Main content area

Residual effect of synthetic nitrogen fertilizers and impact on Soil Nitrifiers

Quemada, Miguel, Alonso-Ayuso, María, Castellano-Hinojosa, Antonio, Bedmar, Eulogio J., Gabriel, Jose L., García González, Irene, Valentín, Francisco, Calvo, Manuel
European journal of agronomy 2019 v.109 pp. 125917
Archaea, DNA, Triticum aestivum, Zea mays, ammonium, ammonium sulfate, biomarkers, corn, crops, fertilizer rates, field experimentation, microbial activity, microbial biomass, nitrates, nitrification inhibitors, nitrogen, nitrogen content, nitrogen fertilizers, phosphates, quantitative polymerase chain reaction, residual effects, soil, soil microorganisms, soil sampling, wheat, Spain
The residual effect of nitrogen (N) fertilizers on subsequent crops might affect N efficiency and soil microorganisms, but little is known about the underlying reasons. Our goal was to elucidate the origin of the residual effect of synthetic N fertilizers, with and without a nitrification inhibitor, in three field experiments located in different regions of Spain that shared a common design in a maize (Zea mays L.) /wheat (Triticum aestivum L.) rotation. Maize was fertilized with ammonium sulphate nitrate (ASN) or with ASN blended with 3,4 dimethylpyrazole phosphate (DMPP) (ASN + DMPP) or was not fertilized with N. Wheat after maize received the recommended N dose, a low N dose or no N application. Yield and N content were determined for each crop and treatment and soil samples were taken to determine non-exchangeable NH4+ as well as C and N in the microbial biomass. DNA extraction was conducted in soil samples at different times. In the two locations where a residual effect occurred as a result of fertilizer application on the previous crop, either as ASN or ASN + DMPP, the C retained in the microbial biomass increased. The abundance of bacterial and archaeal communities was related to the soil’s C biomass, and the quantitative PCR approach was a more sensitive biomarker of the microbial activity than C and N in the microbial biomass. The residual effect was associated with a temporal increase of soil microorganisms caused by fertilizer application. Optical sensors identified the residual effect, opening the opportunity for adjusting the fertilizer rate to actual crop requirements.