Browsing by Author "Hann, Michael J."
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Item Open Access Assessment of an innovative soil aerator on soil physical disturbance and reducing runoff on compacted grassland(Cranfield University, 2009-09) Shanahan, Peter; Simmons, Robert W.; Hann, Michael J.Poor grassland management practices increases compaction and reduces infiltration leading to increasing risk of poaching and runoff generation. On-site impacts of grassland compaction include the loss of topsoil structure which also reduces soil ecosystem functioning. In addition, ongoing diffuse water pollution from compacted grassland limits the ability of the UK’s authorities to meet EU water quality guidelines such as the Water Framework Directive and address flood risks in areas of extensive grassland management (e.g. Boscastle, 2004). This study investigates the effects of an innovative ground-driven rotary soil aerator at alleviating soil compaction and reducing overland flow (designed by Mr. Roger Clay, Herefordshire). The magnitude of soil disturbance from slotting was assessed at the Cranfield University Soil Dynamics Test Centre soil-bin. Draught and vertical force requirements and tillage efficiency were also determined for varying depth and horizontal and vertical angle combinations using an Extended Octagonal-Ring Transducer (EORT). The effect of various slotting treatments on runoff was then investigated on a steep compacted permanent pasture in Herefordshire using erosion plots and simulated rainfall. From the soil-bin assessment, soil disturbance was most efficient (lowest specific draught) at 100 mm depth, a vertical angle of 18° and with increasing horizontal angle (0° to 10°). The draught requirement for a single bladed disc at 18° vertical ranged from 0.88 to 1.24 kN (90-126 kg force) and a maximum vertical force or ballast requirement of 257 kg force per bladed disc. Slotting treatments reduced runoff by 75% as compared with the non-slotted control.Item Open Access Biowaste and vegetable waste compost application to agriculture(Cranfield University, 2008-03) Kokkora, Maria I.; Hann, Michael J.The landfilling of biodegradable waste is proven to contribute to environmental degradation. Compost use in agriculture is increasing as both an alternative to landfilling for the management of biodegradable waste, as well as means of increasing or preserving soil organic matter. This research aimed to contribute to the identification of a system for managing the utilization of vegetable waste (agricultural plant-tissue waste) and biowaste (source-separated biodegradable municipal solid waste) composts for sustainable agriculture, with particular regards to nitrogen availability and leaching.Item Open Access The damaging effect of surface-traffic-generated soil pressures on buried archaeological artefacts(2010-04-12) Dain-Owens, Anne Peregrine; Kibblewhite, Mark G.; Godwin, R. J.; Hann, Michael J.The aim of this work was to investigate the influence of surface loading from conventional field operations on the damage to buried artefacts, both pots and bones. The objectives of this research were a) to investigate the influence of surface loading and resulting breakage relating to the material strengths of buried objects - ceramic (unglazed), and aged bone; b) to assess the magnitudes of peak subsurface pressures transferred through soil under the dynamic surface loading from tyres and other field operations; c) to develop and test an empirical model for predicting the effects of subsurface pressure application on buried objects from surface loads; and d) to explore ways of identifying the potential for damage to buried artefacts under agricultural and other field operations. Experimental investigations were performed in both the laboratory and field. The laboratory work was undertaken to determine the magnitude of subsurface pressure at which buried objects were damaged. Conducted in a sandy-loam-filled soil bin, instrumented ceramic and bone artefacts were buried alongside pressure sensors and subjected to loading by a single smooth tyre appropriately loaded and inflated for subsurface pressure generation. The breakage of the buried objects and the pressures under the moving tyre were recorded in order to allow correlation of the subsurface pressures to buried artefact breakage. The fieldwork was done to determine the magnitudes of subsurface pressure generated by individual field operations whilst travelling in a similar sandy loam field soil. Four plots were established, with each assigned a particular cultivation regime. An accelerated timeframe was utilized so that a years’ series of field operations could be driven over pressure sensors buried in the soil. The peak pressures from each field operation within each plot were recorded and summarized, and the data was analysed relative to field operation type and cultivation regime type. Multiple statistical