Water regime affects soil N2O emission and tomato yield grown under different types of fertilizers

Tomato plants were subjected to three fertilization treatments (M: mineral fertilizer; DMPP: mineral fertilizer + 3,4-dimethylpyrazole phosphate; OM: NKP + organic animal manure) in combination with two water regimes (100% and 50% Evapotranspiration, ET). Plant biomass, fruit production, nitrogen use efficiency (NUE) and N uptake, maximal PSII photochemical efficiency, Fv/Fm and cumulative soil N2O emission were determined. Well-watered OM plants showed higher values of biomass, fruit production, NUE and N uptake than M and DMPP plants; cumulative N2O fluxes were lower in DMPP plots than in M and OM plots. The reduced water supply determined a drop in crop biomass, fruit production, NUE and N uptake, and cumulative N2O fluxes in M and OM treatments that were higher in OM plots, whereas it determined a significant rise in cumulative N2O fluxes in DMPP plots that was lower in absolute term compared to M and OM plots recorded under well-water irrigation. It can be concluded that DMPP added-fertilizer has a good performance in semi-arid environment resulting a better nitrogen source compared to conventional and organo-mineral fertilizers under reduced water supply, able to preserve crop yield and to determine soil N2O emissions (as expressed in CO2 eq) not dangerous for global environment.