CERES :: Browsing by Author "Hannam, Jacqueline A."

Browsing by Author "Hannam, Jacqueline A."

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Open Access
Agricultural decision-making under uncertainty: a loss function on the kriging variance from soil properties predicted by infrared and X-ray fluorescence spectroscopy
(EGU: European Geophysical Union, 2021-04-30) Breure, Timo Samuel; Haefele, Stephan M.; Webster, Richard; Hannam, Jacqueline A.; Corstanje, Ronald; Milne, Alice E.
Open Access
The application of digital soil mapping to improve the resolution of national soil properties across Great Britain.
(Cranfield University, 2018-10) Campbell, Grant; Corstanje, Ronald; Hannam, Jacqueline A.; Black, H. I. J.; Lilly, A.
Many countries have created soil maps to illustrate the variety of soil properties and support how soils can be used. Traditional soil mapping by field survey and interpretation has been the most recognised form of soil mapping for many years and an effective way to capture a variable soil landscape. Such maps have enabled scientists and stakeholders to improve their understanding of relationships between soils and other landscape factors such as geology and land cover. However, with the amount of soil information growing and technology improving, Digital Soil Mapping (DSM) has been developed as an alternative approach to generate soil property predictions and to produce finer resolution soils data. Currently, DSM produces maps based on training of models with observed soils data and environmental covariates and then releases these to stakeholders to evaluate their utility. This PhD has taken a different approach by addressing stakeholder needs at the beginning of the process. The overall aim of this PhD was to improve the spatial resolution of soil properties across Great Britain (GB), as informed by stakeholders. Three main aims were identified. The first assessed what current soils data and information stakeholders currently use, and what improvements they want to see from future soil-related products. The second aim, using information from the questionnaire survey and a comparison of laboratory and analytical methods, is to develop DSM which could be applied across the whole of GB. This was done by comparing two modelling approaches: Boosted Regression Trees (BRTs) and Multivariate Adaptive Regression Splines (MARS) for mapping soil properties (loss-on-ignition, texture and pH) across two pilot areas. The characteristics of MARS and BRT models at both training and deployment stages are examined. The third outcome investigated how well the soil properties mapped across GB, building on the development of DSM in the pilot areas and whether they reflect expert pedological knowledge. This section also focusses on how suitable an independent validation dataset is at evaluating soil property predictions. This PhD has shown that stakeholders are aware of what soils data and information they are using and could clearly express what is needed to improve current maps. Wider use of soil information by non-soil experts would be improved by increasing data accessibility and user- friendly supporting materials. Fundamentally, most stakeholders require finer resolution than what is currently available which identifies an opportunity for DSM to fill some of this gap. To address these gaps and develop DSM across GB, this PhD focussed on mapping soil properties that were directly comparable across Scotland and England & Wales and also key to many stakeholder information needs. After investigation of laboratory and analytical methods from the two national soil surveys of Scotland and England & Wales, soil loss on ignition, soil texture and soil pH were chosen for developing DSM for GB. From the development of DSM, results showed that MARS models produced better statistical performances than BRTs for predicting soil properties within a training environment. However, when MARS models are deployed to larger areas, they extrapolate beyond their means and BRTs performed better. This is because MARS models perform more consistently when many variables are required. Furthermore, MARS models struggle with overfitting and missing data which subsequently leads to incorrect and unfeasible pedological relationships between soil properties. BRT models, despite not performing as well statistically, produce more consistent relationships between pedology and mapped soil properties. This is because BRT models introduce randomness in the boosting which reduces overfitting and improves the predictive performance. BRTs have shown to be more consistent in the mapping outputs than MARS because regressing to the mean is more favourable when most data matches up with one another. However, this does not necessarily mean that the full range of soils in these areas were being captured by the BRT model. This led to scaling up from the pilot areas to modelling soil properties across GB using a single regional BRT model and evaluating its performance. BRT modelling results for GB at 2D and 3D predict well for pH and LOI but less so for texture. Going forward, more data are required to produce more consistent modelling outputs especially for areas across GB where soil properties are not currently being predicted well. The GB modelling results also highlighted a poor performance of the model against an independent validation dataset. This is because the original data for both GB training and validation datasets were analysed and collected for different purposes. These datasets were taken at different time periods under a different sampling design. Furthermore, the data for both training and validation GB datasets were collected at different scales. At present, these first versions of soil property DSM maps for GB have produced variable results. However, this exercise has shown that the development of reliable DSM maps would benefit from interaction between pedologists, modellers and stakeholders to ensure that mapped outputs are of sufficient quality at adequate finer resolution and can be usable. Such DSM maps, alongside management recommendations, will help to address many global challenges associated to soils. However, DSM is not the panacea for all mapping needs. Until such time that DSM fully develops into DSA and adequately incorporates the breadth of information available in traditional soil maps, mapping from field survey and observation will continue to be necessary for stakeholders.
