New rota­tions: The journey to zero inputs

“The world is focusing on regen­er­a­tive agri­cul­ture and food nutri­tion. I really hope it is, because that’s the way that we are pushing,” says Chris, who runs his contract farming part­ner­ship, Cloud Farming, along­side James. Based in central and southern Scot­land, they manage over 600ha of land and put a strong focus on cover crops. With such a wide area under their custo­di­an­ship, the duo work with a range of soil types, whilst also having signif­i­cant climatic chal­lenges to contend with. 

Plan­ning crop rota­tion according to soil and climate

For two decades, Chris’ expe­ri­ence of farming was about pushing for the biggest yields, oper­ating min till and no till systems. But it was a move to East Lothian that prompted a change in tack. The new farm Chris started working for had an interest in envi­ron­mental farming. “It was early days and we hadn’t quite got the soil to the stage it needed to be,” he says. By focusing so much on the ‘no till’ methods, he realised they were missing some­thing more impor­tant. “It isn’t about the no till, the machine or what you apply to the crop. It is really about the cover crop and the soil and getting that right.”

The region has a repu­ta­tion for harder ground, with a lot of stones to contend with, as well as red clay soils which can be very dry, partic­u­larly in spring due to prevailing winds. In addi­tion, some of the farms they manage further north have a much cooler climate, meaning farming becomes more chal­lenging. For example, many nitrogen fixing cover crops like clover simply won’t grow in colder climates. Like­wise, machinery needs to be care­fully consid­ered and adapt­able to the different condi­tions.

Having tested several drill systems, Chris and James even­tu­ally settled on a John Deere 750A. At 6m wide, it can cover ground quickly, which is useful when drilling windows are tight. “Timing is absolutely crit­ical,” says Chris.

Crop rota­tion at Cloud Farming

Finding the right cover crop

When plan­ning cover crops in rota­tions, the previous crop, soil type, soil quality and climate must all be factored in. “We’re constantly analysing,” remarks Chris. Working closely with agri­cul­tural research organ­i­sa­tions in the UK including the Agri­cul­tural Devel­op­ment Advi­sory Service (ADAS) and Yield Enhance­ment Network (YEN) helped him to explore crop rota­tions in more detail. 

Having tried several tech­niques when sowing cover crops, including broad­casting from the sprayer and from straw rakes, it was a learning trip to France that really opened the pair’s eyes to the options avail­able. 

In France, legis­la­tion requires ground cover until Christmas, which has led to exten­sive cover crop trials. Chris and James witnessed different estab­lish­ment tech­niques first­hand, from drones and disc drills to tine drills and power harrow combi­na­tion drills. The variety of crops grown and the resulting soil struc­ture was mind blowing, says Chris.

Further learning at confer­ences led them to discover other useful cover crops – for example, Ornithopus (bird’s foot trefoil). A fast growing, dense rooted nitrogen fixing plant, it helps to improve soil struc­ture and support nutrient cycling. 

Cover crop choice isn’t just a case of ordering a bag of seed – you need to design your crop, thinking about what will work on your soil, in your condi­tions. Ulti­mately, it needs to suppress weeds, prevent pest infes­ta­tions, and either protect an existing crop (when cover is sown before harvest) or benefit your soil. 

Redesigning crop rota­tions

Armed with valu­able infor­ma­tion on cover crop options that can survive the winter, Chris has adapted his planting regime to suit condi­tions. Now in its third year, it includes a mix of beans, winter hairy vetch, Ethiopian mustard and Ornithopus.

The beans were previ­ously grownas a cash crop, but incon­sis­tent yields (ranging from 2-7t/ha) and tight margins meant it wasn’t finan­cially viable. 

“We grow food as a busi­ness” states Chris. They grow spring milling oats, spring and winter milling wheat and seed barley, as well as conven­tional oilseed rape (OSR), for a deeper rooting crop. OSR can also be harvested earlier, allowing time to estab­lish a good cover crop, taking care of slugs and boosting soil biomass.  This is partic­u­larly bene­fi­cial for one client who makes their own whisky; growing spring barley after OSR and a cover crop enables minimal inputs.

