A 100-plot experiment was performed during the growing season of 1976 in a Ste. Rosalie clay soil, using a randomized complete-block design with 25 treatments of machinery traffic within each of four blocks. Three vehicle contact pressures, four numbers of tractor passes, before or after seeding groups and a control of zero traffic were used to relate the growth and yield variables to wheel traffic and resulting soil compaction. Plant emergence and tasselling were delayed with increasing machinery traffic. The plant growth rate monitored at 29, 44, 60, 74 and 88 days from the seeding time was dramatically different from plot to plot. Growth models at different times of the season were derived in terms of the product of contact pressure and number of passes of the vehicle. Plant and ear moisture contents were higher in plots with heavier traffic treatment. Yield, ear yield and grain yield all decreased with increases in machine contact pressure and passes. The reduction in yield was over 50% in some cases, suggesting that careful traffic planning is essential to obtain better production in agricultural fields. Prediction models were obtained for all the plant growth characteristics in terms of traffic variables for both before- and after-seeding treatments. A relation for yield in terms of soil bulk density was established.
Integrating dynamic plant growth models and microclimates for species distribution modelling
