FIELD AND LABORATORY EXPERIMENTS TO VALID ATE PREDICTORY MODELS OF THE EXPERT-SYSTEM HERBASYS APPLIED TO PROBLEMS OF CROPS FOLLOWING THE USE OF HERBICIDES
B. Gottesburen et al., FIELD AND LABORATORY EXPERIMENTS TO VALID ATE PREDICTORY MODELS OF THE EXPERT-SYSTEM HERBASYS APPLIED TO PROBLEMS OF CROPS FOLLOWING THE USE OF HERBICIDES, Weed Research, 34(1), 1994, pp. 63-78
Field and laboratory experiments to valid predictory models of the exp
ert system HERBASYS applied to problems of crops folio wing the use of
herbicides Field and laboratory studies were conducted with the herbi
cides Dicuran (chlorotoluron) and Tramat (ethofumesate) to investigate
their breakdown behaviour and effects on subsequent crops. These stud
ies served to validate the simulation of breakdown and the predictions
for subsequent crops of the expert system HERBASYS. The parameters ne
cessary for the simulation of breakdown were ascertained under differe
nt incubation conditions for various soils (clay loam, loamy sand, loa
my clay) and with the aid of an iterative method of assessment (WALKBA
CK). The breakdown of both active substances was accelerated by increa
ses in soil temperature and moisture, insofar as the optimum levels we
re not exceeded. In the field, breakdown at the various sites was depe
ndent on weather conditions but no clear relationship with sorption-de
termining properties could be estabilished. The simulated residues acc
orded well with those measured in the field and it is possible to tran
sfer the breakdown parameters determined for one chemical-soil combina
tion to other site and climate conditions. In long-term bioassays with
nonsorptive substrates dose-effect relationships were established bet
ween chlortoluron and ethofumesate and various crop plants and the rea
ction of the crops to the herbicides was investigated in field tests.
The effects of available residues on subsequent crops, as calculated f
rom sowing date and sorption, were compared with those known from the
dose-effect relationships. In general, the risk to subsequent crops wa
s well forecasted.