Granular wetting agents ameliorate water repellency in turfgrass of contrasting soil organic matter content

Abstract

The effectiveness of four granular wetting agents to decrease water repellency in sandy soils of contrasting organic matter (OM) content and influences on kikuyugrass [Pennisetum clandestinum (Holst. Ex Chiov)] grown as turfgrass, were evaluated. A laboratory test assessed the wettability of two nonwetting soils (low OM, 4.7%; high OM, 17%) after treatment with granular soil wetting agents, with four being selected for field experimentation. A field experiment included two turfgrass ages (established from 20 week or 20 year old turfgrass in 2005; the latter included a 50 mm 'mat' layer and thus had high OM content in the surface soil), four granular soil wetting agents (plus a 'nil' as control), and five replicates. Surface soil (0-25 mm) water repellency, measured using the molarity of ethanol droplet test (MED), ranged from 0.4 M to 4.3 M during the irrigation season, and repellency was more severe in the soil with high OM (32%) content than low OM (8.6%) content. Soil wetting agents decreased the development of soil water repellency to varying extents, and maintained turfgrass quality; with improvement related to the amount of active ingredient applied. We recommend utilising an effective soil wetting agent, in combination with practices that limit the accumulation of soil OM, to decrease the severity and incidence of soil water repellency in turfgrass grown on sandy soils.

Soil Water Repellency Severity and its Spatio‐Temporal Variation in Burnt Eucalypt Plantations in North‐Central Portugal

“…However, the correlations described in literature between organic matter and SWR are inconclusive. Both a positive correlation (Mataix-Solera & Doerr, 2004;Varela et al, 2005;Rodríguez-Alleres et al, 2007;Zavala et al, 2009;Barton & Colmer, 2011) and a negative or an absence of correlation have been reported (Ritsema & Dekker, 1994;Scott, 2000). It was pointed out that the development of SWR could be more influenced by the quality and degree of decomposition than by the quantity of the organic matter , because not all organic carbon compounds are hydrophobic (Müller & Deurer, 2011).…”

Soil Water Repellency Dynamics in Pine and Eucalypt Plantations in Portugal – A High‐resolution Time Series

“…Differences in SOM content and/or quality are likely to have played a role as well, possibly an additional one. Many authors have reported positive relationships between SOM content and SWR (Bisdom et al, 1993;Kawamoto, 2007;Barton & Colmer, 2011) although a clear relationship has remained obscure, suggested to be caused by confounding effects of differences in SOM quality (Doerr, 2000;Müller & Deurer, 2011), Figure 4. Relationship between median soil moisture content (in vol.%) and median ethanol classes at 2.5 and 7.5 cm for the Eucalypt (n = 37) and the Pine (n = 36) site.This figure is available in colour online at wileyonlinelibrary.com/journal/ldr.…”

Effect of crude petroleum on water repellency in a clayey alluvial soil

“…Usually, soil surfaces are covered with a thin film of water, but when the soil dries completely, water repellent organic compounds (such as hydrocarbons) may attach to the charged soil surfaces through van der Waals forces, causing the soil surface not to be available to interact with water, thus reducing the retention of water and nutrients for plants. This may result in increased run-off and erosion, as well as the overall deterioration of soil structure, generating preferential flow pathways that cause the water infiltration that does occur, to be very uneven (Regalado et al 2005; Jaramillo 2006; Pires et al 2006;Leelamanie et al 2008;Moody and Schlossberg 2010;Barton and Colmer 2011;Nieber et al 2011). Dekker and Ritsema (1994) observed that there was a water content below which the soil became water repellent and above which the soil was wettable.…”