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Nutrient leaching and changes in soil characteristics of four contrasting soils irrigated with secondary-treated municipal wastewater for four years.

Introduction

Application to land is the preferred method to treat wastewaters in New Zealand. Effluent application to land provides the dual benefits of supplying nutrient and water to plants at times of need, while decreasing the risk of eutrophication through direct discharge to receiving water bodies (Haynes et al. 1990; Cameron et al. 1997). For land treatment to be effective, and to avoid adverse effects on the receiving environment, the applied nutrient and contaminants (chemical and biological) need to be absorbed, metabolised, or degraded within the soil profile (Cameron et al. 1997; Tomer et al. 2000). The capacity of different soils to effectively treat effluent depends on their chemical, physical, and biological characteristics; the effluent composition; the timing, volumes, and rates of application; and the prevailing weather conditions. Previous reviews have addressed the major chemical, physical, and biological processes occurring during effluent treatment, such as plant nutrient uptake, soil sorption, denitrification, immobilisation, and decomposition (Polglase et al. 1999; Cameron et al. 1997; Barton et al. 1999). The importance of several factors has been emphasised, including the biologically active topsoil, soil mineralogy and nutrient retention, the way in which wastewater moves through the soil profile, and the vadose zone processes (McLeod et al. 1998; Barton et al. 1999, 2005; McLeod et al. 2001).

New Zealand has diverse soils with a complex distribution in the landscape (Molloy 1988; Hewitt 1998) and not all will be equally suitable for land treatment of effluents. To help understand how different soils would respond to wastewater application we completed a lysimeter study using 4 soils representative of major soil groups in New Zealand (Barton et al. 2005). Our objective was to rank the soils for their suitability for land treatment of effluents: criteria being the effective treatment of wastewater and minimal environmental impact. Data from the 2-year stage of this study were reported by Barton et al. (2005) with an emphasis on the fate of applied N and P in the effluent. The study was terminated after 4 years when the local council decommissioned the wastewater storage ponds. This paper reports the changes in some soil chemical, biochemical, and physical characteristics of the 4 soils after 2 and 4 years of wastewater application, and extends the wastewater, plant uptake, and leachate data from 2 to 4 years.

Materials and methods

The initial soil characteristics, lysimeter construction, experimental design and management have been previously described (McLeod et al. 2001; Barton et al. 2005), so only an abbreviated description is provided here. The New Zealand soil classification is from Hewitt (1998) and Soil Taxonomy from Soil Survey Staff(1996).

Soils

Four soils with strongly contrasting characteristics (Hewitt 1998; Soil Survey Staff 1996) were used: (1) Atiamuri silt loam, an Immature Orthic Pumice Soil, a well-drained loamy sand from rhyolitic tephra, (Typic Udivitrand); (2) Netherton clay, a Typic Acid Gley Soil, a poorly drained clay loam soil formed in estuarine clay alluvium (Typic Endoaquept); (3) Waihou silt loam, a Typic Orthic Allophanic Soil, a well-drained silt loam soil from rhyolitic tephra with a high allophane content (Typic Hapludand); and (4) Waitarere sand, a Typic Sandy Recent Soil, a well-drained sandy loam from dune sands (Typic Udipsamment). The soils differed in horizon designation and depths, soil mass per horizon, and P-retention (Table l).

Lysimeters

Intact soil cores (500 mm diameter by 700 mm depth) were collected as monoliths from each soil type and sealed into casings with petroleum jelly and baseplates as described by Cameron et al. (1992). They were transported to a site at Templeview, 15 km from Hamilton (37[degrees]49'S, 175[degrees]17'E), used by Waipa District for 2 wastewater storage ponds for secondary-treated domestic effluent. The lysimeter design allowed measured amounts of effluent to be sprayed onto the surface of the core, and for leachate to be collected from the base. For each soil order, 8 cores were randomly selected for each treatment (irrigated and non-irrigated). The position of individual cores were not fully randomised across because of technical difficulties in running the irrigation and electrical lines to the cores across different treatments. The cores were buried to ground level with an access track along one edge. Herbicide was applied to kill the existing pasture vegetation on the cores, and they were then resown with Lolium perenne var. Samson.

Experimental design

There were 2 treatments, irrigated and non-irrigated. Wastewater irrigation of the cores began 6 months after collection. The Pumice and Gley Soils were collected in 1998 and irrigation began 23 March 1999, with destructive soil sampling on 22 March 2001 and 13 March 2003. The Allophanic and Recent Soils were collected in 1999; irrigation began 22 February 2000, with destructive soil sampling on 21 March 2002 and 5 February 2004. Irrigated cores received 50 nun of secondary-treated effluent applied every 7 days at the rate of 10 mm/h from perforated sprinkler heads. This application rate and frequency was chosen as it represented current New Zealand practices, where major storage components in the treatment system are not economically feasible. With the exception of the Gley Soil the irrigation was not adjusted according to rainfall or soil water condition as this type of management is not commonly used in land management systems in New Zealand. The Gley soil was prone to surface ponding during winter and from April to September each year was irrigated twice a week (i.e. 10mm/h for 2.5 h on each occasion). Wastewater samples were collected weekly before irrigation onto the cores. Non-irrigated cores received only rainfall. There were 8 replicate cores of each treatment; 4 from each treatment were selected for leachate collection. The amount of nutrient leaching from the cores was measured at least every 14 days. Leachate and effluent samples were frozen before analyses, proportionally bulked every 4 weeks, and analysed for total N, nitrate, ammonium, total P, orthophosphate, total organic carbon (TOC), and pH using methods previously reported (Barton et al. 2005).

Dry matter production and the amounts of N and P taken up by the herbage were calculated by hand clipping the shoots whenever the sward reached 20-25 cm in height, then drying, weighing, and analysing subsamples for N and P content. Over the 4 years the non-irrigated cores received a total of 400 kg N and 200 kg P plus trace elements applied as fertiliser dressings every 2-3 months to balance nutrients removed in the herbage. Irrigated cores also received additional K+ as there was insufficient K in effluent to meet plant needs (Barton et al. 2005).

The effects of long-term effluent applications on the soil chemical, physical, and biological properties were measured by destructive sampling of 4 replicate cores of each treatment after 2 and almost 4 years after irrigation commenced. Soil was collected by soil horizon, and analysed for pH, total C and N, exchangeable cations, soil respiration, microbial biomass C and N, denitrification enzyme activity (DEA), and potentially mineralisable N. Bulk density, saturated and non-saturated hydraulic conductivity, and soil enzyme activities were measured only on the A or 2 surface horizons. Analyses methods were the same as reported by Barton et al. (2005).

Data presentation and analyses

For simplicity, the data for each soil are presented as equal 2-year periods, although the experimental design was staggered by 1 year and the final 'year' of the experiment for the Allophanic and Recent Soils was nearer 11 than 12 months. Gravimetric soil data from each horizon were converted to an area basis using the bulk density and horizon depth data, and expressed as kg/ha for each soil horizon. Because the lower soil horizons were sometimes of greater depth and mass, the total activity or content of lower horizons expressed on an area basis was sometimes greater than in shallower surface horizons. Where appropriate, data for individual horizons were summed to provide data for the whole profile. Hydraulic conductivity data were non-normally distributed and were log-transformed before statistical analyses.

