Agricultural production in semi-arid regions is improved with irrigation, which also increases the organic soil matter (OSM) content, yield and mulch. The objective of this work was io evaluate the dry matter production and the carbon and nitrogen content in soil and biomass of 'Perola' pineapple in drip irrigated alluvial soil. A randomized block design was used with five irrigation treatments: 30% of Class A pan evaporation (691.2mm/year), 50% (1152.0mm/year), 70% (1612.8mm/year; 100% (2304.0mm/year) and 150% of the Class A pan evaporation (3456.0mm/year). Lower contents of soil C (36.32Mg.ha(-1)) and soil N (1.22Mg.ha(-1)) were observed in the irrigation depth of 98% (22579mm/year) and 96% (2211.8mm/ year) of the Class A pan evaporation, respectively. The increase in water at depths between 96 and 98% of ACE reduces the carbon and nitrogen content of the soil, possibly by enhancing the rate of OSM decomposition by soil microorganisms. The highest C and N stocks are in the leaves, showing their importance as soil mulch.