The effect of sludge from citrus peel on the growth of Lolium multiflorum Lam

The present work studied the agronomic aspects relating to the use of sludge as source of nitrogen as an alternative to mineral nitrogen fertilization. The used sludge is a by-product generated during the process of extracting pectins from citrus peels obtained from Cargill Pectin Italy s.r.l. Several uses of the residues from the citrus processing industry have been evaluated in recent decades (animal feed, organic fertilizer and as substrate in biorefinery industries) (Satari and Karimi 2018, Dubis et al., 2020). The sludge is considered as a soil-conditioner able to improve the physical characteristics of the soil (porosity and structure), thanks to its high level of organic matter (Casado-Vela et al., 2006). The aim of this study was to evaluate the effect of different doses of nitrogen fertilization and sludge, containing an equivalent amount of nitrogen, on growth and productivity of a forage grass species, Lolium multiflorum Lam. The experiment was arranged in a randomized block design with three replicates per treatment. Two experimental factors were studied: mineral nitrogen fertilization with three levels (40, 80 and 120 kg N ha-1) and sludge fertilization with an equivalent amount of nitrogen (40, 80, 120 kg N ha-1). Moreover, two additional rates of sludge fertilization (160 and 200 kg N ha-1) were evaluated.