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The effects of soil water repellency (SWR) on runoff and nutrient losses are difficult to isolate. Hydrophobic organic substances coating soil particles can severely delay water infiltration and enhance runoff. We used a portable run-on simulator to investigate the effect of SWR on runoff and nutrient loss. Intact soil slabs, 0.48 m long and 0.19 m wide, were collected from a severely water-repellent Andosol under pasture. One day before simulating 60-min long run-on events with an intensity of 60 mm h −1 , superphosphate was applied at a rate of 45 kg P ha −1 . The effects of SWR were quantified by comparing runoff volumes and nutrient losses from run-on events conducted with water and a fully wetting aqueous ethanol solution as run-on liquids. Further, through conducting multiple consecutive water run-on events with the same soil slab, the hypothesis, that SWR is lost through the washing off of hydrophobic materials, was tested. Finally, runoff dynamics were visualised by adding a dye to the run-on water. In the first run-on experiment, 88% of the water applied was captured as runoff, while no runoff was observed when aqueous ethanol was used as run-on liquid, providing strong evidence that SWR governed runoff generation from this Andosol. In consecutive water run-on experiments, approximately 23% of the applied P was recovered in the runoff from the first event, while the cumulative P loss over ten consecutive run-on events was around 30% of the applied P. This confirms that nutrient losses were associated with SWR and the occurrence of runoff. After ten consecutive run-on events, the persistence of both actual and potential SWR in areas of the slab that had been wetted were significantly ( p  < 0.5) reduced. But the persistence of potential SWR of the soil was still classified as severe, suggesting only minor losses of hydrophobic materials from the soil surface. The persistence of potential SWR and the degree of SWR of the dry areas remained more or less unchanged. In accordance with this, visualisation of the wetted areas showed that runoff occurred as rivulets guided by surface topography, rather than as sheet flow, with the wetted area increasing from approximately 20% of the slab in the first event to around one third of the total slab area in the final event. This pattern is reflected in the cumulative pattern of the P losses over the ten events. Consequently, we conclude that SWR should be considered as a factor in hydrological modelling and should be included in models to address appropriately the risk of surface water contamination by solutes exogenously applied to water-repellent soils. [ABSTRACT FROM AUTHOR]

Soils deliver the regulating ecosystem services of water infiltration and distribution, which can be controlled by macropores. Parameterizing macropore hydraulic properties is challenging due to the lack of direct measurement methods. With tension-disc infiltrometry hydraulic properties near saturation can be measured. Differentiating between hydrologically active and non-active pores, at a given water potential, indirectly assesses macropore continuity. Water flow through macropores is controlled by macropore size distribution, tortuosity, and connectivity, which can be directly derived by X-ray computed tomography (CT). Our objective was to parameterize macropore hydraulic properties based on the imaged macropore network of three horizons of an Andosol and a Gleysol. Hydraulic conductivity K unsat was derived from infiltration measurements. Soil cores from the infiltration areas were scanned with X-ray CT. K unsat was significantly higher in the Andosol than in the Gleysol at all water potentials, and decreased significantly with depth in both soils. The in situ measurements guided the definition of new macroporosity parameters from the X-ray CT reconstructions. For the Andosol, K unsat was best predicted using the imaged-limited macroporosity. A low total macroporosity, coupled with a high macropore density, indicated the abundance of smaller macropores, leading to homogeneous matrix flux. Imaged macropores were not well connected. In contrast, the Gleysol had a bi-modal macropore system with few very large, but well-connected macropores. K unsat was best predicted using the imaged macroporosity consisting only of macropores with diameters between 0.75 and 3 mm. Our research demonstrates that linking traditional soil physical measurements with soil-visualization techniques has a huge potential to improve parameterizing macropore hydraulic properties. The relevance of the relationships found in this study for larger scales and other soil types still needs to be tested, for example by a multi-scale investigation including a much wider range of different soils. [ABSTRACT FROM AUTHOR]

