Circular economy: Using lime stabilized bio-waste based fertilisers to improve soil fertility in acidic grasslands

Abstract

The Circular Economy Package adopted by the European Commission proposes that when a product reaches the end of its life, it should be used again to create further value. In this context, it is important to valorise and characterize the effect of waste on soil fertility and pasture/crops growth. In this experiment we used two types of bio-waste based fertilisers with amendment value stabilized and sanitized with lime. One of the bio-waste was composed by urban sewage sludge (65%), chicken manure (25%) and wood ash (10%) and the other bio-waste by urban sewage sludge (35%), animal by-product (20%), quicklime (18%), wood kindling (17%) and wood ash (10%). The aim of this study was to evaluate the effect of different doses (1, 2.5, 5 and 10 Mg ha−1) of the two bio-waste based fertilisers on the chemical soil properties, pasture production and its botanical composition compared with control conventional treatments (no fertilisation and mineral fertilisation) combined with lime and without lime in pastures established in Galician acid soils (NW Spain). The results of this experiment show that the high doses of the bio-waste based fertilisers improved the soil fertility and therefore increased the pasture production and modified its botanical composition which was more sensible to the variation of soil fertility than the production. These results indicate that the botanical composition could be considered as a good bio-indicator of changes in soil fertility when the bio-waste based fertilisers are used in the agriculture. Moreover, the soil and pasture results associated to the bio-waste amendments were similar to the results obtained when the conventional practices of the area were carried out. Therefore, the partial or total substitution of mineral fertilisers by bio-waste based fertilisers could be a viable alternative to adopt the circular economy concept in the farms.