Effect of sludge on germination and growth of bioenergy crops

Författare

• Mahmoud F. Seleiman
• Pirjo Mäkelä
• Arja Santanen
• Fredrick Stoddard Department of Agricultural Sciences, P.O. Box 27, FIN-00014 University of Helsinki, Finland

DOI: https://doi.org/10.33354/smst.75619

Nyckelord:

ewage sludge, biogas sludge, germination, maize, oilseed rape, hemp

Abstract

Sludge is a good source of plant nutrients, but its use as fertilizer for food or fodder crops is questionable due to its potential content of heavy metals and metalloids.
In two pot experiments, germination and growth of maize (Zea mays L., cv. Ronaldino), fiber hemp (Cannabis sativa L., cv. Uso 31) and oilseed rape (Brassica napus L. ssp. oleifera (DC.) Metzg., cv.Wildcat) were studied when treated with sewage sludge and biogas sludge in comparison with chemical fertilizer during 2011. The experiment included five treatments: soil+sewage sludge, soil+fertilizer, sand mixed with peat+sewage sludge, sand mixed with peat+fertilizer, and soil+biogas sludge. Sludge content was calculated to deliver the same content of nitrogen that was added for each species. Germination percentage was recorded at 7, 10 and 14 days after sowing. Length and dry weight of roots and shoots were measured at 14 days after sowing for all species.
Sewage sludge treatments resulted in higher germination percentage compared to biogas sludge and fertilizer application in soil and sand mixed with peat. The longest roots were in the sewage sludge treatment. In addition, shoot lengths in maize were highest when fertilized with sludge or fertilizer in soil. Furthermore, sewage sludge or fertilizer added to soil increased root and shoot dry weight of maize.
In conclusion, there is an existing excellent potential for using sewage sludge not only as organic matter but also as a valuable plant nutrient source for improving growth of bioenergy crops.