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Providing evidence to improve practice

Action: Crop production: Add sewage sludge to the soil Mediterranean Farmland

Key messages

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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.

 

Supporting evidence from individual studies

1 

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 75oC. 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.

 

Referenced papers

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.