Evaluation of the potential to dispose of sewage-sludge. 1. Soil hydraulic and overland-flow properties of Pinus plantations in Queensland

Soil Research ◽  
1995 ◽  
Vol 33 (6) ◽  
pp. 1041 ◽  
Author(s):  
A Costantini ◽  
RJ Loch ◽  
SF Glanville ◽  
DN Orange

The studies reported in this paper were designed to evaluate the potential for disposal of sewage sludge in commercial Pinus plantations at Beerburrum, 50 km north of Brisbane. Soil descriptions and measurements of hydraulic properties were made in three soils, covering the range of perceived site suitability for sludge application. Disc permeameters and a rainfall simulator were used to characterize surface infiltration properties both with and without sludge, and ponded rings were used to assess permeability of the upper B horizon. Although surface hydraulic conductivities were potentially high, infiltration into dry soil was reduced by water repellence associated with fungal matting at the soil surface and mycelia extending through the Al horizon. Surface runoff could be generated from dry soils by relatively low intensity rainfall events, and the rate and volume of runoff was not increased by broadcast sludge application. Hydraulic conductivities of the upper Bt horizons in the lateritic and yellow podzolic soils were high, suggesting that persistent perched watertable development was unlikely. However, the presence of bleached A2 horizons and gleyed Bt horizons with prominent mottling in these soils were interpreted as evidence of periodic regional ground-water intrusion. By contrast, hydraulic conductivity in the Bt horizon of the soloth was low, suggesting that locally restricted drainage occurs. Likely pathways of water movement were inferred for three representative soil types in the proposed sludge application project. There is potential for both Hortonian runoff when antecedent conditions are dry, and saturated runoff during prolonged wet periods. Potential off-site pollution could therefore occur if either solids or solutes from the sludge are susceptible to transport. In addition, preferential how paths of water infiltration were demonstrated, and the potential for accelerated water and solute movement to ground watertables was inferred. The studies reported in this, and the second, paper in the series were used to appraise the potential for either surface water or ground water pollution from land-based sludge disposal.

2015 ◽  
pp. 71-82
Author(s):  
E. V. Shein ◽  
E. B. Skvortsova ◽  
S. S. Panina ◽  
A. B. Umarova ◽  
K. A. Romanenko

The results of field experiments conducted on the medium loamy agro soddy-podzolic soil showed that due to the hydraulic head of water at the soil surface the moisture movement occurs predominantly through migration ways that deteriorate the hydro-depositary properties of soils. The moisture movement was studied by a special method performed in two soil monoliths identical in size (42 cm in diameter and 60 cm high). The monolith walls were covered by a film, foamed and buried with the view of avoiding the lateral water loss. Both monoliths were simultaneously saturated with water: one of them was under a constant head of water in 5 cm, the other monolith was watered by fine-dispersed sprinkler without the formation of the water layer at the soil surface. The study was aimed at modeling the water movement under conditions of small headed infiltration and without the head of water as well as comparing the calculated and experimental data with the view of assessing the most adequate experimental provision of the model - the major hydrophysical characteristics obtained by empiric methods in the experiment or those calculated on the basis of hydrological constants and soil properties (pedo-transmitting functions). It seemed reasonable to establish that the experimental provision of the model can be shown in the following order: the use of regional pedo-transmitting functions provides better results as compared to the major hydrophysical characteristics, the latter being obtained by the method of tensiometers and capillarometers is better than the pedo-transmitting characteristics used the particle-size distribution as a predictor in Agrotool program (ROSETTA database) as well as those obtained by Voronin’s “secants”.


2000 ◽  
Vol 42 (9) ◽  
pp. 179-186 ◽  
Author(s):  
H. Vanden Bossche ◽  
J. M. Audic ◽  
A. Huyard ◽  
C. Gascuel-Odoux ◽  
F. Trolard ◽  
...  

