Action Synopsis: Soil Fertility About Actions

Amend the soil with bacteria or fungi

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

Biodiversity: One randomized, replicated trial from India showed that adding soil bacteria and arbuscular mycorrhizal fungi resulted in higher microbial diversity.

Soil organic matter: One controlled, randomized, replicated trial from Turkey found increased soil organic matter content in soil under mycorrhizal-inoculated compost applications

Yield: Two randomized, replicated trials (including one also controlled) from India and Turkey found higher crop yields.

SOIL TYPES COVERED: clay-loam, sandy-loam.


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 controlled, randomized, replicated experiment in 2002-2004 on sandy-loam soil in Udham Singh Nagar, India (Srivastava et al. 2007) found that adding soil bacteria and arbuscular mycorrhizal fungi (see background section) increased soil microbial diversity (2.5 x 103 colonies/g soil), compared to the control (1.9 x 103 colonies/g soil). Crop yields in okra Hibiscus esculentus, pea Pisum sativa and cowpea Vigna unguiculata increased when bacteria (33, 25 and 8 kg/ha, respectively) and arbuscular mycorrhizal fungi (40, 28 and 11 kg/ha) were added, compared to the control (22, 21, and 4 kg/ha).  Three crops were grown in rotation: okra, pea and cowpea. Each plot was 16 m2. AMF Glomus intraradices and a bacterium species Pseudomonas fluorescens were added to the soil as treatments. Only crop residues were added during the experiment. There were three replicates. Soil samples were taken and soil microbe numbers were measured. The effect of rotation was not reported.

    Study and other actions tested
  2. A controlled, randomized, replicated experiment from 1996 to 2008 on clay-loam soil in southern Turkey (Celik et al. 2010) found 24% higher organic matter content in soil under mycorrhizal-inoculated compost applications compared to the control. The largest soil aggregations were found under mycorrhizal-inoculated compost (0.11 mm), manure (0.05 mm) and compost (0.07) applications. Crop yield was highest under mineral fertilizer (13720 kg/ha) followed by manure (10500 kg/ha), compost (8780 kg/ha) and mycorrhizal-inoculated compost (7630 kg/ha), compared to the control (5900 kg/ha). Within a wheat Triticum aestivum-maize Zea mays rotation were three replicates five 10 x 20 m treatments: control, mineral fertilizer (300-60-150 kg N-P-K/ha), manure (25 t/ha), compost (equal mixture of grass, wheat stubble and plant leaves, 25 t/ha), mycorrhizal Glomus caledonium-inoculated compost (10 t/ha). Soil samples were taken to 30 cm depth 2008.

    Study and other actions tested
Please cite as:

Key, G., Whitfield, M., Dicks, L.V., Sutherland, W.J. & Bardgett, R.D. (2020) Enhancing Soil Fertility. Pages 613-634 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.


Where has this evidence come from?

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Soil Fertility

This Action forms part of the Action Synopsis:

Soil Fertility
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