Effect of Nitrogen Fertilization and One Nitrification Inhibitor On Soil N Dynamics in Table Grape.

Nitrogen (N) dynamics in soil can be affected by biotic and abiotic factors. Nitrification is one of the most important processes on N transformation in soil; ammonium nitrogen (NH₄⁺) is converted to nitrite (NO₂^-) mostly by chemoautotrophs microorganisms such as Ammonia Oxidizing Bacteria (AOB) including Nitrosomonas sp., Notrosococcus sp. and some Pseudomonas species through the Ammonia Monooxygenase (AMO) enzyme, which catalyzes the oxidation. Finally, NO₂^- is rapidly converted to nitrate (NO₃^-) by another group of microorganisms; so NO₂^- usually does not accumulate in soils. Both, NH₄⁺ and NO₃^- can be taken up by plants, but NO₃^- can be lost by leaching, or denitrification. The use of nitrification inhibitors such as 3,4- dimethylpyrazole phosphate (DMPP), has presented benefits in terms of yield and quality, and reduced N losses, on vegetables and fruit crops, reducing nitrification rates and maintaining NH₄⁺ longer in soils, by reducing Nitrosomonas sp. activity. Despite its benefits, there is little information about the effect of DMPP on table grape and particularly on AMO activity in soil. Thus, the objetive of  the study was to evaluate the effect of DMPP on available N and Ammonia Monooxygenase (AMO) activity in a soil under table grape