Application of modelling by the study of ground water contamination with nitrates under grasslands

Abstract

At permanent grassland in the foothill regions of the Šumava (545 m a.s.l. subassociation Trifolio-Festucetum alopecuretosum Neuhäusl 1972), relations between the use of different doses of N(+PK) and contamination of ground waters with nitrates have been studied with the application of deterministic and probabilistic models with the aim of elaborating a theoretical basis and new methodological approaches for polycriterial optimisation of fertilisation of grass stands. Mutual relations between the use of doses N(+PK), build-up of primary production and perlocations of NO<sub>3</sub><sup>–</sup> into ground waters, expressed by that of unit and marginal values of both these processes showed a mirror-like inversion course with a remarkable co-incidence of reverse local extremes. Within the range of doses from 0 to 100 kg N(+PK)/haP helps, at the ratio of the applied doses P:N 1:1.5–2.5, to a considerable decrease in the concentration of NO<sub>3</sub><sup>–</sup> in ground waters. Specification of suitable doses of N(+PK) to ecologically and phytocenologically similar stands is discussed.