As well as the initial seed mix, it is likely that botanical diversity within solar farms is responding to favourable management practices. All solar farms in this study were constructed on arable or intensive pasture, and therefore had been subjected to intensive agricultural management including regular herbicide treatments and application of chemical fertilizers, as the control plots still were.
7.1.4 For the solar farms included in this study, the intensity of management
has been significantly reduced in terms of agricultural inputs. On one site, herbicide has been widely applied (beneath the panels), but on most sites herbicide application is limited to spot treatment of weeds. It is logical that a reduction in the use of broad-spectrum herbicides would lead to greater diversity of broadleaved plants. No sites were known to be spreading fertilizer. The high soil fertility of arable farmland favours a few dominant species of plant, but as soil fertility reduces in the absence of fertilizer, so the diversity of both grasses and broadleaved plants is able to, and indeed is anticipated to, increase.
7.1.5 Sheep grazing is known to be a good mechanism for grassland diversification where sheep are at lower stocking densities, and especially where grazing is stopped during the flowering season (April to July), as occurs on several sites. However, where sheep grazing is undertaken at higher stocking density, and without a pause for flowering there is little opportunity for the grassland to diversify.
7.1.6 Evidence for the effects of management can be found in sites 10 and 5. Both sites had been sown with diverse grasses and wild flowers, which provided an initial step change in the number of plants. However, both sites too have been grazed with sheep at low stocking density and with a pause for flowering in the spring and summer,