Abstract

In the O’Higgins Region, Chile’s main maize-producing area, it has been observed that during the fallow period of maize cultivation, farmers most commonly use the practice of burning agricultural stubble. As a result, air pollution and soil erosion occur. To avoid this polluting practice, and alternative management is the incorporation of the stubble into the soil, thus obtaining physical, chemical and, biological benefits. The main problem with this management method is the high C/N ratio of the stubble. In order to avoid this, application of nitrogenous fertilizers would diminish the C/N ratio and mineralization would occur. However, excessive applications of fertilizer would increase the risk of contamination of deep-water bodies with nitrates (NO3), principally in sandy soils. For this reason, the study’s objective was to compare the net leaching rates of N in soil columns under controlled greenhouse conditions using different management conditions, with and without nitrogen fertilizer applications. The trial was conducted by the Faculty of Agricultural Sciences at the University of Chile, where 16 PVC fills of 20 cm in diameter and 50 cm of depth were installed, to which were added soil with a sandy texture from an experimental site located in San Luis (SL) (34°22’S, 71°25’0, altitude 124 m), Pichidegua municipality. 4 treatments with 4 repetitions each were stablished, in a design of completely randomized blocks (T0: Control, T1: Stubble without N, T2: Stubble Urea, T3: Stubble Methyl-Urea (slow delivery fertilizer)), and distilled water was applied to the columns simulating the amount of rain falling on SL. Percolated water was determined for pH, CE, N-NO3 (mg) and N-NH4 (mg). The results were statistically analyzed according to a Turkey test (p < 0.05). In relation to the concentration of N-NO3 determined, the T2 and T3 treatments leached a higher concentration than T0 and T1, with significant differences. Nevertheless, the application of slow-delivery fertilizer (T3) had no significant differences from urea treatment (T2) (118.57 vs 194.75 respectively). Concentrations of N-NH4 reacted in a similar manner, without significant differences between T0 and T1 vs T2 and T3. In relation to the pH and CE, the treatments without fertilizer (T0 and T1). Although there were no statically significant differences for N-NO3 between T2 and T3, treatment T3 resulted in significantly lower concentrations, so it could be a more viable and less polluting agricultural management technique than the application of urea and the traditional burning of agricultural fields that are usually practiced.