A method to quantify N fertilizer requirement

• Published in: Nutrient cycling in agroecosystems Vol. 51; no. 2; pp. 155 - 162
• Main Authors: Galvis-Spinola, A. (Centro de Edafologia, Montecillo (Mexico). Colegio de Postgraduados), Alvarez-Sanchez, E, Etchevers, J.D
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.06.1998
• Subjects: ABONOS NITROGENADOS; Barley; BESOIN NUTRITIONNEL; Cereal crops; Crop yield; ENGRAIS AZOTE; Fertilizers; Greenhouses; HORDEUM VULGARE; METHODE; METHODS; METODOS; Mineralization; NECESIDADES DE NUTRIENTES; NITROGEN FERTILIZERS; NUTRITIONAL REQUIREMENTS; Organic matter; Organic soils; Potassium chloride; Soil organic matter; Soils
• ISSN: 1385-1314; 1573-0867
• DOI: 10.1023/A:1009714932119

A methodology to quantify N fertilizer requirement for a barley crop is proposed. The method consists of establishing a relationship between barley N demand (DEM) and an index of soil N supply (NS). NS values were obtained adding the inorganic N, i.e, (N-NO-3 + N-NH+4, (Ni), measured just before planting in the soil to an index of soil N mineralization (Nor):NS = Ni + NorSoil organic matter (SOM) was selected as an index of Nor:Nor = 25.9 + 17.9 (SOM) R2; = 0.89; p < 0.01and Ni was measured in a soil extract obtained with KCl (1N).Ns values were related to both grain yield (Y) and N accumulated in the above ground biomass of barley (AB) grown under greenhouse conditions. The following relationships were obtained:Y = 0.81 + 0.99 (NS) - 0.0002 (NS)2 R2 = 0.77; p < 0.01AB = -0.006 + 0.002 (NS) - 0.000003 (NS)2 R2 = 0.84; p < 0.01A graphic relationship was established between DEM and NS, in order to extrapolate the greenhouse results to field conditions. Using this relationship, AB was converted from g N pot-1 to kg N ha-1, and NS from μg g-1 of N in the soil to kg ha-1.