Abstract

"In the IX Region of Chile, the use of the soil has been intensified due to the increasing demand for higher yields and better wheat (Triticum aestivum L.) quality, leading to an increasing use of nitrogen (N)-fertilizers. In this study three soil tillage systems using 15N were compared to assess the efficiency of recovery of N-fertilizers, and consequently, report on the possibility of reducing the total cost of the crop. The soil management systems compared were: 1) no till and burning crop residues (CL + Q); 2) no till and no burning (CL - Q), which is considered the most protective soil system management, recently adopted by some farmers; and 3) burning crop residues and soil plough down (TRAD). The experimental design was completely randomized blocks with four replicates of each treatment. Commercial Urea fertilizer was used in the ""macroplots"", whereas Urea labeled with 15N fertilizer, 10% atoms in excess (a. e.) was used in ""microplots"". The N-fertilizer ""recovered"" in the soil profile (0 - 80 cm) at the end of the fallow period, prior to seeding the following crop, was 59% for (CL + Q), 58% for (CL - Q), and 49% for (TRAD). By adding the figures of N recovery by plants and soil, the total N recovery was 94; 87; and 81%, for CL + Q, CL - Q and TRAD, respectively."