Treatment differences in soil properties, plant nutrient uptake and nutrient leaching were analysed using General Analyses of Variance in Genstat 6.2 (VSN International 2002) with treatment structures as split-plot analyses, and blocks as soil horizons within each lysimeter. Treatments were designated as (1) baseline samples (prior to irrigation), (2) non-irrigated (receiving rainfall only), and (3) irrigated (irrigated with wastewater). For each soil, combined standard errors of the difference and degrees of freedom for treatment differences are presented for comparisons between soils, treatments, years, and horizons, as appropriate. In several instances the characteristics of the non-irrigatod cores at year 2 differed significantly from the baseline samples taken immediately after collection (e.g. total C in the A horizon of Pumice and Gley soils). This indicated that the relocation, reseeding and experimental conditions resulted in changes in the soil independent of any irrigation treatment. Further changes in the non-irrigated soils also occurred between years 2 and 4 (e.g. total C in the A horizon of Recent soil). Consequently, to assess changes attributable to the irrigation treatment, the irrigated cores should preferably be compared against the equivalent non-irrigated cores at the same sampling time rather than the baseline values.

Results

Composition of the applied effluent

Characteristics of the wastewater applied to the cores are presented on a kg/ha basis (Table 2). Overall, volumetric and chemical loadings onto all 4 soils were similar. Over the 4-year period, the equivalent of >3700 kg C/ha, >1295 kg N/ha, and >504 kg P/ha was applied to the soils from >94[m.sup.3]/ha of wastewater. Generally, more than half the loading of C and N was in organic forms. The wastewater was slightly alkaline (Table 2).

Changes in soil characteristics

Some changes in soil chemical characteristics were consistent across all 4 soils (Tables 3-6). All irrigated soils showed a rise in pH of up to 1 pH unit relative to the non-irrigated soil. The pH rise was greater in the upper soil horizons. All soils showed a 3-6-fold increase in exchangeable [Na.sup.+]. The increase in exchangeable [Na.sup.+] was markedly greater after 4 years of irrigation than 2 years, and occurred in all soil horizons. In addition to these common trends, there were also some individual trends amongst the different soils. Soil C was significantly lower in the A horizon of the irrigated Gley soil, and when sampled after 4 years, extractable N[H.sub.4.sup.+] was higher in all horizons of the irrigated treatment (Table 4). In the Recent sand, total C contents in the A horizon of the irrigated soils were significantly lower than in the non-irrigated soils when sampled after 2 and 4 years, and exchangeable [Mg.sup.2+] and [K.sup.+] were higher (Table 6). We were unable to detect any significant change in the total amounts of N and P stored in any of the soils (data not presented).

The 4 soils showed no consistent changes in biochemical characteristics that could be attributed to irrigation with wastewater. The data are not presented here but are available as Accessory Material (from the author or the journal website). Patterns that were shown after irrigation for 2 years were not repeated after 4 years' irrigation, and sometimes showed contrary trends. Characteristics that might have been expected to respond to the increased loading of C, N, and P did not show consistent responses. For example, despite all soils receiving similar P loadings, over 2 years phosphatase activities were increased in the irrigated Pumice soil, were unchanged in the Gley and Allophanic soils and lowered in the irrigated Recent soil. Anaerobic mineralisable N contents showed no consistent trends. Microbial biomass contents were lower in the irrigated Pumice and Recent Soils compared to the non-irrigated soil (Accessory tables 1, 4) but were unchanged or variable in the Gley and Allophanic soils (Accessory tables 3, 4). Respiration rates were variable and were not responsive to wastewater irrigation, while DEA and nitrification potential remained consistently low under all treatments.

After 2 years of wastewater irrigation, the saturated conductivity of the surface horizon of the Gley soil was significantly lower than the non-irrigated soil (Table 7). Other soils showed no significant change. After 4 years of irrigation, both the saturated and near-saturated hydraulic conductivity of the surface horizon of the Gley soil were markedly less than the non-irrigated. Other soils showed no significant changes after 4 years irrigation.

Herbage production

Wastewater irrigation significantly increased the annual and total herbage production, and N and P uptake in all soils (Table 8). Total herbage production over 4 years ranged from <18.2 Mg DM/ha on non-irrigated soils to >63.5 Mg DM/ha on the soils irrigated with wastewater. Dry matter production and uptake of N and P were greatest on the Allophanic soil, with and without irrigation. The proportional response to irrigation was greatest on the Recent sandy soil.

Wastewater renovation and leaching

The volumes of leachate draining from the 4 soils were generally similar, ranging from 94 to 107 [m.sup.3]/ha over 4 years (Table 9). Volumes draining from the irrigated cores were 3-4 times greater than the non-irrigated cores. The leachate draining from the irrigated cores was of higher pH than the non-irrigated cores. The Recent soil leached considerable amounts of N and P from both the irrigated (307kgN/ha, 41 kg P/ha) and non-irrigated cores (74 kg N/ha, 8.2 kg P/ha). This soil also leached the greatest amounts of C. For all soils, about half of the C and N leached from irrigated and non-irrigated cores were in organic forms (Table 9). Concentrations of nitrate in the leachate were generally low (<2 mg/L), there were occasional higher 'spikes' but these never exceeded 10 mg/L. More than half of the N leached was in organic form (Table 9).

Over the 4 years, about 1.3 Mg N/ha and about 0.5 Mg P/ha, respectively, were applied to the irrigated cores (Table 10), and 400 kg N and 200 kg P to the non-irrigated cores (as fertiliser to replace nutrients removed in herbage). A total of 290 kg and 307 kg N from wastewater were leached from the Gley and Recent soils, respectively; this represents approximately 20% of that applied. In contrast, <5% of the wastewater N (69 and 44 kg, respectively) was leached from the irrigated Pumice and Allophanic soils. The Recent non-irrigated soil leached 74 kg N over 4 years, this being 19% of the fertiliser applied. That figure will be an overestimate as some of the N leached from this soil will have been derived from the breakdown of soil organic matter. The Allophanic non-irrigated soil leached 5 kg N, about 5% of the amount applied (Table 10).

The patterns were similar for leaching losses of phosphorus. The irrigated Gley and Recent soils leached a total of 66 and 41 kg P, respectively, whereas the Pumice and Allophanic soils leached <5kg P. Over 4 years, about 8.5kg P leached from the non-irrigated Gley and Recent soils and <3 kg P from the Pumice and Allophanic Soils (Table 10).

Discussion

Changes in soil characteristics

All irrigated soils showed a moderate rise in soil pH and a much increased exchangeable cation content, particularly exchangeable [Na.sup.+]. Compared to the equivalent non-irrigated soil, the irrigated Gley clay soil had markedly lower hydraulic conductivity, and the irrigated Gley and Recent soils had lower total C and microbial biomass C in the A horizons than the equivalent non-irrigated soil. A small rise in soil pH is common for soils irrigated with wastewater, and even tertiary-treated effluents can raise soil pH (Schipper et al. 1996). The small rise in pH was unlikely to have had adverse effects on pasture production or soil biology, and adverse effects would be compensated by the increased supply of water and nutrients.

