Impact of organic waste amendments on soil hydraulic properties and on water partitioning

Abstract

Land application of organic wastes can lead to contamination of ground-and surface waters. The pathway taken by particulate contaminants, such as microorganisms, is entirely dependent on the partitioning of the incoming rain or irrigation water. The soil hydraulic properties are critical in determining the infiltration:runoff water-partitioning ratio. Components of the land applied organic waste can modify the soil hydraulic properties and thus alter this ratio. It was shown that liquid manure impacted matrix and macropore flow differently; favouring the later through obstruction of the former. In contrast solid manure favoured matrix flow over macropore flow thereby increasing the water storage in soil, which tended to reduce the likelihood of runoff. The relationships between soil hydraulic conductivity and soil textural and structural properties in repacked soil columns was unrelated to the relationships obtained for the same soils maintained in their natural undisturbed field state.Key words: organic waste, manure, soil type, hydraulic conductivity, water partitioning, transport, contaminants.Résumé : Le dépôt de déchets organiques sur le sol peut mener à la contamination des eaux de surface et souterraines. Le chemin pris par les contaminants particulaires, tels que les micro-organismes, dépend entièrement du partage des eaux de pluie et d'irrigation. Les propriétés hydrauliques du sol déterminent essentiellement le rapport de partage infiltration:ruissellement de l'eau. Les composantes des déchets organiques déposés sur le sol peuvent modifier les propriétés hydrauliques du sol et, ainsi, affecter ce rapport. Il a été démontré que le fumier/lisier liquide a un impact différent sur l'écoulement à travers la matrice et les micropores, favorisant ces dernières par l'obstruction de la matrice. À l'opposé, le fumier/lisier solide favorise l'écoulement à travers la matrice par rapport à celui dans les macropores, augmentant ainsi le stockage de l'eau dans le sol, ce qui tend à réduire la probabilité de ruissellement. Les relations entre la conductivité hydraulique du sol et les propriétés texturales et structurales du sol dans des colonnes de sol recompacté n'étaient pas reliées aux relations obtenues pour les mêmes sols maintenus dans leur état naturel non perturbé sur le terrain.

Soil and Waste Matrix Affects Spatial Heterogeneity of Bacteria Filtration during Unsaturated Flow

“…The same soils receiving dewatered biosolids had fewer single event active areas and fewer inactivated areas ( Figure S2). This data is in agreement with previous indications [14] that addition of solid, dewatered biosolids, to finer textured soils, will lead to a larger effective hydraulic conductivity than when the same soils receive liquid waste. Both this and the current results likely suggest a dispersive clogging of pores in clay and clay loams receiving liquid organic wastes.…”

“…Following LMB application, the λf means for the density distribution decreased during events following the 1st event. This clearly indicates that LMB did not favour continuity in transport pathways [14] and that newly opened pathways allowed re-mobilization of fewer bacteria. Both enhanced retention and die-off might be invoked to explain this.…”

“…Application of liquid waste led to pathway instability and thus a variable role for straining effectively enhancing a soil's effective capacity to retain tracers. It is evident that waste type affects both transport parameters [14] and survival [33], differentially across soil types. As such, straining and empirically fitted filtration equations based transport modelling might be more amenable for liquid waste soil amendments.…”

“…Management options, including type of waste, affect transport pathway stability [14]. For systems with continuous transport pathways remobilization of microbes is strictly an electrostatic phenomenon.…”

Development of a risk-based index for source water protection planning, which supports the reduction of pathogens from agricultural activity entering water resources

“…In loamy and finer-textured soils, the application of dilute liquid manure can both encourage surface runoff and enhance preferential flow. Until solid manure has been incorporated, it acts as mulch and encourages infiltration rather than surface runoff (Unc and Goss, 2006b).…”