Open Access
BEETSOIL: a decision support tool for forecasting the impact of soil conditions on sugar beet harvest
(Elsevier, 2019-04-09) Gabarron Galeote, Miguel; Hannam, Jacqueline A.
Sugar beet in the UK is harvested in autumn and winter, when soil moisture is usually close to field capacity. This, together with the heavy machinery used can lead to serious environmental problems such as topsoil disturbance, subsoil compaction and soil erosion. BEETSOIL is a decision support tool (DST) developed to help plan the sugar beet harvest campaign by assessing if soil conditions are suitable for harvest whilst minimising the occurrence of soil damage. The core of BEETSOIL is a soil water balance model that, using a rainfall source selected by the user, predicts soil water content in a determined prediction window. The resulting soil water content is used to predict soil trafficability, wheel sinkage, soil stickiness and soil loss due to harvest on a daily basis. The soil water balance module was validated with measured soil water content at three field sites with contrasting clayey, silty and sandy textures and showed RMSE of 0.91%, 0.96% and 0.52%, respectively. The sensitivity of the trafficability modules of BEETSOIL were tested using several scenarios using different initial soil water contents at the start of the harvest campaign combined with rainfall amounts that simulate wet, median and dry conditions during the harvest period. Analysis of the scenarios showed the trafficability module was very sensitive to changes in texture, initial soil water content of the simulation and rainfall. This information can be used to assess the suitability of new sugar beet growing areas, where the proportion of time during which fields can be trafficked by vehicles (harvested effectively) can be predicted under different scenarios and therefore give an indication of any consistent harvest difficulties. The model outputs of sinkage, trafficability and soil loss by harvest have yet to be validated, but the first outputs provide indications of how the DST can be used across the whole growing area to schedule harvest operations to target areas that can be harvested most effectively.
Open Access
Comparing the effect of different sample conditions and spectral libraries on the prediction accuracy of soil properties from near- and mid-infrared spectra at the field-scale
(Elsevier, 2021-10-07) Breure, Timo Samuel; Prout, Jonah M.; Haefele, Stephan M.; Milne, Alice E.; Hannam, Jacqueline A.; Moreno-Rojas, S.; Corstanje, Ronald
The prediction accuracy of soil properties by proximal soil sensing has made their application more practical. However, in order to gain sufficient accuracy, samples are typically air-dried and milled before spectral measurements are made. Calibration of the spectra is usually achieved by making wet chemistry measurements on a subset of the field samples and local regression models fitted to aid subsequent prediction. Both sample handling and wet chemistry can be labour and resource intensive. This study aims to quantify the uncertainty associated with soil property estimates from different methods to reduce effort of field-scale calibrations of soil spectra. We consider two approaches to reduce these expenses for predictions made from visible-near-infrared ((V)NIR), mid-infrared (MIR) spectra and their combination. First, we considered reducing the level of processing of the samples by comparing the effect of different sample conditions (in-situ, unprocessed, air-dried and milled). Second, we explored the use of existing spectral libraries to inform calibrations (based on milled samples from the UK National Soil Inventory) with and without ‘spiking’ the spectral libraries with a small subset of samples from the study fields. Prediction accuracy of soil organic carbon, pH, clay, available P and K for each of these approaches was evaluated on samples from agricultural fields in the UK. Available P and K could only be moderately predicted with the field-scale dataset where samples were milled. Therefore this study found no evidence to suggest that there is scope to reduce costs associated with sample processing or field-scale calibration for available P and K. However, the results showed that there is potential to reduce time and cost implications of using (V)NIR and MIR spectra to predict soil organic carbon, clay and pH. Compared to field-scale calibrations from milled samples, we found that reduced sample processing lowered the ratio of performance to inter-quartile range (RPIQ) between 0% and 76%. The use of spectral libraries reduced the RPIQ of predictions relative to field-scale calibrations from milled samples between 54% and 82% and the RPIQ was reduced between 29% and 70% for predictions when spectral libraries were spiked. The increase in uncertainty was specific to the combination of soil property and sensor analysed. We conclude that there is always a trade-off between prediction accuracy and the costs associated with soil sampling, sample processing and wet chemical analysis. Therefore the relative merits of each approach will depend on the specific case in question.