Of greater concern were the large increases in exchangeable [Na.sup.+] contents of the irrigated cores, which have the potential to cause clay deflocculation and decrease soil hydraulic conductivity (Menneer et al. 2001; Rengasamy 2002). A decrease in hydraulic conductivity was only observed in the Gley Soil. This soil differed from the others in being poorly drained and having a higher total clay content dominated by smectite clays (Aislabie et al. 2001; McLeod et al. 2001). We were surprised by the high level of exchangeable [Na.sup.+] accumulating in irrigated cores, and have presumed it derived from the added wastewater. In retrospect, [Na.sup.+] concentrations of the wastewater and leachates would have been useful additional characteristics to monitor. We did not include [Na.sup.+] in our suite of measures because most municipal and domestic sewage effluents in New Zealand are reported to have low [Na.sup.+] contents, and [Na.sup.+] accumulation in soil is usually not an issue (Potts and Ellwood 2000). The risk of applied [Na.sup.+] causing adverse effects on soils is moderated by the cation exchange capacity, and soils with high CEC are less susceptible to structural degradation (Potts and Ellwood 2000; Snow et al. 1998). However, when the exchangeable [Na.sup.+] content of our soils was calculated as the exchangeable sodium percentage (ESP, exchangeable Na/sum of all exchangeable cations), the levels in the Gley soil were similar to those in Allophanic and Recent soils (0.7-2.8% in the non-irrigated, 3.9-8.8% in the irrigated). The Pumice soil had the highest ESP (3.8-6.5% in the nonirrigated soil, 7.2-22.1% in the irrigated soil). An ESP of 15% has been suggested as the level above which soil structure could be adversely affected (Potts and Ellwood 2000). The irrigated Pumice soil had a maximum ESP of >22%, but showed no significant decrease in hydraulic conductivity. In contrast, the Gley Soil with an ESP of 3.9-5.0% in the irrigated cores, showed a marked decrease in hydraulic conductivity. Snow et al. (1998) considered that damage to soil structure could occur at ESP <15% and that heavy clays and silts would be more susceptible than free-draining pumice soils. Our results are consistent with those views. Menneer et al. (2001) noted that effluent high in [Na.sup.+], as well as causing deflocculation and loss of hydraulic conductivity, could also cause some dissolution of soil organic matter. This mechanism, as well as greater mineralisation because of the enhanced nutrient and moisture levels, may also have contributed to the lower total C in the irrigated Recent and Gley Soils. However, a considerable decline in soil C also occurred in non-irrigated cores of the Recent Soil, showing this sandy Recent Soil was susceptible to organic matter loss and mineralisation. The loss of C from soils is of concern as this could contribute to a deterioration of soil structure, decreased cation exchange, decreased biological activity, and less capacity to store N in organic matter.

A loss of soil C and a decline in microbial C in surface horizons of soil irrigated with dairy factory effluent was noted by Degens et al. (2000). However, they reported an accumulation of C at lower soil depths. On our soils irrigated with municipal effluent the loss of soil C was greatest in the A horizon of Recent sand, but there was no accumulation lower in the profile. A substantial amount of the C in the leachate was in organic forms, and some of which may have been solubilised from the soil organic C. Barton et al. (2005) commented on the high proportion of organic C, N, and P in the leachate from these soils after 2 years. Their observations are confirmed by our present findings where, over the 4 years of monitoring, more than half of the N and P leached were in organic form. These organic forms may ultimately be mineralised to inorganic forms and contribute to total environmental load. We concur with Barton et al. (2005) that it is important to include the organic fraction to get a true measure of nutrient loading from wastewaters and leachate.

Biochemical characteristics were not useful monitoring tools in this study. When organic C is lost from soils, there is commonly an accompanying loss of microbial C and other microbial characteristics (Wardle 1998). The biochemical characteristics we measured were no more responsive to irrigation than were the more general soil characteristics, and showed inconsistent trends. Speir (2002) reviewed the effects of effluent irrigation on the biochemical properties of New Zealand soils and concluded that changes generally occurred slowly unless a severe adverse effect was observed. Sparling et al. (2003) noted that biochemical characteristics (microbial biomass, soil enzyme activities) of eroded soils during the recovery phase were no more responsive than general chemical characteristics such as total C and total N.

Wastewater treatment

Overall, the 4-year trial clearly demonstrated the contrasting strengths and weaknesses of the different soils in terms of their suitability for the land application of municipal wastewater. The trends in leachate volumes and composition from the different soils confirm those reported after 2 years by Barton et al. (2005). The Allophanic Soil was the most effective in retaining nutrients within the soil profile for herbage production and to minimise leaching losses. The low amounts leached (<3% N and <1% P applied) can be attributed partly to uptake of N and P by herbage and partly to the high P retention characteristics of Allophanic Soils (Saunders 1968). However, if P was being retained by accumulating in the soil, then it was not detectable as a significant change in total P contents. Of the 4 soils tested, the ability to retain nutrients, combined with high production, low leaching losses, good drainage characteristics and high hydraulic conductivity in the presence of high exchangeable Na, makes the Allophanic Soil the best suited for land treatment of wastewater. The Pumice Soil also performed well over the 4-year period, although leaching losses of N were greater than from the Allophanic Soil.

In contrast, the Gley Soil and the Recent Soil performed poorly compared to the Pumice and Allophanic soils. The Gley Soil leached considerable amounts of N and P, and showed a marked deterioration in hydraulic conductivity over the 4 years of the trial. This soil has poor P retention, and exhibits by-pass flow (McLeod et al. 2001). Poorly draining soils with by-pass flow are not well suited for land treatment of effluents. Application rates must be moderate to avoid ponding and encouraging by-pass flow, otherwise the bulk of solute has minimal contact with the main body of the soil. The design of wastewater irrigation schemes will need to allow for these undesirable traits and adjust application rates and loadings accordingly. Unless monitored and corrected, some deterioration in performance during operation on these soils can also be expected if the effluent composition further decreases hydraulic conductivity.

The free-draining nature of the sandy Recent Soil makes it suitable to accept large volumes of wastewater. However, the concentrations of N and P in the leachate were high, reflecting the minimal N and P retention and rapid passage of solutes through the soil; with less opportunity for plant uptake and microbial breakdown. Wastewater treatment using soils with these characteristics will need to ensure that any nutrients from the wastewater do not reach sensitive water bodies, and cause a decline in quality. It is likely that at least a part of the nutrients leaching from the Recent Soil were derived from enhanced mineralisation of the existing soil organic matter under irrigation rather than coming solely from the applied wastewater.

We used a 'cut and carry' method in this lysimeter experiment where pasture herbage was removed from site and there were no returns from grazing animals. In New Zealand it is the current practice that livestock for human food production are not grazed on pastures irrigated with waters derived from human wastes. This practice is driven by cultural preference and market perceptions, and not connected with food safety or the efficiency of wastewater treatment. However, for other wastewaters, such as those derived from dairy sheds and dairy factories, livestock grazing on irrigated pastures may be acceptable. Urine and dung patches from grazing animals contain high concentrations of nutrients and can be potent sources of N and P in leachates (Silva et al. 1999). Consequently, in pastures receiving both wastewaters and direct deposition from grazing animals, we would anticipate the contrast between the better performing Allophanic and Pumice soils and the poorly performing Gley and Recent soils would be even greater than shown in our study.

Acknowledgments

We thank Waipa District Council for permission to conduct the field trial at their site, and Environment Waikato for financial assistance during the establishment of the trial. Additional technical support was provided by students from the University of Waikato. Science staff from AgResearch, Ruakura and Lincoln Environmental, Hamilton, provided advice on pasture management and irrigation. The New Zealand Foundation for Research Science and Technology provided funding under contracts C09802, C09X0217, and C09X0304.

