increasing plant diversity

The use of monocultures or simplified rotations leads to simplification in the soil food web.  Increases in plant diversity, whether in space or time, are very likely to lead to increase in species richness of soil biota through more diverse litter, exudates, rooting patterns, and plant associations. Management of the farmed landscape rather than fields per se is also important as field margins, hedges etc provide an important reservoir of soil organisms that may recolonise disturbed areas, as well as themselves providing a diversity of niches for a wider range of organisms.

Consider the following recommended practices

  • Use locally adapted rotations with grass-clover leys
  • Introduction of diverse seed mixes e.g. mixed species awards including deep rooting species and herbs, species mixtures for whole-crop silage
  • Integration of green manures into crop rotations

Green manures, cover crops and grass leys provide opportunities for increasing organic matter inputs to the soil in situ. In arable rotations, diversification of crop rotations compared with monoculture or minimal break crops and/or the integration of green manures (including cover crops) into crop rotations have positive benefits for soil health.

However, relatively little work has been carried out to develop specific advice on the most appropriate green manures for any soil/ rotation combination and the most appropriate management of them (cutting/ grazing regimes etc.). Nonetheless green manures/ cover crops have been used in practice for a number of years, so that farmer understanding of practical combinations is increasing. 

Within livestock systems and mixed farming systems, diversification within forage crops and in grazed swards may be an important tool to increase on-farm plant diversity. Whole-crop silage is increasing in extent and species mixtures are increasingly common including legumes to increase forage protein levels and reduce N fertiliser requirements.  Mixed species swards may address a number of farm objectives including fertiliser reduction and improvement in livestock health; hence there is a range of farmer experience following implementation that could be shared. 

It seems likely that the integration of tree crops within grassland systems would also have significant benefits; there is some research evidence confirming this but little practical farmer experience. Integration of lignin rich/woody crops into farming systems as energy crops may provide an opportunity to further consider agroforestry approaches. 

In a Natural England project (2011-12) expert judgement on the impacts of the practices was linked with farmer feedback on their likely uptake and effectiveness. A summary of the recommended practices for increasing plant diversity on-farm for grassland systems can be downloaded hereStockdale, E.A. & Watson, C.A. 2012. Managing soil biota to deliver ecosystem services.  Natural England Commissioned Report, No. 100.

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