Time to assess soils following tricky autumn

Yorkshire-based Agronomist Bob Wilkin is part of Agrovista’s dedicated Soil Health team. In our latest blog, Bob reviews soil health status in his region, following the problematic weather many experienced this autumn.  

Bob Wilkin, Agronomist for Agrovista

“During the past three months the soil in our fields has had a rough time thanks to a wet August and mostly delayed harvest. In hindsight, on the more challenging land it would have been better to group fields into two categories - those with grassweeds, and those without. Anything clean could have been early drilled whilst leaving land with grassweed infestations until the spring and using a cover crop to protect them.

The delayed harvest pushed operations onto vulnerable and tender soils in September and the resulting stubbles were often not the most conducive to anyone wanting to direct drill. This, combined with the later date, left little time to perform much needed remedial operations after last season’s extreme weather. To compound this, often the soil at or below any damage was too wet to pull a tine through without smearing and making things worse. 

Heavier soils

It’s noticeable now at the start of December where the heavier clays are in our region. These are often very high in magnesium (Mg) meaning they can easily become less porous and tight if managed incorrectly. Earlier drilled crops on these soils have stood out as they’ve germinated and grown away in good time. 

Crops drilled later however have been hampered by the late September and October rainfall and are showing signs of rotting seed with bare areas over the fields. It’s particularly evident where excessive cultivations have taken place to try and achieve an ‘ideal’ seedbed. Often if a pit is dug in these areas, the soil below cultivation depth is much dryer and the fines created when cultivating have simply run through the profile, blocking pore spaces and stopping natural drainage. 

Less can be more

The farmer would have been better doing less in these scenarios knowing rain was forecast - a rough seedbed on heavy soils can establish well if looked after as the water has more pore space to percolate through. If the worst happens and areas rot off, it’s still better to having spent less money on diesel and wearing metal in the first place.

On the flip side where fields were late direct drilled, while the soil structure hasn’t been disturbed, any areas of damage haven’t been remediated adequately and excess water hasn’t been able to get away. The effect is similar to over cultivation. 

Where zero till has been employed on heavier high Mg clays, tine drills have fared better with disc drills leaving not enough tilth and a smeared slot. I must point out that this isn’t a condemnation of disc direct drills, just to note they haven’t tended to fare well in this scenario, especially where the soil is still in the infancy of direct drilling.

On the surface it seems like there’s been no ‘right’ way to establish some of these crops. And this may be true for some fields that simply need a good spell of dry weather next autumn. But, there’s been notable success where harvest traffic has been controlled and targeted loosening has been speedily carried out where needed. Many of these difficult fields have at the time of writing, a decent look on. 

Regular field walking to assess soil status

It cannot be overstated that walking fields after harvest with a spade can save a lot of time needlessly cultivating and will enable a timelier and successful establishment.

Cover crops have been a tale of two halves in the brief period between the OSR and the wheat harvest. Some managed to drill cover crops towards the middle of August, and these have for the most part performed well, now protecting the soil above ground with a large amount of biomass and below ground with a prodigious root structure. 

Many however didn’t clear fields ready to drill the covers until early September and these have been very slow and on occasion haven’t even made it out of the ground. Thankfully improved conditions in November have started to rally some of these into a respectable crop, particularly on kinder soils.

Soils in 2021

Looking forward to the new year, it’s a good opportunity to get out and walk the fields again with a spade to identify surface damage and any fundamental drainage problems. Taking soil samples of a more advanced nature in problem areas will prove very useful in identifying issues that go deeper than just what is visual. 

It’s key now, after more than 12 months of erratic weather, that as much land as possible is brought round to a more stable structure that can consistently establish a crop each year. Where this isn’t the case, it may be best to look to stewardship or the up and coming ELMs scheme to find an income.”