Uptake of mineral nitrogen from subsoil by winter wheat

Abstract

The apparent uptake of mineral nitrogen (N_min) from top- and subsoil layers during the growth of winter wheat (Triticum aestivum L.) was studied in Prague-Ruzyne on clay loam Chernozem soil in years 1996–2003. Two (N0, N1) and three treatments, unfertilized (N0), fertilized with 100 kg (N1) and 200 kg (N2) nitrogen per hectare were observed in years 1996–2000 and 2001–2003, respectively. The apparent uptake of nitrogen from soil layers was calculated from the changes of N_min content between sampling terms. Most of available mineral N in the soil down to 90 cm was almost fully depleted between tillering and anthesis in treatment N0. The uptake from subsoil layers was delayed and it continued during the period of grain filling in fertilized treatments. Nitrogen fertilization reduced utilization of N from subsoil. The apparent uptake of N from the zone 50–120 cm ranged from 21 to 62 kg N/ha in N0 and from 15 to 60 kg N/ha in N1 in years 1996–2000. In years 2001–2003 the corresponding values (50–130 cm) were 24–104 kg, 43–130 kg and 29–94 kg N/ha in treatments N0, N1 and N2, respectively. The uptake from 120 (130)–150 cm was around zero in a half of experimental years, and it reached at maximum 12 kg/ha in N0 in 1997. There was a strong linear relation between the amount of N_min in spring and the depletion of nitrogen from the zone 50–120 (130) cm, R²= 0.94, 0.91 and 0.99 in N0, N1 and N2, respectively.