Soil water repellency (SWR) of soils is a property with significant consequences for agricultural water management, water infiltration, contaminant transport, and for soil erosion. It is caused by the presence of hydrophobic agents on mineral grain surfaces. Soils were samples in different depths at three forest sites in Japan and three pasture sites in New Zealand, covering soil organic carbon (SOC) contents between 1 and 26%. The SWR was measured over a range of water contents by three common methods; the water drop penetration time (WDPT) test, the molarity of an ethanol droplet (MED) method, and the sessile drop method (SDM). The aim to (i) compare the methods, (ii) characterize the soil-water repellency characteristic curves (SWRCC) being SWR as a function of the volumetric soil-water content ( θ ) or matric potential ( ψ ), and (iii) find relationships between SWRCC parameters and SOC content. The WDPT, MED, and SDM generally agreed well in predicting the θ range where SWR occurred, and there was close agreement between SWR results determined by average MED and SDM at similar θ . Generally, SWR was only found within the top 20 cm of the soil profiles. Six SWR parameters were introduced: (i) the area under the curve ( S WR ( θ ) ); (ii) θ at the maximum SWR ( θ WR-max ), (iii) θ where SWR ceased ( θ non-WR ), (iv) the maximum SWR ( CA i -max ), (v) pF at the maximum SWR ( pF WR-max ) and (vi) pF where SWR ceased ( pF non-WR ). The relationship between the first three parameters and SOC content were best described with Langmuir type equations (r 2 of 0.5–0.7), while the other three parameters changed linearly with SOC contents. [ABSTRACT FROM AUTHOR]

We developed a laboratory-scale run-off measurement apparatus (ROMA) to quantify for the first time directly the impact of soil water repellency (SWR) on run-off from undisturbed soil slabs in the laboratory. We tested and evaluated the performance of ROMA with multiple consecutive run-off experiments using water followed by a fully-wetting liquid, namely an ethanol solution. We found that a 30% (v/v) ethanol solution was needed to ensure that the soil hydrophobicity had no influence on the infiltration rate of the liquid. The results demonstrated the ROMA is a robust and reproducible tool that performs at a high standard with instrument errors below 2%. We conducted ROMA run-off experiments with air-dried soil slabs (480mm long×190mm wide×50mm deep) collected from four pastoral sites, representing three major soil orders in the North Island, New Zealand. They were the Kashmir-Recent Soil (Fluvisol), Hawke's Bay-Recent Soil (Fluvisol), Taranaki-Gley Soil (Gleysol), and Taranaki-Organic Soil (Histosol). These soils had a high degree and persistence of SWR. The contact angles were 97, 97, 98 and 104°, the potential water drop penetration times (WDPT) were 4, 42, 54 and 231min, and the run-off fractions were 16, 19, 28, and 96% respectively. However, even the extremely hydrophobic Taranaki-Organic Soil, which had a runoff coefficient of 96%, only lost 13% of the applied bromide via run-off. This demonstrates that run-off occurred in rivulets covering only a small fraction of the surface. Multivariate regression analyses showed that the soil organic carbon content and the degree of SWR explained 89% of the variability of the run-off coefficients. We identified difficulties around the meaningfulness of the persistence of SWR, as determined by the WDPT test, since it just measures SWR at a single point. Alternatively, our ROMA experiments integrate the spatial variability of SWR of an undisturbed soil slab. In addition, the method is faster for extremely hydrophobic soils once the ROMA is set up. [ABSTRACT FROM AUTHOR]

Abstract Organic matter can render soil hydrophobic and cause soil water repellency (SWR) which has large implications for agriculture. Consequences such as fingered flow, uneven wetting patterns, and increased overland flow reduce irrigation efficiency and plant nutrient availability. The phenomenon of SWR is a transient soil property depending, inter alia , on soil water content (w). Soil can exhibit SWR from oven-dry w until the critical w where it again becomes fully wettable (w NON). The total SWR can be obtained from the nonlinear SWR- w relationship as the integrated trapezoidal area under the SWR- w curve (SWR AREA). We analyzed 78 soil samples, representing five dominant soil orders in the South Island of New Zealand. The soils had a large range in clay (0.000–0.520 kg kg−1) and organic carbon (OC) content (0.021–0.217 kg kg−1). The degree of SWR was measured on soils at air-dry conditions (SWR AD) and after heat-pretreatment at 60 (SWR 60) and 105°C (SWR 105). Further, SWR was measured in small w increments above air-dry w until w NON was reached. The SWR- w curves were either unimodal or bimodal, or no SWR occurred. SWR AREA ranged from 0.16 to 26.82 mN m−1 kg kg−1. Among the five soil orders tested, the Podzols exhibited the highest severity in SWR, whereas the Semiarid soils were the least hydrophobic soils. In conclusion, OC was the main factor for controlling the severity of SWR. Though, pH also had minor effects on SWR. Further, an upper limit critical water content was derived from the simple relationship between the w NON and OC, which could be applied to improve irrigation practices of pastoral soils. However, there is a need for further testing on different soils and land uses. Highlights • Soil water repellency versus water content curves were highly non-linear. • OC was the main controller of soil water repellency. • Within five soil orders, the Podzols were most severe in soil water repellency. • pH affected soil water repellency to a lesser degree than OC. • An upper limit critical water content was obtained from OC for irrigation support. [ABSTRACT FROM AUTHOR]

