Short-term immobilisation and crop uptake of fertiliser nitrogen applied to winter wheat: effect of date of application in spring

• Published in: Plant and soil 1999-09, Vol.206 (2), p.137-149
• Main Authors: Recous, S. (Unite d'Agronomie INRA, Laon (France).), Machet, J.M
• Format: Article
• Language: English
• Subjects: ABSORCION DE SUSTANCIAS NUTRITIVAS; ABSORPTION DE SUBSTANCES NUTRITIVES; Agricultural site preparation; Agricultural soils; Agronomy. Soil science and plant productions; APLICACION DE ABONOS; AZOTE; Biological and medical sciences; FERTILISATION; FERTILIZER APPLICATION; Fertilizers; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Grassland soils; IMMOBILISATION; IMMOBILIZATION; INMOVILIZACION; Life Sciences; NITROGEN; Nitrogen fertilization; Nitrogen, phosphorus, potassium fertilizations; NITROGENO; NUTRIENT UPTAKE; Organic soils; Plants; Soil microorganisms; Soil water; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Spring; TRITICUM AESTIVUM; Urea; Vegetal Biology; Wheat; Wheat soils; Winter wheat
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1023/A:1004377006602

Previous studies on the fate of fertiliser nitrogen applied to winter wheat in temperate climates have shown that nitrogen (N) applied early, at tillering for wheat, was less efficiently taken up than N applied later in the growth cycle. We examined the extent to which the soil microbial N immobilisation varied during the wheat spring growth cycle and how microbial immobilisation and plant uptake competed for nitrogen. We set up a pulse-¹⁵N labelled field experiment in which N was applied at eight development stages from tillering (beginning of March) to anthesis (mid-June). Each application was 50 kg N ha⁻¹ as ¹⁵N labelled urea except for the first application which was 25 kg N ha⁻¹. The distribution of fertiliser ¹⁵N in shoots, roots, mineral and organic soil N was examined by destructive sampling 7 and 14 days after each ¹⁵N pulse. The inorganic ¹⁵N pool was almost depleted by day 14. The N uptake efficiency increased with later applications from 45% at tillering to 65% at flowering. N immobilisation was rather constant at 13-16% of N applied, whatever the date of application. The increase in plant ¹⁵N uptake resulted in an increase in the total ¹⁵N recovery in the plant-soil system (¹⁵N in soil + ¹⁵N in plant), suggesting that gaseous losses were lower at the later application dates.