Nicholas Holden

• BSc (Hons), MSc, MEngSc, PhD
• Professor at University College Dublin

A long grazing season improves the profitability of pasture-based dairy production. It can entail grazing under wet soil conditions and the risk of damaging swards. Housing cows either temporarily or completely while soil moisture is high can avoid damaging swards. An experiment with 4 grazing systems was conducted over 3 yr (Sep. 1, 2013, to Aug....

The variation in sorption and desorption of phosphorus (P) among soil types is not captured in current agronomic advice for agri-environmentally sustainable use of P. Phosphorus use is typically based on soil test P (STP) and soils are assumed to have the same rate of response to added P, regardless of sorption properties. The development of P sorp...

Phosphorus is a macro nutrient essential for optimum crop growth and animal health. The soil's ability to supply P in an available form is influenced by sorption capacity and P binding energies in soil. These properties are usually derived from sorption isotherms that are time consuming and difficult for routine analysis. Mid-infrared diffuse refle...

Field data collected at key maize crop growth stages from 10m x 10m GPS-mapped quadrates in 60 fields in Malawi. Field data and multispectral 0.8m resolution images from Maxar, providing 156 pixels per 10m x 10m quadrat, used to identify the crop reflectance that gives the strongest correlations with FAW damage and build a model from a propriety ve...

Visual soil evaluation (VSE) techniques, established in soil management and quality assessment are categorised into spade and profile methods. Both approaches have merits and limitations. For example, VESS, a widely used spade method, requires basic equipment and is quick, thereby enabling wide spatial deployment, but only gives a general indicatio...

Land degradation neutrality (LDN) was introduced to provide a policy framework to achieve Sustainable Development Goal (SDG) 15. Land use policy and management changes can alter the status of land-based natural capital, and exert an influence on ecosystem functioning and interactions with a socio-ecological system. Over the last 30 years, continued...

The environmental impact of dairy production in Ireland has been widely studied and it is known that regional differences in management and impact are driven by climate. Climate change projections for Ireland predict increasing temperature, change in rainfall patterns and decreasing in solar radiation, varying by agroclimatic region. This study eva...

Abolition of the milk quota in the European Union and favourable market conditions have stimulated the expansion of the dairy sector in Ireland, causing more milk to be produced from poorly drained land. This work evaluated the environmental impacts of alternative agricultural uses for poorly drained farm land in Ireland using life cycle assessment...

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 su...

Carbon storage in the soils on the Qinghai–Tibetan Plateau plays a very important role in the global carbon budget. In the 1990s, a policy of contracting collective grasslands to smaller units was implemented, resulting in a change from the traditional collective grassland management to two new management patterns: a multi-household management patt...

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 measu...

Agriculture is a critical sector of the EU economy, providing the food, feed, and bioresources that help sustain society. This sector in particular is at the centre of the challenges associated with population growth, food security, climate change and resource scarcity. In the last 50 years, agriculture has become more resource intensive, relyi...

Slurry spreading is a beneficial nutrient recycling activity on livestock farms, but nutrients may be lost to the environment. On-farm decision support based on the Hybrid Soil Moisture Deficit Model and weather data has the potential to forecast when conditions are best for slurry application. Such an approach will only be accepted by farmer?stake...

The implementation of site-specific land drainage system designs is usually disregarded by landowners in favour of locally established ‘standard practice’ land drainage designs. This is due to a number of factors such as a limited understanding of soil–water interactions, lack of facilities for the measurement of soil’s physical or hydrological par...

Topography has an influence on both abiotic (e.g. soil) and biotic (e.g. vegetation) factors influencing soil organic carbon (SOC). In this study, three slope aspects, south-facing, semi-sunny (southwest), and semi-shady (northwest) of mountainous grassland in the middle of the Qilian Mountains were sampled to explore the variation in SOC caused by...

Core Ideas Model ensemble, or model averaging, was used to combine vis‐NIR/MIR and pXRF model outcomes. Synergistic use of Vis‐NIR, MIR, and pXRF spectroscopy increased the number of well predicted elements. Synergistic use of Vis‐NIR, MIR, and pXRF spectroscopy improved the accuracy of predicted elements A combinatorial approach to spectral modeli...

The goal of this study was to assess the potential environmental impact of producing organic fertiliser by recycling organic materials via composting (compost) and pyrolysis (biochar), as well its combination (compost-biochar blend). Application of the processed residues to agricultural soils, including the end-of-life phase were taken into account...

