Abstract

In field studies in 1992 and 1993, biosolid applications of 2 t/ha with supplements of mineral N and P were compared with a standard mineral fertiliser application (20 kg N/ha, 20 kg P/ha, 1.8–2.8 kg Zn/ha, 1.4–1.9 kg Cu/ha, 0.5–4 kg Mn/ha) on 4 soil types. Biosolid rates from 2 to 10 t/ha were applied in 1993. Shoot dry matter production at different stages of plant development (9 and 15 weeks after sowing) and grain production of Triticum durum and Hordeum vulgare, as well as nutrient concentration in shoots and grain, were taken as indicators for comparing nutrient availability of the 2 sources. A 2-t biosolid application was found to enhance dry-matter production and yield to the same extent as a mineral fertiliser application of 20 kg N/ha, 20 kg P/ha, and 1.8–2.8 kg Zn/ha. In some crop rotations and on sites with a high yield potential, additional nitrogen with 2 t biosolids/ha would be necessary to achieve such yields. However, development of durum wheat fertilised with 2 t biosolids was slower and P uptake lower than with mineral fertiliser until late booting. Durum wheat fertilised with 4 t biosolids showed similar P-uptake values as plants fertilised with the mineral fertiliser. The Zn-uptake of plants was positively correlated with biosolid application rates, showing a linear relationship. A 2-t biosolid application alleviated micronutrient deficiency to the same extent as the same rate of Zn (and Cu) given in mineral form.