干旱区生态环境知识资源中心

The objectives were i) to assess indicators for potential nitrogen (N) mineralization and ii) to analyze their relationships for predicting winter wheat (Triticum aestivum L.) growth parameters (yield and N uptake, N-up) in Mollisols of the semi-arid and semi-humid region of the Argentine Pampas. Thirty-six farmer fields were sampled at 0-20 cm. Several N mineralization indicators, wheat grain yield and N-up at physiological maturity stage were assessed. A principal component (PC) analysis was performed using correlated factors to grain yield and N-up. The cluster analysis showed two main groups: high fertility and low fertility soils. In high fertility soils, combining PCs in multiple regression models enhanced the wheat yield and N-up prediction significantly with a high R-2 (adj R-2=0.71-0.83). The main factors that explained the wheat parameters were associated with water availability and N mineralization indicator, but they differ according to soil fertility.Abbreviations: N: nitrogen; SOM: soil organic matter; POM: particulate organic matter; SOC: soil organic carbon; SON: soil organic nitrogen; POM-C: particulate organic carbon; POM-N: particulate organic nitrogen; N-an: anaerobic nitrogen; N-hyd: hydrolyzable N; NO3-N: cold nitrate; N-205: N determined by spectrometer at 205 nm; N-260: N determined by spectrometer at 260 nm; Pe: extractable P; N-up: wheat N uptake; NO3-N: inorganic N in the form of nitrate; FR: fallow rainfalls (March-Seeding rainfall); FLR: flowering rainfalls (October-December rainfall); GFR: grain filling rainfall (November rainfall); CCR: crop growing season rainfall (June-December rainfall); PCA: principal component analysis; PC: principal component; MR: multiple regression