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Maintaining a supply of potable water is a growing concern in the USA, particularly in many southern and western states. One method of sustaining water supply in these areas is the use of greywater for commercial and residential landscape irrigation. Greywater is derived from residential use such as showers, laundering and bathing, and accounts for approximately 65% of residential waste water. I investigated the effects of municipal tap water, harvested rain water, washing machine and bath water (greywater) on the carbon and nutrient dynamics of soil, foliage and leachate and on soil microbial diversity. I also examined the presence or absence of E. coli in source water and leachate. There was a significant difference in leachate chemistry among irrigation treatments. Average leachate pH and conductivity was significantly lower in treatments irrigated with harvested rain water. Fertilization did not affect any of the leachate chemistries with the exception of orthophosphate-P, but significantly reduced carbon in soil without grass (blank) and domestic tap water treatments. E. coli colonies were detected in source water (greywater), but not in leachate suggesting that there was no movement through the soil profile. The results of principal component analysis (PCA) on whole-soil fatty acid methyl ester (FAME) profiles indicated distinct differences in soil microbial community composition due to irrigation with greywater as compared to rainwater, suggesting that water source may affect soil microbial community composition.

Review of the literature suggested possible deficiencies of micronutrients in soils of North Western Zambia. Soil analysis, pot and field experiments were employed to investigate possible deficiencies. The pot experiments investigated how raising soil pH through liming influenced extractable micronutrients and their uptake by plants. Plant Mo and Ca were positively correlated with soil pH, while Mn and Zn were inversely correlated, aggravating the zinc inadequacy on all soils and that for Mn on arenosols. Effects of liming on plant uptakes of micronutrients generally followed the same trends as those on soil extraction. Incubating the soil under grass house conditions was found to influence amounts of extractable micronutrients, increasing most times above their levels before the soil was incubated. Field experiments generally showed that applying micronutrients were beneficial to crop yield only at some sites. Grain yield variables responded variously and were most significantly correlated with overall grain yield. Soil analysis usefully predicted deficiencies of Zn for both maize and soybean. However, predictions for B and Mo were ideal for soybean than maize. Cu also seemed to have been wrongly predicted for soybean. However, plant nutrient concentration was better at predicting nutrient status in relation to grain yield, but the lower limits of the suggested optimal concentration ranges may need to be worked out again. Soybean was found to have more micronutrient latent deficiencies at majority of the sites than maize. One of the characteristics of applied micronutrients was their beneficial residual effects of crop yield. The residual benefit was also noticed on maize when the fertilisers were directly applied to soybeans a season before, suggesting a possibility of crop rotation, thus spreading the costs. Results would suggest changing the current fertiliser recommendations in the region.

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Implementation of Sustainable Management Practices at Two California Central Coast Vineyards and Their Effects on Soil Fertility Dawn Michelle Stimson “Sustainable agriculture” has gained increased popularity in recent years. This study was conducted to determine the effects of sustainable management practices on soil fertility at two California Central Coast vineyards. The effects of cover crops (Erosion Control Mix - blando brome [Bromus hordeaceus], hykon rose clover [Trifolium hirtum All.], and zorro annual fescue [Vulpia mourns]), green waste compost (Forest Blend), and reduced tillage on soil fertility were investigated in San Luis Obispo, California on a clay and sandy loam soil. Between the fall 2007 and spring 2008, which had a low precipitation amount (13.3 & 15.6 inches), there was a significant difference (P <0.001 to 0.007) between vineyards in terms of their mean soil nutrient and ratio concentrations. The range of soil values (soil pH, P, K, exchangeable Ca, Mg, and K, OM, Ca/Mg and C/N ratios) was either completely separate or different between Vineyard One and Two. There was almost no significant difference found between treatments and their effects on soil nutrients, exchangeable cations, and ratios. However, there were some noticeable effects on soil nutrients, exchangeable cations and ratios. Soil P and K concentrations increased in most areas (except cover crop/till where it decreased slightly). Soil P increases ranged from 14 to 143% while potassium increases ranged from 9 to 78%. Soil OM increased in all areas at both vineyards (5 to 55%). Ca/Mg ratios increased in some areas between 8 and 43%. C/N ratios increased in all areas between 5 and 85%. Soil type appears to affect soil nutrients, exchangeable cations, and ratios more than sustainable management practices. Keywords: Sustainable, vineyard, and soil nutrients.

