Good Green Manures

Field Lab Report: Benefits

Resource explained

Green manures are often sown between other crops to provide multiple benefits for the soil and the wider environment. This report is from a field lab being run in south Lanarkshire that is comparing four different green manure seed mixes and evaluating whether they can (a) improve soil quality, (b) benefit the following crop, and (c) justify the cost of cultivation. The green manure mixes were planted in September and incorporated into the soil before a spring barley crop was sown. This report provides a useful summary for each of the green manure mixes of what was looked at in the early spring; soil structure, earthworm counts, full forage analysis, mineral content, available and total nitrogen content, and cost of establishment. No single seed mix emerged as a clear winner in all categories of the assessment, emphasising the need to tailor green manures to your farm goals.

Findings & recommendations

  • The oats and rye combination had the highest yield, captured the most nitrogen, and was the cheapest mix.
  • A diverse mix of species with different growth forms (e.g. oats, vetch and phacelia) is particularly good at helping to improve soil structure.
  • Adding leguminous species such as vetch can help improve soil total nitrogen content.
  • Cultivation methods and sowing also have a significant impact on soil structure and biodiversity. Discing and broadcast sowing resulted in around 4x more earthworms than other methods!
  • While seed costs for green manures can be high, these can be significantly reduced by saving seed from the previous green manure crop.
  • There is no all-round best green manure mix. Always tailor the mixture to your own goals on the farm.

View another report here containing more detailed information from the trials including sowing rates, methodology and results.

Also see here for more information on the field lab.

Associated Agricology Partner Organisation(s):

Related articles

Making the Most of Green Manures

Improve your understanding of how to use green manures and the many potential ways in which they can benefit your farm business with this audio...

Manifold green manures – Part I: Sainfoin and birdsfoot trefoil

An article outlining properties of two species that could be considered for fertility-building mixes, trialed in the Legume LINK project.

Manifold green manures Part 2: Alsike and crimson clovers

Details on alsike and crimson clover that will help assess suitability for inclusion in fertility-building mixes, as defined in Legume LINK.

Manifold green manures Part 3: Black medic and lucerne

Two lesser-used legume species with properties that you can make use of in fodder, green manure or hay crops, as highlighted in Legume LINK.

Manifold green manures – Part 4: Large birdsfoot trefoil, meadow pea and white clover

An article outlining properties of three species that could be considered for fertility-building mixes, trialed in the Legume LINK project.

Sort out your soil

This Cotswold Seeds / Garden Organic publication provides detailed, practical information to help you select and use green manure crops.

Establishing summer cover crops before winter cereals in low tillage systems on sandy soils

Abstract created as part of the DiverIMPACTS project outlining some of the benefits that can be attained from establishing summer cover crops on sandy soils...

Opportunities for cover crops in conventional arable rotations

An introduction to the potential environmental and agronomic benefits of cover crops in arable systems.

Cover, Catch and Companion Crops

A comprehensive guide to help you protect and improve biological ecosystems and crop management, and your arable and livestock enterprises.
To top