The objective is the evaluation and consolidation of the scientific basis describing the processes governing the fluxes of water and solutes filtering through soil under different crops and land management systems along with adaptation and validation of models in view of their use in the assessment of the environmental hazards from farm management practices.
An integrated analysis of water and solute flow has been undertaken to predict the environmental hazard of farm management strategies in the European Community. Identification and coordination of concepts and working procedures were carried out. Intensive measurements of physical, chemical and biological soil properties required for application of the modelling tools was undertaken and, quantification of the variability of the unit on which the model will be applied. Field studies in 5 countries have been conducted for 3 years. Lysimeters are currently in operation at 4 sites. Measurements, using a variety of field and laboratory techniques have been used at all sites to obtain all the basic hydraulic properties, as well as many of the chemical transport characteristics. Workshops were organized to discuss the yearly results and to design field program accounting for the data requirement of the model used in the last stage to describe water and solute transport as well as nitrogen dynamics. It was also decided to compare 1 method to determine the hydraulic conductivity of the soil (ie the suction infiltrometer) with other methods being used previously by each team. A suction infiltrometer was shipped to every measuring site. It was also decided that a bare soil site should be used to obtain directly an estimation of the mineralization of nitrogen by the soil. Finally an attempt has been made at each site to characterize the mass flux of water, as well as the mass flux of leached nitrogen, by the use of Darcy's law combined with soil solution concentration, for various crop management conditions.
The project consists of 5 parts as follows.
Part 1 is the identification and coordination of concepts and working procedures.
Part 2 is the intensive measurement of physical, chemical and biological soil properties required for application of the modelling tools, quantification of the variability of the unit on which the model will be applied, and development of pedotransfer functions for minimizing future laboratory and field work.
Part 3 is the critical evaluation of data needs for application of the different models of potential use: SWATRE and ANIMO (Wageningen); LEACH (Cornell), CAPACITY MODEL (Grenoble), and SWATNIT (Leuven). This will relate particularly to use of flow equations, prediction of root patterns, transport of agrochemicals, and crop uptake as a function of different management practices. Of concern is the level of detail of the required data. This should be comparable for the different submodels and for the evaluation capabilities of deterministic versus capacity type models, and the mechanistic versus stochastic approaches. Specific attention will be paid to the characterization of heterogeneous soils, and to preferential flow patterns down macropores and through stratifications.
Part 4 is the validation of process submodels using field data and data from lysimeters. Measured and calculated data will be compared following statistical and functional criteria. Extensive use of sensitivity analysis will allow identification of those parameters that are particularly important for determining water and solute fluxes. In addition, comparisons will include the measured variability of parameters and the use of both scaling techniques and Monte Carlo simulations.
Part 5 is the prediction of the environmental impact of farming practices on a regional scale using a geographic soil information system.
Funding SchemeCSC - Cost-sharing contracts
6701 AR Wageningen