The Heihe River Basin is a globally significant carbon pool, but its soil organic carbon dynamics is poorly understood. Soil samples taken between 2500 m and 4100 m revealed that the majority (>75%) of soil organic carbon was from 0-40 cm. It showed a negative relationship with pH and soil bulk density, and a positive relationship with altitude and...

The Hybrid Soil Moisture Deficit (HSMD) model has been used for a wide range of applications, including modelling of grassland productivity and utilisation, assessment of agricultural management opportunities such as slurry spreading, predicting nutrient emissions to the environment and risks of pathogen transfer to water. In the decade since its p...

This book with nine chapters describes the main methods for visual soil evaluation (VSE) of soil structure and soil-related properties. It includes clear visual images of the variation of soil quality and how these relate to soil productivity and environmental sustainability. Such images raise awareness and provide a measure of the soil degradation...

Ireland is obliged to achieve a 20% reduction in non-ETS greenhouse gas emissions(which include emissions from agriculture and transport) by 2020. Land-use change will be needed to reach this target, but other rural development targets must also be considered. Ideally, the integration between targets for land-use will be based on insights from R&D....

Soil quality (SQ) assessment has numerous applications for agricultural management. Conventional quantification of SQ is based on laboratory analysis and integrative indices that can be costly and time consuming to obtain. A rapid, quantitative method using soil spectra, following the successful process of soil characterization by visible (VIS)–nea...

Mechanistic understanding of scale effects is important for understanding the processes that control the global carbon cycle. Greater attention should be given to scale in soil organic carbon (SOC) science so that we can devise better policy to protect/enhance existing SOC stocks and ensure sustainable use of soils. Global issues such as climate ch...

There is uncertainty regarding the suitability of some soils for mole drainage. Soils with questionable potential for the formation of stable mole channels generally have <45% clay and >20% sand, and gravel mole drainage is an alternative. However, this technique is unattractive due to its relative cost (2014 price: €1500–2800 ha−1 versus €125–300...

Sustainable grassland management is critical to many agricultural economies because of the significant proportion of agricultural commodities derived from grass-fed livestock (milk and meat). Mismanagement will result in a cycle of soil quality deterioration and reduced productivity. This study estimated carbon (C) and nitrogen (N) stocks in relati...

Biochar added to soil can improve crop growth through both direct and indirect effects, particularly in acidic, highly weathered soils in subtropical and tropical regions. However, the mechanisms of biochar improving crop growth are not well understood. The objectives of this study were i) to determine the crop responses to biochar addition and ii)...

A robust, globally implementable and simple empirical model to predict the arsenic pollution affected life expectancy using a stepwise regression was developed. Life expectancy calculated using a life table technique requires crude death rates data that are not available for small administrative units, complex calculations and does not consider soc...

There is little empirical evidence to indicate that dairy cow live weight affects the extent of soil damage at the hoof-soil interface during grazing on poorly drained permanent grassland. In the present study the impact of Holstein-Friesian (HF) dairy cows with a mean (±standard deviation) live weight of 570 (±61) kg were compared with Jersey × Ho...

Objective The objectives of this study are to determine appropriate indicators, the most appropriate scoring function (linear or non-linear) and integrating procedure (additive and weighted additive) for a soil quality index for typical temperate, maritime grassland management (e.g. livestock grazing and silage production). Methods The study was c...

In this study satellite data from five different multispectral sensors were used in a change detection study of vegetation disturbance on an Irish active raised bog. Radiometric normalisation was performed using Temporally Invariant Clusters (TIC) and cross calibration applied using linear regression of radiometrically stable ground-based targets....

Application of visible (VIS) and near-infrared (NIR) spectroscopy for prediction of soil properties may offer a cost and time effective approach for evaluation of soil structural quality. Spectral data are often suitable for estimation of biochemical soil quality indicators such as soil organic carbon (SOC), total nitrogen and microbial biomass, wh...

The core concepts, or threads, of biosystems engineering (BSEN) are variously understood by those within the discipline but have never been unequivocally defined due to BSEN’s early stage of development. This makes communica-tion and teaching difficult compared to other well-established engineering disciplines. Biosystems engineering is a field of...

Many studies have considered spectroscopy for measurement of soil carbon (SC), and there is potential for spectroscopy to be used as a cost and time effective approach to assess soil quality (SQ). In this research, the relationship between SC and SQ in Irish grassland soils was studied; particularly the efficiency of spectroscopy and chemometric te...

