Abstract:
One promising way to reuse and recycle brewery spent diatomite sludge (BSDS) is by direct application
to croplands as a soil amendment. This paper assesses the value of BSDS as a soil amendment and organic
fertilizer. BSDS samples of different ages were analyzed to determine physicochemical properties and
trace metal concentrations. All BSDS samples were alkaline (pH 8.3e8.7) with high concentrations of
available phosphorus (373e416 mg kg 1
) and potassium (883e3297 mg kg 1
). Organic carbon and total
nitrogen content were also found to be relatively high (3.1% and 0.22%, respectively) in the freshly
dumped BSDS. The total porosity and available water holding capacity of BSDS were found in the range of
71e73% and 145e176 mm m 1
, respectively, which indicate favorable conditions for plant growth.
Concentrations of potentially toxic trace metals in BSDS were much lower than the standards set for land
application, implying that BSDS is safe for use as organic fertilizer. In addition, field trials with teff
(Eragrostis abyssinica Zucc.) and wheat (Triticum aestivum L.) were conducted to measure the effects of
BSDS amendments on grain yield as compared to recommended inorganic fertilizers and farmyard
manure. For both cereals, application of BSDS resulted in two-fold higher grain yields than the control
and 50% increases over farm yard manure. Post-harvest analysis also revealed an improvement in
physicochemical properties of soil. Wheat and teff grown in fields treated with BSDS showed higher
grain protein content than controls, and nearly as high as those treated with recommended inorganic
fertilizers. In conclusion, BSDS has great potential to be used as a soil amendment to increase crop
productivity and nutritional quality
