Crop production: Add sewage sludge to the soil

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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How is the evidence assessed?

Effectiveness

80%
Certainty

25%
Harms

0%

Calculating overall effectiveness category

Study locations

Key messages

Crop yield (1 study): One replicated, randomized, controlled study from Spain found higher barley yields in plots with added sewage sludge, compared to plots without it.

Crop quality (0 studies)

Implementation options (1 study): One replicated, randomized, controlled study from Spain found higher barley yields in plots with low amounts of added sewage sludge, but not high amounts, compared to plots without added sewage sludge.

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

A replicated, randomized, controlled study in 2002–2005 in a barley field in Toledo, Spain, found higher barley yields in plots with added sewage sludge, compared to plots without it. Crop yield: Higher grain yields were found in plots with added sewage sludge, compared to plots without it, in one of two comparisons (with low amounts of sewage sludge: 2.0 vs 1.2 t/ha). Higher straw yields were found in plots with added sewage sludge, compared to plots without it (2.7–4.2 vs 1.2 t/ha). Implementation options: Similar grain yields were found in plots with high amounts of added sewage sludge and plots without added sewage sludge (1.5 vs 1.2 t/ha). Methods: The sewage sludge was thermally dried at 75^oC. There were four plots (10 x 3 m) for each of four fertilizer treatments (20 or 80 t sewage sludge/ha, applied once in three years or once/year) and there were four control plots (no fertilizer). Plots were fertilized in mid-September and planted in mid-October. Barley plants were harvested (1 m²/plot), in June 2005.
Study and other actions tested
Referenced paper
Fernández J.M., Plaza C., García-Gil J.C. & Polo A. (2009) Biochemical properties and barley yield in a semiarid Mediterranean soil amended with two kinds of sewage sludge. Applied Soil Ecology, 42, 18-24.

Please cite as:

Shackelford, G. E., Kelsey, R., Robertson, R. J., Williams, D. R. & Dicks, L. V. (2017) Sustainable Agriculture in California and Mediterranean Climates: Evidence for the effects of selected interventions. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

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This Action forms part of the Action Synopsis:

Mediterranean Farmland

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