Livestock products from grass contributed is an element of 24 billion to the Irish economy in 2011. Mismanagement due to pressure to intensify production results in soil quality deterioration and reduced productivity. This study assessed soil C content (0-10 cm) over a range of land use management from 20 arable crop farms and 20 grassland farms in...

The link between the small (<mm) scale spatial organisation of soil carbon (C) and the long-term security of the abiotic C store is poorly understood. The research presented here is the first step of a methodology that is being developed to map carbon concentration in an intact soil profile by adapting X-ray fluorescence (XRF) scanning for soils. T...

Twenty sites representing the typical range of grass-based beef and dairy production management intensity in Ireland were used to assess soil structural quality with the Visual Evaluation of Soil Structure (VESS) method combined with laboratory analysis. The results showed that VESS was suitable for assessing soil structural quality for grassland p...

Climate change and overgrazing are believed by policy makers to have been the drivers of grassland degradation in China over the past thirty years. However, recent work has suggested that policies that have led to privatization of use rights and household enclosures are more important drivers of degradation. An analysis of available evidence from s...

This study investigated the extent of soil damage caused by field traffic associated with different levels of soil moisture deficit (SMD). The hybrid SMD model was used for computing temporal patterns of SMD which can be accurately predicted for a range of soil types in Ireland. The aim of this study was to determine SMD threshold limits to traffic...

Northern peatlands have accumulated a carbon pool of approximately 455 to 547 GtC, and they can make significant contributions to national carbon fluxes. Ireland is an example of a northern latitude country where peatlands are of significance for carbon management. Peatlands in Ireland cover ~20 per cent of the Country and contain nearly two-thirds...

Conventional methods for assessing soil quality under different management practices require considerable time and knowledge. A visual method based on field assessment can provide a reliable, rapid evaluation of soil quality. The aim of this study was to use the visual evaluation of soil structure (VESS) method in arable soil in Ireland and to asse...

Rangeland degradation on the Qinghai–Tibetan Plateau is a growing concern, often attributed to climate change and overgrazing. A minority of researchers have suggested instead that degradation may be caused by changes in land management, particularly enclosures and the contracting of long-term rangeland use rights to households. However, these clai...

Agricultural specialists, particularly animal scientists, tend to use process-based life-cycle assessments (LCA), which describe the production system as a series of processes, to study the environmental impact of milk production based on their experimental data. Another approach called input–output (I–O) based LCA, which uses the economic transact...

Nutrient loss from agricultural land following organic fertilizer spreading can lead to eutrophication and poor water quality. The risk of pollution is partly related to the soil water status during and after spreading. In response to these issues, a decision support system (DSS) for nutrient management has been developed to predict when soil and w...

The application of slurry nutrients to land can be associated with unintended losses to the environment depending on soil and weather conditions. Correct timing of slurry application, however, can increase plant nutrient uptake and reduce losses. A decision support system (DSS), which predicts optimum conditions for slurry spreading based on the Hy...

Nitrous oxide (N2O) emission from grassland-based agriculture is an important source of atmospheric N2O. It is hence crucial to explore various solutions including farm nitrogen (N) management to mitigate N2O emissions without sacrificing farm profitability and food supply. This paper reviews major N management practices to lower N2O emission from...

The EU FOCUS scenarios are a set of nine standard scenarios based on a combination of crop, soil and weather data used throughout Europe to evaluate the leaching potential of pesticides to groundwater. In Ireland, two predefined EU FOCUS scenarios (Okehampton and Hamburg) appear to be the most appropriate to Irish conditions. However, there is conc...

Little consideration has been given to how farm management, specifically tactics used to implement the management strategy, may influence the carbon footprint (CF) and land use for milk produced on commercial farms. In this study, the CF and land use of milk production from 18 Irish commercial dairy farms were analyzed based on foreground data from...

Radiometric normalization is a vital stage in any change detection study due to the complex interactions of radiance and irradiance between the Earth's surface and atmosphere. Compensation for variables such as sun's angle, surface profile, atmospheric conditions, and sensor calibration coefficients are essential in achieving a radiometrically stab...

Compaction is regarded as one of the main causes of degradation of agricultural soils (Håkansson, 1986). The vulnerability of a soil to compaction depends on the soil moisture content (Earl, 1996). The aim of this study was to investigate the use of the hybrid soil moisture deficit (SMD) model (Schulte et al., 2005) as a proxy for volumetric soil w...