[Display omitted] • A paired site study to explore land use effects on soil hydraulic properties (SHPs). • Maize cropping degraded SHPs relative to pasture grazing in two contrasting soils. • Interaction effect on SHPs existed between land use and soil depth but not soil order. • Maize cropping in Gley soils had greatest SHP degradation. Soil hydraulic properties (SHPs), including available water content and near-saturated hydraulic conductivity (K ns), affect hydrological and biochemical processes. The SHPs information is crucial to agricultural water management. The objective of this study using paired sites was to investigate the effects of land use on SHPs in two contrasting soil orders. Soil water retention curves and K ns at three soil depths (0–10, 10–20 and 20–30 cm) were measured under two land uses (pasture, consisting of a rye grass [ Lolium perenne L.] and white clover [ Trifolium repens L.] mix, and maize [ Zea mays L. ] cropping > 10 years) in Waikato, New Zealand. For each land use, two soil orders with contrasting soil structural vulnerability were selected: less vulnerable Allophanic soil and more vulnerable Gley soil. Compared with pasture, maize cropping reduced macroporosity, readily available water capacity and K ns of 0–30 cm, and the effect was greater in the deep layer (20–30 cm). This indicated that maize cropping practices result in greater structural degradation to soils compared with pasture, which include the potential for greater subsoil compaction. There was no land use by soil order interaction effect on SHPs, suggesting that the relative SHP degradation under maize cropping compared with pasture grazing was not associated with soil structural vulnerability. Our study emphasised that long-term continuous cropping with maize on the more vulnerable soil (i.e. Gley soil) resulted in the poorest soil physical health. [ABSTRACT FROM AUTHOR]

• Methods and influencing factors of soil structural vulnerability are critically reviewed. • Soil structural susceptibility, vulnerability, and risk are distinguished by their controls. • Current state of soil structure and vulnerability need be included to assess soil structure. • Effects on ecosystem services are highlighted in soil structural vulnerability assessment. Soil structure affects a range of soil functions (e.g., water, air, heat, and nutrient transport) and ecosystem services (e.g., production, climate regulation). Agricultural intensification is a dominant factor in global soil structural degradation. Understanding the vulnerability of soils to structural degradation may be important to land use planning and identifying management practices that mitigate the risk of degradation. We review the current methods for assessing soil structural vulnerability and the influencing factors, focussing on soil compaction and aggregate breakdown as two key measures of structural degradation. Methods for assessing risk of soil structural degradation and management practices affecting the risk are also discussed. Critical research gaps are identified, including the lack of studies that demonstrate the link between soil structural vulnerability and loss of soil functions or ecosystem services. Our review of the literature identified that the terms susceptibility, vulnerability, and risk are often used interchangeably. We propose definitions that can be used to distinguish these terms. Soil properties (relatively static), soil wetness, and land use stress (e.g., climate and management practices) are progressively included in the assessments of soil structural susceptibility, vulnerability, and risk. Existing indicators for assessing soil structural vulnerability may not be suitable to predict potential effects on ecosystem services. We highlight that soil structural vulnerability assessments should focus on key soil structural indicators (e.g., pore network-based hydraulic properties) affecting soil functions and ecosystem services. Both the state (i.e., condition) of soil structure and its vulnerability should be included for assessing soil structural degradation. To overcome the limitations of previous assessments, we developed a conceptual model linking soil structural vulnerability assessment to loss of soil functions and ecosystem services. Our review provides insights on assessment metrics and frameworks to develop management practices that improve soil structure and delivery of ecosystem services. [ABSTRACT FROM AUTHOR]