analyses were performed, as the laboratory data and field data were independently evaluated before being correlated together. An empirical relationship between buried object damage and subsurface pressure magnitude was developed. The different pot types and bone orientations broke at different subsurface pressures. The four pot types listed in ascending order of strength to resist damage (with breakage pressure threshold value) are: shell tempered (1.3 bar), grog tempered (1.6 bar), flint tempered (3.1 bar), and sand tempered (3.6 bar). Aged human radius bones were tested, and the parallel bone orientation proved stronger than the perpendicular orientation, where 2.8 bar was the lowest subsurface pressure found to cause damage. The primary field operations, presented in ascending order relative to peak magnitude of subsurface pressure per specific operation, are: roll (0.68 bar), drill (1.03 bar), heavy duty cultivator (1.21 bar), spray 1 (1.27 bar), harvester (1.30 bar), spray 2 (1.31 bar), tractor / trailer (1.46 bar), shallow mouldboard plough (1.61 bar), deep mouldboard plough (2.04 bar). The relationships between vehicle specification and subsurface pressure generation potential were described, relating to the vehicle mass, tyre/track physical properties, and tyre inflation pressure. The effect of cultivation method on overall magnitude of subsurface pressure was defined, with lowest pressure generation within a zero-till cultivation regime (1.08 bar), higher in a non-inversion cultivation regime (1.13 bar), followed by the shallow inversion regime (1.22 bar), and highest within a conventional inversion scheme (1.30 bar). The laboratory and field results were correlated by a statistical analysis comparing breakage point to peak subsurface pressure. The shell tempered pot was found to be most susceptible to damage. The grog tempered pot was less vulnerable to damage, followed by the flint tempered pot. The quartz tempered pot was predicted to survive intact under all field operations within this research. In conclusion, this research has developed a functional and predictive empirical relationship between damage to pot and aged bone artefacts from subsurface soil pressures generated by surface traffic. It has been found that different types of buried pot and bone artefacts break at different subsurface pressures. In addition, a complete dataset consisting of peak subsurface pressures recorded under a year’s range of field operations within a sandy loam soil at field-working moisture content has been compiled. The effect of different cultivation methods on the generation of subsurface pressures was also evaluated. The breakage thresholds specific to each artefact type have been related to the in-field subsurface soil pressures. A correlation of breakage to the subsurface pressures under each operation yields a prediction of percentage of artefact-type breakage. From this correlation, relationships are observed between vehicle specification, subsurface pressure generation, and consequential artefact breakage. The achievements provide knowledge about how field operations affect specific types of buried archaeology, providing a valuable asset to farmers, land managers, and regulatory bodies. It is evident that agricultural practices, choice of track or tyre type, and inflation pressures must be carefully managed if the intention is to protect or mitigate damage to buried archaeological artefacts. Thus, a contribution has been made to the development of ‘best management practices’ and to the specification and use of field operations relative to intended mitigation of buried artefact damage.Item Open Access Efficacy of mulch and tillage options to reduce runoff and soil loss from asparagus interrows(Elsevier, 2020-04-01) Niziolomski, Joanna C.; Simmons, Robert W.; Rickson, R. Jane; Hann, Michael J.In the UK, conventional asparagus cultivation practices on sloping land, erodible soils and increased frequency of extreme rainfall events combine to promote runoff generation and soil loss, particularly from interrows. This instrumented field study investigated the interactive effect of mulch and shallow soil disturbance (working depth of 0.175 m) on reducing runoff and soil loss. Ten treatments were installed in a commercial asparagus field near Ross-on-Wye (England, UK) during May 1st–July 17th, 2012. Straw and compost were applied to the interrows at high and low application rates (straw = 5 t ha−1 and 3 t ha−1 and compost = 18 t ha−1 and 8 t ha−1, respectively), both with or without shallow soil disturbance (SSD and Non-SSD) as compared with a bare soil, unamended Control. Across five sampling periods, Non-SSD straw mulch applied at 5 t ha−1 and 3 t ha−1; Non-SSD compost mulch at 18 t ha−1; and straw mulch applied at 5 t ha−1 with SSD all significantly reduced cumulative total soil loss by 53–72% as compared with the Control. Further, mulch treatments with SSD were in general