Open Access
Controlling factors for the spatial variability of soil magnetic susceptibility across England and Wales
(Elsevier Science B.V., Amsterdam., 2009-08-01T00:00:00Z) Blundell, A.; Dearing, J. A.; Boyle, J. F.; Hannam, Jacqueline A.
We review the nature and importance of soil factors implicated in the formation of secondary ferrimagnetic minerals in soils and palaeosols worldwide. The findings are examined with respect to temperate regions through a comprehensive analysis of over 5000 samples of surface soil from England and Wales taken from a 5 × 5 km grid. Over 30 soil and environmental attributes are considered for each sample as proxies for soil forming factors. Measurements of low field magnetic susceptibility (mass specific) and frequency dependent susceptibility (mass specific and percentage) on each sample provide estimates of the concentration and grain size of ferrimagnetic minerals. Maps of soil magnetism across England and Wales show non-random distributions and clusters. One subset of data is clearly linked to contamination from atmospheric pollution, and excluded from subsequent analyses. The concentration of ferrimagnetic minerals in the non-polluted set is broadly proportional to the concentration of minerals falling into the viscous superparamagnetic domain size range (~ 15–25 nm). This set shows clusters of high magnetic concentrations particularly over specific parent materials such as schists and slates, mudstones and limeston
Open Access
Developments in land information systems: examples demonstrating land resource management capabilities and options
(Wiley, 2017-10-17) Hallett, Stephen H.; Sakrabani, Ruben; Keay, Caroline; Hannam, Jacqueline A.
Land Information Systems (LIS) provide a foundation for supporting decision-making across a broad spectrum of natural resource applications: agronomic, environmental, engineering and public good. Typically, LIS constitute a computerized database repository holding geospatial components, ‘mapping unit’ geometry and related georeferenced materials such as satellite imagery, meteorological observations and predictions and scanned legacy mapping. Coupled with the geospatial data are associated property, semantic and metadata, representing a range of thematic properties and characteristics of the land and environment. This paper provides examples of recent developments of national and regional LIS, presenting applications for land resource capabilities and management. These focus on the ‘Land Information System’ (LandIS) for England and Wales, and the ‘World Soil Survey Archive and Catalogue’ (WOSSAC) and consider Agricultural Land Classification in Wales, an Irish land and soil information system, and a scheme to optimize land suitability for application of palm oil biofertilizers in Malaysia. Land Information Systems support purposeful environmental interpretations, drawing on soil and related thematic data, offering insight into land properties, capabilities and characteristics. The examples highlight the practical transferability and extensibility of technical and methodological approaches across geographical contexts. This assessment identifies the value of legacy-based natural resource inventories that can be interoperated with other contemporary sources of information, such as satellite imagery.
