What are the principle modes of action of wetting agents and how can they aid turfgrass quality while Improving water conservation?

Martin, Thomas and Rothwell, Shane and Stevens, Carly (2019) What are the principle modes of action of wetting agents and how can they aid turfgrass quality while Improving water conservation? Masters thesis, Lancaster University.

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Abstract

Wetting agents are a class of surfactant - organic chemicals that reduce the surface tension between two materials. The sandy soils that many golf courses are constructed on can develop water repellency due to an organic coating that forms around sand particles. Wetting agents allow water to effectively bind with sand particles and can significantly reduce the length of time that water sits on the soil surface. Along with potentially improving turf quality, this has positive implications in terms of reducing surface runoff and improving water use efficiency. To explore the effects of wetting agents on grass physiology, development and soil interactions, investigations were conducted using three different wetting agent treatments on two cool-season turfgrass species - Highland bentgrass Agrostis castellana and Annual meadow grass Poa annua. Assessments of the effects of wetting agent treatments on seed germination, plant growth rate, nutrient uptake, rhizosheath properties, rooting characteristics and drought interactions were made over the course of three experiments carried out in controlled conditions. It was found that plant and turf growth rate can be affected in the two species to different extents depending on the wetting agent used, with positive implications for turf quality in the field for a newly developed wetting agent. The same treatment also significantly improved germination success in A. castellana and resulted in significant differences between the two species in terms of rhizosheath size and root diameter, with A. castellana being positively affected. The evidence presented in this study shows that wetting agents can affect the distribution of water resources in the soil by shifting the rhizosheath water content to bulk soil water content ratio to potentially maximise water and nutrient uptake by the roots. The results also show that another wetting agent treatment has the potential to improve drought tolerance in drought susceptible species through analysis of plant growth rate under drought conditions, stomatal conductance and leaf relative water content. It is hypothesised that the combination of effects caused by a wetting agent treatment may lead to improved water use efficiency and a more desirable sward composition for golf course owners in the field, resulting in water conservation and a reduction in the need to use herbicides to combat weed species.