Manuscript submitted 24 June 2005, accepted 16 December 2005

References

Aislabie J, Smith JJ, Fraser R, McLeod M (2001) Leaching of bacterial indicators of faecal contamination through four New Zealand soils. Australian Journal of Soil Research 39, 1397-1406. doi: 10.1071/SR00086

Barton L, McLay CDA, Schipper LAS, Smith CT (1999) Annual denitrification rates in agricultural and forest soils: A review. Australian Journal of Soil Research 37, 1073-1093.

Barton L, Schipper LA, Barkle GF, McLeod M, Speir TW, Taylor MD, McGill AC, van Schaik AP, Fitzgerald NB, Pandey SP (2005) Land application of domestic effluent onto four soil types: plant uptake and nutrient leaching. Journal of Environmental Quality 34, 635-43.

Cameron KC, Di HJ, McLaren RG (1997) Is soil an appropriate dumping ground for our wastes? Australian Journal of Soil Research 35, 995-1035. doi: 10.1071/S96099

Cameron KC, Smith NP, McLay CDA, Fraser PM, McPherson RJ, Harrison RJ, Harbottle P (1992) Lysimeters without edge flow: an improved design and sampling procedure. Soil Science Society of America Journal 56, 1625-1628.

Degens BP, Schipper LA, Claydon JJ, Russell JM, Yeates GW (2000) Irrigation of an allophanic soil with dairy factory effluent for 22 years: responses of nutrient storage and soil biota. Australian Journal of Soil Research 38, 25-35.

Haynes AR, Mancino CF, Pepper IL (1990) Irrigation of turfgrass with secondary effluent 1. Soil and leachate water quality. Agronomy Journal 82, 939-943.

Hewitt AE (1998) 'New Zealand Soil Classification.' (Landcare Research New Zealand, Ltd: Lincoln, New Zealand)

McLeod M, Schipper LA, Taylor MD (1998) Preferential flow in well drained and poorly drained soils under different overhead irrigation regimes. Soil Use Management 14, 96-100.

McLeod M, Aislabie J, Smith J, Fraser R, Roberts A, Taylor M (2001) Viral and chemical tracer movement through contrasting soils. Journal of Environmental Quality 30, 2134-2140.

Menneer JC, McLay CDA, Lee R (2001) Effects of sodium-contaminated wastewater on soil permeability of two New Zealand soils. Australian Journal of Soil Research 39, 877-891. doi: 10.1071/SR99082

Molloy L (1988) 'Soils in the New Zealand landscape. The living mantle.' (Mallinson Rendell: Wellington, New Zealand)

Polglase PJ, Tompkins D, Steart LG, Falkiner RA (1999) Mineralization and leaching of nitrogen in an effluent irrigated pine plantation. Journal of Environmental Quality 24, 911-920.

Potts R, Ellwood B (2000) Sewage effluent characteristics. In 'New Zealand guidelines for utilisation of sewage effluent on land. Part 2: Issues for design and management'. (Eds LJ Whitehouse, C Wang, MD Tomer) pp. 1-20. (New Zealand Land Treatment Collective and Forest Research: Rotorua, New Zealand)

Rengasamy P (2002) Sodic soils, processes, characteristics and classification. In 'Encyclopedia of soil science'. (Ed. R Lal) pp. 1221-1223. (Marcel Dekker: Basel)

Saunders WMH (1968) Phosphorus. In 'Soils of New Zealand, Part 2. Ch. 7.7'. New Zealand Soil Bureau Bulletin No. 26(2). (Ed. AR Shearer) pp. 95-103. (Government Printer: Wellington, New Zealand)

Schipper LA, Williamson JC, Kettles HA, Speir TW (1996) Impact of land-applied tertiary-treated effluent on soil properties. Journal of Environmental Quality 25, 1073-1077.

Silva RG, Cameron KC, Di HJ, Hendry T (1999) A lysimeter study of the impact of cow urine, dairy shed effluent, and nitrogen fertiliser on nitrate leaching. Australian Journal of Soil Research 37, 357-369.

Snow VO, Bond WJ, Smith C J, Falkiner RA (1998) 'Fate of salts in soils. Land application of agro-industrial wastes.' New Zealand Land Treatment Collective Technical Review No. 17. (Blenheim NZLTC: Rotorua, New Zealand)

Soil Survey Staff (1996) 'Keys to Soil Taxonomy.' 7th edn. USDA-NRCS. (US Government Print Office: Washington, DC)

Sparling GP, Ross D J, Trustrum NA, Arnold G, West AW, Speir TW, Schipper LA (2003) Recovery of topsoil characteristics alter landslip erosion in dry hill country of New Zealand, and a test of the space-for-time hypothesis. Soil Biology and Biochemistry 35, 1575-1586. doi: 10.1016/j.soilbio.2003.08.002

Speir TW (2002) Soil biochemical properties as indices of performance and sustainability of effluent irrigation systems in New Zealand-a review. Journal of the Royal Society of New Zealand 32, 535-553.

Tomer MD, Charleson TH, Smith CT, Barton L, Thorn AJ, Gielen GJHP (2000) Evaluation of treatment performance and process after five years of wastewater application at Whakarewarewa forest New Zealand. In The forest alternative: principles and practices of residual use'. (Ed. CL Henry) pp. 155-162. (College of Forest Resources, University of Washington: Seattle, WA)

VSN International (2002) 'Genstat.' 6th edn. Version 6.2.0.325. (VSN International: Hemel Hempstead, UK)

Wardle DA (1998) Controls of temporal variability of the soil microbial biomass--a global-scale synthesis. Soil Biology and Biochemistry 30, 1627-1637. doi: 10.1016/S0038-0717(97)00201-0

G. P. Sparling (A,E), L. Barton (B), L. Duncan (A), A. McGill (A), T. W. Speir (D), L. A. Schipper (A), G. Arnold (C), and A. Van Schaik (D)

(A) Landcare Research, Private Bag 3127, Hamilton, New Zealand.

(B) School of Plant Biology, The University of Western Australia, Crawley, WA 6009, Australia.

(C) Landcare Research, Private Bag 11052, Palmerston North, New Zealand.

(D) ESR, PO Box 50 348, Porirua, New Zealand.

(E) Corresponding author. Email: sparlingg@landcareresearch.co.nz
Table 1. Selected characteristics of the Pumice, Gley, Allophanic,
and Recent Soils

Soil
Order (A) Soil P
and Soil Drainage and Depth mass retention
Taxonomy (B) texture Horizon (m) Mg/ha (%)

Pumice Soil, Well-drained, A 0-0.10 637 52
Typic loamy sand Bw 0.10-0.23 1045 44
Udivitrand Bc 0.23-0.40 1488 29
 C 0.40-0.70 2644 18

Gley Soil, Poorly Ap 0-0.14 1117 27
Typic drained, Bg1 0.14-0.39 2599 40
Endoaquept clay loam Bg2 0.39-0.70 2965 43

Allophanic Well-drained, A 0-0.18 1206 90
Soil, Typic silt loam Bw1 0.18-0.28 676 98
Hapludand Bw2 0.28-0.63 554 98
 Bw3 0.63-0.70 2312 98

Recent Soil, Well drained, A 0-0.12 1233 2
Typic sand B 0.12-0.22 1447 1.8
Udipsamment Bc 0.22-0.55 4810 2.1
 C 0.55-0.70 2258 2.6

(A) Hewitt (1998).

(B) Soil Survey Staff (1996).