less effective at reducing total soil loss as compared to non-SSD mulch treatments. Compost application was less effective than straw, due to sub-optimal compost blanket depths as dictated by N restrictions for Nitrate Vulnerable Zones, in which the study took place. Despite an overall reduction in total soil loss of 72% (associated with Non-SSD straw mulch applied at 5 t ha−1), soil erosion rates exceeded 1.4 t ha−1 yr−1, considered to be a tolerable erosion rate in the EU. In addition, measured sediment concentrations in the runoff consistently exceeded the EU water quality guideline value of 25 mg l−1. The results indicate that the efficacy of the treatments tested was not adequate to reduce soil erosion in commercial asparagus fields in the UK to tolerable rates. This may in large part be due to daily foot trafficking events that occur during the asparagus harvesting period (April–June) which disturbs and degrades the treatments applied reduing their efficacy. This study demonstrates that additional research is required in order to identify effective erosion control measures to ensure the sustainability of commercial asparagus production systems in the UKItem Open Access Improvements to furrow press performance(1989-03) Hagan, B; Hann, Michael J.The objective of this project was to, improve the performance of the furrow press, with particular regard to three applications: i) consolidation in light land ii) clod breaking in clay soils iii) tilth production in medium soils Work conducted by Ansell (1986) led to the suggestion that a press consisting of different diameter wheels on the same axle might satisfy some or all of these requirements. This project began by studying the action of a press in two dimensions (horizontal-vertical plane) using short sections of press wheels in a glass sided soil tank. Different combinations and spacings were considered and their effectiveness measured by breaking clods in the soil. Different shaped sections were also tested, using loose soil to study the effect of shape on soil movement. Following the two-dimensional testing, a range of different diameter press rings were tested in the Silsoe College Soil Bin. A number of diameter /spacing combinations were used, and each was evaluated at three different weight levels. The resulting soil profiles were measured, together with plate penetrometer tests as an indicator of soil density. It was found that an excess of weight could cause a reduction in average soil strength by greatly reducing surface bulk density. Using the combinations selected from the work in the soil bin a number of full width presses were tested on seven field sites, ranging from a very sandy loam to a wet clay loam. Profiles were measured before and after passing a tractor over the work. The sinkage was proportional to the soil strength. Photographs were taken and analysed to rank the treatments in terms of clod size reduction. Evaluation of the field trials has led to the development of a composite press with a geometry and weight arrangement that has produced significant improvements in light land consolidation, clod size reduction and tilth production.Item Open Access Injecting bio solids into grass and arable crops. Part II: Development of a shallow application technique(Elsevier, 2004-04) Pullen, D. W. M.; Godwin, R. J.; Grundon, P.; Hann, Michael J.Digested sludge contains valuable crop nutrients but these are largely lost because current application techniques limit where and when it can be applied. Soil injection to depths in excess of 150 mm to reduce odour problems can only be used on fallow land or grass because of the damage it can cause. This leads to applications at high rates being applied with increased environmental risk. The aim of this study was to determine the benefits and limitations of injecting digested sewage sludge into land growing arable crops using shallow, less than 100 mm deep, injection techniques. Agronomic trials conducted over 2 years with winter wheat and rape showed that the crops were surprisingly resistant to mechanical damage during the growing season. Crop yields were not effected by injecting sludge into the crop up to March, equivalent to growth stage 30 in winter wheat, using a conventional tractor-based system working. Injection is possible later in the growing season based on systems with the tractor operating along "tramlines" for field traffic control.Item Open Access Investigation into the fate of nutrients and crop growth following application of sewage sludge to land(Cranfield University, 1996-10-30) Collins, O. J.; Hann, Michael J.Investigations into nitrate leaching from sludge and sludge injection into grassland have been undertaken for many years, however phosphate leaching from soils and shallow injection of sludge into grassland are relatively new ideas. This lysimeter study sets out to investigate the influence of the type of slurry and application rate