This research aims to develop the present knowledge of arid zone rehabilitation by scientifically testing topsoiling and seeding treatments on the Eyre Peninsula, South Australia, in a way that enables the widest application and comparison to other mining leases throughout the arid lands.

The aim of this research is to assess various options for the management of topsoil stockpiles on disturbed lands and to evaluate the viability and germinability over time of the seedbanks in these stockpiles for use in rehabilitation. To predict their success, experimental trials were designed and conducted.

This research aims to develop the present knowledge of arid zone rehabilitation by scientifically testing topsoiling and seeding treatments on the Eyre Peninsula, South Australia, in a way that enables the widest application and comparison to other mining leases throughout the arid lands.

Page xvi is missing from both the electronic and print copy / One-third of the North Island of New Zealand has been identified as requiring increased soil conservation if pastoral farming is to be sustainable. For over 50 years the planting of widely spaced poplar trees (Populus spp.) has been one of the main methods used to control soil erosion on hill pastures. Research has shown that these plantings have successfully decreased soil erosion but their impact on the productivity of pastoral farming has received little research attention. The research that has been undertaken has found poplars can suppress understorey pasture production by up to 40%, suggesting that farmers require more research information on the impact of planting conservation trees on the productivity of their farm if the use of conservation trees is to be more widely adopted on erosion prone land. The objective of this thesis was to provide comprehensive data on the relationship between the range of poplar densities used for soil conservation on the light and soil under poplars, and consequently the effect on understorey pastures. Three field sites on commercial sheep and beef hill farms, in regions with contrasting summer soil moisture availability, Manawatu (one site) and Central Hawke's Bay (two sites), were monitored for two years. Tree stocking rates ranged from 0 to 375 trees/ha. Measurements were based on units of four trees with most measurements either directly below the tree crowns or in the gaps between the trees, but more intensive transect measurements were also made. Photosynthetically active radiation (PAR) and the ratio of red to far red light (R:FR) were measured under the trees and in open pasture controls. Stand density indices used included all the commonly used measures of tree canopies, including digital photography, and stem diameter at breast height (DBH). PAR transmission was inversely related to all of the stand density indices with canopy closure based on digital photographs being the most robust of the indices used. PAR under the trees, relative to open pasture, was greater in the gaps than below tree crowns. Under a completely closed canopy, PAR transmission was reduced to 15-20% and 50-55% of the open pasture in summer and winter, respectively. The RFR under the trees, relative to open pasture, decreased markedly at high stand densities (allowing less than 40% PAR transmission) in summer, but was similar in winter. The change in PAR under the trees was shown to be a major factor limiting pasture growth, particularly directly below the tree crowns. For both summer and winter, canopy closure measured with a standard digital camera was strongly related to stand level PAR transmission (r2=0.88-0.97; P<0.0001) and was also a practical method of measuring canopy closure in the field. The soil measurements confirmed earlier research that soil pH increases under mature poplar trees. There was a 0.2 - 0.7 unit increase in soil pH in the upper 75 mm of soil over both contrasting regions. The soil fertility under the trees in terms of requirements for pasture growth was similar to that of the open pasture with calcium and potassium up to 2.2 and 9.0 quick test units higher in the soil under the trees than in the open pasture, respectively. The direct cause of the increased concentration of some cations under the trees was the annual tree leaf litter. Overall, the soil fertility under the trees had the potential to produce similar pasture production to that of the open pasture with the added advantage of less acid conditions. Averaged over all sites the respective annual net herbage accumulation (ANHA) under poplar canopy closures of 25, 50 and 75 % was estimated from the equations developed to be 77, 60 and 48% of the open pasture. The greatest decrease was directly below the tree crowns where at canopy closures greater than 20% the ANHA was a relatively constant 50% of open pasture. In the vertically projected gap between trees the ANHA decreased by 6.6% relative to open pasture for each 10% increase in canopy closure. At approximately 80% canopy closure there was no difference between the ANHA directly below the trees and in the gap. Pasture net herbage accumulation (NHA) under the trees relative to open pasture was at its lowest in summer and autumn (36% of open pasture under a closed canopy), and at its greatest in early spring before tree canopy leafed out (72% of open pasture under a closed canopy). The botanical composition and feed value of the pasture under the trees was broadly similar to that of the open pasture. The greatest impact of the poplars on the pasture was decreased NHA due to shading. The decrease in NHA directly below mature unpruned poplars is substantial and would decrease farm profitability if the poplar stand density were high over a large area of the farm. The use of poplars for soil conservation is essential but these results show the importance of managing trees through pruning and thinning so that canopy closure is minimised. ANHA under the trees can be maintained at 75% of the open pasture if canopy closure is prevented from exceeding 30-40%.

