Huella hídrica de las explotaciones lecheras según tipología de alimentación

Abstract

Fifty-three dairy farms situated in Galicia, Asturias, Cantabria and Navarra were previously selected and classified according to the INIA-RTA 2012-00065-C05 project in six types of feeding: a) Ecological (Eco); b) Conventional grazing (PasCon); c) Harvest-Grazing (PePa); d) Grass silage (EHba); e) Corn silage (EMz) and f) Grass and corn silage (EHba-EMz). Values from these farms were used to estimate the water footprint of the forages produced on the farm (HHf ) and the water footprint of a litre of milk corrected for fat (HHECM ). The HHf was statistically different between the various forages, with averages of 895 l of water per kg of dry matter. HHf showed the higher value in prairie grass (719 l) and the lower value lower in corn and Italian ryegrass, with 301 l and 267 l respectively. The HHf had 85.6 % as green, 1.2 % blue and 13 % gray water. The lowest gray water value was registered in the meadow (9.3 %) and the maximum (24.2 %) in Italian ryegrass. Among typologies, blue water value was higher in EHba-EMz and EMz, with 20.4 % and 19.3 %, respectively. The HHECM was 1080 l, with maximum in Eco (1304 l) and minimum in EMz (716 l). The HHECM had 948 l, 40 l and 91 l of green, blue and gray water, res-pectively. The highest percentage of green water was located in Eco (89.9 %) and the lowest in EHba-EMz and EMz (83.5 %). The upper blue water value was found in EHba-EMz and the lowest in EHba. The HHECM of the farms with annual forage crops decreased by 23.2 % equivalent to 258 l. Food pur-chases represented 62.7 % of the footprint of a litre of milk. The variables related to the pasture and the consumption of concentrate tends to increase the water footprint; meanwhile, production and de-dication of the surface to forage crops tends to reduce it.