Biochemical properties and barley yield in a semiarid Mediterranean soil amended with two kinds of sewage sludge

Published source details 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.
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This study is summarised as evidence for the following.

	Action	Category
	Crop production: Add sewage sludge to the soil Action Link
	Crop production: Use organic fertilizer instead of inorganic Action Link
	Crop production: Add compost to the soil Action Link
	Soil: Use organic fertilizer instead of inorganic Action Link
	Soil: Add sewage sludge to the soil Action Link
	Soil: Add compost to the soil Action Link

Crop production: Add sewage sludge to the soil

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.
Crop production: Use organic fertilizer instead of inorganic

A replicated, randomized, controlled study in 2002–2005 in a barley field in Toledo, Spain, found higher grain and straw yields in plots with organic fertilizer, compared to inorganic fertilizer. Crop yield: Higher grain yields were found in plots with organic fertilizer, compared to inorganic fertilizer, in two of eight comparisons (with 20 t thermally dried sewage sludge/ha/year: 2.0 vs 1.6 t/ha; with 80 t composted sewage sludge/ha once in three years: 2.8 vs 1.6 t/ha), and higher straw yields were found in six of eight comparisons (2.7–4.2 vs 1.8 t/ha). Methods: There were four plots (10 x 3 m) for each of eight organic fertilizers (20 or 80 t thermally dried sewage sludge/ha, applied once in three years or once/year; 20 or 80 t composted sewage sludge/ha, applied once in three years or once/year) and one mineral fertilizer (15-15-15 NPK: 400 kg/ha/year). Plots were fertilized in mid-September and planted in mid-October. Barley was harvested in June 2005 (1 m²/plot).
Crop production: Add compost to the soil

A replicated, randomized, controlled study in 2002–2005 in a barley field in Toledo, Spain, found no difference in grain yields, but found higher straw yields, in barley plots with added compost, compared to barley plots without added compost. Crop yield: Similar grain yields were found in barley plots with or without added compost (0.7–1.9 vs 1.2–1.6 t dry weight/ha). Higher straw yields were found in barley plots with added compost, compared to plots without added compost (3.3–3.4 vs 1.3–1.8 t dry weight/ha). Methods: The compost was made from sewage sludge. There were four plots (10 x 3 m) for each of four fertilizer treatments (20 or 80 t compost/ha, applied once in three years or once/year) and one control (no fertilizer). Plots were fertilized in mid-September and planted in mid-October. Barley plants were harvested (1 m²/plot), in June 2005.
Soil: Use organic fertilizer instead of inorganic

A replicated, randomized, controlled study in 2002–2005 in a barley field in Toledo, Spain, found more microbial biomass in soils with organic fertilizer, compared to inorganic fertilizer. Soil organisms: More microbial biomass (measured as carbon) was found in soils with organic fertilizer, compared to inorganic fertilizer, in two of eight comparisons (composted sewage sludge: 157–266 vs 83 mg C/ha). Methods: There were four plots (10 x 3 m) for each of eight organic fertilizers (20 or 80 t thermally dried sewage sludge/ha, applied once in three years or once/year; 20 or 80 t composted sewage sludge/ha, applied once in three years or once/year) and one mineral fertilizer (400 kg NPK/ha/year; 15-15-15 NPK). Plots were fertilized in mid-September and planted in mid-October.
Soil: Add sewage sludge to the soil

A replicated, randomized, controlled study in 2002–2005 in a barley field in Toledo, Spain, found similar amounts of microbial biomass in soils with or without added sewage sludge. Soil organisms: Similar amounts of microbial biomass (measured as carbon) were found in soils with or without added sewage sludge (86–136 vs 76 mg C/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.
Soil: Add compost to the soil

A replicated, randomized, controlled study in 2002–2005 in a barley field in Toledo, Spain, found more soil organisms in plots with added compost, compared to plots without added compost, in two of four comparisons. Soil organisms: More microbial biomass (measured as carbon) was found in soils with low amounts of added compost, compared to plots without added compost (one application: 157 vs 76 mg C/ha; one application/year: 265 vs 76), but significant differences were not found between plots with high amounts of added compost and plots without added compost (one application: 95 vs 76; one application/year: 136 vs 76). Methods: The compost was made from sewage sludge. There were four plots (10 x 3 m) for each of four fertilizer treatments (20 or 80 t compost/ha, applied once in three years or once/year) and one control (no fertilizer). Plots were fertilized in mid-September and planted in mid-October.