ABSTRACT
About 50% of agricultural land in Denmark is composed of sandy soils. Therefore supplementary irrigation is important to maintain a high and steady production. Good returns on irrigation equipment and efficient utilization of water resources are determined by adapting crop, irrigation capacity and irrigation strategy, mainly based on knowledge of how the crops react on water stress in different growth stages.
Experiments are being carried out in which the crop is exposed to different degrees of water stress during the growth period. Crops under investigation are grass, winter wheat, winter barley, rye, perennial ryegrass for seed, rape, peas, potatoes, maize, fodder beet and poppy. The influence of supplemental irrigation on other growth factors is also being investigated in these experiments, and emphasis has been put on the interrelationship between irrigation and nitrogen. An understanding of these interrelations may lead to a more efficient use of water resources and irrigation capacity and of other growth factors. E.g. nitrogen was better used by the crops, resulting in greater efficiency in the use, thereby reducing the risk of undesirable effects on the environment.
During the next couple of years a system for irrigation scheduling will be designed, using the results from the experiments and the water balances for crops or fields. This will give farmers a greater opportunity for better irrigation scheduling, assisted by modern computer techniques.