on the amount of phosphorus and nitrogen lost by leaching. The field trial assesses the influence of application methods on grass yield, sward damage and ritrogen loss by leaching through analysing the effects on a grass crop using two different methods of injection and comparing them with surface application and granular fertilizer. Losses of P from sandy loam soils were found to be minimal therefore contamination of groundwater is thought to be unlikely. Similar leacling patterns were observed from both the cake and liquid sludges at all four rates_ applied, however the liquid sludge released more phosphate than the cake sludge, resulting in higher concentrations recorded. The lysimeter study also found leaching losses of ritrate from both sludge types to be well above the EC maximum permissible level of 11.3 mg nitrate-N l`l at all four rates. Residual N from the previously cropped soil masked the nitrate concentrations during the initial stages of the study. Losses of N from the cake sludge was lower than from the liquid treated plots due to slow release. It was also found that environmental factors such as high temperatures and rainfall influence nitrate leaching. The field trial analysed various disposal methods in terms of nitrate leached, crop yield and sward damage. N losses from shallow injection were reduced compared to the deep injection plots, as the sludge was placed in closer proximity to the crop roots. Olibhe Collins, Silsoe College, 1996. In overall terms the shallow injection system yielded the greatest quantity compared to surface applied or the inorganic fertilizer. Damage caused by the tines during shallow injection was not evident compared to the deeper injection system where sward damage and dieback was considerable. The results from the field trial indicate that the shallow injection of sewage sludge has proved to the most environmentally friendly method for the disposal of sludge to farm land.Item Open Access Tine options for alleviating compaction in wheelings(Elsevier, 2016-05-27) Niziolomski, Joanna; Simmons, Robert W.; Rickson, R. Jane; Hann, Michael J.Repeated trafficking and harvesting operations lead to high levels of compaction in inter-row wheelings used in asparagus (Asparagus officinalis) production. This reduces soil porosity and infiltration resulting in water ponding on the soil surface. Even on gently sloping land this can result in runoff generation and an increased risk of soil erosion. A winged tine (WT) is currently used by a leading asparagus grower to loosen compacted inter-row wheelings. In order to test the effectiveness of this tine for alleviating compaction and implications for runoff and soil erosion control, it was evaluated alongside several other tine configurations. These were a narrow tine (NT); a narrow tine with two shallow leading tines (NSLT); a winged tine with two shallow leading tines (WSLT); and a modified para-plough (MPP). Testing was conducted under controlled conditions on a sandy loam soil in the Soil Management Facility at Cranfield University, Bedfordshire, UK. Tine performance was assessed at 3 depths (175, 250 and 300 mm) by draught force; soil disturbance (both above and below ground); specific draught for a given level of soil disturbance; surface roughness; and estimated change in soil bulk density. The effectiveness of tines for compaction alleviation and potential for mitigating runoff and soil erosion varied with depth. The most effective tines were found to be the MPP NSLT and the WSLT at 175 mm, 250 mm and 300 mm depth, respectively.Item Open Access The use of biosolids compost as a soil conditioner in newly reclaimed sandy soils(Cranfield University, 2002-01) Abdel-azeim, M. M.; Hann, Michael J.Egypts population was projected to increase from 20 million in the 1960s to 67 million by 2000. With this increase in the population, an increase in food production of 200% to 300% is become necessary to meet food demands. In addition to the increasing demand for food, the population increase will result in increased amounts of human wastes. This will, in tum, need to be disposed of in ways other than the traditional dumping in the nearest stream or the Nile River. It is therefore vitally important to utilize as much as possible of this human waste (biosolids) as an organic fertilizer and soil conditioner to increase sandy soil productivity in Egypt. Composting is recognized as a cost-effective environmentally sound process for treatment of biosolids, even though they may contain substances, which pose potential hazard to the environment or food chain. The aim of this study was therefore set out to develop a management strategy that used biosolids compost as a soil conditioner and fertilizer to increase their agronomic benefits and minimize their environmental impacts when applied to newly reclaimed sandy soil. The agronomic benefits and the environmental impacts of applying biosolids compost to