Open Access
Digital mapping of GlobalSoilMap soil properties at a broad scale: a review
(Elsevier, 2021-11-30) Chen, Songchao; Arrouays, Dominique; Mulder, Vera Leatitia; Poggio, Laura; Minasny, Budiman; Roudier, Pierre; Libohova, Zamir; Lagacherie, Philippe; Shi, Zhou; Hannam, Jacqueline A.; Meersmans, Jeroen; Richer-de-Forges, Anne C.; Walter, Christian
Soils are essential for supporting food production and providing ecosystem services but are under pressure due to population growth, higher food demand, and land use competition. Because of the effort to ensure the sustainable use of soil resources, demand for current, updatable soil information capable of supporting decisions across scales is increasing. Digital soil mapping (DSM) addresses the drawbacks of conventional soil mapping and has been increasingly used for delivering soil information in a time- and cost-efficient manner with higher spatial resolution, better map accuracy, and quantified uncertainty estimates. We reviewed 244 articles published between January 2003 and July 2021 and then summarised the progress in broad-scale (spatial extent >10,000 km2) DSM, focusing on the 12 mandatory soil properties for GlobalSoilMap. We observed that DSM publications continued to increase exponentially; however, the majority (74.6%) focused on applications rather than methodology development. China, France, Australia, and the United States were the most active countries, and Africa and South America lacked country-based DSM products. Approximately 78% of articles focused on mapping soil organic matter/carbon content and soil organic carbon stocks because of their significant role in food security and climate regulation. Half the articles focused on soil information in topsoil only (<30 cm), and studies on deep soil (100–200 cm) were less represented (21.7%). Relief, organisms, and climate were the three most frequently used environmental covariates in DSM. Nonlinear models (i.e. machine learning) have been increasingly used in DSM for their capacity to manage complex interactions between soil information and environmental covariates. Soil pH was the best predicted soil property (average R2 of 0.60, 0.63, and 0.56 at 0–30, 30–100, and 100–200 cm). Other relatively well-predicted soil properties were clay, silt, sand, soil organic carbon (SOC), soil organic matter (SOM), SOC stocks, and bulk density, and coarse fragments and soil depth were poorly predicted (R2 < 0.28). In addition, decreasing model performance with deeper depth intervals was found for most soil properties. Further research should pursue rescuing legacy data, sampling new data guided by well-designed sampling schemas, collecting representative environmental covariates, improving the performance and interpretability of advanced spatial predictive models, relating performance indicators such as accuracy and precision to cost-benefit and risk assessment analysis for improving decision support; moving from static DSM to dynamic DSM; and providing high-quality, fine-resolution digital soil maps to address global challenges related to soil resources.
Open Access
Do cover crops give short term benefits for soil health?
(Association of Applied Biologists, 2018-12-31) Storr, Tom; Simmons, Robert W.; Hannam, Jacqueline A.
Cover crop use in the UK is increasing with establishment often before spring cereal crops. Therefore trials were implemented to assess two different cover crop mixtures for i) their ability to remediate soil compaction, ii) aid water management and iii) increase earthworm numbers. Two cover crop mixtures; frost sensitive (black oats, oil radish and mustard) and winter hardy (forage rye, oil radish and berseem clover) were compared to control plots. This replicated trial was based at G’s Growers on an organo-mineral soil with a cover crop sown between wheat harvested in August 2016 and maize sown in May 2017. The results suggest that in the short term there are small differences in soil physical characteristics. Notably at a depth of 10–20 cm there is a reduction in soil strength as measured by the penetrologger and shear vane following the frost sensitive cover crop mix. Juvenile earthworm population was significantly greater in the control treatment compared to the frost sensitive cover crop treatment. In May 2017 maize was established across all plots.
Open Access
The effect of cover crops on soil quality indicators in a cereal and salad rotation.
(2019-01) Storr, Tom; Hannam, Jacqueline A.; Simmons, Robert W.
Cover crop (CC)s influence soil function and thus affect crop yield and ecosystem services provided by soil. CCs are a relatively new soil management practice in U.K. agriculture, but are gaining in popularity amongst farmers. However, research on the effect of CCs on soil function in the short term and how to manage CCs effectively in the U.K. is limited. Therefore, field trials investigated the effect of CCs on physical (visual evaluation of soil structure, penetration resistance, bulk density, soil shear strength and soil moisture), chemical (total organic carbon and soil available nitrogen) and biological (earthworm abundance, microbial biomass and diversity) soil quality indicators, as well as crop yield. CCs were established between wheat and forage maize. A companion crop established with the maize remained overwinter after maize harvest until lettuce establishment the following spring. CCs placed between wheat and maize only affected available soil nitrogen with limited significant effects on other soil quality indicators. The addition of a companion crop significantly improved earthworm abundance, microbial community diversity and biomarkers associated with fungi. The companion crop significantly reduced bulk density and soil shear strength at 0.05 and 0.15m, respectively as well as penetrative resistance at 0-0.03m depth. Thus, continued plant presence, achieved through the establishment of cover and companion crops in the rotation allows for the accumulation of positive effects on soil quality and function in a short period of time (20months). Additionally, a survey distributed to U.K. farmers (n = 117) provided an understanding of the use, management and challenges associated with CCs. Respondents reported that the Basic Payment Scheme supporting CC use is not suitable and could be more flexible. Additionally, it took >3 years to realise benefits to soil structure. The knowledge gained from the survey can be used to inform future research and policy so that CCs can be implemented effectively to benefit the ecosystem services provided to the farmer and wider community.