Table 2. Total volume, and total amounts of N, C, and P compounds
in municipal effluent applied to a Pumice, Gley, Allophanic, and
Recent Soil over a 4-year period

 Nitrogen applied (kg/ha)
 Total vol.
Soil ([m.sup.3]/ha) N[H.sub.4]+ N[O.sub.3]-

Pumice 98 464 337
Gley 87 433 282
Allophanic 105.3 635 316
Recent 94.7 534 300
s.e.d. 2.89 19.1 12.3
d.f. 43 46 45

 Nitrogen applied (kg/ha)

Soil Inorg. Org. Total

Pumice 800 654 1454
Gley 715 581 1295
Allophanic 951 625 1576
Recent 834 556 1389
s.e.d. 27.8 15.7 42.9
d.f. 44 41 43

 C applied (kg/ha)

Soil Inorg. Org. Total

Pumice 1539 2645 4184
Gley 1416 2298 3714
Allophanic 1908 2522 4430
Recent 1656 2243 3899
s.e.d. 48.5 72.8 120
d.f. 43 41 42

 P applied (kg/ha)

Soil Reactive Total pH

Pumice 404 532 8.25
Gley 406 504 8.26
Allophanic 560 756 8.09
Recent 492 519 8.10
s.e.d. 11.2 14.3 0.20
d.f. 42 42 42

Table 3. Soil chemical characteristics of Pumice Soil after 0, 2,
and 4 years irrigation with secondary treated municipal wastewater
compared to non-irrigated cores and baseline samples

 C N
 Irrigation
Year treatment Horizon (Mg/ha)

Year 0 Baseline A 37.4 2.90
 Bw 11.1 0.97
 Bc 5.45 0.58
 C 3.62 0.51

Year 2 Non-irrigated A 49.3 3.73
 Bw 18.0 1.33
 Bc 5.26 0.34
 C 1.92 0.027

 Irrigated A 41.7 3.30
 Bw 20.4 1.39
 Bc 6.93 0.44
 C 2.53 0.032

Year 4 Non-irrigated A 42.9 3.35
 Bw 21.4 1.77
 Bc 7.40 0.88
 C 2.71 0.82

 Irrigated A 38.3 3.14
 Bw 14.3 1.38
 Bc 5.43 0.82
 C 3.44 1.02

 s.e.d. (A) 2.19 0.17
 d.f. (A) 59 56

 Irrigation C:N
Year treatment Horizon ratio

Year 0 Baseline A 12.9
 Bw 11.4
 Bc 9.5
 C 7.0

Year 2 Non-irrigated A 13.3
 Bw 13.7
 Bc 17.1
 C 71.1

 Irrigated A 12.7
 Bw 14.4
 Bc 16.5
 C 90.9

Year 4 Non-irrigated A 12.8
 Bw 12.1
 Bc 8.3
 C 3.4

 Irrigated A 12.2
 Bw 10.3
 Bc 6.6
 C 3.4

 s.e.d. (A) 5.5
 d.f. (A) 60

 Extract. N (kg/ha)
 Irrigation
Year treatment Horizon N[H.sub.4] + -N N[O.sub.3] - -N

Year 0 Baseline A 2.9 1.6
 Bw 1.0 0.8
 Bc 1.3 0.2
 C 1.3 0.0

Year 2 Non-irrigated A 2.6 0.5
 Bw 0.2 0.2
 Bc 0.4 0.1
 C 0.7 0.0

 Irrigated A 3.7 0.7
 Bw 0.4 0.0
 Bc 0.4 0.0
 C 0.7 0.0

Year 4 Non-irrigated A 0.6 0.0
 Bw 0.6 0.0
 Bc 0.8 0.0
 C 0.4 0.0

 Irrigated A 6.4 1.5
 Bw 4.8 0.0
 Bc 6.6 0.0
 C 2.2 0.0

 s.e.d. (A) 2.37 0.40
 d.f. (A) 31 48

 Irrigation
Year treatment Horizon Soil pH

Year 0 Baseline A 5.78
 Bw 6.00
 Bc 6.15
 C 6.51

Year 2 Non-irrigated A 5.33
 Bw 6.04
 Bc 6.33
 C 6.35

 Irrigated A 7.18
 Bw 6.91
 Bc 6.85
 C 6.74

Year 4 Non-irrigated A 5.38
 Bw 5.84
 Bc 6.28
 C 6.48

 Irrigated A 6.78
 Bw 6.54
 Bc 6.60
 C 6.62

 s.e.d. (A) 0.05
 d.f. (A) 49

 Exchangeable cations (cmol/ha)
 Irrigation
Year treatment Horizon Ca Mg

Year 0 Baseline A 764 69.7
 Bw 265 22.9
 Bc 138 15.4
 C 260 31.6

Year 2 Non-irrigated A 1008 135
 Bw 474 48.4
 Bc 263 29.9
 C 360 44.4

 Irrigated A 1995 328
 Bw 501 44.0
 Bc 222 26.4
 C 295 34.0

Year 4 Non-irrigated A 902 110
 Bw 911 58.1
 Bc 763 28.9
 C 804 36.5

 Irrigated A 2115 282
 Bw 436 69.9
 Bc 566 36.1
 C 901 54.3

 s.e.d. (A) 160 23.9
 d.f. (A) 59 58

 Exchangeable cations (cmol/ha)
 Irrigation
Year treatment Horizon K Na

Year 0 Baseline A 64.8 14.1
 Bw 88.7 25.8
 Bc 158 23.0
 C 421 33.3

Year 2 Non-irrigated A 171 50.4
 Bw 147 32.4
 Bc 237 55.0
 C 484 137

 Irrigated A 122 169
 Bw 89.4 163
 Bc 155 179
 C 348 279

Year 4 Non-irrigated A 125 45.0
 Bw 120 42.9
 Bc 235 46.1
 C 674 105

 Irrigated A 132 195
 Bw 65.9 167
 Bc 122 165
 C 341 368

 s.e.d. (A) 55 19.5
 d.f. (A) 58 40

 Olsen P Total P
 Irrigation
Year treatment Horizon (kg/ha)

Year 0 Baseline A 40.7 928
 Bw 2.5 419
 Bc 1.5 149
 C 0.5 364

Year 2 Non-irrigated A 24.4 716
 Bw 4.50 392
 Bc 2.17 231
 C 2.68 380

 Irrigated A 44.9 884
 Bw 3.20 473
 Bc 2.12 282
 C 1.90 376

Year 4 Non-irrigated A 20.9 690
 Bw 5.72 482
 Bc 2.38 277
 C 2.84 406

 Irrigated A 31.0 787
 Bw 7.21 394
 Bc 3.59 237
 C 5.48 434

 s.e.d. (A) 3.5 55
 d.f. (A) 48 47

(A) For comparison between treatments, years, and horizons.

