Predicting Field‐Apparent Nitrogen Mineralization from Anaerobically Incubated Nitrogen

Abstract

Core IdeasStudy aimed to predict field N mineralization (Nmin) from anaerobically incubated N (Nan).Nandid not predict Nminin areas with contrasting edaphic‐climatic properties.Nminwas predicted by a model including Nan, temperature and rainfall.The nitrogen (N) released after a 7‐d anaerobic incubation (Nan) is a good estimator of the size of the soil N mineralizable pool. However, there is a lack of information on how soil properties and climate affect the apparent field N mineralization (Nmin) of this pool. The objective of our study was to develop and validate a simple model to estimate Nminfrom Nanin corn (Zea maysL.) and wheat (Triticum aestivumL.) fields. To this end, we performed 100 field experiments where we measured Nmin, Nan, rainfall, temperature (TC), soil texture, pH, soil organic matter (SOM), and pre‐sowing mineral N concentration (Ninitial). We performed a stepwise analysis to develop a model to predict Nminusing data from 70 sites, while the rest of the data was saved for model validation. The Nanranged from 16 to 94 mg kg–1while Nminranged from 22 to 232 kg ha–1. There was a strong association between Nanand Nminwithin regions with similar climate and edaphic properties. However, we could not fit a single significant model to estimate Nminbased solely on Nanto be used in all regions. By considering other variables besides Nan, we developed a model that allowed predicting Nminindependently from the site [Nmin= –252 + 12.3(TC) + 1.37(Nan) + 0.27(rainfall)] (R2= 0.89, model validationR2= 0.83). This model could be useful to adjust N fertilizer recommendations for corn and wheat, reducing the economic and environmental impact of fertilization.