Open Access
Finding common ground: co-producing national soil policy in Wales through academic and government collaboration
(Elsevier, 2023-06-24) Sánchez-García, Carmen; Button, Erik S.; Wynne-Jones, Sophie; Porter, Helen; Rugg, Ian; Hannam, Jacqueline A.
Several agricultural reforms are in progress in the UK following its withdrawal from the EU. This is an opportunity to formulate a Welsh Soils Policy Statement (SPS) that raises the status of soils and ensures that their protection and sustainable management are integrated into future policy. We share and reflect on our novel approach at co-producing a SPS for Wales involving academic researchers and policy teams and provide clear insights into soil policy development. Building consensus among the various government departments and agencies formed the basis of our approach. For pragmatic reasons, it was decided to focus on agricultural soils, which cover 85% of Wales. A rigorous evidence review and synthesis formed the foundation for the development of the SPS, which devises a vision, and primary and secondary objectives for Welsh agricultural soils. A first draft was conceived by the researchers, with further iterations developed between the researchers and the policy team. The researchers were embedded into the policy teams, and this proved to be an effective mechanism for evidence-based policy development that also enhances the science-policy relationship in the longer term. New structures and incentives that promote the engagement between researchers and policymakers should be developed to support environmental policymaking across the board.
Open Access
The implications of a changing climate on agricultural land classification in England and Wales
(Cambridge University Press, 2012-10-30) Keay, C. A.; Jones, Robert J. A.; Hannam, Jacqueline A.; Barrie, I. A.
The agricultural land classification (ALC) of England and Wales is a formal method of assessing the quality of agricultural land and guiding future land use. It assesses several soil, site and climate criteria and classifies land according to whichever is the most limiting. A common approach is required for calculating the necessary agroclimatic parameters over time in order to determine the effects of changes in the climate on land grading. In the present paper, climatic parameters required by the ALC classification have been re-calculated from a range of primary climate data, available from the Meteorological Office's UKCP09 historical dataset, provided as 5 km rasters for every month from 1914 to 2000. Thirty-year averages of the various agroclimatic properties were created for 1921–50, 1931–60, 1941–70, 1951–80, 1961–90 and 1971–2000. Soil records from the National Soil Inventory on a 5 km grid across England and Wales were used to determine the required soil and site parameters for determining ALC grade. Over the 80-year period it was shown that the overall climate was coolest during 1951–80. However, the area of land estimated in retrospect as ‘best and most versatile (BMV) land’ (Grades 1, 2 and 3a) probably peaked in the 1951–80 period as the cooler climate resulted in fewer droughty soils, more than offsetting the land which was downgraded by the climate being too cold. Overall there has been little change in the proportions of ALC grades among the six periods once all 10 factors (climate, gradient, flooding, texture, depth, stoniness, chemical, soil wetness, droughtiness and erosion) are taken into account. This is because it is rare for changes in climate variables all to point in the same direction in terms of ALC. Thus, a reduction in rainfall could result in higher grades in wetter areas but lead to lower classification in drier areas.
Open Access
The importance of soil education to connectivity as a dimension of soil security
(Elsevier, 2022-05-12) Brevik, Eric C.; Hannam, Jacqueline A.; Krzic, Maja; Cristine, Muggler; Uchida, Yoshi
The connectivity concept within soil security posits that people need to have a connection to soil in order to properly value it. Showing how soil is important in everyday life can create connections to soil, because people care about things they see as impacting their quality of life. Education can demonstrate these connections and may take place in either formal or informal settings and over a wide range of age groups. Creating an effective educational environment is critical, which involves understanding the specific group being addressed, including their existing knowledge of and interest in soil. Soil scientists increasingly teach to student groups that need to know about soils within their chosen careers but are not necessarily training to be soil specialists. Within this formal setting, education that demonstrates the various functions that soils provide in support of human wellbeing may be important to connectivity because it clearly demonstrates the impact of soils on peoples’ lives. In less formal settings, it will be important to identify concepts that will resonate with the public or stakeholders, such as terroir, soil health, or soil security, and to effectively reach these groups with a message built around these concepts. Social marketing, social media, storytelling, soil apps, and soil games are all approaches that have promise to deliver the desired message, therefore creating connections between people and soil.
