Grassland Science in Europe, Vol. 20 – Grassland and forages in high output dairy farming systems 215 Efect of diferent doses of an amendment and an organo- mineral fertiliser on the production of forage maize Ferreiro-Domínguez N., Rigueiro-Rodríguez A. and Mosquera-Losada M.R. Crop Production Departament, Escuela Politécnica Superior, Universidad de Santiago de Compostela, 27002-Lugo, Spain; mrosa.mosquera.losada@usc.es Abstract Animal feed is the main cost on dairy farms. Maize can produce quality silage for dairy cattle at less cost than silage from grass, and at the same time increases milk yield and milk protein content. Moreover, supplementation with concentrates can be reduced and proitability is improved. he correct use of amendments and fertilisers could improve maize production and its nutritional content and also reduce costs. he aim of this study was to evaluate the efect on forage maize production of diferent application rates of an amendment (5, 15, 25 and 35 Mg ha -1 ) and an organo-mineral fertiliser (50, 100, 150 and 200 kg N ha -1 ) developed with organic matter from industrial wastes and with inorganic sulphur from a reinery, in comparison with the mineral fertilisation usually carried out in the area where the experiment was conducted (Spain). he results obtained did not show a signiicant efect of the diferent rates of the amendment on maize production, probably because the amount of N applied to the soil was similar. However, high rates of the organo-mineral fertiliser increased the production of forage maize, probably by the soil fertility improvement associated with this treatment. Keywords: dairy farms, nutrition, yield, management, Zea mays Introduction On dairy farms, green fodder is the most valuable and cheapest source of animal feed. Maize occupies a key position as one of the most important fodder crops for animal consumption because of the high production of maize in comparison with other fodder crops (Muzafar et al., 2014). Moreover, maize produces quality silage for dairy cattle at less cost than silage made from grass, which reduces the need for supplementation with concentrates and improves the farm proitability (Ali et al., 2012). On the other hand, the correct use of amendments and fertilisers is vital for the success of the crop because it greatly inluences not only the yield of the crop and its nutritional content but also its production costs. New products developed from wastes from industries could be used as amendments and fertilisers. his could reduce the use of inorganic fertilisers at the same time as residues are recycled. Several studies have shown that the use of wastes from industries as amendments and fertilisers can increase crop yields and quality and result in signiicant economic returns for producers (Hue, 1992). he aim of this study was to evaluate the efect on forage maize production of diferent rates of application of an amendment (5, 15, 25 and 35 Mg ha -1 ) and of an organo-mineral fertiliser (50, 100, 150 and 200 kg N ha -1 ) developed with organic matter from industrial wastes and with inorganic sulphur from a reinery. he results obtained were compared with the mineral fertilisation usually carried out in the area of Spain where the experiment was conducted. Materials and methods he experiment was established in León (NW Spain) in 2013 when the soil was ploughed and the experimental plots were established. Each plot occupied 11.25 m 2 and in spring of 2013 the plots were sown with forage maize (Zea mays L.). he distance between plant rows was 0.55 m and the distance between plants in each row was 0.155 m. he experiment was arranged as a randomized complete block design with four replicates and nine treatments. he treatments consisted of the application of four rates of an amendment (5, 15, 25 and 35 Mg ha -1 ) and four rates of an organo-mineral fertiliser (50, 100,