Browsing by Author "Tibbett, Mark"

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    Amenity grassland quality following anaerobic digestate application
    (Wiley, 2018-06-19) Pawlett, Mark; Owen, Andy; Tibbett, Mark
    Anaerobic digestate applied to land is a source of readily available nutrients, yet there is a paucity of knowledge regarding effects on grassland. To address this, we investigated the viability of using digestate as an alternative to mineral fertilizer for Lolium perenne L. grassland maintenance. We present findings of two independent field‐trials, where food‐waste digestate was applied over two growing seasons at two rates (100 and 200 kg N ha−1 year−1) and compared to mineral fertilizer (N:P:K‐12:4:6 at 100 kg N ha−1 year−1) and control (no additions) plots. L. perenne nutrition (N, P and K), chlorophyll and sward composition were assessed in the summer and autumn to observe treatment and seasonal effects. The sward benefited from digestate application in the summer with reduced occurrence of dead L. perenne. Both the digestate and mineral fertilizer shifted the sward composition similarly and in favor of Poa annua L. in summer and L. perenne in autumn, with reduced broad‐leaved weeds and bare soil coverage regardless of season. Quantities of foliar N and K uptake were similar between the digestate and mineral fertilizer; however, the highest rate of digestate application was required to supply similar quantities of P to the grass compared to the mineral fertilizer. Grass chlorophyll was not adversely affected by the high ammonium‐N in the digestate. These broadly positive results for digestate present opportunities for the development of digestate use as a fertilizer on amenity grassland such as outfields in sports facilities, parks, and road verges as well as showing potential for supplementing the fertility of pasture systems.
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    Ecto- and arbuscular mycorrhizal symbiosis can induce tolerance to toxic pulses of phosphorus in jarrah (Eucalyptus marginata) seedlings
    (Springer Science Business Media, 2014-10-01T00:00:00Z) Kariman, Khalil; Barker, Susan J.; Finnegan, Patrick M.; Tibbett, Mark
    In common with many plants native to low P soils, jarrah (Eucalyptus marginata) develops toxicity symptoms upon exposure to elevated phosphorus (P). Jarrah plants can establish arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) associations, along with a non-colonizing symbiosis described recently. AM colonization is known to influence the pattern of expression of genes required for P uptake of host plants and our aim was to investigate this phenomenon in relation to P sensitivity. Therefore, we examined the effect on hosts of the presence of AM and ECM fungi in combination with toxic pulses of P and assessed possible correlations between the induced tolerance and the shoot P concentration. The P transport dynamics of AM (Rhizophagus irregularis and Scutellospora calospora), ECM (Scleroderma sp.), non-colonizing symbiosis (Austroboletus occidentalis), dual mycorrhizal (R. irregularis and Scleroderma sp.), and non-mycorrhizal (NM) seedlings were monitored following two pulses of P. The ECM and A. occidentalis associations significantly enhanced the shoot P content of jarrah plants growing under P-deficient conditions. In addition, S. calospora, A. occidentalis, and Scleroderma sp. all stimulated plant growth significantly. All inoculated plants had significantly lower phytotoxicity symptoms compared to NM controls 7days after addition of an elevated P dose (30mg Pkg−1 soil). Following exposure to toxicity-inducing levels of P, the shoot P concentration was significantly lower in R. irregularis-inoculated and dually inoculated plants compared to NM controls. Although all inoculated plants had reduced toxicity symptoms and there was a positive linear relationship between rank and shoot P concentration, the protective effect was not necessarily explained by the type of fungal association or the extent of mycorrhizal colonization.
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    Evaluating heathland restoration belowground using different quality indices of soil chemical and biological properties
    (MDPI, 2020-08-05) Duddigan, Sarah; Gil-Martínez, Marta; Fraser, Tandra; Green, Iain; Diaz, Anita; Sizmur, Tom; Pawlett, Mark; Raulund-Rasmussen, Karsten; Tibbett, Mark
    Reversion of agricultural land to heathland and acid grassland is a priority for the conservation of these rare habitats. Restoration processes require interventions to reverse the effects of fertilization and acidity amelioration undertaken during decades of agricultural production. Belowground assessments of restoration success are few, and we have examined the utility of soil indices as a rationalized tool for land managers and restoration practitioners to assess the efficacy of restoration practice. To achieve this, we assessed a large number of variables, many of which might be near redundant, that could be optimized for such indices. We used a 14-year field experiment contrasting acidified pasture (treated with elemental sulphur), control (untreated) pasture, and adjacent native heathland and acid grassland sites. Based on biotic and abiotic parameters, several ‘heathland restoration indices’ (resembling soil quality indices) were generated using a minimum dataset identified through principal component analysis and a linear scoring system. For comparison we also conducted alternative analyses of all parameters, using nonmetric multidimensional scaling plots and analyses of similarity (ANOSIM). Use of heathland restoration indices showed that elemental sulphur application had changed the soil chemical conditions, along with the vegetation assemblage, to be comparable to that of native acid grassland, but not the belowground biology. ANOSIM on full datasets confirmed this finding. An index based on key variables, rather than an analysis of all biotic and abiotic parameters, can be valuable to land managers and stakeholders in acid grassland and heathland restoration.
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    The impact of anecic earthworms on the dispersal of Microdochium nivale in amenity sports turf
    (Cranfield University, 2012-09) Young, Matt; Ritz, K.; James, Iain; Tibbett, Mark
    In sports surface management, integrated disease management (IDM) is useful in identifying the parameters for which disease can occur. The host, pathogen and environment are factors that are intrinsically linked for disease to manifest. When either of these causal components is not present then plant disease is prevented. Soil biotas have been implicated in the movement of pathogenic soil microbes through both consumption and ejection and by external contamination, the propagule attaching itself to the external wall of the earthworm. Soil biota could therefore be included as a causal factor in disease development. The aim of this thesis was to investigate the impact anecic earthworms have on the dissemination of Microdochium nivale in amenity sports turf. An initial experiment to ascertain viability of M. nivale spores post ingestion through Lumbricus terrestris was performed. Sterilised soil pre-inoculated with M. nivale was fed to earthworms and propagules re-isolated from the faecal matter using a soil dilution technique. Results showed that 10% of viable propagules of M. nivale fed to earthworms survived the digestion process and were evident in the faecal matter (cast). A turf microcosm experiment was established to record whether the casts containing propagules of M. nivale could lead to infections of Fusarium patch, the plant disease caused by M. nivale in amenity turf. Spiked casts (M. nivale) were placed in pots containing Lolium perenne and the incidence and severity of disease was recorded using image analysis. The conclusions were that the spiked cast material was no more infectious than spore solutions of M. nivale inoculated onto the plant material. A final investigation of the effects the presence and absence of earthworms have on the dissemination of M. nivale propagules in turf grass was conducted. Turf microcosms containing Agrostis stolonifera were pre-inoculated with a spore solution of M. nivale in either the presence or absence of earthworms. Rate and progression of disease was recorded using image analysis, dispersal of propagules was assayed through leaf sampling in the microcosm. Results indicated that the presence of earthworms had a greater effect on both the manifestation of Fusarium patch, and the dispersal of M. nivale propagules than in the absence of earthworms. This study has provided a contribution to understanding the interactions between L. terrestris and M. nivale. It is clear that earthworm interaction with M. nivale enhances the dispersal of viable propagules, potentially leading to fresh manifestation of disease. Recommendations regarding the management of terrestris, already considered a nuisance on fine turf due to its casting; would be to mitigate these earthworms in areas of intensively managed turf, whereby the advantages of high earthworm activity are neither necessary nor required.