title: Nitrification during extended co-composting of extreme mixtures of green waste and solid fraction of cattle slurry to obtain growing media.
abstract: Next generation of waste management systems should apply product-oriented bioconversion processes that produce composts or biofertilisers of desired quality that can be sold in high priced markets such as horticulture. Natural acidification linked to nitrification can be promoted during composting. If nitrification is enhanced, suitable compost in terms of pH can be obtained for use in horticultural substrates. Green waste compost (GW) represents a potential suitable product for use in growing medium mixtures. However its low N provides very limited slow-release nitrogen fertilization for suitable plant growth; and GW should be composted with a complementary N-rich raw material such as the solid fraction of cattle slurry (SFCS). Therefore, it is important to determine how very different or extreme proportions of the two materials in the mixture can limit or otherwise affect the nitrification process. The objectives of this work were two-fold: (a) To assess the changes in chemical and physicochemical parameters during the prolonged composting of extreme mixtures of green waste (GW) and separated cattle slurry (SFCS) and the feasibility of using the composts as growing media. (b) To check for nitrification during composting in two different extreme mixtures of GW and SFCS and to describe the conditions under which this process can be maintained and its consequences. The physical and physicochemical properties of both composts obtained indicated that they were appropriate for use as ingredients in horticultural substrates. The nitrification process occurred in both mixtures in the medium-late thermophilic stage of the composting process. In particular, its feasibility has been demonstrated in the mixtures with a low N content. Nitrification led to the inversion of each mixture's initial pH.
authors: IRTA, Research and Technology, Food and Agriculture, GIRO Unit, Carretera de Cabrils km 2, 08348 Cabrils, Catalonia, Spain. Electronic address: rafaela.caceres@irta.cat.
authors: Rafaela
authors: R
authors: Cáceres
authors: IRTA, Research and Technology, Food and Agriculture, GIRO Unit, Carretera de Cabrils km 2, 08348 Cabrils, Catalonia, Spain.
authors: Narcís
authors: N
authors: Coromina
authors: Institute of Environmental Engineering, Czestochowa University of Technology, Brzeźnicka 60a, 42-200 Częstochowa, Poland.
authors: Krystyna
authors: K
authors: Malińska
authors: Universitat Politècnica de Catalunya (UPC), ASQUAS Research Group, Campus del Baix Llobregat, c/Esteve Terradas, 8, 08860 Castelldefels, Catalonia, Spain.
authors: F Xavier
authors: FX
authors: Martínez-Farré
authors: Universitat Politècnica de Catalunya (UPC), ASQUAS Research Group, Campus del Baix Llobregat, c/Esteve Terradas, 8, 08860 Castelldefels, Catalonia, Spain.
authors: Marga
authors: M
authors: López
authors: Universitat Politècnica de Catalunya (UPC), ASQUAS Research Group, Campus del Baix Llobregat, c/Esteve Terradas, 8, 08860 Castelldefels, Catalonia, Spain.
authors: Montserrat
authors: M
authors: Soliva
authors: IRTA, Research and Technology, Food and Agriculture, GIRO Unit, Carretera de Cabrils km 2, 08348 Cabrils, Catalonia, Spain.
authors: Oriol
authors: O
authors: Marfà
mesh_terms: D000383:Agriculture / Q000379:methods; D000641:Ammonia / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002417:Cattle; D004553:Electric Conductivity; D006863:Hydrogen-Ion Concentration; D008372:Manure; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism; D058465:Nitrification; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism; D012987:Soil / Q000737:chemistry; D013696:Temperature; D013997:Time Factors; D018505:Waste Management / Q000379:methods*
chemical_list: D008372:Manure; D009566:Nitrates; D012987:Soil; D000641:Ammonia; D009584:Nitrogen
keywords: Green waste; Growing medium; Natural acidification; Nitrification; Physicochemical properties; Separated cattle slurry