Talking arable with Hannah Darby: Our eyes have been opened to the importance of what we do to our soil

I know we are not alone reporting a depressing spring oat harvest; we all knew that they should have been a 6 tonnes/hectare crop coming into the shed, but instead the high winds the week before August 22 meant around 3t/ha were harvested and 3t/ha were on the floor. The fields now show that our seed crop had good germination! The barley suffered similar fate, but I was not expecting anything special as slugs had hampered their establishment and nearly 5t/ha seems a fair return for the effort put in.

On the other hand, the spring wheat seems to be our saviour, across the 82ha our average yield of 6.5t/ha is pleasing but all these figures hide a huge amount of variability which was caused by the conditions of the soil coming out of winter.

Cultivations

Over the last 20 years we have been reducing the level of cultivation on our soils on the farm; yearly ploughing was replaced by every few years, mainly when the weed burden deemed it was needed.

It was replaced by a homemade cultivator which moved and levelled the soil to six inches, and more recently a Vaderstadt Carrier or straw rake to try and encourage grass-weeds to germinate. We bought a Weaving Big Disc Drill in 2012 and started the journey towards no-till. We ploughed for the final time in the first years I returned to the farm. I realised that it would bury black-grass seeds and give us a clean start, but I never wanted to see a plough on the farm again.

Soil

Our organic soils have incredibly low levels of naturally occurring manganese available to our plants roots and when researching conditions that made the deficiency worse, ‘fluffy’, high pH and organic soils seemed to keep coming up. Manganese deficiency inhibits photosynthesis, the yield maker and therefore reduces dry matter, disease resistance and yield.

Our fen soils become fluffy when ploughed or cultivated and with the new big disc, if we moved any soil we would have to roll the field a number of times to be able to drill. We had unfortunately removed any structure left behind by worms or previous crops roots and reduced the ability of the seed to form a good contact with the soil around it. If we were subjected to high winds our soil would blow away.

Resilience

Looking back, we were on a path to decreasing resilience of our crops, increasing weeds through lack of plant competition, increasing inputs, reduced yield, and overall profitability.

Since I attended a soil systems course at Cranfield University in 2017, our eyes have been opened to the importance of what we do to our soil. In the last four autumns, we have taken a spade to the field and dug numerous holes assessing for the presence of compacted layers, horizontal fissures, the arrangement of soil particles and the presence of worms, as well as giving it a good sniff.

We have worked with a soil expert to get to a stage where most fields are now direct drilled, this year we are straw raking and rolling beforehand to help with slug pressures and all spring crops are planted with a cover crop. Compaction is lifted at depth with our Howard Paraplow, which is only used after sugar beet or potatoes.

Root crops make the situation more difficult.

We let land out for potatoes and grow and lift our own sugar beet. This year we strip tilled our beet but uneven chopped straw, delayed cover crop desiccation, lead to difficulties with emergence, late frosts meant we had to re-drill and virus has made the crop look sorry.

No system is easy but our move towards a lower input, more conservative approach seems to be providing more benefits than problems.