This study has provided fundamental information on the fate of urine nitrogen (N) when applied to pasture soils. In this work the three pasture soils used were a Bruntwood silt loam (BW), an old well-developed (lime and fertilizer incorporated and farmed for more than 20 years) peat soil (OP) and a young peat (YP) which was less developed (farmed for about 10 years). Initial soil chemical and physical measurements revealed that the peat soils were acidic, had higher cation exchange capacities, had greater carbon:nitrogen ratios and were better buffered against changes in soil pH than the BW soil. However, the BW soil was more fertile with a higher pH. The peat soils had lower bulk densities and higher porosities. Four experiments were performed. In the first experiment ¹⁵N-labelled urine was applied at 500 kg N ha⁻¹ to intact soil cores of the three soils. Treatments imposed were the presence and absence of a water table at two temperatures, 8°C or 23° C, over 11-14 weeks. ¹⁵N budgets were determined. This first experiment showed that the nitrification rate was faster in the BW soil and was retarded with a water table present. Significant leaching of nitrate occurred at 8°C in the BW soil without a water table. This was reduced when a water table was present. Leaching losses of urine-N were lower in the peat soils than in the BW soil. Apparent denitrification losses (i.e. calculated on a total-N recovery basis) ranged from 18 to 48 % of the ¹⁵N-applied with the greatest losses occurring in the peat soils. The second experiment examined denitrification losses, over 30 days, following the application of synthetic urine-N at 420 kg N ha⁻¹ to small soil cores situated in growth cabinets. The effects of temperature (8°C or 18°C) and synthetic urine (presence or absence) were measured on the BW and OP soils. Nitrous oxide (N₂0) measurements were taken from all soil cores and a sub-set of soil cores, at 18°C, had ¹⁵N-labelled synthetic urine-N applied so that ¹⁵N-labelled nitrogen gases could be monitored. This experiment showed that the application of synthetic urine and increased soil temperature enhanced denitrification losses from both soils. Denitrification losses, at 18°C, as ¹⁵N-labelled nitrogen gases accounted for 24 to 39 % of the nitrogen applied. Nitrous oxide comprised less than half of this denitrification loss. Losses of N₂0 in leachate samples from the soil cores accounted for less than 0.1 % of the nitrogen applied. A third experiment, using Iysimeters, was performed over a 150 day period in the field. The six treatments consisted of the 3 soils with applied synthetic urine, with or without a simulated water table; each replicated three times. Lysimeters were installed in the field at ground level and ¹⁵N-labelled synthetic urine-N was applied (500 kg N ha⁻¹) on June 4 1992 (day 1). Nitrification rates differed between the soils following the trend noticed in the first experiment. As in the first experiment, nitrate was only detected in the leachate from the BW soil and the inclusion of a water table reduced the concentration of nitrate. In the BW soil, the leachate nitrate concentrations exceeded the World Health Organisation's recommended limit (< 10 mg N L-1) regardless of water table treatment. No nitrate was detected in the leachates from the peat soils but there was some leaching of organic-N (< 5 % of N added) in all the peat soil treatments. Denitrification losses were monitored for the first 100 days of the experiment. In the BW soil without a water table, N₂0 production peaked at approximately day 20 and accounted for 3 % of the nitrogen applied. In the peat soils the measured denitrification losses accounted for less than 1 % of the nitrogen applied. Apparent denitrification losses in the peats were, however, calculated to be approximately 50 % of the ¹⁵N-labelled synthetic urine-N applied. It is postulated that the difference between apparent denitrification losses and those measured could have been due to; loss of dinitrogen in leachate, protracted production of dinitrogen below detectable limits, production of denitrification gases after measurements ceased (i.e. days 100 to 150) and entrapment of dinitrogen in soil cores. Due to the apparent denitrification losses being so high, further research into this nitrogen loss pathway was performed. The fourth and final experiment measured denitrification directly using highly enriched (50 atom %) ¹⁵N-labelled synthetic urine-N. It was performed in a growth cabinet held initially at 8°C. The ¹⁵N-labelled synthetic urine was applied at 500 kg N ha⁻¹ to small soil cores of each soil type. Fluxes of N₂0 and ¹⁵N-labelled gases were measured daily for 59 days. On day 42 the temperature of the growth cabinet was increased to 12°C in an attempt to simulate the mean soil temperature at the end of the field experiment. Up to this time, production of nitrogenous gases from the YP soil had been very low. Interpretation of gaseous nitrogen loss in the YP soil was difficult due to the possibility of chemodenitrification occurring. However, in the OP and BW soils, gaseous losses of nitrogen (determined as ¹⁵N-labelled gas) represented 16 and 7 % of the nitrogen applied respectively. Nitrous oxide comprised approximately half of this gaseous nitrogen loss, in both the OP and BW soils. This work implies that urine-N applied to the mineral soil (BW) could potentially threaten the quality of ground water due to nitrate contamination through leaching. In contrast, denitrification appears to be the major loss mechanism from the peat soils, with the production of nitrous oxide being the primary focus for any environmental concern. Future work should examine the fate of the nitrate leached from the BW soil and the potential for dilution, plant uptake or denitrification below a 30 cm soil depth. A better understanding of the denitrification mechanisms could help reduce denitrification and thereby improve the efficiency of nitrogen use and reduce the output of nitrous oxide.

