Fresenius Envir Bun 4: 59-64 (1995) (e) 1995 Birkhauser Verlag, Basd/Switzerland 10IS-4619/95/010059-06 $ 1.50+0.20/0 NITROGEN MINERALlZATION IN SOlLS AME'SDED WITH ORGANIC BY· PRODUCTS OF OLIVE OlL AND SUGARBEET PROCESSING INDUSTRIES P. Martín-Olmedo. R. López, F. Cabrera and 1.M. Murillo. Instituto de Recursos Naturales y Agrobiología de Sevilla. CSIC.Apanado 1052. 41080 Sevilla, Spain. Summary: Mineralization of organic-N supplied te two different types of soils by an alpechín (olive-oil mili waste water)-compost and a beet vinasse after three consecutive years was studied. Results were compared with those obtained for a mineral ferúlízer treatment and a control (unferúlized). N-mineralizaúon can be described by a first order kineúc model. Both organic residues produced an important increase in me organic-N loading of the soils which is slowly released over a time. Keywords: N-mineralízaúon; potentially mineralizable-N; olive-waste-water, vinasse. INTRODUCTION Agriculturaluse of "alpechín" (olive oi! mili water) and vinasse (a by-product [rom sugar industries), bom with a high organic load, is recognized environmentally and economically, as a desirable method of disposal.l. 2 Soils receiving organic residues for several years are likely to have relaúvely high N-supplying capacities.3.4 The quanúty of residue-N in soils available to plants, is influenced by the application rate and residue characteristics. 3 • 5 However, inforrnation on the rate and extent of N mineralízaüon is necessary to achieve optimum erop yields while avoiding potential poUution of groundwater:" 6. 7 The aim of this paper is to study me mineralizaúon pattem of the organic-N supplied to soils by an alpechín-compost and a vinasse after threc years of treatment, comparing results to those obtained using a mineral fertilizcr and a control (unfertilized). MATERIALS A'D METHODS Soil samples were eollected from containers (0.42 m 2 and 50 cm depth), filled with two different soils. where eomparative sludies were canied out for three eonsecutive years 8 on the yield and nutritional state oi ILolium mufriflorum¡ ror diffcrem soil (AC) alpechín