The depth distribution of NO3-N and SO4-S in the soil profile was examined in 2001, in the 28th year of an NPK mineral fertilisation experiment set up on chernozem loam soil with lime deposits at the institute's Experimental Station in Nagyhörcsök. The fertilisers were applied in the form of calcium ammonium nitrate with a 25% N content, 18% superphosphate and 50% potassium chloride. The groundwater was at a depth of 13-15 m and the area was prone to drought. The N0P0K0, N 1P1K1, N2P2K2, N3P3K3 and N1, N2, N3 treatments were investigated in two replications. Two drillings were made in each plot to a depth of 6 m, taking samples every 20 cm. The samples were united for each plot/level, giving a total of 420 samples, which were analysed after extraction with 1 M KCl. The major results were as follows: 1. According to earlier analyses, 40-60% of the surplus N shown by the N balance to have been introduced with mineral fertiliser and not absorbed by the crop could be detected in the form of NO3-N in the upper 6 m of soil. By the 28th year of the experiment a substantial part of the NO3-N reserves had been leached to a depth of more than 6 m, so the leaching boundary could not be identified. Only 5-18% of the surplus N could be detected in the 0-6 m soil profile in the form of NO3-N in 2001. 2. A similar leaching profile was exhibited by SO4-S, maximum values of which were recorded in the upper 1 m and the lowest, 5-6 m layers, in accordance with the timing of replenishment fertilisation with superphosphate. As the result of replenishment fertilisation in autumn 1999 there was an accumulation of SO 4-S in the 0-80 cm layer. The accumulation profile of replenishment fertilisation carried out 20 years earlier in 1980 began at a depth of around 5 m, but the lower boundary of leaching was already below 6 m, so it could not be identified. It is estimated that 80-90% of the S remaining in the soil could be detected in the form of SO4-S in the 0-6 m soil layer. 3. The vertical movement of NO3-N and SO4-S took place at a rate of 20-40 cm/year, according to examinations carried out so far. The water content of the lower soil layers fluctuated around a value of 10% during recent drillings (1995, 2001).
|Translated title of the contribution||Leaching of NO3-N and SO4-S in a 28-year mineral fertilisation experiment|
|Number of pages||14|
|Publication status||Published - Dec 1 2004|
ASJC Scopus subject areas
- Agronomy and Crop Science