Urban development alters the physical and chemical properties of soil which presents challenges for vegetation establishment. Compost, when applied as a soil amendment, can help to ameliorate these challenges. In field trials, we evaluated the effect of surface-applied composts and standard hydroseeding applications on changes in soil properties and turfgrass stand on a highway roadside. The short-term effects of (1) no compost application; (2) 2.5 cm compost surface mulch; (3) 2.5 cm compost application, incorporated; (4) 5.0 cm compost application, incorporated; (5) 0.6 cm compost blanket; and (6) straw mat on turfgrass establishment, quality and changes in soil properties were measured on an urban soil devoid of topsoil. In greenhouse studies, we compared the effect of depth of planting of two variously-sized turfgrass seeds in compost. The soils of the disturbed roadside and the urban soil had increased Mehlich I-extractable soil K, Mg, and P following compost application. Analysis of botanical composition on the highway roadside demonstrated that the percentage of fescue decreased with time, while weed species increased inversely in both treatments. Compost amendments on the urban soil increased turfgrass color over time, whereas turfgrass density was not affected by time. Turfgrass density was greatest in applications of a 5 cm depth compost incorporated 7-10 cm into the soil. No differences were observed in biomass harvested among treatments. Tall fescue seeds had greater germination and establishment than smaller sized bermudagrass seeds when sown below the surface of compost, regardless of depth. Composts help to regenerate topsoil-like functionality in disturbed soils by promoting vegetation establishment, including weeds, on highway roadsides and improving turf quality on urban soils. / Master of Science

Les invasions biologiques sont une cause majeure de perte de biodiversité à l’échelle mondiale. L’impact direct des espèces exotiques envahissantes (EEE) sur la structure et la composition des communautés a été bien documenté. Par contre, leur impact sur le fonctionnement des écosystèmes a été comparativement moins étudié. Dans le présent travail, j’ai mesuré sur le terrain et en conditions expérimentales l’impact de 7 espèces de plantes exotiques particulièrement envahissantes en Europe sur les propriétés chimiques du sol, sur la productivité et sur le stock d’éléments minéraux dans la biomasse. Malgré la diversité des groupes fonctionnels considérés dans notre échantillon (des espèces annuelles aux arbres), des impacts récurrents ont pu être mis en évidence. Les EEE ont toujours une biomasse et une productivité supérieures à celles de la végétation qu’elles envahissent. Il en va de même pour le stock d’éléments minéraux dans la biomasse aérienne. En ce qui concerne le sol, les traits fonctionnels des espèces ne permettent pas de prédire la direction et l’amplitude des impacts. Par contre, ces impacts sur le sol se sont révélés partiellement prévisibles en fonction des conditions écologiques initiales (contexte pédologique). La disponibilité des cations et du P et la concentration en C et N organiques augmentent suite à l’invasion dans les sites initialement pauvres alors que ces mêmes paramètres baissent dans les sites plus eutrophes au départ. Les EEE entraînent, dans une certaine mesure, une homogénéisation des conditions écologiques dans les écosystèmes envahis. Dans un deuxième temps, je me suis attaché à identifier les mécanismes de l’impact de Fallopia japonica sur le cycle de l’azote. Cette espèce, perenne rhizomateuse, adopte une gestion très conservatrice de l’azote en retransloquant jusqu’à 80 % de l’azote des tiges et des feuilles vers le système racinaire en automne avant l’abscission des feuilles. La litière restituée est, de ce fait, pauvre en azote. Ce paramètre, combiné à une teneur élevée en lignine, explique sa faible vitesse de décomposition par rapport à celle de la végétation non envahie. Une grande partie de l’azote de l’écosystème tourne donc en cycle quasi fermé entre les organes de réserve et les parties aériennes de la plante, tandis que l’azote restant est en grande partie bloqué dans la nécromasse de la plante et est donc non disponible pour les espèces concurrentes indigènes. Ce mécanisme explique, sans doute, en partie le succès invasif de l’espèce. A l’avenir, les implications des impacts sur le sol en terme de restauration des communautés devront être étudiées. L’hypothèse d’une influence positive de ces impacts sur l’aptitude compétitive des espèces envahissantes devra être testée. Enfin, une étude plus fonctionnelle des impacts de ces espèces dans des sites contrastés devrait permettre d’identifier les mécanismes impliqués./Biological invasions are a major cause of biodiversity loss worldwide. The direct impact of alien invasive species (AIS) on community structure and composition has been well documented. On the other hand, their impact on ecosystem functioning has been comparatively less studied. In this work, I measured, on the field and in experimental conditions, the impact of 7 highly invasive alien plant species in Europe on soil chemical properties, biomass and aboveground nutrient stock. Despite the high diversity in considered functional groups (from annuals to trees), recurring impacts have been found. AIS had always higher biomass and aboveground nutrient stocks than invaded resident vegetation. Concerning soil, species functional traits did not allow us to predict impact direction and intensity. On the other hand, impacts on soil were partially predictable based on initial ecological conditions (pedologic context). Thus, cations and P availability and organic C and N concentrations increased in initially poor sites and decreased in eutrophic ones. AIS tend to homogenize soil properties across invaded landscapes. In a second part, i tried to identify the mechanisms of the impacts of Fallopia japonica on N cycling. This perrennial rhizomatous species manage N in a very conservative way. About 80 % of aboveground N is translocated to rhizomes before leaves abscission. The litter is therefore poor in N. This parameter combined with a high lignin concentration explains its slow decomposition rate compared to that of uninvaded vegetation. A big part of the ecosystem N is engaged in a nearly closed cycle between above and belowground organs while the remaining N is blocked in the necromass and is thus not available for the indigenous competitors. This mechanism probably explains the invasive success of this species. In the future, the implications of soil properties modifications in terms of community restoration should be studied. The hypothesis of a positive influence of these modifications on the competitive ability of AIS should be tested. At last, a functional study of these soil impacts in contrasted sites should allow us to identify the implied mechanisms.

