3,4-dimethylpyrazole phosphate en naranjo dulce en el noreste Argentino

The aim of this study was to evaluate the 3,4-dimethylpirazol phosphate (DMPP) effect on the efficiency of ammonium-N fertilization on sandy soil of Corrientes, Argentina. The experiment was carried out with sweet orange [Citrus sinensis (L.) Osbeck] 'Valencia late' grafted on Rangpur lime (Citrus limonia, Osbeck) rootstock under field conditions during three consecutive years, the orchard was established on an alfic Udipsamment soil. A randomized complete block statistical design with four replications was used and the treatments were: 1. (Control) 150 kg N [ha.sup.-1] (fertilizer 15-6-15-6); 2. 75 kg N [ha.sup.-1] (ammonium sulphonitrate (SNA) 26% N) treated with DMPP (0.8% compared to ammonia N); 3. 150 kg N [ha.sup.-1] (SNA 26% N), treated with DMPP (0.8% compared to ammonia N). Leaf samples from fruitful branches were taken in autumn and the amount of N, P and K were analysed. At harvest, yield per plant was measured (kg) and quality of fruits was assessed. The results obtained demonstrate that in sandy soils, the addition of DMPP improves the efficiency of nitrogen fertilization. Identical nitrogen supply, increase yields and foliar concentrations of N and with the half N dosage, control equivalent yields were achieved. Index terms: nitrification inhibitor--Citrus sinensis--fertilization--productivity. El objetivo del trabajo fue evaluar el efecto del 3,4-dimetilpirazol fosfato (DMPP) en la eficiencia de la fertilizacion amoniacal, en naranjo dulce [Citrus sinensis (L.) Osbeck] 'Valencia late' sobre suelo arenoso, en la provincia de Corrientes, Argentina. Durante tres campanas se trabajo en un huerto de naranjo 'Valencia late' injertado sobre lima de Rangpur (Citrus limonia, Osbeck), sobre un suelo tipo Udipsamment alfico. Se utilizo un Diseno de Bloques Completos al Azar con cuatro repeticiones, parcela util una planta mas borduras, con los tratamientos: 1. (Testigo) 150 kg de N [ha.sup.-1] (fertilizante 15-6-15-6); T2. 75 kg de N [ha.sup.-1] (sulfonitrato de amonio (SNA) 26 % N) tratado con DMPP (0,8% respecto al N amoniacal); T3. 150 kg de N [ha.sup.-1] (SNA 26 % N), tratado con DMPP (0,8% respecto al N amoniacal). En el otono se tomaron muestras foliares de ramas fructiferas, determinandose contenido de N, P y K. En la cosecha se determino produccion por planta (kg) y se evaluo calidad de frutos. Los resultados obtenidos permiten establecer que en suelos arenosos, el agregado de DMPP mejora la eficiencia de la fertilizacion nitrogenada. Con igual