Importance of organic nitrogen fractions in sandy soils, obtained by electro-ultrafiltration or CaCl2 extraction, for nitrogen mineralization and nitrogen uptake of rape

摘要: Sandy soils have low reserves of mineral N in spring. Therefore organic-bound is the most important pool available for crops. The objective present investigation was to study importance extracted by electro-ultrafiltration and a CaCl2 solution supply rape mineralization. Mitscherlich-pot experiments carried out with 12 different sandy (Germany) showed highly significant correlation between organic (two fractions) uptake (electroultrafiltration extract: r=0.76***; r=0.76***). Organic both methods before application fertilizer also significantly correlated mineralization (electro-ultrafiltration r=0.75***; r=0.79***). increased soil pH decreased an increasing C:N ratio proportion sand soils. Ninety-eight percent variation determined differences net N. This show that (NO inf3 sup- -N, NH 4 + -N) or solutions indicates variance plant-available Total not related plants nor