• Soil water repellency (SWR) was investigated on 145 Greenlandic agricultural soils. • 98% of the investigated samples exhibited extreme SWR at their maximum SWR. • Loss-on-ignition at 550 °C was an excellent predictor of SWR. • SWR at the wilting point decreased at clay/OC ratios > 2. • The SWR was highly similar to New Zealandic pasture soils from the literature. The rapid warming of the Arctic is changing the conditions for agricultural activity in southwest Greenland markedly, which necessitates studies of the physical properties of the soil resource. Soil water repellency (SWR) is a soil property that changes soil functional behaviour across a soil-specific range in water-content (W). Although SWR occurs worldwide, it has not been studied in sub-arctic pasture and grass fields. Thus, the aim was to examine the prevalence of SWR in South Greenland and to establish pedotransfer functions for SWR on soil properties that are faster to measure than SWR, i.e. soil organic fractions, texture and soil water retention. This study included 145 soil samples from 22 sub-arctic agricultural fields distributed across three areas of South Greenland, with broad distributions in texture (clay: 0.017–0.194 kg kg−1) and organic carbon (OC) (0.009–0.241 kg kg−1) contents. The degree of soil water repellency (SWR) as a function of water content (SWR-W curve) was measured from oven-dry conditions to the water-content at which the soil became hydrophilic (W NON), and total SWR (SWR AREA) was calculated as the integrated trapezoidal area (SWR AREA) of the SWR-W curve. A total of 99% and 98% of the soil samples were water-repellent and extremely water repellent at their maximum SWR, respectively. Among the three soil organic fractions (OC, Loss-on-ignition at 550 °C, and 225 °C (LOI 550 and LOI 225)), LOI 550 was the best predictor of SWR AREA and W NON (both with r2 = 0.93). Multiple linear regressions including clay content increased r2 adj to 0.92 and 0.95 with OC and LOI 550 , respectively. The Campbell-Shiozawa (CS) model was fitted to the soil–water retention curves (pF 3.0–6.9), and the inverse slope (−α−1) of the CS model exhibited a high correlation to both SWR AREA (r2 adj of 0.87) and W NON (r2 adj of 0.93), thus suggesting that soil water retention governs SWR. Lastly, it was shown that the coefficient of proportionality between OC and both SWR AREA and W NON for these sub-arctic soils coincided with pasture soils from New Zealand. [ABSTRACT FROM AUTHOR]

• Irrigated pasture had greater SWRP than dryland pasture and irrigated crop. • Soils with SOC < 2% tended to be wettable and soils with SOC > 4% repellent. • SWRP curve described by a Gaussian model with three physically meaningful parameters. • Model parameters and SWRPC could be predicted by SOC. Soil water repellency (SWR) affects hydrological processes such as water infiltration, preferential flow, run-off, and evapotranspiration. Understanding the relationship between SWR and volumetric soil water content (θ) is critical for predicting hydrological processes in hydrophobic soils. In this study, water droplet penetration time (WDPT) was used to investigate the SWR persistence (SWRP) in three soil types with contrasting drainage levels, namely a well-drained Lismore (LIS) stony silt loam, a moderately well-drained Templeton (TEM) silt loam, and a poorly drained Waterton/Temuka (WAT) clay loam under three long-term (>20 years) land uses (irrigated pasture [IP], dryland pasture [DP], and irrigated crop [IC]) in Canterbury, New Zealand. The three soils belong to different soil orders (i.e., Brown, Pallic, and Gley, respectively) in the New Zealand soil classification. Within each land use, 9, 12, and 9 sites were sampled in the LIS, TEM, and WAT soils respectively. There was strong evidence of SWR in all three soil types under three land uses. The maximum SWRP (WDPT max), ranging from 6 to 1470 s with the median value of 56 s, differed with land use by following descending order of IP > DP > IC. The effects of land use on SWRP differed with soil type. Compared with other two soils, LIS soil had higher differences in WDPT max between IP and DP, but lower differences in WDPT max between DP and IC. Most of the SWRP parameters were significantly correlated with soil organic carbon (SOC) content. In soils with higher SOC content, SWR usually developed under drier conditions and declined as soils were maintained under wetter conditions. This study suggests that the WDPT max appears at soil water contents of 0.17 to 0.19 cm3 cm−3 (equivalent to 0.15 to 0.16 g g−1). Soil water repellency persistence was positively related to SOC content. Soils with SOC content < 2% tended to be wettable, while soils with SOC content > 4% tended to be water-repellent. A Gaussian model with three physically meaningful parameters was developed to successfully fit the SWRP curve (SWRPC, LnWDPT as a function of θ). Our study also showed the possibility to predict the model parameters and SWRPC using SOC content. The model needs to be tested across other soil types, land uses, and climates before it can be widely applied to predict the SWR occurrence from SOC data. Future work should also focus on the impacts of SOC composition on SWRP parameters and other hydrological properties for predicting soil water processes in water-repellent soils. [ABSTRACT FROM AUTHOR]

