The research was set up in the Neretva River valley in the Southern part of Croatian Karst area, where implementation of modern hydrotechnical practices within the river catchment’s area led to intrusion of seawater to groundwater resulting in soil salinization in the delta. The region has great agro-ecological potential for intensive production of vegetables and Mediterranean fruits. Since the combination of the effects of saline groundwater and the use of this water for irrigation may have disastrous effects on the productivity of agricultural soils water, a project was started in order to set up a permanent monitoring network. The aim of this study was to determine the salt dynamics in the surface water on five locations which are considered as potential sources of the irrigation water (Modric canal, Neretva River near Opuzen, Crepina, Jasenska and Vidrice pumping station) during a 4-year period (1999–2002). The surface water samples had been collected on monthly basis and analyzed for all parameters required in the irrigation water quality classification. The results show considerable spatial and temporal variability of determined parameters. Thus, in the Neretva River near Opuzen, total salt concentrations in water ranged from 0.4 to 7.7 dS·m–1, and in Modric from 1.65 up to17.2 dS·m–1. Dominant cations and anions on all observed locations were Na+ and Cl–. Constantly high concentration of Na+ in sampled surface waters is of a special concern. Utilization of the water of such quality may cause problems related to the use of alkaline waters for irrigation, which can further cause permanent loss of fertile soil.

One of the rational ways of energy saving is to use the heat of wastewater from energy companies for open ground heating and cultivation crops. The most significant sources of heat are thermal and nuclear power plants that produce low-thermal waters of 28–35°C.
Heating of the ground with the use of circulating warm water allows to increase temperature at all points of the soil profile. The maximum thermal effect from heating ground is observed at the depth of pipe heaters (7.3– 11.1°C).
Ground heating allows to extend the growing season for crops by 3–4 weeks, which can expedite harvesting and thus maximise the harvest. In natural moisture conditions, ground heating does not lead to significant reduction of moisture reserves in the active layer throughout the growing period. There is a redistribution of moisture in a soil profile. It decreases in the zone of pipe heaters and redistributes toward the top. The formation of the nutrient regime changes, the content of mobile phosphorus and potassium, and nitrate nitrogen increases, whereas the content of ammonia nitrogen is reduced. Ground heating is a new special heat reclamation technique. It allows not only to control temperature of the agricultural crop environment, but also to dissipate heat in the ground, and promote the utilisation of waste heat and the stabilisation of the environment.