fertilizer application nitrogen 10 Argentina 6 Nitrogen 6 nutrient availability 6 nutrient uptake 6 savanna 6 Brazil 4 Cerrado 4 Chubut 4 Fertilization 4 Glauconitic sandstones 4 Phosphorus 4 Potassium alternative sources 4 Potassium fertilizer 4 Salamanca Formation 4 South America 4 agronomy 4 article 4 bioassay 4 biomass 4 concentration (composition) 4 feldspar 4 glauconite 4 irrigation 4 leaching 4 leaf area 4 nutrient limitation 4 phosphorus 4 plant leaf 4