This thesis aIms to produce a distinctive model for the sustainable horticultural development of Maori resources, primarily land. It is inclusive of tikanga Maori and indigenous production systems based on the unique body of knowledge aligned to Maori. The integration of this knowledge with western science is both argued and applied through the model itself. The hypothesis applied was that matauranga Maori relevant to horticulture and pedology can inform and add value to the future development of Maori land resources. The thesis is bui lt on a unique set of contributing knowledge bases aligned to soils and horticultural management supported by three case studies, identified through their common association i.e. whakapapa links. The format of the thesis intentionally follows science principles in structure and presentation and some assumptions are made regarding base knowledge surrounding Maori cultural factors and the science disciplines relative to soils and horticul ture. The indigenous element, including Maori knowledge, is incorporated into the model using a triadic kosmos/corpus/praxis approach. Where kosmos is applied as Te A o Miiori, corpus as miitauranga Miiori and praxis as tikanga Miiori, the relationship between each element is clear and the interpretation of the associated knowledge becomes more apparent and can be applied to cultural assessments of resources, i ncluding land. The crux of the cultural assessment model is the quality of information used to assess Maori resources, especially from the cultural perspective. The Maori cultural paradigm, traditional horticulture and pedology, and various decision systems are purposefully accessed to act as contributors to the assessment model and to highlight the diversity and quality of information land managers have at their disposal. The ability to apply a cultural layer drawn from a body of knowledge not previously included in decision models relative to land utility in New Zealand is the key point. of difference of the model. The model is discussed from the perspective of its beneficial role for future use by Maori and how it can be continuously refined to meet the needs of Maori land owners and thus contribute to the rangatiratanga of Maori.

This thesis aIms to produce a distinctive model for the sustainable horticultural development of Maori resources, primarily land. It is inclusive of tikanga Maori and indigenous production systems based on the unique body of knowledge aligned to Maori. The integration of this knowledge with western science is both argued and applied through the model itself. The hypothesis applied was that matauranga Maori relevant to horticulture and pedology can inform and add value to the future development of Maori land resources. The thesis is bui lt on a unique set of contributing knowledge bases aligned to soils and horticultural management supported by three case studies, identified through their common association i.e. whakapapa links. The format of the thesis intentionally follows science principles in structure and presentation and some assumptions are made regarding base knowledge surrounding Maori cultural factors and the science disciplines relative to soils and horticul ture. The indigenous element, including Maori knowledge, is incorporated into the model using a triadic kosmos/corpus/praxis approach. Where kosmos is applied as Te A o Miiori, corpus as miitauranga Miiori and praxis as tikanga Miiori, the relationship between each element is clear and the interpretation of the associated knowledge becomes more apparent and can be applied to cultural assessments of resources, i ncluding land. The crux of the cultural assessment model is the quality of information used to assess Maori resources, especially from the cultural perspective. The Maori cultural paradigm, traditional horticulture and pedology, and various decision systems are purposefully accessed to act as contributors to the assessment model and to highlight the diversity and quality of information land managers have at their disposal. The ability to apply a cultural layer drawn from a body of knowledge not previously included in decision models relative to land utility in New Zealand is the key point. of difference of the model. The model is discussed from the perspective of its beneficial role for future use by Maori and how it can be continuously refined to meet the needs of Maori land owners and thus contribute to the rangatiratanga of Maori.

