English Abstract In this report the first version of the model CLEAN is
presented. CLEAN stands for Crops, Livestock and Emissions from Agriculture
in the Netherlands. The model has been developed as part of the project
EXPECT (EXPloring Environmental Consequences for Tomorrow) by a team of
agricultural specialists, model builders and computer programmers at RIVM
and the Agricultural University of Wageningen. The model is designed to
function in the EXPECT system for construction of agricultural policy
scenarios. The eutrophication issue has been the leading theme in the
design of CLEAN 1.0. The manure production is calculated from development
of the livestock numbers and the excretion rates per livestock category.
The model distinguishes volume of manure and nitrogen, phosphate and
potassium content. To calculate the total excretion and NH3 emissions, the
differences between livestock on pastureland and in stables and between
various manure storage systems are recognized in the model. The model
allows simulation of manure distribution over crop classes which are linked
to soil type and groundwaterlevel classes. The first step to assess the
amount allocated to the local crops, in accordance with fertilization
standards. Next, surplusses are allocated within the region, in line with
an acceptance level by farmers for external manure. And the last step is to
export remaining surplusses to regions with a demand for manure, or to
manure processing plants or abroad. The allocation follows a transport cost
minimization algorithm. Subsequently, the model calculates the NH3
emissions resulting from stables, manure storage and manure application to
the land, and the additional chemical fertilizer application with the
associated NH3 emissions.