Table 4. Soil chemical characteristics of Gley Soil after 0, 2, and
4 years irrigation with secondary treated municipal wastewater
compared to non-irrigated cores and baseline samples

 C N
 Irrigation
Year treatment Horizon (Mg/ha)

Year 0 Baseline Ap 84.8 7.86
 Bg1 33.1 4.22
 Bg2 23.9 3.16

Year 2 Non-irrigated Ap 69.8 6.29
 Bg1 47.8 4.63
 Bg2 24.2 2.38

 Irrigated Ap 65.7 6.05
 Bg1 43.3 3.74
 Bg2 25.3 2.45

Year 4 Non-irrigated Ap 63.5 5.98
 Bg1 39.5 4.84
 Bg2 23.6 3.21

 Irrigated Ap 49.1 4.91
 Bg1 40.4 4.90
 Bg2 23.6 3.29

 s.e.d. (A) 6.2 4.41
 d.f. (A) 41.7 44.7

 Irrigation C:N
Year treatment Horizon ratio

Year 0 Baseline Ap 10.8
 Bg1 7.8
 Bg2 7.5

Year 2 Non-irrigated Ap 11.1
 Bg1 10.4
 Bg2 10.2

 Irrigated Ap 10.8
 Bg1 11.7
 Bg2 10.4

Year 4 Non-irrigated Ap 10.6
 Bg1 8.2
 Bg2 7.4

 Irrigated Ap 9.9
 Bg1 8.2
 Bg2 7.2

 s.e.d. (A) 0.98
 d.f. (A) 30.3

 Extract. N (kg/ha)
 Irrigation
Year treatment Horizon N[H.sub.4] + -N N[O.sub.3.sup.-] -N

Year 0 Baseline Ap 3.8 13.0
 Bg1 0.5 9.4
 Bg2 2.5 9.2

Year 2 Non-irrigated Ap 1.5 11.4
 Bg1 0.0 7.9
 Bg2 2.1 3.1

 Irrigated Ap 1.1 16.4
 Bg1 0.2 10.0
 Bg2 1.2 3.0

Year 4 Non-irrigated Ap 1.9 16.8
 Bg1 0.7 6.2
 Bg2 2.1 1.8

 Irrigated Ap 29.3 4.9
 Bg1 84.4 2.9
 Bg2 17.7 1.6

 s.e.d. (A) 20.4 3.23
 d.f. (A) 29.6 37.6

 Irrigation
Year treatment Horizon Soil pH

Year 0 Baseline Ap 5.53
 Bg1 5.00
 Bg2 4.77

Year 2 Non-irrigated Ap 5.34
 Bg1 5.33
 Bg2 4.96

 Irrigated Ap 6.22
 Bg1 5.57
 Bg2 5.17

Year 4 Non-irrigated Ap 5.19
 Bg1 4.97
 Bg2 4.73

 Irrigated Ap 6.08
 Bg1 5.44
 Bg2 4.96

 s.e.d. (A) 0.011
 d.f. (A) 39.5

 Exchangeable cations (cmol/ha)
 Irrigation
Year treatment Horizon Ca Mg

Year 0 Baseline Ap 7266 2075
 Bg1 7091 4854
 Bg2 6843 7403

Year 2 Non-irrigated Ap 5890 1370
 Bg1 9052 4547
 Bg2 8236 8160

 Irrigated Ap 5896 1348
 Bg1 8395 4212
 Bg2 8568 7760

Year 4 Non-irrigated Ap 6284 1571
 Bg1 10 930 5082
 Bg2 10 624 8741

 Irrigated Ap 5852 1367
 Bg1 10 978 4864
 Bg2 9798 8007

 s.e.d. (A) 719 374
 d.f. (A) 42.6 34.7

 Exchangeable cations (cmol/ha)
 Irrigation
Year treatment Horizon K Na

Year 0 Baseline Ap 335 116
 Bg1 495 249
 Bg2 710 400

Year 2 Non-irrigated Ap 359 51.1
 Bg1 322 149
 Bg2 447 228

 Irrigated Ap 400 319
 Bg1 396 449
 Bg2 728 533

Year 4 Non-irrigated Ap 401 64.1
 Bg1 301 167
 Bg2 427 270

 Irrigated Ap 203 394
 Bg1 366 745
 Bg2 441 737

 s.e.d. (A) 89.8 61.4
 d.f. (A) 29.5 25.0

 Olsen P Total P
 Irrigation
Year treatment Horizon (kg/ha)

Year 0 Baseline Ap 96.6 2041
 Bg1 30.8 1084
 Bg2 1.9 271

Year 2 Non-irrigated Ap 86.0 1946
 Bg1 25.1 1221
 Bg2 8.7 583

 Irrigated Ap 71.7 1917
 Bg1 34.7 1109
 Bg2 17.1 642

Year 4 Non-irrigated Ap 95.1 1773
 Bg1 39.2 1097
 Bg2 20.0 543

 Irrigated Ap 60.5 1285
 Bg1 41.1 975
 Bg2 18.3 493

 s.e.d. (A) 12.3 191
 d.f. (A) 33.4 32.7

(A) For comparison between treatments, years, and horizons.

Table 5. Soil chemical characteristics of Allophanic Soil after 0,
2, and 4 years irrigation with secondary treated municipal
wastewater compared to non-irrigated cores and baseline samples

 C N
 Irrigation
Year treatment Horizon (Mg/ha)

Year 0 Baseline A 125.32 12.06
 Bw1 24.8 2.26
 Bw2 10.9 0.99
 Bw3 28.4 2.56

Year 2 Non-irrigated A 104.0 9.56
 Bw1 24.1 2.05
 Bw2 12.4 0.98
 Bw3 32.3 2.69

 Irrigated A 105.1 9.68
 Bw1 26.7 2.38
 Bw2 14.5 1.29
 Bw3 28.9 2.47

Year 4 Non-irrigated A 91.5 8.69
 Bw1 23.3 2.13
 Bw2 13.8 1.23
 Bw3 38.1 3.24

 Irrigated A 98.9 9.57
 Bw1 24.2 2.22
 Bw2 9.42 0.89
 Bw3 24.7 2.38

 s.e.d. (A) 4.99 0.459
 d.f. (A) 58.9 58.8

 Irrigation C:N
Year treatment Horizon ratio

Year 0 Baseline A 10.4
 Bw1 11.0
 Bw2 11.1
 Bw3 11.1

Year 2 Non-irrigated A 10.9
 Bw1 11.8
 Bw2 12.7
 Bw3 11.8

 Irrigated A 10.8
 Bw1 11.2
 Bw2 11.3
 Bw3 11.7

Year 4 Non-irrigated A 10.5
 Bw1 10.9
 Bw2 11.2
 Bw3 12.0

 Irrigated A 10.3
 Bw1 10.9
 Bw2 10.5
 Bw3 10.4

 s.e.d. (A) 0.34
 d.f. (A) 60

 Extract. N (kg/ha)
 Irrigation
Year treatment Horizon N[H.sub.4] + -N N[O.sub.3.sup-] -N

