Researchers at Wageningen University and research in the Netherlands has established how different grass specifically responds differently to the presence or lack of moisture in the soil.
The researchers examined the differences in roots of different grasses from trial plots where soil moisture levels had consistently been kept at over 15% to more than 30% during the summer of 2022. The results were compared to grass roots of plots that had been dependent on natural rainfall. Here, the soil moisture percentage was roughly between 5% and 15% during the same period.
In the irrigated plots, roots of these grasses tended to remain with the 0-5 cm top layer rather than in the 5-10 cm and 10-20 cm depth.
However, in the non-irrigated part, fescue rooted, particularly in the deepest 10-20 cm layer. A difference of over 7% was established, compared to fescue roots in the irrigated plot. The biomass in the intermediate 5-10 cm layer for the non-irrigated plot remained almost similar (1% difference), while significantly less root biomass was found in the top layer. It can therefore be said that during drought, fescue invests in the deepest category of roots at the expense of the root mass just below ground level.
Tetraploid ryegrass in the non-irrigated plot also invested in roots at depth. Here, roots of 5-10 cm were measured the most. For the plots where the soil moisture percentage was kept constant, the relative root biomass distribution between tetraploid ryegrass and tall fescue was the same.
Samples were taken from plots that are being used for a multi-year study that studies grass and its interaction with the climate and biodiversity. For this study, eight different monocultures and four grass mixtures are being investigated.
The research was conducted earlier this year. Samples were divided into four sections: the stubble, 0-5 cm below the surface, 5-10 cm below the surface, and 10-20 cm below the surface. Subsequently, the samples were stripped of sand and dried in an oven at 70 degrees Celsius for more than 48 hours. Finally, all samples were weighed with a precision scale.