• More intensive land use led to higher risk of soil structural degradation (SSD) in NZ. • Pasture production declined by 2.5% for each 1% (0.01 cm3 cm−3) decrease in macroporosity. • Compaction increased N 2 O emissions by 51–814% (grazing) and 19–1300% (traffic). • Compaction effects on contaminant losses via runoff and drainage were inconsistent. • Estimating costs of SSD is challenging due to the lack of data. Agricultural intensification has enhanced productivity, but has also negatively affected soil structure and environmental outcomes. Agriculture is among New Zealand (NZ)'s largest industries. Like other countries, significant land use intensification over the last 20–30 years has occurred in NZ, resulting in undesirable side-effect of soil structural degradation (SSD) (e.g., soil compaction, aggregate fragmentation). Using NZ as a case study, we reviewed and, where possible, quantified the extent of SSD in NZ and its impacts and implications on production, contaminant losses via drainage and runoff, and N 2 O emissions. Knowledge gaps were identified that will help guide future research both in NZ and internationally. Our review revealed that SSD is common in many regions and under different land uses in NZ. At the national scale, 44% of sites monitored between 2014 and 2017 were below the national target for macroporosity (pore diameter > 30 μm). The occurrence of SSD was greater under more intensive land uses such as dairying and continuous cropping. Soil structural degradation from compaction is typically associated with reduced pasture and crop production. In NZ, pasture production was estimated to decrease by an average of 2.5% for every 1.0% (0.01 cm3 cm−3) decrease in macroporosity (0–10 cm soil). Compaction from livestock treading and wheel traffic has been shown to increase N 2 O emissions by 51–814% and 19–1300%, respectively, with no significant evidence that this increase is related to N loading. Effects of compaction on contaminant losses via runoff and drainage, and in particular via preferential flow, are less well researched and findings were less consistent and dependent on many factors including the degree of compaction. Important knowledge gaps include a lack of quantitative relationships between degree of SSD and soil hydraulic properties and processes (e.g., water movement and contaminant losses), and poor knowledge of critical thresholds or optimum ranges of soil physical indicators in relation to critical ecosystem services (e.g., pasture yield, gas and water regulation in soils). We also found few estimates of SSD-induced costs related to production and environmental outcomes (e.g., contaminant losses and N 2 O emissions) at either farm system, regional or national scales. More data are needed to better determine the true costs and implications for farm production and environmental effects associated with SSD. [ABSTRACT FROM AUTHOR]

• The hydrochar-derived DOM-mediated reduction of δ -MnO 2 released aqueous Mn(II). • Hydrochar-derived DOM was transformed via both decomposition and polycondensation. • The molecular characteristics of reacted DOM were more similar to NOM. Hydrochar produced from hydrothermal carbonization of agricultural waste becomes a promising soil conditioner, and especially, its labile fraction, dissolved organic matter (DOM) may play an important role in improving soil fertility and quality. However, little is known about the interaction and transformation of hydrochar-derived DOM with soil reactive components after its amendment into soil. The abiotic transformation of hydrochar-derived DOM by a common soil metal oxide, δ -MnO 2 at environmentally relevant pHs (4, 6 and 8) was investigated by using a combination of batch experiments and advanced spectroscopic techniques. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) and fluorescence spectroscopy revealed that lignins and carboxyl-rich alicyclic molecules were predominant in hydrochar-derived DOM and phenolic fluorophores were the dominant fluorescent composition. In the presence of δ -MnO 2 , hydrochar-derived DOM was rapidly transformed via both decomposition and polycondensation, resulting in significant structure changes of hydrochar-derived DOM with increasing humic-like fraction similar to soil organic matter (SOM). The transformation process of hydrochar-derived DOM molecules was highly pH-dependent, with polycondensation occurring preferentially at pH 8 and more rapid oxidation at pH 4. Meanwhile, δ -MnO 2 was reduced to Mn(II) and Mn(III) during the reaction, and the accumulation of Mn(III) in the solid phase of δ -MnO 2 reached a maximum at pH 4. Collectively, the results characterized the transformation mechanism of DOM by δ -MnO 2 at molecular level, which provided a new perspective for better understanding of the biogeochemical processes of biochar for its application in soil quality improvement and remediation. [ABSTRACT FROM AUTHOR]

