Release, movement and recovery of 3,4-dimethylpyrazole phosphate (DMPP), ammonium, and nitrate from stabilized nitrogen fertilizer granules in a silty clay soil under laboratory conditions
F. Azam et al., Release, movement and recovery of 3,4-dimethylpyrazole phosphate (DMPP), ammonium, and nitrate from stabilized nitrogen fertilizer granules in a silty clay soil under laboratory conditions, BIOL FERT S, 34(2), 2001, pp. 118-125
In model experiments under laboratory conditions the release of 3,4-dimethy
lpyrazole phosphate (DMPP; ENTEC), NH4+-N, and NO3--N from the ENTEC-fertil
izer granules placed on a silty clay soil was studied. The air-dried soil c
ontained in Petri dishes was moistened to 18% or 24% water holding capacity
, and incubated for 10 days at 4 degreesC, 15 degreesC or 25 degreesC after
placing the granules in the centre of the plates. Plates without granules
served as controls. At appropriate intervals, soil cores were taken at 5-20
and 25-40 mm distance from the granules and analysed for DMPP, NH4+-N and
NO3--N. Amongst the three fertilizer ingredients, NO3- was found to be the
most mobile showing a fairly uniform distribution in both soil zones during
10 days of incubation. Under the different temperature and moisture condit
ions, more than 80% of DMPP remained within the 0- to 5-mm region around th
e granule. Between 5% and 15% of DMPP was found in the 5- to 20-mm region,
and <3% moved into the 25- to 40-mm region. Increasing temperature and mois
ture facilitated the movement of DMPP in soil. NH4+ diffused faster than DM
PP and showed a recovery of up to 13% in the 25- to 40-mm region under the
given conditions. NH4+ was separated from the DMPP within 10 days, as revea
led by an increase in the NH4+-N to DMP ratios. An intensive N2O flux was o
bserved within the 5- to 20-mm zone of the fertilizer granules. which was a
scribed to heterotrophic denitrification rather than nitrification.