The Hybrid Soil Moisture Deficit (SMD) model predicts soil water status relative to field-capacity and can be calculated directly as a soil water mass balance for three drainage classes (well-drained, moderately drained and poorly drained). For the Hybrid SMD model to be deployed, grassland fields must be assigned to the correct drainage class. A s...

The aim of this study was to quantify the adsorption-desorption isotherms of (4 –chloro-2-methylophenoxy) acetic acid (MCPA) in selected Irish grassland soils, and to assess its mobility potential to groundwater. The sorption isotherms were determined using a batch equilibrium method and were very well described by the linear and the Freundlich equ...

The transport of pesticides through the soil is one of many processes controlling their final distribution in the environment. The presence of pesticides in soil, groundwater, surface water and air may cause considerable adverse effects on ecosystems and human health. Human health may be affected by pesticide residues in food and drinking water, wh...

Carbon footprint (CF) calculated by life cycle assessment (LCA) was used to compare greenhouse gas emissions from pasture-based milk production relying mainly on (1) fertilizer N (FN), or (2) white clover (WC). Data were sourced from studies conducted at Solohead Research Farm in Ireland between 2001 and 2006. Ten FN pastures stocked between 2.0 an...

The adsorption and desorption behaviour of two phenoxyalkanoic acid herbicides (MCPA and mecoprop-p) in a Haplic Cambisol with tillage and grassland management was examined using a batch equilibrium method. Additionally, the effect on adsorption of the simultaneous presence of the two herbicides was also studied. The sorption equilibrium was reache...

A batch equilibrium experiment was conducted to determine the adsorption and desorption isotherms of chlorothalonil for a range of agricultural soils in Ireland. The sorption isotherms in tillage soils were described by the Freundlich model in a nonlinear form while in the grassland soil, the adsorption was almost linear. The experimental sorption...

In grassland areas subject to degradation caused by overgrazing such as the Maqu grasslands, excess livestock could be removed in order to balance available forage and animal numbers. As the number of animals owned by a herder family represents wealth, income, lifestyle, and culture, reducing livestock numbers is problematic and some form of compen...

Soil compaction impairs soil performance by increasing its resistance to penetration, and by reducing fertiliser use efficiency and water infiltration. Moisture content is the main factor that determines the strength of the soil, and therefore it’s resistance to compaction. The purpose of this study was to examine the potential of a soil moisture d...

Soil compaction negatively affects soil productivity, fertiliser use efficiency and water infiltration. Due to the large weights involved vehicle traffic has the potential to cause substantial compaction of the soil. The extent of compaction is dependant on the strength of the soil, which is influenced by the soil moisture content. The purpose of t...

The objective of this research was to develop a hyperspectral imaging system for estimating copper concentration in soils as an alternative to standard chemical analyses and to evaluate the analytical accuracy of the system using the visible–near-infrared and near-infrared regions. Hyperspectral imaging is a complex technology providing elevated in...

Eutrophication of both fresh and coastal water bodies is one of the greatest threats to water quality in Europe and other developed countries. Sources of pollution are multiple but agriculture is known to be a large contributor, due to farm nutrient management such as land spreading of fertilisers and their subsequent loss via overland flow to surf...

Adequately quantifying C sequestration in soil, post 2012, can be used to offset C losses in national greenhouse gas inventory but requires very large sample numbers and rapid analytical methods. Wet and dry combustion methods are analytically accurate but expensive and slow while optical techniques have the potential to provide rapid, cost-effecti...

Soil compaction is a serious threat to the productivity of agricultural enterprises. While the increased size of farm vehicles has led to greater pressures exerted upon agricultural soils, it is the soil moisture content at the time of trafficking which remains the most significant determinant of the extent of deformation incurred. The purpose of t...

The digenean trematode Alaria alata, an intestinal parasite of wild canids is widely distributed in Europe. The recent finding of the mesocercarial life cycle stage in the paratenic wild boar host suggests that it may potentially infect humans Mohl et al. (Parasitol Res 105:1-15, 2009). Over 500 foxes were examined during a wildlife survey for zoon...

Dye and bromide tracers are established methods of assessing the presence, function, and extent of hydrological pathways in soil. Prediction of E. coli transport pathways in soil, using brilliant blue (BB) dye and bromide tracers, was investigated using in situ field trials on three grassland soil types, under different moisture regimes. Passive tr...

Preferential flow is a well recognized mechanism for the accelerated leaching of nutrients and pollutants through soil, contributing to the contamination of surface-and groundwater bodies. This study assessed the risks associated with slurry spreading and the potential effects of preferential flow, under natural rainfall, on four soil types with co...

