As previously stated the Macintyre Wind Farm is on traprock country. It is very infertile and the main vegetation up on the ridgelines where the turbines are small hardy Acacias, Cassias, Eremophilas, Hakeas and the like that can gain a foothold in the fractures between the rocks . Sheep and goats do browse on them but they obtain most of their nutrition from the flats that are "irrigated" by water and minerals flowing in from above.
"As such, the operational phase of the project, it is unlikely that turbines will impact the productivity of the agricultural land on which they are located (Walker & Swift 2015)." You say thats impossible but in the case of the Macintyre wind farm it is true. There maybe a slight positive impact because the property owner gains some access roads, the sheep and goats are given a flat area to camp up on the ridge and more grass will grow in the road gutters, at the whoa boys and around the turbine than before but according to the landowners there is definitely no negative impact on agricultural productivity from the turbines.
Similarly with the decommissioning when it happens, the traprock is only marginally more fertile than concrete (ok maybe thats a bit sarcastic) but some landholders have requested that the foundation pads are covered with imported soil during decommissioning so they are more productive afterwards than they were originally.