Managing a predom­i­nantly spring crop­ping system, rota­tions look different for Chris now. For the past two years they have been using a second­hand Horsch CO to estab­lish cover crops as quickly as possible after harvest, and they’ve been ‘ruth­less with rota­tions’. They direct drill wheat after spring oats, and / or plant a cover crop after OSR, spring barley and spring oats. 

The selec­tion of cover crop species is crucial for Chris, who is trying to move away from chem­ical use. Bras­sicas and beans are helpful with soil struc­ture and securing nitrogen, and there’s no need to apply chem­i­cals to kill them off, as they can be managed with cultivation. Vetch is great at out-competing weeds due to its linear growth, while broadleaved cover crops reduce grass weeds. 

For Chris and James, the ulti­mate goal is maximising soil organic matter and nutri­ents, to benefit the next crop using a mulching and discing system. Using a crimper knife roller, they chop to around 50mm (the optimum length to benefit soil microbes and ensure quicker nutrient cycling). They follow this up with a disc to help incor­po­rate nutri­ents into the soil before mulch drilling the next crop.

After testing several drill-sowing systems, Chris and James finally opted for a John Deere 750A.

Close-up of the 750A’s single-disc openers and depth gauge wheels. The opener design allows the drill to work in both no-till and low-till condi­tions.

Vetch is great at out-competing weeds due to its linear growth.

For every cover crop, the carbon to nitrogen ration is crucial, and mulching is a good way to opti­mise this. “We are trying to feed the ground, under­stand the soil and microbes, and what cover crops we can grow, so that we don’t need to apply as much arti­fi­cial inputs,” says Chris. “Our goal is to grow crops without addi­tional nitrogen.” 

People think we can put more on and get a better result – you can’t. The answer is not in a can. Instead, they should look at growing their own nitrogen. That is key to farming in the next decade, as far as I see.

Chris Leslie

When it comes to estab­lish­ment, their biggest success was broad­casting OSR into a standing crop of wheat. This enabled the OSR to estab­lish so it was growing away once the wheat was harvested. The duo have also had success direct drilling wheat after spring oats. This mixes high amounts of carbon from the oat stubble into a very shallow surface – which uses up nitrogen as it decom­poses, reducing weed growth. However, with open struc­tured crops like OSR, it’s better to sow cover crops like beans and vetch in one pass, as slugs don’t tend to touch them.

Evolving this set up has taken plenty of trial and error. For Chris, the biggest failure came from planting wheat after OSR, given the short window for applying pesti­cides to manage slugs. Here, the only options are using slug pellets (not very envi­ron­men­tally friendly), or cultivation – which on the stony land presents other issues. 

Less fertiliser, better soil: the bene­fits of cover crops

Chris’ efforts and invest­ments in cover crops could be consid­ered a lot, but Chris believes it’s worth it. Sowing a cover crop in winter protects the soil, supresses weeds and fixes nitrogen, while also improving the soil struc­ture and health, and providing an excel­lent seed bed for spring drilling. These bene­fits can then be seen in subse­quent cash crops, with excel­lent estab­lish­ment and cheaper crop nutri­tion. 

Chris calcu­lates that on a fresh weight basis their cover crops deliver about 80kg/ha of nitrogen, 100kg/ha of potash and 40kg/ha of phos­phate. “We’re getting to the stage that in two to three years’ time, we might be able to grow a crop with no arti­fi­cial inputs.”

But it’s impor­tant to keep an eye on soil struc­ture with continued use of no-till, he warns. “After all, you need tilth, oxygen in the soil, and an uncom­pacted 10-inch layer. Compaction is a killer.” There­fore, he isn’t averse to subsoiling or applying gypsum when needed to help improve soil struc­ture and add addi­tional nutri­ents. 

Another chem­ical Chris is keen to move away from is glyphosate – which is why he has explored other ways to destroy the cover crop. In his view, growers of the future should avoid the ‘more-on approach’. “People think we can put more on and get a better result – you can’t. Instead, they should look at growing their own nitrogen,” he says. “That is key to farming in the next decade, as far as I see.”