Add carbon to soil before or after seeding/planting

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

  • Two studies examined the effects of adding carbon to soil before or after seeding/planting on grassland vegetation. Both studies were in the USA.




About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A replicated, randomized, controlled study in 2000–2006 in a former arable field in Minnesota, USA (Grygiel et al. 2012; same study site as Grygiel et al. 2014) found that adding carbon to soil after sowing seeds led to a decrease in the density of seeded and unseeded forb species compared to sowing without carbon. After 1–5 years, forb density was lower in plots where carbon was added and seeds were sown (seeded forbs: 9–35 plants/m2; unseeded forbs: 13–70 plants/m2) than in plots where no carbon was added and seeds were sown (seeded forbs: 30–128 plants/m2; unseeded forbs: 32–186 plants/m2). In autumn 2000, two 2.8 × 2.8 m plots in each of ten blocks were tilled and seeded with a combination of native grasses and forbs at a rate of 25 kg/ha. In spring 2001, carbon was added (granular sugar at a rate of 0.5 kg/m2) to one plot/block, while no carbon was added to the other plot. Vegetation was sampled in August 2002–2006 using four randomly placed 0.25-m2 quadrats/plot.

    Study and other actions tested
  2. A replicated, randomized, paired, controlled study in 1998–2010 in a former arable field in Minnesota, USA (Grygiel et al. 2014; same study site as Grygiel et al. 2012) found that adding carbon to soil after sowing seeds did not alter the density of sown native forb species. After 10–12 years, the average density of sown forb species did not differ significantly between plots where carbon was applied after seeds were sown (29 plants/m2) and plots where carbon was not applied after seeds were sown (40 plant/m2). In autumn 1998, two 4 x 3 m plots in each of five blocks were tilled and sown with a seed mixture containing four native grasses and 12 native forbs. In spring 1999, one plot/block had carbon applied (granular sugar at a rate of 0.5 kg/m2), while the other plot had no carbon applied. In July–August 2005–2010, the density of sown forb species was estimated in each of the 10 plots.

    Study and other actions tested
Please cite as:

Martin, P.A., Ockendon, N., Berthinussen, A, Smith, R.K. and Sutherland W.J. (2021) Grassland Conservation: Global evidence for the effects of selected interventions. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

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Grassland Conservation

This Action forms part of the Action Synopsis:

Grassland Conservation
Grassland Conservation

Grassland Conservation - Published 2021

Grassland Synopsis

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