Impacts of grass removal on wetting and actual water repellency in a sandy soil

Soil water content and actual water repellency were assessed for soil profiles at two sites in a bare and grasscovered plot of a sand pasture, to investigate the impact of the grass removal on both properties. The soil of the plots was sampled six times in vertical transects to a depth of 33 cm between 23 May and 7 October 2002. On each sampling date the soil water contents were measured and the persistence of actual water repellency was determined of field-moist samples. Considerably higher soil water contents were found in the bare versus the grass-covered plots. These alterations are caused by differences between evaporation and transpiration rates across the plots. Noteworthy are the often excessive differences in soil water content at depths of 10 to 30 cm between the bare and grass-covered plots. These differences are a consequence of water uptake by the roots in the grass-covered plots. The water storage in the upper 19 cm of the bare soil was at least two times greater than in the grass-covered soil during dry periods. A major part of the soil profile in the grass-covered plots exhibited extreme water repellency to a depth of 19 cm on all sampling dates, while the soil profile of the bare plots was completely wettable on eight of the twelve sampling dates. Significant differences in persistence of actual water repellency were found between the grass-covered and bare plots

Effects of a soil surfactant on grass performance and soil wetting of a fairway prone to water repellency

This study reports on the effects of applications of a soil surfactant on improvement of grass performance and wetting of a sandy golf course fairway, located near Arnhem, the Netherlands. In addition, the influence of the surfactant on soil water repellency and the nitrogen contents in grass leaves, roots and upper 18 cm of the soil profile was investigated. The sandy soil of the fairway exhibits a water repellent behaviour resulting in a lot of localized dry spots (LDS) and poor turf quality during dry periods in spring and summer. In 2012 an experimental site on fairway 10 was divided into eight plots of 2 m by 2 m. Four plots were used as control and on four plots the surfactant was applied 6 times. The effects of the surfactant were studied on the wetting of the soil by measuring the volumetric water content at depths of 0–5 cm with a hand-held Time Domain Reflectometry (TDR) device. The grass performance was estimated in 3 distinct classes with percentages of the existence of green grass. Actual water repellency was assessed by putting water drops at regular distances along soil cores which were taken to a depth of 25 cm with a small, 1.5 cm diameter, auger. Applications of the soil surfactant resulted in dramatically improved soil wetting and turfgrass performance. Surfactant applications also resulted in more homogeneous wetting of the soil, reduced development of water repellency and preferential flow paths, and higher N concentration in soil. Since microbial mediated N mineralization is affected by moisture content, the higher N concentrations in the soil are thought to be related to the higher and more homogeneous moisture levels in the treated versus untreated plots. In addition to improved moisture availability, the better turf performance is likely affected by the increased plant available N in the soil which resulted from the more desirable and uniform moisture levels.</p

A new wireless underground network system for continuous monitoring of soil water contents

A new stand-alone wireless embedded network system has been developed recently for continuous monitoring of soil water contents at multiple depths. This paper presents information on the technical aspects of the system, including the applied sensor technology, the wireless communication protocols, the gateway station for data collection, and data transfer to an end user Web page for disseminating results to targeted audiences. Results from the first test of the network system are presented and discussed, including lessons learned so far and actions to be undertaken in the near future to improve and enhance the operability of this innovative measurement approach

Cocktails of pesticide residues in conventional and organic farming systems in Europe – Legacy of the past and turning point for the future

Considering that pesticides have been used in Europe for over 70 years, a system for monitoring pesticide residues in EU soils and their effects on soil health is long overdue. In an attempt to address this problem, we tested 340 EU agricultural topsoil samples for multiple pesticide residues. These samples originated from 4 representative EU case study sites (CSS), which covered 3 countries and four of the main EU crops: vegetable and orange production in Spain (S–V and S–O, respectively), grape production in Portugal (P-G), and potato production in the Netherlands (N–P). Soil samples were collected between 2015 and 2018 after harvest or before the start of the growing season, depending on the CSS. Conventional and organic farming results were compared in S–V, S–O and N–P. Soils from conventional farms presented mostly mixtures of pesticide residues, with a maximum of 16 residues/sample. Soils from organic farms had significantly fewer residues, with a maximum of 5 residues/sample. The residues with the highest frequency of detection and the highest content in soil were herbicides: glyphosate and its main metabolite AMPA (P-G, N–P, S–O), and pendimethalin (S–V). Total residue content in soil reached values of 0.8 mg kg−1 for S–V, 2 mg kg−1 for S–O and N–P, and 12 mg kg−1 for P-G. Organic soils presented 70–90% lower residue concentrations than the corresponding conventional soils. There is a severe knowledge gap concerning the effects of the accumulated and complex mixtures of pesticide residues found in soil on soil biota and soil health. Safety benchmarks should be defined and introduced into (soil) legislation as soon as possible. Furthermore, the process of transitioning to organic farming should take into consideration the residue mixtures at the conversion time and their residence time in soil.</p