Influence of nitrogen fertilizer sources and lime applications on water use efficiency of oats (Avena sativa L.) under no-tillage management in andisols of Southern Chile

Food production under rainfedagriculture, is limited due to soil water storage, mainly from low and variable rainfall. The aim of this study was to evaluate the effects of nitrogen fertilization sources and lime applications on WUE of oats ( Avena sativa L.), under no- tillage management in a Typic Haploxerand soil, during the growing season 2008-09. The experimental design was a randomized complete block with three replicates and four treatment.The treatments were: (T 1 ): triple superphosphate+sodium nitrate; (T 2 ), urea+mono-ammonium phosphate, MAP; (T 3 ): urea +MAP + 750 kgha -1 lime and (T 4 ) urea + MAP + 1500kgha -1 lime. Evapotranspiration was measured by the water balance method olumetric soil water content was monitored with a neutron probe. Dry matter was measured in the phenological stages of tillering (T), panicle emergence (PE), milky grain (MG) and dough grain (DG).Total dry matter and grain yield were measured at maturity. Water use efficiency was determined in the phenological stages of: tillering (T)-panicle emergence (PE), PE-milky grain (MG) and MG-dough grain (DG). The results showed that treatments with ammonium fertilizers and lime application enhanced WUE. The higher WUE was observed between PE-MG. The ammonium fertilization (T 2 ) showed lower values for WUE, rate growth and harvest index. The source of nitrogen did not affect crop evapotranspiration and the NP fertilization with lime improves the WUE of oats with no-tillage management in Andisols of Southern Chile.