Sewage sludge is used as fertilizer, owing to its nutrient contents. But little is known about the consequences of sludge disposal on erosion intensity and P losses from soil to runoff. This paper reports on a study of three simulated storm events (40 mm h-1 during 30 min), performed on a field supplied with liquid sludge (23 g L-1 of dry solid). The sludge phosphorus content was 26.5 g kg-1 of dry solid. The runoff and erosion intensity as well as the P losses were monitored during the experiment. The distribution of phosphorus on the soil surface, was investigated after the last simulation. Sludge disposal reduced the total amount of runoff water collected during the experiment from 290 m3 ha−1 to 134 m33 ha−1. It also decreased the quantity of sediment exported from 1200 kg ha−1 to 500 kg ha−1 and the total phosphorus loss from 2.7 kg ha-1 P to 1.4 kg ha−1 P. But, it increased the average concentration of dissolved phosphorus in the overland flow from 0.15 mg L−1 P to 0.57 mg L−1 P. The distribution pattern of P and organic matter, on the soil surface, after the simulations, showed a heterogeneity induced by the runoff processes. This effect is increased by sludge disposal.


Soil Research ◽  
1991 ◽  
Vol 29 (6) ◽  
pp. 745 ◽  
Author(s):  
KE Lee ◽  
RC Foster

Significant effects of soil fauna on soil structure are achieved mainly by a few groups among the larger soil invertebrates that are widely distributed and generally present in large numbers. Of these groups the most important are earthworms, termites and ants. The review deals mainly with earthworms, which are distributed throughout all but the coldest and the driest regions of the world. The effects of termites and ants on soil structure are also discussed. These groups of soil animals are also widely distributed, but are most common and most effective in influencing soil structure in tropical and warm temperate regions. A brief section deals with the influence of microarthropods, which are commonly found in large numbers, but because of their small size are unable to make large burrows in the mineral soil horizons, and are largely confined to pre-existing voids in litter and surface soil horizons. Their faecal pellets are granular and largely organic, with little included mineral soil material, and they sometimes make up the major proportion of forest litter layers. Quantitative assessment of the influence of earthworms on soil structure is available, but information on other groups is largely qualitative. The burrows of earthworms contribute to macroporosity and so influence water infiltration and aeration. Anecic species, that live in semi-permanent burrows opening to the soil surface and feed at the surface, provide more or less vertical channels for water infiltration and gas exchange. Endogeic species, that burrow continuously in search of food within the soil, provide more horizontally oriented, frequently extensive and intersecting networks of macropores that promote water movement and gas diffusion. Burrows that penetrate soil surface crusts are particularly important for water entry to the soil. Water movement through pores of the dimensions of earthworm burrows is important only when rainfall or irrigation supplies water at rates that exceed the capacity of the soil surface for capillary uptake. The combination of increase in surface area available for capillary uptake through the burrow walls and of hydraulic pressure resulting from the column of water in a water-filled burrow increases infiltration. Occupied burrows of anecic species may be sealed with soil or plant litter by the resident earthworm when water is ponded on the soil surface, or blocked by the earthworm's body, so as to be ineffective for water infiltration. When burrows are air-filled they provide surfaces that penetrate below ground and facilitate gas exchange.


1975 ◽  
Vol 55 (3) ◽  
pp. 287-294 ◽  
Author(s):  
N. E. STEWART ◽  
E. G. BEAUCHAMP ◽  
L. R. WEBBER ◽  
C. T. CORKE

Anaerobically digested sewage sludge was applied to a loam soil at rates of 1.25, 2.5 and 5.0 cm ha−1. Treatments were replicated four times, and all plots were cropped to corn. The soil in the 0- to 90-cm profile under each plot was sampled every month from May to October in 1972 and analyzed for NO3−-N and NH4+. The two highest sludge application rates resulted in significant increases in soil NO3−-N in the 0- to 90-cm soil profile, which persisted until October following crop harvest. Of the N supplied by the sludge, only about 3–12% was recovered by the corn crop. At the conclusion of the experiment, in October, 6–10% of the N supplied by the sludge remained in the soil and on the soil surface in the residual solids. Sludge applications in excess of 1.25 cm ha−1 did not produce significant increases in the yields of grain or stover.


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