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1
Simulation of nitrate leaching from an organic
dairy crop rotation with different manure types
and loads
J. Berntsen, J.E. Olesen, B.M. Petersen, J.
Eriksen Danish Institute of Agricultural Sciences
Introduction Management of nitrogen in dairy
systems is especially difficult due to the use of
organic manures and the residual effects of
pastures. During grazing a considerable build-up
of soil N is often observed. Ploughing of the
grassland is therefore followed by a large
mineralisation that might exceed the demand of
the subsequent crop. This might lead to large
amount of nitrate being leached. In addition,
rotations dependent on organic manures rather
than mineral fertilizers are believed to have a
higher risk of nitrate leaching.  
Both simulations and measurements indicate that
the effects of the different types of organic
input are small and the effect of the level of
input is between 3-7 kg-N/ha.
Method A dairy crop rotation experiment was
established at Foulum, Denmark in 1994 (Table 1
and Eriksen et al. 1999) with four treatments
high slurry (HS), low slurry (LS), high deep
litter (HL) and low deep litter (LL). These
levels correspond to livestock densities of 0.9
and 1.4 livestock units ha-1. The FASSET model
(Berntsen et al., 2003) was used to simulate the
above experiment. The model is a whole farm model
that contains a crop-soil-atmosphere model, which
simulates daily changes in crop growth, soil
organic matter and transport of several solutes.
The soil organic matter model is based on
Petersen et al. (2003). The model simulated all
the different treatments in the years 1993 to
2002 using observed management, measured manure
application and composition, measured climate
data and soil characteristics.  
The crops had different leaching potential.
Winter wheat had the highest simulated nitrate
leaching followed by barley/pea mixture, oat,
spring barley, beets and grass-clover. A similar
crop ranking was observed in the measurements.

• Scenarios
• Based on the above crop rotation a set of
  scenarios was constructed focusing on the
  following effects
• Soil type sandy (Jyndevad) and loamy sand
  (Foulum)
• Climate wet (Jyndevad) and dry (Tystofte)
• Soil Fertility 3 and 1.5 C in top soil.

Results Simulated and observed nitrate
concentrations are shown in figure 1 for the HL
treatment. There was a general good agreement
between simulations and observations.
Conclusions The FASSET model was able to capture
the general trends in experimental data set.
Effects of manure type and level on nitrate
leaching were small and less than 10 kg-N ha-1.
The scenarios showed that the nitrate leaching
depends on soil type, climate and fertility. The
range was from 39 kg-N ha-1 at the low fertility
loamy sandy soil with a dry climate to 85 kg-N
ha-1 at the high fertility sandy soil with a wet
climate.
References Berntsen, J.,Petersen, B. M.,
Jacobsen, B. H., Olesen, J. E., and Hutchings, N.
J. 2003. Evaluating nitrogen taxation scenarios
using the dynamic whole farm simulation model
FASSET. Agricultural Systems 76 817-839 Eriksen,
J.,.Askegaard, M., and Kristensen, K. 1999.
Nitrate leaching in an organic dairy/crop
rotation as affected by organic manure type,
livestoc density and crop. Soil Use and
Management 15 176-182 Petersen, B. M., Berntsen,
J., Jensen, L. S., and Hansen,S. 2003. CN-SIM a
model for the turnover of soil organic matter. I
Long term carbon and radiocarbon development.
Soil Biology and Biochemistry (subm.)
Fig 1. Observed and simulated N-leaching in the
HL treatment.
Archived at http//orgprints.org/00001700