No description available.

No description available.

No description available.

The water industry recognises significant cost advantages in recycling sewage sludge (biosolids) to agricultural land compared with alternative more expensive disposal options such as incineration or landfill. A recent technique was proposed by United Utilities plc for the production of organomineral fertilisers (OMF) from biosolids granules which adds additional nitrogen to the biosolids’ nutrients to form a balanced NPK fertiliser. The aim of this research was to determine the effects in cereal and grass crops of using organomineral fertilisers (OMF) made from nutrients-enriched biosolids granules and to contribute towards the understanding of nutrient management and dynamics in agricultural systems. The research included soil incubation, glasshouse, lysimeters and field studies which used winter wheat (Triticum aestivum L.) and ryegrass (Lolium perenne L.). A theoretical model was developed for fertiliser particle distribution studies which required the determination of key physical properties of the products. Two OMF formulations have been suggested: OMF10 and OMF15 which have the following NPK compositions: 10:4:4 and 15:4:4 respectively. These were suggested for use in grassland as well as arable cropping. The particle trajectory model showed that the particle size range for OMF10 and OMF15 should be between 1.10 and 5.50 mm and between 1.05 and 5.30 mm in diameter respectively. Cont/d.

Smallholdings (<5 ha) represent 73% of the total agricultural production systems in Mexico. Many are of low productivity, and little quantitative data has been published on the impact of traditional nitrogen (N) management practices on environmental performance at farm scale. Nitrogen is the most important nutrient for increasing crop yields. While the benefits from the use of N fertilizer are self evident, it has resulted in low efficiency of N utilization and environmental problems. This project aimed to assess N dynamics in Integrated Agricultural Systems (lASs) in central Mexico. Nitrogen inputs, outputs and internal transfers were assessed and the impact of selected management practices on nitrogen flow, productivity and environmental performance were analyzed using nitrogen use efficiency (NUE) indices. A predictive framework tool was developed following whole farm methodologies to quantify N flow, and to assess selected (NUE) indices such as 0/1 ratio, N loss, accumulated N, and the change of N in the soil pool at farm scale. Data used for the development of the predictive framework was derived from experimental evaluations of ammonia emissions during vermicomposting, and integrated with data from the literature, together with data from an integrated agricultural systems prototype in Montecillo Mexico. The main N inputs into integrated agricultural systems in the Texcoco region were estimated to be in the following order of significance: biological N fixation (11 - 532), manure (15 - 225), fertilizer (0 - 140) and rainfall water (30 - 35 kg haˉ¹ aˉ¹). The main N outputs were: N losses (70 - 528 kg haˉ¹ aˉ¹) and exported N in marketable products (72 - 338 kg haˉ¹ aˉ¹). Experimentally derived estimates of ammonia emissions during vermicomposting of sheep manure ranged from 10 - 15 kg Mgˉ¹ DM which corresponded to 42 - 47% of the initial N content in the manure substrate. The impact of current management practices showed 0/1 ratios ranging from 0.30 - 0. 76, N losses ranged from 76 to 210 kg haˉ¹ aˉ¹ and N depletion/ accumulation ranged from -25 - 143 kg haˉ¹ aˉ¹. The effect of selected management practices on 0/1 ratio was as follows: crop sequence > stocking density > livestock type > manure management. Whereas for N loss it was stocking density > livestock type > manure management > crop sequence. Higher productivity together with a more benign environmental impact could be attained in smallholder by implementing simple recommended manure management practices at farm scale.

No description available.