Open Access
A loss function to evaluate agricultural decision-making under uncertainty: a case study of soil spectroscopy
(Springer, 2022-03-12) Breure, Timo Samuel; Haefele, S. M.; Hannam, Jacqueline A.; Corstanje, Ronald; Webster, R.; Moreno-Rojas, S.; Milne, A. E.
Modern sensor technologies can provide detailed information about soil variation which allows for more precise application of fertiliser to minimise environmental harm imposed by agriculture. However, growers should lose neither income nor yield from associated uncertainties of predicted nutrient concentrations and thus one must acknowledge and account for uncertainties. A framework is presented that accounts for the uncertainty and determines the cost–benefit of data on available phosphorus (P) and potassium (K) in the soil determined from sensors. For four fields, the uncertainty associated with variation in soil P and K predicted from sensors was determined. Using published fertiliser dose–yield response curves for a horticultural crop the effect of estimation errors from sensor data on expected financial losses was quantified. The expected losses from optimal precise application were compared with the losses expected from uniform fertiliser application (equivalent to little or no knowledge on soil variation). The asymmetry of the loss function meant that underestimation of P and K generally led to greater losses than the losses from overestimation. This study shows that substantial financial gains can be obtained from sensor-based precise application of P and K fertiliser, with savings of up to £121 ha−1 for P and up to £81 ha−1 for K, with concurrent environmental benefits due to a reduction of 4–17 kg ha−1 applied P fertiliser when compared with uniform application.
Open Access
Microbial community composition of translocated ancient woodland soil: a case study
(Wiley, 2021-12-16) Borchers, Nicolas; Hannam, Jacqueline A.; Pawlett, Mark
Soil translocation is an ecological habitat restoration technique, which consists of moving the entire topsoil from a donor site to a chosen receptor site. We investigated soil chemistry and microbiology changes three growing seasons after the salvage of semi-ancient woodland soil (0.94 ha) to a nearby receptor pasture due to road widening works (Kent, United Kingdom). We sampled (1) Intact woodland soils adjacent to the area of soils that was translocated to represent the lost donor site; (2) The soil from three growing seasons after it had been translocated; and (3) Grassland soils adjacent to the translocated soil to represent the original receptor site. The intention was to ascertain if shifts in soil chemistry and microbial community composition (phospholipid fatty acid analysis, PLFA) occurred due to soil translocation. PLFA signature biomarkers demonstrated the overall microbial community profile of the translocated and woodland soils were similar; however, salvaged soils had a 40% increase in the arbuscular mycorrhizal fungi bioindicator fatty acid 16:1ω5, a 10% decrease in the Gram-positive bacterial fatty acids, and increased pH (5.01–5.77) compared to the original donor woodland soil. Microbial community composition (PLFA) correlated well with soil pH across all sites. Considering that pH increases with soil depth in this location, it is likely that mixing of soil horizons during translocation increased the topsoil pH causing changes in the soil microbial communities. We concluded that after three growing seasons, the chemical and microbial properties of the salvaged soil were characteristic of a woodland soil but showed signs of disturbance.
Open Access
Monitoring urban sealing from space: The application of remote sensing to identify and measure changes in the area of soil prevented from carrying out functions by sealing
(Cranfield University; National Soil Resources Institute, 2006-08) Wood, Gavin; Braganza, Steven; Brewer, Timothy R.; Kampouraki, Mary; Harris, Jim A.; Hannam, Jacqueline A.; Burton, Rodney; Deane, Graham
Overview Urban development presents the greatest driver of soil loss due to sealing-over by buildings, pavement and transport infrastructure. To this end, soil sealing is recognised as one of the major threats to soil. The ability to monitor the rates, types and geo-spatial distribution of soil sealing is crucial to understanding the severity of pressure on soils and their impact on European and global socio-economic and environmental systems. The overall objective of this work was to test the feasibility of using space-derived information to support the Defra Soils Team (ST) in monitoring the extent and pattern of soil sealing. The rate and nature of sealing should be routinely measured in order for it to be managed to best effect. Monitoring soil sealing is intended to be a part of a national soil monitoring scheme and to inform policy creation. This report identifies appropriate Earth Observation (EO) technology and processing procedures to deliver a range of baseline and monitoring information, and assesses the practical scope for the routine use of EO information to support the delivery of the required tasks of the Defra ST1 . The project was funded under the British National Space Centre’s GIFTSS2 programme with support from Defra.