Artificial soils have been employed within the Biomes of the Eden Project since its construction in 2000. Produced from sand, bark, composted green waste and lignite clay, these soils were designed to have their nutrient concentrations controlled through careful fertiliser applications. However, following variable environmental conditions, management practices and planting, the soils across the site are performing variably with regard to nutrient retention and storage. Experiments were conducted to assess the performances of an artificial soil in terms of nutrient cycling. This was carried out in three phases: Firstly, soils from the Humid Tropics and Outdoor biomes were sampled and examined, using a range of analytical techniques, to determine the nutrient characteristics of the established artificial soils from across the Eden Project site. This demonstrated that many of the nutrient concentrations of the artificial soils were consistent with those reported for naturally formed soils within comparable environments. All soil samples were of sandy loam texture (ISO 14688-1), with the sand-sized fraction representing > 50 % of the particle size composition. Statistical analyses suggested that management practices had a greater impact on the nutrient characteristics of artificial soils than environmental conditions. Secondly, an artificial soil was produced, following the Eden Project protocol, to examine its performance under controlled environmental conditions. This was packed into 4 columns (1 m height by 110 mm diameter), maintained at 15 ˚C and subjected to an irrigation regime for 52 weeks. Following 26 weeks of irrigation, 2 of the 4 columns were fertilised. Leachate was analysed for dissolved constituents as were solid samples of the fresh soil and of soil samples collected from the columns following 52 weeks irrigation. Leachate concentrations for all nutrients, excepting phosphate, were observed to decline over the irrigation period. Leached phosphate concentrations increased from weeks 0 to 2, and then remained relatively constant. Low nitrogen concentrations within the leachate from weeks 2 to 38 were caused by nitrogen immobilisation within the soil, whilst subsequent mineralisation resulted in increased concentrations from Week 38. Analyses of solid phase constituents determined little variation with depth. Fertiliser application demonstrated a significant (p < 0.05) increase in leachate concentrations for some dissolved organic nitrogen and nitrate, phosphate, magnesium and calcium and a decrease in pH. Fertiliser application observations showed less prominent differences for the extracted and solid phase constituents. Thirdly, biochar was applied to the artificial soil at three concentrations (10 %, 5 % and 2 %) plus a control (0 %), to determine whether biochar application may improve nutrient characteristics of artificial soils. The biochar amended soils were packed into mesocosms and maintained at 15 ˚C for 6 weeks. In general, leachate analyses demonstrated a decrease in nutrient losses to leaching with increasing biochar concentration, highlighting the potential for improved nutrient retention within the soils.

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