European and National legislations in the UK have created a tremendous pressure on the waste management industry for a major expansion of the composting industry over recent years. Also, with the greater awareness of the health and environmental safety within the community, compost producers are forced to provide an authenticated form of quality compost to the consumers. The work presented in this thesis focuses on quality enhancement of mature green-waste derived compost using vermicomposting and air separation techniques. A vermicomposting trial was conducted for a period of 18 weeks by utilising re-hydrated mature green-waste compost produced at Carmarthenshire Environmental Resource Trust (CERT) composting facility as a feedstock. It was found that a minimum average compost mass reduction of 16% was observed by using an average mass throughput of 32.6 kg m 2 week"1. The greatest reduction in volatile solids was observed only during the initial stages of the trial. However, no significant reduction was noted towards the end of the vermicomposting process, when worm mass had reduced to approximately 1.3 kg/m . Replicated growth trials on coriander and tomato were conducted using two commercially available multipurpose composts and five waste-derived composts. It was found that commercial composts showed better plant growth when compared to waste-derived composts. This was followed by another set of growth trials undertaken with lettuce, using pure worm casts (VC), green waste compost (FS) and mixtures of the two Le. 50/50 and 20/80 (VC:FS, v/v) mix. Results showed that plant biomass production was optimal with 20/80 (v/v) mix, whilst VC and FS yielded poor plant growth. In general, the vermicomposting process did not result in an increased availability of nutrients or potentially toxic elements, the only exception being Zn. Characterisation studies were also conducted on unscreened mature compost samples to identify the physical contaminants followed by laboratory and commercial scale air separation trials. Of the coarser fraction from Bryn Pica compost, 1% of plastic film was found. The laboratory air separation trial showed that at the minimum average air velocity of 4.24 m/s, 100% plastic film was removed along with 73% of <10 mm CERT compost During the commercial scale trial, it was found that following screening, the <25 mm fraction would meet the physical contaminant limits of the BSI PAS-100:2005 standard. The 'Komptech Hurrikan' removed 91% of the light materials from the compost oversize (>25 mm). The air jig trial showed promising results and that, in less than 2 minutes, various sizes of stones were separated from the compost stone mix sample.

This study investigated the effect of fertiliser application on methane oxidation and nitrous oxide emissions. During this study a combination of ¹³C-CH₄ and ¹⁵N stable isotope techniques were applied to laboratory soil incubations and traditional gas flux methodologies were applied to culture incubations. It was found that fertiliser application rate and soil pH were major influences on both methane oxidation and nitrous oxide emissions from an arable soil. Profiles of the main nitrous oxide producing processes were obtained, and it was shown that nitrification was the predominant source of nitrous oxide from most aerobic soil incubations and that soil acidification greatly reduced nitrous oxide emissions from nitrification. Additionally denitrification was shown to not be restricted to anaerobic conditions. Similar profiles were obtained for ¹³C soil incubations and the effect of increasing fertiliser concentrations on methane oxidation was determined. Methane oxidation was inhibited by fertiliser concentrations up to 20 g N m^-2. However, above 20g N m^-2 inhibition declined and there was no apparent effect of increasing fertiliser concentration on methane oxidation. Culture incubations aimed to determine the contribution of methane oxidising bacteria to nitrous oxide emissions and ammonia oxidation. Ammonia oxidation was observed in all methylotrophic bacterial cultures. Nitrous oxide production was only observed in <i>Methylomicrobium chloromethanicum </i>and <i>Methylocystis parvus </i>and it was not possible to determine if this nitrous oxide was produced via ammonia oxidation, nitrate reduction or via the reduction of nitrite produced during ammonia oxidation, in a process similar to nitrifier denitrification that has been observed in autotrophic ammonia oxidising bacteria.

Agricultural intensification can have negative impacts on the environment and there isincreasing interest in the use of low intensity or organic agricultural methods toimprove sustainability. Fertiliser is an important component of all agriculturalsystems and can affect the performance of crop pests and their natural enemies. Thisthesis presents the results from a quantitative review of the literature on both farmingsystem and organic and conventional fertiliser effects on pests and natural enemies. Results from a series of laboratory and field experiments investigating the effectsorganic and conventional fertiliser on cereal aphids and their natural enemies arereported. The review demonstrates that crop pests and their natural enemies benefit fromorganic or low intensity methods and this is evident for natural enemies in farm scaleexperiments. The effect of organic and conventional fertilisers on arthropod pests isvariable although the influence of manures is consistently negative while the effect ofplant composts is positive. More studies investigating organic and conventionalfertilisers and the response of natural enemies are needed. Field and laboratory experiments show that conventional fertilisers can benefit cerealaphids but the mechanism behind this response is species specific. Rhopalosiphumpadi is sensitive to temporal nutrients availability and is influenced by the timing offertiliser application, while Metopolophium dirhodum is responsive to plantmorphology with aphids performing better on plants with a high proportion ofvegetative matter. The implications of pest performance on fertiliser managementstrategies are discussed. Parasitoid abundance in the field was not found to beinfluenced by fertiliser treatment although in the laboratory, indirect effects offertiliser, mediated through its aphid host, were found to affect parasitoid fitness withlarger parasitoids emerging from larger aphids. A positive influence of conventionalfertiliser on syrphid oviposition in the field was also apparent.

No description available.