Open Access
Predicting the growth of lettuce from soil infrared reflectance spectra: the potential for crop management
(Springer, 2020-08-10) Breure, Timo Samuel; Milne, Alice E.; Webster, R.; Haefele, Stephan M.; Hannam, Jacqueline A.; Moreno-Rojas, S.; Corstanje, Ronald
How well could one predict the growth of a leafy crop from refectance spectra from the soil and how might a grower manage the crop in the light of those predictions? Topsoil from two felds was sampled and analysed for various nutrients, particle-size distribution and organic carbon concentration. Crop measurements (lettuce diameter) were derived from aerial-imagery. Refectance spectra were obtained in the laboratory from the soil in the near- and mid-infrared ranges, and these were used to predict crop performance by partial least squares regression (PLSR). Individual soil properties were also predicted from the spectra by PLSR. These estimated soil properties were used to predict lettuce diameter with a linear model (LM) and a linear mixed model (LMM): considering diferences between lettuce varieties and the spatial correlation between data points. The PLSR predictions of the soil properties and lettuce diameter were close to observed values. Prediction of lettuce diameter from the estimated soil properties with the LMs gave somewhat poorer results than PLSR that used the soil spectra as predictor variables. Predictions from LMMs were more precise than those from the PLSR using soil spectra. All model predictions improved when the efects of variety were considered. Predictions from the refectance spectra, via the estimation of soil properties, can enable growers to decide what treatments to apply to grow lettuce and how to vary their treatments within their felds to maximize the net proft from the crop
Open Access
Redefining soil health
(Microbiology Society, 2021-01-25) Pawlett, Mark; Hannam, Jacqueline A.; Knox, Jerry W.
Open Access
Relationship between magnetic properties and reddening of tropical soils as indicators of weathering
(Elsevier, 2017-05-19) Preetz, Holger; Igel, Jan; Hannam, Jacqueline A.; Stadler, Susanne
This study evaluates the use of magnetic properties as an indicator of weathering of tropical soils. Soil samples collected across the tropical belt were analysed for magnetic susceptibility and its frequency dependence. Frequency dependence is caused by superparamagnetic (SP) ferrimagnetic nanoparticles, which are commonly attributed to neoformation during soil forming processes. Magnetic properties are compared to the redness rating of soil colour, which is related to the hematite content and is an established proxy for soil weathering. The investigated samples comprise material of different weathering stages from unweathered and weathered rock to subsoil and strongly weathered topsoil. They cover a broad variety of parent materials: ultrabasic, basic, intermediate, acid igneous rocks, clays and clay slates, phyllites and sandstones. The results show that soil reddening, magnetic susceptibility and in particular frequency-dependent susceptibility generally increase with proceeding weathering. However, there is a lithologic overprint and the parent material has to be taken into consideration. Soils stemming from acid igneous rocks, clays, clay slates and phyllites show a positive correlation between reddening and susceptibility or frequency dependent susceptibility, rendering these properties suitable for indicating weathering. In contrast, soils stemming from ultrabasic, basic and intermediate igneous rocks and sandstones show no significant correlation. The reason is the strong lithogenic overprint of ferrimagnetic minerals including SP particles, which commonly occur in these rock types.
Open Access
S.O.S. - Save our soil today to meet the food challenges of tomorrow
(The Institution of Environmental Sciences, 2017-02-28) Hannam, Jacqueline A.
Open Access
Soil water and available nitrogen during cover crop growth
(Association of Applied Biologists, 2018-12-31) Storr, Tom; Simmons, Robert W.; Hannam, Jacqueline A.
A field trial in Ely, Cambridgeshire was set up to investigate the soil moisture and nitrogen dynamics of a frost sensitive cover crop compared to a control of an over winter stubble. Cover crops were established in late summer following wheat harvest and a summer tillage operation. Soil and aboveground biomass sampling commenced in September 2017 was continued at 2–3 week intervals until May 2018. The results highlight the fast growth of cover crops which rapidly reduced the total oxides of nitrogen present in the soil by late autumn. During winter a gradual increase in total oxides of nitrogen is measured as the cover crop residue is mineralized. The use of the frost sensitive cover crop permitted ease of management and termination, though it is not completely reliable and termination times can vary from year to year.