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The quality of a soil is its ability to deliver functions providing ecosystem services, human health and well-being. Soil physical quality (SPQ) values use different parts of the soil water retention curve (SWRC) to calculate SPQ. For example, the plant available water capacity (PAWC) method is the difference in water content between permanent wilting point and field capacity. The S-index uses the slope of the SWRC at its inflection point and the relative air-water energy (AWr) is the integral of "dry" divided by the "wet" area of the SWRC. Increasing demand for soil monitoring policies calls for reliable and sensitive soil quality indicators (SQIs). The objectives of the study were to assess the sensitivity and applicability of SPQ indicators using direct and indirect data inputs. The indirect approach provided sufficient data complexity for the PAWC and S-index values, but the more complex AWr required the direct approach. PAWC and S-index values were identified as static SPQ indicators. The values obtained from these approaches should be used to form baseline static datasets and therefore have an indicative role only. The AW value was identified as a dynamic SPQ indicator and provided required sensitivity to pick up temporal changes in SPQ. This indicator could be used at multiple scales and could even guide grassland management in terms of SPQ. Higher SWRC data resolution will require more complex hydraulic models to fit and will ultimately improve the accuracy of soil hydraulic data and improve the sensitivity of AWr as a SPQ indicator. [ABSTRACT FROM AUTHOR]

Abstract: Visual evaluation of soil structure (VESS) is used for assessing arable management impact on soil quality. When used on pastures, operators have identified limitations because VESS does not consider a surface root‐mat typical of managed grassland. The structure of the root‐mat may be indicative of nutrient use efficiency, pollution potential and subsurface compaction. The objectives of this research were to develop GrassVESS for grassland soil management, to compare it with VESS and quantitative physical indicators and to assess its utility for soil management. GrassVESS maintained the methodological strengths of VESS, but uses a flow chart, grassland images and a new root‐mat score. A focus group found GrassVESS to be quicker, dealt better with technical information and made root‐mat evaluation easier. The range of structural quality scores assigned by the focus group for a site was less for GrassVESS than VESS, suggesting the procedure is more reproducible, thus suitable for use by a range of stakeholders. GrassVESS was also deployed at 30 grassland sites across Ireland. Results indicated that GrassVESS generated the same overall diagnoses as VESS, but the GrassVESS root‐mat structural quality score was better related to bulk density, total porosity at 5–10 cm and a visual estimation of damaged sward area. It was concluded that GrassVESS has improved the VESS method for the specific assessment of grassland soil structural quality and could be used in real‐time farm management decision support. [ABSTRACT FROM AUTHOR]

Abstract: Cost‐effective strategies for using chemically amended organic fertilizers need to be developed to minimize nutrient losses in surface and groundwater. Coupling specific soil physical and chemical characteristics with amendment type could increase their effectiveness. This study investigated how water‐extractable phosphorus (P) was affected by chemical amendments added to pig slurry and how this effect varied with soil properties. A 3‐month incubation study was conducted on 18 different mineral soils, stored at 10 °C and 75% humidity and treated with unamended and amended slurry which was incorporated at a rate equivalent to 19 kg total P (TP)/ha. The amendments examined were commercial‐grade liquid alum, applied at a rate of 0.88:1 [Al:TP], and commercial‐grade liquid poly‐aluminium chloride (PAC), applied at a rate of 0.72:1 [Al:TP]. These amendments were previously identified by the authors as being effective in reducing incidental losses of P. The efficacy of the amendments varied with the soil test P, the degree of P saturation (DPS) and the Mehlich aluminium, iron and calcium, but not soil texture. Chemical amendments were most effective in soils with DPS over approximately 20%. Due to their high cost, the incorporation of amendments into existing management practices can only be justified as part of a holistic management plan where soils have high DPS. [ABSTRACT FROM AUTHOR]

Soil structure forms a key component of soil quality, and its assessment by semi-quantitative visual soil evaluation ( VSE) techniques can help scientists, advisors and farmers make decisions regarding sampling and soil management. VSE techniques require inexpensive equipment and generate immediate results that correlate well with quantitative measurements of physical and biochemical properties, highlighting their potential utility. We reviewed published VSE techniques and found that soils of certain textures present problems and a lack of research into the influence of soil moisture content on VSE criteria. Generally, profile methods evaluate process interactions at specific locations within a field, exploring both intrinsic aspects and anthropogenic impacts. Spade methods focus on anthropogenic characteristics, providing rapid synopses of soil structure over wider areas. Despite a focus on structural form, some methods include criteria related to stability and resiliency. Further work is needed to improve existing methods regarding texture influences, on-farm sampling procedures and more holistic assessments of soil structure. [ABSTRACT FROM AUTHOR]

