growth throughout the season and ensures a stable, consistent environment to direct drill into. Some direct drills may require more stubble preparation than others depending on what the operator is  trying to achieve. 

The Takeaway Message

Not all stubble is created equal. Low volume stubbles such as Rape, Bean sand wheat straw that has been baled are all very straightforward for the majority of single pass drills. However, larger volumes of straw on the surface can cause challenges particularly for drills with close row spacings or low frames with little clearance. When combined with heavy soils, these scenarios can prove even more challenging and effect the success of the establishment. There are however a few important steps that we can take to balance the benefits of drilling into stubble with the need for effective seeding. Straw raking or light discing is always going to be a helpful tool when dealing with high volumes of surface straw, as is also avoiding drilling into heavy soils when wet. It is also important to consider the drill being used and its clearance, stagger and row spacing. But perhaps the most important thing to take away, is the importance of starting straw management with the combine. It is essential to ensure a short stubble length and if not baled a well chopped spread of straw to give the best canvas ahead of drilling.