Year 0 Baseline A 0.0 42.0
 Bw1 0.0 4.3
 Bw2 0.0 0.4
 Bw3 0.0 0.0

Year 2 Non-irrigated A 0.0 10.1
 Bw1 0.0 0.2
 Bw2 0.0 0.1
 Bw3 0.0 0.2

 Irrigated A 0.5 15.5
 Bw1 0.0 0.5
 Bw2 0.0 0.1
 Bw3 0.0 0.2

Year 4 Non-irrigated A 2.0 3.6
 Bw1 1.1 0.0
 Bw2 0.8 0.0
 Bw3 2.7 0.0

 Irrigated A 2.8 6.0
 Bw1 1.0 0.1
 Bw2 0.4 0.1
 Bw3 2.5 0.0

 s.e.d. (A) 0.81 2.5
 d.f. (A) 54.5 58.6

 Irrigation
Year treatment Horizon Soil pH

Year 0 Baseline A 6.34
 Bw1 6.20
 Bw2 6.40
 Bw3 6.58

Year 2 Non-irrigated A 6.40
 Bw1 6.05
 Bw2 6.36
 Bw3 6.62

 Irrigated A 6.56
 Bw1 6.25
 Bw2 6.39
 Bw3 6.66

Year 4 Non-irrigated A 6.14
 Bw1 6.09
 Bw2 6.34
 Bw3 6.53

 Irrigated A 6.29
 Bw1 6.48
 Bw2 6.51
 Bw3 6.42

 s.e.d. (A) 0.17
 d.f. (A) 24.7

 Exchangeable cations (cmol/ha)
 Irrigation
Year treatment Horizon Ca Mg

Year 0 Baseline A 9816 492
 Bw1 1130 56.4
 Bw2 858 49.3
 Bw3 4481 233

Year 2 Non-irrigated A 6072 343
 Bw1 810 39.8
 Bw2 791 38.6
 Bw3 3926 175

 Irrigated A 5847 471
 Bw1 635 57.9
 Bw2 571 39.2
 Bw3 3626 172

Year 4 Non-irrigated A 6019 396
 Bw1 982 58.8
 Bw2 858 49.8
 Bw3 3938 227

 Irrigated A 6082 477
 Bw1 1011 98.5
 Bw2 658 63.9
 Bw3 3243 192

 s.e.d. (A) 644 40.9
 d.f. (A) 56.1 52.4

 Exchangeable cations (cmol/ha)
 Irrigation
Year treatment Horizon K Na

Year 0 Baseline A 170 55.5
 Bw1 24.2 10.1
 Bw2 15.6 9.1
 Bw3 52.9 52.6

Year 2 Non-irrigated A 166 40.8
 Bw1 26.8 23.1
 Bw2 20.8 16.7
 Bw3 51.0 64.0

 Irrigated A 88.1 217
 Bw1 24.5 71.9
 Bw2 12.3 62.1
 Bw3 86.4 236

Year 4 Non-irrigated A 85.8 47.8
 Bw1 15.9 25.5
 Bw2 4.0 19.7
 Bw3 29.6 87.9

 Irrigated A 45.4 292
 Bw1 11.6 105
 Bw2 10.9 70.1
 Bw3 38.3 337

 s.e.d. (A) 30.2 11.8
 d.f. (A) 39.4 58.5

 Olsen P Total P
 Irrigation
Year treatment Horizon (kg/ha)

Year 0 Baseline A 12.2 3427
 Bw1 1.06 327
 Bw2 0.79 n.d.
 Bw3 0.97 958

Year 2 Non-irrigated A 14.83 2698
 Bw1 1.93 611
 Bw2 1.32 372
 Bw3 5.16 1186

 Irrigated A 17.4 2820
 Bw1 2.18 661
 Bw2 1.37 422
 Bw3 8.12 1041

Year 4 Non-irrigated A 7.14 2352
 Bw1 0.81 590
 Bw2 0.48 386
 Bw3 1.44 1094

 Irrigated A 12.1 2744
 Bw1 1.22 592
 Bw2 0.55 277
 Bw3 1.32 794

 s.e.d. (A) 1.86 140
 d.f. (A) 58 47.6

n.d., Not detected.

(A) For comparison between treatments, years, and horizons.

Table 6. Soil chemical characteristics of Recent Soil after 0, 2,
and 4 years irrigation with secondary treated municipal wastewater
compared to non-irrigated cores and baseline samples

 C N
 Irrigation
Year treatment Horizon (Mg/ha)

Year 0 Baseline A 38.3 2.99
 Bw1 12.9 1.07
 Bw2 9.93 0.65
 C 2.45 0.12

Year 2 Non-irrigated A 42.1 3.11
 Bw1 7.74 0.45
 Bw2 8.38 0.46
 C 2.93 0.09

 Irrigated A 23.9 1.86
 Bw1 4.38 0.27
 Bw2 7.04 0.38
 C 2.19 0.10

Year 4 Non-irrigated A 29.7 2.58
 Bw1 5.17 0.51
 Bw2 8.97 0.98
 C 2.76 0.28

 Irrigated A 15.7 1.45
 Bw1 5.96 0.65
 Bw2 9.04 1.29
 C 2.29 0.29

 s.e.d. (A) 4.82 0.38
 d.f. (A) 60 60

 Irrigation C:N
Year treatment Horizon ratio

Year 0 Baseline A 12.7
 Bw1 12.0
 Bw2 15.2
 C 20.7

Year 2 Non-irrigated A 13.7
 Bw1 16.7
 Bw2 18.8
 C 30.8

 Irrigated A 12.9
 Bw1 16.8
 Bw2 18.9
 C 22.2

Year 4 Non-irrigated A 11.3
 Bw1 10.3
 Bw2 9.3
 C 10.2

 Irrigated A 10.8
 Bw1 9.2
 Bw2 7.0
 C 8.1

 s.e.d. (A) 2.03
 d.f. (A) 60

 Extract. N (kg/ha)
 Irrigation
Year treatment Horizon N[H.sub.4] + -N N[O.sub.3.sup.-] -N

Year 0 Baseline A 0.0 44.5
 Bw1 0.0 49.4
 Bw2 0.0 163.0
 C 0.0 74.5

Year 2 Non-irrigated A 0.0 4.5
 Bw1 0.0 0.2
 Bw2 0.0 0.8
 C 0.0 0.3

 Irrigated A 3.3 6.9
 Bw1 0.0 4.5
 Bw2 0.0 13.0
 C 0.0 5.3

Year 4 Non-irrigated A 0.5 0.4
 Bw1 0.1 0.0
 Bw2 0.0 0.0
 C 0.0 0.1

 Irrigated A 6.3 2.0
 Bw1 0.8 0.2
 Bw2 1.1 0.4
 C 1.5 0.0

 s.e.d. (A) 3.65 1.31
 d.f. (A) 47 53

 Irrigation
Year treatment Horizon Soil pH

Year 0 Baseline A 6.38
 Bw1 6.51
 Bw2 6.67
 C 6.69

Year 2 Non-irrigated A 6.12
 Bw1 6.12
 Bw2 6.30
 C 6.43

 Irrigated A 6.68
 Bw1 6.70
 Bw2 6.87
 C 6.72

Year 4 Non-irrigated A 5.83
 Bw1 6.27
 Bw2 6.54
 C 6.61

 Irrigated A 6.97
 Bw1 6.96
 Bw2 6.93
 C 6.96

 s.e.d. (A) 0.10
 d.f. (A) 47

 Exchangeable cations (cmol/ha)
 Irrigation
Year treatment Horizon Ca Mg

Year 0 Baseline A 2928 641
 Bw1 729 171
 Bw2 1696 458
 C 763 215

Year 2 Non-irrigated A 2356 552
 Bw1 757 180
 Bw2 1906 534
 C 885 250

 Irrigated A 2276 477
 Bw1 529 180
 Bw2 1882 559
 C 809 239

Year 4 Non-irrigated A 1661 379
 Bw1 740 172
 Bw2 2204 527
 C 976 254

 Irrigated A 1744 266
 Bw1 811 223
 Bw2 2140 692
 C 975 266

 s.e.d. (A) 309 69.6
 d.f. (A) 60 60

 Exchangeable cations (cmol/ha)
 Irrigation
Year treatment Horizon K Na

Year 0 Baseline A 157 32.9
 Bw1 106 16.7
 Bw2 462 50.9
 C 200 24.8

Year 2 Non-irrigated A 156 4.9
 Bw1 113 7.8
 Bw2 407 17.3
 C 216 6.4

 Irrigated A 83.4 67.2
 Bw1 76.8 27.3
 Bw2 322 181
 C 174 102

Year 4 Non-irrigated A 86.5 21.3
 Bw1 110 18.8
 Bw2 410 47.1
 C 278 43.9

 Irrigated A 47.6 91.4
 Bw1 72.4 68.1
 Bw2 304 195.4
 C 138 115

 s.e.d. (A) 49.7 20.6
 d.f. (A) 60 59

 Olsen P Total P
 Irrigation
Year treatment Horizon (kg/ha)

