Effect of Dried Pig Manure Fertilization on Barley Macronutrients and Sodium in a Nitrate Vulnerable Zone

Abstract

Dried pig manure (DPM) may be valorized as a fertilizer suitable for barley crop in nitrate vulnerable zones (NVZs). The aim of this study was determine the macronutrients and sodium contents in barley (Hordeum vulgare L.) resulting from its application in a NVZ in Fompedraza (Valladolid, Spain). DPM was applied at three rates (85, 133, and 170 kg N ha−1 year−1); the mineral fertilizer with a nitrification inhibitor was applied at two rates (90 and 108 kg N ha−1 year−1), and these were compared with the control treatment (without fertilization) in a randomized complete block design. Nutrients were monitored in four different plant growth stages and in grain over a 3-year period. DMP-based fertilization increased P and Na contents in plant and decreased those of Ca and Mg. These changes were only translated into a P increase in grain. The Na content in plant should not affect the final crop yield, making this waste management strategy viable even in NVZs. However, N content in plant in tillering and stem elongation stages was lower for DPM-based fertilization than for mineral fertilization, and so was the C content, both in plant and in grain. Since N content is a limiting factor for crop development, supplementary mineral fertilization would be advised to compensate for N immobilization if this organic waste material is to be valorized as a fertilizer.