Jonathan Swift’s ‘Gulliver’s Travels’ (1726) wrote of the warring Big-Endians and Little-Endians within Lilliput who believed that boiled eggs should be broken at the big end rather than at the little end. This seems to chime when those wedded to ploughing square up to the no-till or min-till factor. Of course, neither approach is always right or always wrong…it all depends! As Catchment Sensitive Farming is very strongly focused on soil health it’s inevitable that our bias is towards minimising disturbance by cultivation. Here’s the case for reducing cultivation:
Pro
Opportunities for growers to save costs and improve crop margins
Comment
Factors influencing the economics of reduced tillage are numerous and varied. Fewer passes made with a cultivator should lower the fixed costs
Cons
Soil structure, seedbed preparation, crop establishment along with pest control needs increased management for margins to be maintained
Grass weed control costs can escalate and affect gross margins, if a complimentary cultural and chemical strategy is not implemented
Pros
Increases in soil biota, through less physical disturbance to the soil, can increase nutrient recycling and help reduce leaching
Reduced tillage that leads to an increase in surface crop residues, helps farmland birds, aquatic biodiversity, mammals and insects
Comment
The importance of soil biology through, beneficial nematodes and bacteria demands a better understanding on carbon and nitrogen recycling. Plant root growth and relationships with fungi such as mycorrhiza are delicate and can be affected by crop choice, cover crops and plant protection products
Cons
Requires specialist kit although the system can be based around a cultivator drill
Soils sometimes need restructuring as a separate pass
Pro
Greenhouse gas emissions of carbon dioxide can be reduced with less cultivation
Comment
Careful management of soil is required to minimise an increase of nitrous oxide
Con
Generally reliant on rotations and/or chemicals for weed control
Pro
Single pass system with flexibility for some cultivation
Pro
Allows appropriate mix of tillage and drilling on soils needing both
Pro
Low-cost operation (other than capital investment)
Pro
Low disturbance for weed management
What follows are some useful articles gleaned from the farming press – food for thought for those who are open-minded about giving up the plough or perhaps just reducing its dependency.
Maize Trial – comparison of three establishment methods
- Conventional (Plough/power harrow/drill)
- Horsch Sumo cultivator
- Mzuri Direct-drilled
Findings…
Conventional: smaller cobs, less stable soils, higher incidence of slaking.
Sumo: better digestibility, energy starch and protein content, 2- 3x higher worm numbers, 0.5% – 0.6% less carbon lost, higher organic matter, lowest carbon footprint.
Direct Drill: better digestibility, energy starch and protein content, 2-3x higher worm numbers, 0.5% – 0.6% less carbon lost, less CO2 produced than conventional.
Weeds in no-till – some expert pointers
The half-life of the active ingredients within herbicides are usually longer under no till.
Pre-emergence herbicides applied on crop residues may be less effective but, residues may suppress weed germination (mulch effect) reducing reliance on herbicides.
Weed seed density increases in the top 5cm of soil with fresh weed seeds concentrated at that depth and not mixed with older seeds.
Weed seeds left on an undisturbed surface (post-harvest) have a higher mortality than where slightly buried.
Cultivation may be better at encouraging germination under wet conditions than dry when it would be better to leave undisturbed.
Introducing no-till – a guide
Planning – It would be a mistake to switch to no-till in a hurry. Always expect that there will be a learning period with a degree of trial and error. As such, some assessment of risk to the farm’s economy must be considered but many find the rewards are worth the journey. Introducing a change within the rotation such as a no-till oilseed rape crop could be a starting point.
Soil Carbon – A biologically active soil is one of the most important benefits resulting from no-till. This requires an increase of organic matter to feed the bacteria, fungi and protozoa – the living components that support healthy plant growth and better yields.
Minimising disturbance – Keeping soil intact will secure a build-up of carbon and, as the structure improves, it becomes more resilient to drought and flood. Weeds seed left on the surface will naturally be more likely to die reducing the need for herbicides.
A ‘duvet’ for soil – Soil health benefits when protected against the elements: wind, rain and cold. Cover crops or any form of green cover will prevent the loss of nitrogen, reduce run-off/leaching and keep the living soil components thriving. Whether no-till or not, leaving bare soil over the winter really should always be avoided.
Diversity – Nature thrives on diversity so expanding the range of crops and making sure livestock contribute to soil health is important when switching towards no-till
Ploughing – unfriendly to farmland birds?
The connection between good populations of farmland birds and a cessation of ploughing appears to be soil health. A staggering x10 increase in bird numbers over winter has been revealed by research, part of Syngenta’s Conservation Agriculture and Sustainable Farming Initiative. Another study recorded a 145% increase where fields were established by direct-drilling/light till. Leaving the plough in the shed means food for birds is nearer the soil surface and accessible. Both inset and seed-eating birds were seen to benefit. Worm numbers are consistently higher where soil is not ploughed, clearly a much sought after food item.
Five-year Direct Drilling Trial
Syngenta’s conservation agriculture project compared three methods of cultivation techniques:
- Conventional plough-based 15-20cm depth inversion
- Min-till 10-15cm depth non-inversion cultivation + cover crops
- Direct-drill 0-10cm depth cultivation/direct drill + cover crops.
The key findings were that direct -drilling could increase profitability, reduce the production of greenhouse gasses (8% ) and increase earthworm numbers. These provide a food source for farmland birds and a subsequent increase in their numbers the farm can support.
Conclusion
Reducing the use of the plough has many potential benefits but it is not a straight choice to either continue or give it up permanently. The best advice is to talk to those who have made the switch. Min or no-till is clearly being encouraged. See for instance the generous grants that have recently been made available via the Farming Equipment & Technology Fund (FETF). In terms of the need to reduce greenhouse gases the ‘nudge’ is perhaps to minimise the energy required in cultivation. Reducing diesel consumption alone may also do much to improve profitability in the long term.