Year 0 Baseline A 16.0 493
 Bw1 21.4 331
 Bw2 35.1 1714
 C 8.5 586

Year 2 Non-irrigated A 34.8 638
 Bw1 21.9 455
 Bw2 39.3 1294
 C 8.7 592

 Irrigated A 31.6 624
 Bw1 23.0 450
 Bw2 41.6 1227
 C 9.11 587

Year 4 Non-irrigated A 34.6 568
 Bw1 17.3 491
 Bw2 33.4 1475
 C 12.7 715

 Irrigated A 26.7 537
 Bw1 22.5 544
 Bw2 45.5 1583
 C 10.9 718

 s.e.d. (A) 5.47 47.3
 d.f. (A) 52 38

(A) For comparison between treatments, years, and horizons.

Table 7. Saturated hydraulic conductivity ([K.sub.SAT]) and near
saturated hydraulic conductivity ([K.sub.-40]) of topsoils of Pumice,
Gley, Allophanic, and Recent Soils after 2 and 4 years irrigation
with secondary treated municipal wastewater

 [K.sub.SAT]
Soil Year Non-irrigated Irrigated Sign.

Pumice 2 71 316 n.s.
 4 139 245 n.s.
Gley 2 200 133 **
 4 567 56 ***
Allophanic 2 48 21 n.s.
 4 258 92 n.s.
Recent 2 493 218 n.S.
 4 354 n.s. n.s.

 [K.sub.-40]
Soil Non-irrigated Irrigated Sign.

Pumice 44 72 n.s.
 65 63 n.s.
Gley 48 10 n.s.
 40 3 ***
Allophanic n.d. n.d.
 38 25 n.s.
Recent n.d. n.d.
 124 160 n.s.

n.d., Not determined.

** P [less than or equal to] 0.01, 0.01.

*** P [less than or equal to] 0.001: significantly
different from the non-irrigated treatment for that
year.

n.s., not significant at P = 0.05.

Table 8. Herbage dry matter production and N and P uptake (kg/ha) from
non-irrigated Pumice, Gley, Allophanic, and Recent soils and after 2
and 4 years of irrigation with secondary treated municipal wastewater
(50 mm per week)

 Non-irrigated

Soil Year Dry matter N P

Pumice 2 8621 159 28
 4 9589 158 30
 Total 18 210 317 57

Gley 2 10 513 178 37
 4 17 509 227 42
 Total 28 022 405 79

Allophanic 2 18 532 357 62
 4 16 804 229 47
 Total 35 336 586 109

Recent 2 11 803 157 39
 4 5710 127 18
 Total 17 513 284 58

s.e.d. (24 d.f.) Total 3222 61.8 12.5

 Irrigated

Soil Year Dry matter N P

Pumice 2 17 141 389 74
 4 26 315 525 98
 Total 43 456 914 173

Gley 2 15 427 248 41
 4 34 165 526 104
 Total 49 592 774 145

Allophanic 2 32 708 734 124
 4 30 836 646 112
 Total 63 544 1380 236

Recent 2 33 968 652 162
 4 24 443 559 95
 Total 58 411 1211 257

s.e.d. (24 d.f.) Total 3222 61.8 12.5

Table 9. Total volume ([m.sup.3]/ha) and amounts (kg/ha) of N, C, and
P leached from Pumice, Gley, Allophanic, and Recent Soil irrigated or
non-irrigated with secondary-treated municipal wastewater for 4 years

Soil Treatment Volume pH Organic N

Pumice Irrigated 104.9 7.7 44.6
 Non-irrigated 23.9 6.2 8.8

Gley Irrigated 92.2 7.1 203.9
 Non-irrigated 29.8 5.1 16.7

Allophanic Irrigated 106.9 7.9 24.5
 Non-irrigated 22.0 6.2 4.2

Recent Irrigated 94 7.8 228.1
 Non-irrigated 29 6.4 59.7
 s.e.d. 2.69 0.21 5.86
 d. f. 91 79 88

Soil Treatment Total N Organic C Total C

Pumice Irrigated 69.3 546 1486
 Non-irrigated 20.4 86.1 159

Gley Irrigated 290.2 1339 1735
 Non-irrigated 26.5 206.2 225

Allophanic Irrigated 44 173.7 1450
 Non-irrigated 5.3 36.9 146

Recent Irrigated 307.1 3278 3975
 Non-irrigated 74.1 879 967
 s.e.d. 10.8 56.9 67.2
 d. f. 81 96 96

Soil Treatment Reactive P Total P

Pumice Irrigated 1.81 4.34
 Non-irrigated 1.56 2.76

Gley Irrigated 28.49 65.6
 Non-irrigated 4.85 8.5

Allophanic Irrigated 1.78 4.71
 Non-irrigated 0.2 0.84

Recent Irrigated 31.6 40.9
 Non-irrigated 5.75 8.17
 s.e.d. 2.66 3.3
 d. f. 87 96

Table 10. Total N and P (kg/ha) applied to Pumice, Gley,
Allophanic, and Recent soils over a 4-year period, and
the amounts removed in herbage and leached from the soils

Values in parentheses show the amount leached as a
percentage of that applied in effluent or fertiliser

 Irrigated
 cores
 Applied in Removed in Leached
Soil effluent herbage from cores

 Total N (kg/ha)

Pumice 1454 914 69 (5%)
Gley 1295 774 290 (22%)
Allophanic 1576 1380 44 (3%)
Recent 1389 1211 307 (21%)
s.e.d. (A) 34.2 61.8 14.2
d.f. 140 24 24

 Total P (kg/ha)

Pumice 535 173 4.3 (<1%)
Gley 504 145 65.6 (13.%)
Allophanic 564 236 4.7 (<l%)
Recent 519 256 40.9 (8%)
s.e.d. (A) 11.5 12.5 3.4
d.f 140 24 24

 Non-
 irrigated
 cores Leached
 Applied as Removed from
Soil fertiliser in herbage cores

Pumice 400 317 20.4 (5%)
Gley 400 405 26.5 (7%)
Allophanic 400 586 5.3 (1%)
Recent 400 284 74.1 (19%)
s.e.d. (A) 61.8 14.2
d.f. 24 24

Pumice 200 57.3 2.8 (1%)
Gley 200 79.1 8.5 (4%)
Allophanic 200 109 0.8 (05%)
Recent 200 57.6 8.2 (4%)
s.e.d. (A) 12.5 3.4
d.f 24 24

(A) For comparison of values between soils
within each irrigated or non-irrigated treatment.
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Author:Sparling, G.P.; Barton, L.; Duncan, L.; McGill, A.; Speir, T.W.; L.A. Schipper; Arnold, G.; Van Scha
Publication:Australian Journal of Soil Research
Geographic Code:8NEWZ
Date:Mar 15, 2006
Words:9311
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