A more meaningful test would be to compare circle and matrix soil as grass growth progresses after rains. (journals.plos.org)
If farmers cop a price cut, it couldn't come at a worse time, with Australia's top dairy producing areas facing dry conditions and the least amount of grass growth in more than 40 years. (afr.com)
More recently, Jankowitz et al. [5] found that grass growth in pots was poor inside the circles but not the matrix when the pot was open below, but not when it was closed, and suggested a semi-volatile toxic factor. (journals.plos.org)