Sustainable Nitrogen Management in Agriculture: An Action Programme towards Protecting Water Resources in Walloon Region (Belgium) - Water and Agriculture: Sustainability, Markets and Policies - page 398

The systematic use of nitrate catch crops after harvest of the cereals, peas, early
maturing potatoes and other crops (when these are not harvested too late making the
use of catch crop meaningless) if no winter crop follows. These catch crops are plants
growing fast, with a strong rooting system and valuing well nitrates. The main catch
crops used in Belgium are mustard, phacelia ( phacelia tanacetifolia), ryegrass
(English or Italian) and rye. These catch crops must be established before 15 th
September and destroyed after 30 November.
The application of a quantity of nitrogen fertiliser resulting of a balance between the
needs of the plants and the nitrogen mineralised, left in the soil by the previous crop …
This type of balance, recommended to all farmers, is compulsory in the framework of
the Quality Approach for all crops likely to leave substantial nitrate residues leached
during winter, (such as maize, potatoes… see Table 2).
The cattle stocking rate on grassland must be limited before winter, as urine patches
leave a substantial amount of nitrate and the vegetation cannot value too much
nitrogen during this period. More precisely, the stocking rate must not exceed 150
Livestock Unit.day.ha -1 from 15 September to 31 December.
These latter measures are compulsory for each farmer registered in the Quality
Approach. On top of them, the farmer and the advisors of Nitrawal may choose between
various other ways of limiting nitrate pollution, on a case by case basis. Let us mention:
Optimisation of the feeding of ruminants by calculating regularly the rations and
analysing the fodder.
Optimising the feeding of pigs and poultry by precisely adapting the diet to the age of
the animal and using feeds enriched in essential amino-acids but poorer in other
proteins.
Composting solid manure.
Using a more performing equipment for spreading slurries (advanced band spreader,
trailing shoe spreader, shallow injector).
Inserting a temporary grassland in the rotation.
Protecting water streams with a fence.
Using early maturing maize, or potato varieties so as to harvest before 15 th September
and enable a catch crop or winter crop to be grown efficiently, and
If the previous measure is not practicable, establishing a rye crop not destroyed before
15 th February.
Performances control
The most important aspect of the Quality Approach is to be found in the fact that the
performance of the farmers are assessed in regard with nitrate pollution and in the way
this assessment is performed. Indeed, one of the best ways agricultural practices in a