Trifolium repens, Lotus pedunculatus and Holcus lanatus were oversown on two recent soil slip surfaces at AgResearch’s Ballantrae pastoral hill‐country farm near Woodville. The two slip surfaces were located on (Manamahu steepland soil) sedimentary mudstone. One slip had a north aspect and the other had a south aspect. Both slips were located on a land class 6 with slope 28‐330. The pasture species were oversown during early spring and the percentage seedling emergence and early establishment from viable seeds oversown was analysed at early spring (Day 15), late spring (Day 45), early summer (Day 90), and late summer (Day 120). The slip surfaces showed micro‐climatic extremes in terms of both soil moisture and surface temperatures during the summer period. Significant differences (P < 0.05) were found in soil moisture between north and south facing slip surfaces. Higher soil moisture and lower soil mean temperature were recorded on the south aspect slip surface. Significant differences (P < 0.05) were found between the three pasture species in terms of seedling emergence and early establishment. Significant differences (P < 0.05) were also found with aspect. The south aspect slip surface had a higher percentage of seedling emergence and earlier establishment for all the species. Interaction between species by aspect became significantly different (P < 0.05) at Day 90 and Day 120. The main effects of time and species were also significantly different (P < 0.05) illustrating seedling emergence and establishment as a race against time. Trifolium repens was a more successful pasture specie, than L. pedunculatus and H. lanatus due to its higher consistency on both north and south slip surfaces. Oversowing T. repens during early spring is a viable option for rehabilitation of recent soil slips in Manawatu.

Soil P fractionation was used to examine changes in soil inorganic and organic P under grazed irrigated pasture in a long-term field trial at Winchmore in Mid-Canterbury. The soil P fractionation scheme used involved sequential extractions of soil with O.5M NaHCO₃ @ pH 8.5 (NaHCO₃ P), 0.1M NaOH (NaOH I P), 1M HCl (HCl P) and 0.1M NaOH (NaOH II P). The Winchmore trial comprised 5 treatments: control (no P since 1952), 376R (376 kg superphosphate ha⁻¹ yr⁻¹ 1952-1957, none since), 564R (564 kg superphosphate ha⁻¹ yr⁻¹ 1952-1957, none since) 188PA (188 kg superphosphate ha⁻¹ yr⁻¹ since 1952) and 376PA (376 kg superphosphate ha⁻¹ yr⁻¹ since 1952: Topsoil (0-7.5cm) samples taken from the different treatments in 1958, 1961, 1965, 1968, 1971, 1974 and 1977 were used in this study. Changes in soil P with time showed that significant increases in soil inorganic P occurred in the annually fertilised treatments (l88PA, 376PA). As expected, the overall increase in total soil inorganic P between 1958 and 1977 was greater in the 376PA treatment (159 µg P g⁻¹) than that in the 188PA treatment (37 µg P g⁻¹). However, the chemical forms of inorganic P which accumulated in the annually fertilised treatments changed with time. Between 1958 and 1971 most of the increases in soil inorganic P in these treatments occurred in the NaHCO₃ and NaOH I P fractions. On the other hand, increases in soil inorganic P in the annually fertilised treatments between 1971 and 1977 were found mainly in the HCl and NaOH II P fractions. These changes in soil P forms were attributed to the combined effects of lime addition in 1972 and increased amounts of sparingly soluble apatite P and iron-aluminium P in the single superphosphate applied during the 1970's. In the residual fertiliser treatments (376R, 564R) significant decreases in all of the soil inorganic P fractions (i.e. NaHCO₃ P, NaOH I P, HCl P, NaOH II p) occurred between 1958 and 1977 following the cessation of P fertiliser inputs in 1957. This was attributed to continued plant uptake of P accumulated in the soil from earlier P fertiliser additions. However, levels of inorganic P in the different soil P fractions in the residual fertiliser treatments did not decline to those in the control which indicated that some of the inorganic P accumulated in the soil from P fertiliser applied between 1952 and 1957 was present in very stable forms. In all treatments, significant increases in soil organic P occurred between 1958 and 1971. The overall increases in total soil organic P were greater in the annually fertilised treatments (70-86 µg P g⁻¹) than those in the residual fertiliser (55-64 µg P g⁻¹) and control (34 µg P g⁻¹) treatments which reflected the respective levels of pasture production in the different treatments. These increases in soil organic P were attributed to the biological conversion of native and fertiliser inorganic P to organic P in the soil via plant, animal and microbial residues. The results also showed that annual rates of soil organic P accumulation between 1958 and 1971 decreased with time which indicated that steady-state conditions with regard to net 'organic P accumulation were being reached. In the residual fertiliser treatments, soil organic P continued to increase between 1958 and 1971 while levels of soil inorganic P and pasture production declined. This indicated that organic P which accumulated in soil from P fertiliser additions was more stable and less available to plants than inorganic forms of soil P. Between 1971 and 1974 small (10-38 µg P g⁻¹) but significant decreases in total soil organic P occurred in all treatments. This was attributed to increased mineralisation of soil organic P as a result of lime (4 t ha⁻¹) applied to the trial in 1972 and also to the observed cessation of further net soil organic P accumulation after 1971. Liming also appeared to affect the chemical nature of soil organic P as shown by the large decreases in NaOH I organic P(78-88 µg P g⁻¹) and concomitant smaller increases in NaOH II organic P (53-65 µg P g⁻¹) which occurred in all treatments between 1971 and 1974. The chemical nature of soil organic P in the Winchmore long-term trial was also investigated using 31p nuclear magnetic resonance (NMR) spectroscopy and gel filtration chromatography. This involved quantitative extraction of organic P from the soil by sequential extraction with 0.1M NaOH, 0.2M aqueous acetylacetone (pH 8.3) and 0.5M NaOH following which the extracts were concentrated by ultrafiltration. Soils (0-7.5cm) taken from the control and 376PA annually fertilised treatments in 1958, 1971 and 1983 were used in this study. 31p NMR analysis showed that most (88-94%) of the organic P in the Winchmore soils was present as orthophosphate monoester P while the remainder was found as orthophosphate diester and pyrophosphate P. Orthophosphate monoester P also made up almost all of the soil organic P which accumulated in the 376PA treatment between 1958 and 1971. This indicated that soil organic P in the 376PA and control treatments was very stable. The gel filtration studies using Sephadex G-100 showed that most (61-83%) of the soil organic P in the control and 376PA treatments was present in the low molecular weight forms (<100,000 MW), although the proportion of soil organic P in high molecular weight forms (>100,000 MW) increased from 17-19% in 1958 to 38-39% in 1983. The latter was attributed to the microbial humification of organic P and indicated a shift toward more complex and possibly more stable forms of organic P in the soil with time. Assuming that the difference in soil organic P between the control and 376PA soils sampled in 1971 and 1983 represented the organic P derived from P fertiliser additions, results showed that this soil organic P was evenly distributed between the high and low molecular weight fractions. An exhaustive pot trial was used to examine the relative availability to plants of different forms of soil inorganic and organic P in long-term fertilised pasture soils. This involved growing 3 successive crops of perennial ryegrass (Lolium perenne) in 3 Lismore silt loam (Udic Ustochrept) soils which had received different amounts of P fertiliser for many years. Two of the soils were taken from the annually fertilised treatments in the Winchmore long term trial (188PA, 376PA) and the third (Fairton) was taken from a pasture which had been irrigated with meatworks effluent for over 80 years (65 kg P ha⁻¹ yr⁻¹). Each soil was subjected to 3 treatments, namely control (no nutrients added), N100 and N200. The latter treatments involved adding complete nutrient solutions with different quantities of N at rates of 100kg N ha⁻¹ (N100) and 200kg N ha⁻¹ (N200) on an area basis. The soil P fractionation scheme used was the same as that used in the Winchmore long-term trial study (i.e. NaHCO₃ P, NaOH I P, HCl P, NaOH II p). Results obtained showed that the availability to plants of different extracted inorganic P fractions, as