sandy soil were identified through a series of glasshouse, pot, and incubation trials using tomatoes and grass crop. Tomato was chosen as it represents a vegetable with a high potential for heavy metals uptake and because of its world-wide important as vegetable crop. The results of this work showed that, compost application had the capacity to stimulate vigorous growth, nutritional status, production levels of tomato plants, 'and to increase N recovery by tomato plants compared to control. The major nutrient concentrations of N, P, and K in tomato leaves taken from plants grown on compost M.M. Abdel-azeim, Ph.D. Thesis, 2002. The stem radius of tomato plants grown on the compost amended-plots were about twofold thicker in the case of the highest compost application rate (360 t/ha) than the plants from control plots. At 360 t/ha application rate, the tomatoes production level response for the compost-treated plots was 13.3 kg/plot while it was 1.8 kg/plot for the control. This represents an increase of more than 700% over the control plots. Nitrogen recovered by tomato crop following compost addition exceeded 20% of the total applied N after one and two compost applications. All these improvements in growth quality parameters of tomato plants were not significantly different at the higher compost application rates of 240 and 360 t/ha. This finding indicates that the plant response due to the increasing of compost application rate is subject to diminishing returns. The incorporation of biosolids compost into sandy soil has established sufficient grass covering area and improved soil aggregate stability compared to mulched-applied compost. The range in grass covering was a low of 7.9% for the control to 100% for incorporated applied compost at all application rates. The grass covering ranged from 7.9% for the control to 70% for mulched applied compost at the highest application rate. Incorporated-applied compost had more large aggregates and less small aggregates and consequently the overall aggregate stability ranged from 25 to 30% compared to 6 to 11% in the case of mulched-applied compost. The superiority of the incorporated-applied compost to the mulched-applied compost on aggregate stability was due to the stabilizing effects of the organic matter. The N mineralization rate has suggested that rapid and extensive N accumulated in the soil solution soon (60 days) after compost addition and the amount of N recovered was in excess of 20% of the total applied N. This value is higher than the 10% value reported elsewhere in the literature. Soil analysis of the compost treated plots revealed significant increases in soil pH, organic matter, CEC, soluble salts, and total heavy metals compared to control. Major considerations in recycling of biosolids compost on newly reclaimed sandy soils are the increase in soluble salts, the groundwater contamination by nitrate M.M. Abdel-azeim, Ph.D. Thesis, 2002. The increase in soluble salts following compost addition was at a level that could reduce yields in sensitive crops. High application rates of compost at high moisture status resulted in high levels of nitrate in the soil solution (> 50 mg/l). Another concern was the increased amounts of heavy metal accumulation in the soil profile where more than 90% of the compost- applied heavy metals were present in the top 20 cm of soil plots, but these increased amounts were still far below the plant toxicity levels. The results of this study clearly indicated that incorporated biosolids compost does increased agronomic benefits and does not pose the same environmental problems as mulched biosolids compost when used as a fertilizer with large-scale application rate. Application of biosolids compost significantly increased the concentration of heavy metals in tomato fruit compared to control. Crop recovery of compost-applied Zn and Cu by tomato plants was less than 0.5% at all compost application rates regardless of the method of application, and was significantly greater by tomato plants grown on compost-mulched plots than incorporated. Crop recovery of compost-applied Ni, Pb, Cd, and Cr by tomato plants was less than 0.08% at all compost application rates. In general, no health problems could be foreseen to humans or animals from food chain movement of these negligible amounts of heavy metals. With regard to heavy metal concentrations in the soil leachate, the data gave wide assurance that the environment is successfully protected. From this study, it could be concluded that high loading rates of good quality compost to sandy soils is ergonomically valuable with limited potential environmental risk if managed properly. Under the conditions of this study, incorporation of biosolids compost into sandy soil using drip irrigation system was the best management strategy practice to reach optimum agronomic benefits while minimizing environmental impacts. M.M. Abdel-azeim, Ph.D. Thesis, 2002.