Supported by:
This Farm Net Zero trial investigates the effect of alternative cultivation systems on soil and yield of maize. Two systems will be investigated:
1- strip till-cultivating only the drilled strip and leaving the rest unmoved.
2- Disc cultivation instead of plough-based system-considered to be more min-till based, cultivating the whole field to shallower depth without full inversion
Strip tilling involves cultivating narrow strips of soil where seed is drilled, leaving the ground between the strips undisturbed. The strips are prepared either by a one-pass till-and-drill combination based on a special cultivator plus standard precision drill units, or by a 2-pass system where the ground is strip tilled at the first pass and drilled at the second.
Maize is a very valuable silage crop for the dairy industry due to its high starch and high dry matter yield potential. Traditionally maize is established through heavy cultivation, usually including ploughing and power harrowing. This heavy cultivation combined with shallow root systems and late harvest period can leave the soil in maize fields vulnerable to erosion and runoff, especially at harvest. This runoff, often phosphate-heavy, can cause pollution to nearby watercourses.
By trying alternative establishment methods including strip tilling, farmers are hoping to:
Year 1: Farms will drill trial strips using normal practice (control), strip till and disc cultivated. Farmers who plan to grow maize in the following year will plant green cover crops when appropriate to assess effect of different green covers on yield and soil health metrics.
Soil samples and yield analysis will be undertaken at harvest to assess any differences due to drilling practice.
Year 2: the same drilling techniques will be repeated either on the same fields to look at long term effects, or following overwinter green manure mixes to compare effects of covercrops and cultivation on yield and quality of maize.
By testing alternatives to ploughing, farmers are hoping to reduce the harmful impact of maize growing on soil structure, causing less erosion and runoff and reduce costs by using less fossil fuels.
Results from the trial are still being processed but our initial thoughts are noted here. There are 3 fields with different systems:
The first set of results comparing strip till with ploughing showed that a strip till system didn't result in visibly lower yields than a standard plough based system.
When the weight of the yields were compared they showed that strip tilled plots had 5% less yield than ploughed strips, but with a significantly lower cost of production with less time and fuel use.
There were more weeds present in the strip tilled area despite the same herbicide treatments on all plots. However, this was mainly grass weeds and biennial crops like thistles which were not effectively controlled by the pre drilling glyphosate.
In the second field the comparison was between a strip till, light cultivations and direct drilling. Drilling system and pre drill cultivation did have some effects, with the highest yield being a strip till plot followed by the min-till plot. The lowest yield was the direct drilled plot, although differences were not large.
There was again little to see from what the crop looked like to determine which was better without the weights.
The third set of results are still to be analysed.
After a difficult few weeks of spring the farmers have drilled the maize in the trial plots
May 23
September 23
October 23
October 2023
May 2024
September 2024
October 2024
Soil Association
Bristol / UK-wide
Arable & Soils Advisor at Soil Association, and farmer. I ran the family farm in Devon for 25 years, farming dairy, then organic beef, sheep and arable units with holiday cottage conversions. Former chairman of a local farmer owned co-op grain store, and involved in the grain supply chain nationally.