• • Phytolith-occluded carbon (PhytOC) plays an important role in terrestrial long-term carbon sequestration. • • Phytolith stores along precipitation gradient were significantly and positively correlated with MAP. • • Elevated MAP would enhance ecosystem primary productivity and consequently promote soil PhytOC storage. • • The soil phytolith dynamics in East Asian steppe should be considered in predicting global climate change. Climatic factors including mean annual precipitation (MAP) significantly influence the carbon (C) cycle in terrestrial ecosystems and Earth overall. Phytolith-occluded carbon (PhytOC) is an important C sequestration mechanism and as such plays a vital role in global long-term C sequestration. Understanding the spatial variability in the storage of soil phytoliths and PhytOC and its relationship with climate is critical for evaluating the impact of global climate change on terrestrial ecosystem functions. However, little is known about the responses of soil phytoliths and PhytOC to MAP in grassland ecosystems. This study sampled soil from 24 natural, semi-arid steppe sites along a 2,500 km transect with a precipitation gradient of 243–481 mm yr−1 in northern China. We investigated the influence of precipitation on the spatial distributions of soil phytoliths and PhytOC storage. Storage of soil phytoliths in bulk soil (0–100 cm depth) ranged from 21.3 ± 0.4 to 88.4 ± 20.3 t ha−1 along the precipitation gradient. Amounts of soil phytoliths and PhytOC storage were significantly and positively correlated with MAP. Multiple regression analysis revealed that phytolith storage in bulk soil was best predicted by MAP (R = 0.5) and soil organic carbon (SOC, R = 0.4), with these two variables accounting for about 58% of the total variation observed. Considering the forecasted increase in MAP in the Inner Mongolian steppe due to climate change, and the strong influence of MAP on the annual net primary productivity (ANPP) and related soil PhytOC input from litter decomposition in this region, we expect that ecosystem primary productivity will increase from deserts to meadow steppe and thereby promote soil PhytOC storage. These findings have important implications for understanding the dynamics of soil phytoliths, and predicting the impacts of global climate change on ecosystem functions and management practices in the East Asian steppe ecosystems. [ABSTRACT FROM AUTHOR]

• New Zealand soils had an extreme gradient in glyphosate sorption coefficient (K d). • A multiple linear regression for K d included aluminum, phosphorous and pH. • The soil properties controlling K d could be predicted with vis–NIRS. • Improved K d predictions using vis–NIRS spectral subsets were obtained. • Vis–NIRS provided more accurate determination of K d than basic soil properties. Glyphosate [N-(phosphonomethyl) glycine] is the active ingredient in Roundup, which is the most used herbicide around the world. It is a non-selective herbicide with carboxyl, amino, and phosphonate functional groups, and it has a strong affinity to the soil mineral fraction. Sorption plays a major role for the fate and transport of glyphosate in the environment. The sorption coefficient (K d) of glyphosate, and hence its mobility, varies greatly among different soil types. Determining K d is laborious and requires the use of wet chemistry. In this study, we aimed to estimate K d using basic soil properties, and visible near-infrared spectroscopy (vis–NIRS). The latter method is fast, requires no chemicals, and several soil properties can be estimated from the same spectrum. The data set included 68 topsoil samples collected across the South Island of New Zealand, with clay and organic carbon (OC) contents ranging from 0.001 to 0.520 kg kg−1 and 0.021 to 0.217 kg kg−1, respectively. The K d was determined with batch equilibration sorption experiments and ranged from 13 to 3810 L kg−1. The visible near-infrared spectra were obtained from 400 to 2500 nm. Multiple linear regression was used to correlate K d to oxalate extractable aluminium and phosphorous and pH, which resulted in an R2 of 0.89 and an RMSE of 259.59 L kg−1. Further, interval partial least squares regression with ten-fold cross-validation was used to predict K d by vis–NIRS, and an R2 of 0.93 and an RMSECV of 207.58 L kg−1 were obtained. Thus, these results show that both basic soil properties and vis–NIRS can predict the variation in K d across these samples with high accuracy and hence, that glyphosate sorption to a soil can be determined with vis–NIRS. [ABSTRACT FROM AUTHOR]