IMPORTANCE OF LONG-TERM EXPERIMENTS IN AGRICULTURE AND A CASE STUDY WITH FIELD CROPS FROM LATVIA

Field experiments are recognized as long-term if they have been conducted for more than 20 years; if the long-term experiment (LTE) has already run for 50 years or more, it is called "classical". The very first LTEs were established in Rothamsted Research Station (UK) in 1843 and they are still in use. It is possible to study crop production, nutrient cycling, environmental impact of agriculture etc., using LTEs. LTEs can help us to evaluate sustainability of agriculture and to predict the consequences of different activities thinking of legacy for the next generations. Data obtained from LTEs can be used also for validation of diverse computer-based models. Many LTEs started in the 19th and 20th century have not survived until nowadays due to different reasons. Such is the fate of almost all the LTEs established in Latvia: six LTEs were set up in different places of the country starting with the very first in 1958, but only two are running now; the only classical LTE faces crucial changes, but remaining three have been closed irreversibly. This paper is aimed to describe the importance of LTEs in the world mentioning some most impressive examples from the experience of other countries and to discuss the fate of LTEs established in Latvia. One example of still running experiments is newly established LTE (in 2008; it is even not LTE in its full meaning), but the other two are not financed properly, therefore the authors would like to draw the attention of the society, individuals and science sponsors to the importance of LTEs.