Assessment of the effect of optimised field plot size on the crop yield

The presented research deals with the effect of plot size changes on the crop yield. Three plots were chosen in a company engaged in conventional agriculture, on which yields were monitored from 2019 using yield maps. In 2020, the plots (initial size > 30 ha) were divided into different parts sized < 30 ha. In 2021, these newly arisen parts of the plots were harvested. Changes in the yield of grown crops were analysed using yield maps acquired by the harvesting machines. Relative yields (%) and absolute yields (t/ha) were determined on all experimental land parts arising from the initial plots' division. The values were then compared with yields recorded before the division of individual plots using zonal statistics. Measured relative yield values clearly show (P < 0.05) that the division of plots resulted in the increased heterogeneity of crop yields. On the initial plots as well as on the newly arisen plots, the relative yield was divided into the following categories: < 70, 70-85, 85-95, 95-105, 105-115, 115-130 and > 130%, with the value of 100% representing average yield. The analysis of measured yield data showed that the division of plots into smaller parts resulted in an uneven yield distribution because if a divided plot was heterogeneous in terms of yield levels, a cumulation of "higher yield levels (> 100%)" could have occurred in one specific newly arisen plot at the expense of another one. Moreover, new marginal parts of lands came into being during the division of larger soil complexes, and hence zones with potentially reduced yields.