engleski

Effect of nitrogen fertilization for oilseed rape on nitrogen leaching with subsurface drainage water

Effect of nitrogen fertilization for winter oilseed rape upon the concentration of nitrate nitrogen in subsurface drainage water was studied in an agrotechnical trial with different mineral nitrogen rates. The trail was set up so that the area of each fertilizing treatment embedded two drainpipes, in their full length. One pipe was installed with and the other without gravel backfill. Trial treatments were: 1.Check&#8211 ; unfertilized, 2. N0 PK, 3. N100 PK, 4. N150 PK, 5. N200 PK, N250 PK, N250 PK + Phosphogypsum, N250 PK + Zeolite tuff + CaCO3, 9. N300 PK and 10. Black fallow. Pursuant to the research method, the following nitrogen rates were applied with basic fertilization in August 1997: 30, 45, 60, 75 and 90 kgha-1. The amount of P2O5 was 90 kgha-1 and of K2O 180 kgha-1 for all fertilized trial treatments. The first discharge used to take water samples from drainpipes occurred in mid November 1997 and the last one at the end of the first decade of March 1998. Average nitrogen leaching of 7.1 kg ha-1 NO3- N was recorded in the check treatment, and 7.8 kgha-1 in treatment No. 2 with phosphorus and potassium. This was followed by treatment No. 3, in which 30 kgha-1 nitrogen was applied with basic fertilization, 8.1 kgha-1 of which was leached by drainpipes. Treatment No. 4 involved application of 45 kgha-1 nitrogen, 16.5 kgha-1 of which was leached through drainpipes. Out of 60 kg nitrogen added in treatment No. 5, 21.4 kg was leached, while the leaching in treatments 6, 7 and 8 amounted to 27.2, 29.8 and 24.1 kg, respectively. In the latter treatments, 75 kgha-1 nitrogen was applied with basic tillage. Out of the maximum 90 kg nitrogen applied for winter oilseed rape in treatment No. 9, an average amount of 30.2 kg nitrogen was leached through drainpipes. With its 14.7 kgha-1 of leached nitrogen, the last treatment &#8211 ; black fallow &#8211 ; ranks rather high, between treatment 3, in which 30 kg nitrogen was applied, and treatment 4, with 45 kg nitrogen. Total loss of ammonia nitrogen in all trial treatments was below 1 kgha-1, in most cases even below 0.5 kgha-1.

Subsurface drainage; Nitrogen; Leaching; Oilseed rape

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