Preferential flow is a well recognized mechanism for the accelerated leaching of nutrients and pollutants through soil, contributing to the contamination of surface and groundwater bodies. This study assessed the risks associated with slurry spreading and the potential effects of preferential flow, under natural rainfall, on four soil types with co...

The Sustainable Nutrient Management Decision Support System (SNM-DSS) has been developed to provide farmers with advise on minimising Nitrogen and Phosphorous loss from land spread organic and mineral fertilisers. Within the SNM-DSS, the Hybrid Soil Moisture Deficit (SMD) model (Schulte et al., 2005) is used to assess when slurry spreading is ‘safe...

In 2009 the project “Transatlantic Biosystems Engineering Curriculum and Mobility (TABE.NET)” was funded by the EU-US Atlantis programme with four European partners and two US partners. One of the key objectives of TABE.NET is to advance internationalization of Biosystems Engineering curricula and to develop a global awareness within the discipline...

The core concepts, or threads, of biosystems engineering (BSEN) are variously understood by those within the discipline but have never been unequivocally defined due to BSEN's early stage of development. This makes communication and teaching difficult compared to other well-established engineering disciplines. Biosystems engineering is a field of e...

In this study satellite data from five different multispectral sensors were used in a change detection study of vegetation disturbance on an Irish active raised bog. Radiometric normalisation was performed using Temporally Invariant Clusters (TIC) and cross calibration applied using linear regression of radiometrically stable ground-based targets....

Peatlands contain large amounts of soil organic carbon. In a pristine state they sequester atmospheric carbon dioxide (CO2), however, when they are disturbed they emit it. In Ireland peatlands are extensive and cover 20% of the national land area. They contain between 53% and 62% of the total national soil organic carbon. However, large areas of Ir...

In Maqu County, Gansu Province, China, there are two types of grazing management. Under multi-household (MH) management, grassland is jointly managed by two or more households without fences between pastures. Under single-household (SH) management, fenced-off parcels of grassland are used. SH management was imposed in the belief that it would allev...

At the global scale peatlands are an important soil organic carbon (SOC) pool. They sequester, store and emit carbon dioxide and methane and have a large carbon content per unit area. In Ireland, peatlands cover between 17% and 20% of the land area and contain a significant, but poorly quantified amount of SOC. Peatlands may function as a persisten...

Hyperspectral imaging is an attractive technique for soil analysis that provides both spectral and spatial information in a three-dimensional image. Scanning a larger sample area than that permitted in soil spectroscopy allows a larger spatial area to be selected to represent the "average spectra" by means of an interactive region of interest (ROI)...

Cryptosporidium is an environmentally robust pathogen that has caused severe waterborne disease outbreaks worldwide. The main source of zoonotic Cryptosporidium parvum oocysts in human drinking water is likely to be from farm animals via catchment pathways with water as the main transport vector. The vast majority of small agricultural catchments a...

Irish peat soils are extensive, covering approximately 14–20% of the national land area. They contain between 53% and 62% of the national soil organic carbon stock. Montane blanket bog covers approximately 25% or 242 650 ha of the total peatland area in Ireland and is the dominant peatland type covering the upland area of Wicklow. Blanket bogs are...

Soil organic carbon (SOC) is frequently determined by the Walkley-Black (WB) method. A limitation of the test is incomplete oxidation of the carbon fraction and underestimation of SOC. Automated dry combustion methods are expensive and slow. Optical sensing and chemometric analysis offer the potential of an economical method capable of quantifying...

A potentially significant cause of damage to grassland soils is compaction of unsaturated soil and poaching of saturated or nearly saturated soil by animal hooves. Damage is caused when an applied stress is in excess of the bearing strength of the soil and results in a loss of soil structure, macroporosity and air or water conductivity. Severely da...

Raised bogs in the Irish Midlands are spatially extensive and disturbed. Peatland disturbance is relatively easy to identify on the ground, but it is difficult to quantify and more difficult to systematise a method of isolating where disturbance has occurred. The extent of raised bogs was delineated from the Derived Irish Peat Map version 2. An obj...

The effect of treading by dairy cows of three different weights on soil physical properties was investigated under different soil moisture deficit (SMD) treatments in the south of Ireland. SMD was used as a readily predicable surrogate for volumetric water content. Animal treading in grassland ecosystems is known to affect soil and vegetation prope...