Increases in growth and nutrient uptake of alfalfa grown in soil amended with microbially-treated sugar beet waste

Sugar beet waste (SB), treated by Aspergillus niger under the conditions of 10-, 20-, and 30-day-solid state fermentation, supplemented or not with rock phosphate (RP), was added to a soil-plant system. Plant growth responses depended on the time period of preincubation of the agrowaste characterized by different lignocellulosic composition and N and P contents before introduction into soil. Maximum growth and nutrient uptake of alfalfa during three crop cycles were recorded in a soil amended with microbially-treated SE waste+RP. This effect was more pronounced in treatments with arbuscular mycorrhizal (AM) fungus grown in soil enriched with 10- and 20-day-microbially-treated SB+RP, when the respective average total plant growth increased 233% and 343% over the non-mycorrhizal control containing untreated SE. Compared to other treatments, plant mycorrhization was ineffective when 30-day-treated agrowaste was used. Similarly, plant nodule numbers and uptake of metal ions depended on both the time period of waste preincubation and mycorrhization. (C) 1999 Elsevier Science B.V.