Carbon (C) losses from agricultural soils to surface waters can migrate through water treatment plants and result in the formation of disinfection by-products, which are potentially harmful to human health. This study aimed to quantify total organic carbon (TOC) and total inorganic C losses in runoff after application of dairy slurry, pig slurry, or milk house wash water (MWW) to land and to mitigate these losses through coamendment of the slurries with zeolite (2.36-3.35 mm clinoptilolite) and liquid polyaluminum chloride (PAC) (10% Al2O3) for dairy and pig slurries or liquid aluminum sulfate (alum) (8% Al2O3) for MWW. Four treatments under repeated 30-min simulated rainfall events (9.6 mm h-1) were examined in a laboratory study using grassed soil runoff boxes (0.225 m wide, 1 m long; 10% slope): control soil, unamended slurries, PAC-amended dairy and pig slurries (13.3 and 11.7 kg t-1, respectively), alum-amended MWW (3.2 kg t-1), combined zeolite and PAC-amended dairy (160 and 13.3 kg t-1 zeolite and PAC, respectively) and pig slurries (158 and 11.7 kg t-1 zeolite and PAC, respectively), and combined zeolite and alumamended MWW (72 and 3.2 kg t-1 zeolite and alum, respectively). The unamended and amended slurries were applied at net rates of 31, 34, and 50 t ha-1 for pig and dairy slurries and MWW, respectively. Significant reductions of TOC in runoff compared with unamended slurries were measured for PACamended dairy and pig slurries (52 and 56%, respectively) but not for alum-amended MWW. Dual zeolite and alum-amended MWW significantly reduced TOC in runoff compared with alum amendment only. We conclude that use of PAC-amended dairy and pig slurries and dual zeolite and alum-amended MWW, although effective, may not be economically viable to reduce TOC losses from organic slurries given the relatively low amounts of TOC measured in runoff from unamended slurries compared with the amounts applied. [ABSTRACT FROM AUTHOR]

Diffuse pollutant losses containing phosphorus (P), nitrogen (N), and suspended solids (SS) can occur when agricultural wastes are applied to soil. This study aimed to mitigate P, N, and SS losses in runoff from grassed soils, onto which three types of agricultural wastes (dairy slurry, pig slurry, and dairy-soiled water [DSW]), were applied by combining amendments of either zeolite and polyaluminum chloride (PAC) with dairy and pig slurries or zeolite and alum with DSW. Four treatments were investigated in rainfall simulation studies: (i) control soil, (ii) agricultural wastes, (iii) dairy and pig slurries amended with PAC and DSW amended with alum, and (iv) dairy and pig slurries amended with zeolite and PAC and DSW amended with zeolite and alum. Our data showed that combined amendments of zeolite and PAC applied to dairy and pig slurries reduced total P (TP) in runoff by 87 and 81%, respectively, compared with unamended slurries. A combined amendment of zeolite and alum applied to DSW reduced TP in runoff by 50% compared with unamended DSW. The corresponding reductions in total N (TN) were 56% for dairy slurry and 45% for both pig slurry and DSW. Use of combined amendments reduced SS in runoff by 73 and 44% for dairy and pig slurries and 25% for DSW compared with unamended controls, but these results were not significantly different from those using chemical amendments only. The findings of this study are that combined amendments of zeolite and either PAC or alum reduce TP and TN losses in runoff to a greater extent than the use of single PAC or alum amendments and are most effective when used with dairy slurry and pig slurry but less effective when used with DSW. [ABSTRACT FROM AUTHOR]

The article presents a study on the comparison of the nutrient and sediment releases of five Irish tillage soils. It says that phosphorus loss is an important pathway in agro-environments in which dissolved reactive phosphorus (DRP) is available for biological uptake that poses threat for algal growth. The study was made for the quantification of DRP, particulate phosphorus (PP), and total phosphorus (TP) released in surface runoff which account for fertilizer usage of tillage crops. An analysis of the soil test phosphorus (STP) of Irish tillage soils through the relationship of STP and DTP is made. The results indicate the possibility of producing surface runoff phosphorus concentration by tillage soils.

The article discusses the potential for ochre to sequester phosphorus in an environmentally sustainable fashion. Ochre deriving from coal mine drainage sites in the United Kingdom displays a high phosphorus retention capacity without highly mobilizing metals, indicating that it can potentially adsorb phosphorus from agricultural wastewaters and be used as a fertilizer. A study focused upon untreated acid mine drainage from an abandoned copper-sulfur mine in a catchment of southeast Ireland. Ochre was mixed with phosphorus-amended water in batch experiments and a maximum adsorption capacity was calculated from the Langmuir equation.

This study examined the quantity of mineral N in soil and nitrate-N losses to groundwater from grassland-based dairy production in 2001 and 2002. There were four treatments with different inputs of N, through fertilizers, concentrates and biological fixation, and four associated stocking densities. Nitrogen inputs were 205, 230, 300 and 400 kg ha−1, respectively, and annual stocking densities were 1·75, 2·10, 2·50 and 2·50 cows ha−1. There were 18 cows per treatment. Grazed herbage accounted for 0·64, grass-silage for 0·26 and concentrates 0·10 of annual DM consumed by the cows. Quantities of mineral N (nitrate-N and ammonium-N) in soil were measured, following extraction in 2 M KCl (1:2 w/v) shaken continuously for 2 h, on three occasions between late September and early February each winter. Concentrations of nitrate-N in groundwater from wells inserted vertically to a depth of 1 m were determined throughout both winters. Quantities of mineral N in the soil increased ( P < 0·001) with higher N inputs and declined ( P < 0·001) with later sampling date. There were no relationships between nitrate-N concentrations in groundwater and N inputs, N surpluses, deposition of excreta-N at the soil surface and soil mineral N during both winters. Low losses of nitrate-N to groundwater were primarily attributed to high rates of denitrification associated with a heavy soil texture, wet anaerobic soil conditions, relatively high organic carbon contents throughout the soil profile and mild soil temperatures throughout the year. Uptake of N by herbage made an important contribution to low N losses over the winter. [ABSTRACT FROM AUTHOR]