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-1 (fertilizer 15-6-15-6); 2. 75 kg N ha-1 (ammonium sulphonitrate (SNA) 26% N) treated with DMPP (0.8% compared to ammonia N); 3. 150 kg N ha-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.
nitrification inhibitor; Citrus sinensis; fertilization; productivity