measured by decreases in P fractions before and after 3 successive crops, followed the order: NaHCO₃ P > NaOH I P > HCl P = NaOH II P. Overall decreases in the NaHCO₃ and NaOH I inorganic P fractions were 34% and 16% respectively, while corresponding decreases in the HCl and NaOH II inorganic P fractions were small «10%) and not significant. However, a significant decrease in HCl P (16%) was observed in one soil (Fairton-N200 treatment) which was attributed to the significant decrease in soil pH (from 6.2 to 5.1) which occurred after successive cropping. Successive cropping had little or no effect on the levels of P in the different soil organic P fractions. This indicated that net soil organic P mineralisation did not contribute significantly to plant P uptake over the short-term. A short-term field experiment was also conducted to examine the effects of different soil management practices on the availability of different forms of P to plants in the long-term fertilised pasture soils. The trial was sited on selected plots of the existing annually fertilised treatments in the Winchmore long-term trial (188PA, 376PA) and comprised 5 treatments: control, 2 rates of lime (2 and 4 t ha⁻¹ ) , urea fertiliser (400kg N ha⁻¹ ) and mechanical cultivation. The above ground herbage in the uncultivated treatments was harvested on 11 occasions over a 2 year period and at each harvest topsoil (0-7.5 cm) samples were taken from all of the treatments for P analysis. The soil P fractionation scheme used in this particular trial involved sequential extractions with 0.5M NaHCO₃ @ pH 8.5 (NaHCO₃ P), 0.1M NaOH (NaOH P), ultrasonification with 0.1M NaOH (sonicate-NaOH p) and 1M HCl (HCl P). In addition, amounts of microbial P in the soils were determined. The results showed that liming resulted in small (10-21 µg P g⁻¹) though significant decreases in the NaOH soil organic P fraction in the 188PA and 376PA plots. Levels of soil microbial P were also found to be greater in the limed treatments compared with those in the controls. These results indicated that liming increased the microbial mineralisation of soil organic P in the Winchmore soils. However, pasture dry matter yields and P uptake were not significantly affected. Although urea significantly increased dry matter yields and P uptake, it did not appear to significantly affect amounts of P in the different soil P fractions. Mechanical cultivation and the subsequent fallow period (18 months) resulted in significant increases in amounts of P in the NaHCO₃ and NaOH inorganic P fractions. This was attributed to P released from the microbial decomposition of plant residues, although the absence of plants significantly reduced levels of microbial P in the cultivated soils. Practical implications of the results obtained in the present study were presented and discussed.

A two-year lysimeter study was undertaken to compare the environmental effects (e.g. nitrate leaching and nitrous oxide emissions) of soil applied lactose-depleted dairy factory effluent (LD-DFE) with lactose-rich DFE. The aim of this experiment was to determine the fate of nitrogen from LD-DFE and dairy cow urine applied to a Templeton fine sandy loam soil (Udic Ustrochrept), supporting a herbage cover of ryegrass (Lolium perenne) and white clover (Trifolium repens). Measurements were carried out on the amount of nitrogen lost from the soil via leaching, lost by denitrification, removed by the pasture plants, and immobilized within the soil organic fraction. Further, a comparison between the fate of nitrogen in LD-DFE irrigated onto land under a "cut and carry" system, as opposed to a "grazed" pasture system was undertaken. Lactose-depleted dairy factory effluent was applied at three-weekly intervals during the summer months at rates of 25 and 50 mm, until nitrogen loading targets of 300 and 600 kg N ha⁻¹ yr⁻¹ had been achieved. Measured leaching losses of nitrogen averaged 2 and 7 kg N ha⁻¹ yr⁻¹ for Control 25 and Control 50 treatments; 21, 20 and 58 kg N ha⁻¹ yr⁻¹ for 25 and 50 mm "cut and carry" treatments respectively; and 96 kg N ha⁻¹ yr⁻¹ for the 25 mm "grazed" treatment. The range of nitrate-N leaching loss from LD-DFE plus urine is no different from the lactose-rich DFE nitrate leaching loss. Uptake of nitrogen by the growing pasture averaged 153, 184,340,352,483, and 415 kg N ha⁻¹ yr⁻¹ for Control 25, Control 50, LD-DFE 25 and LD-DFE 50 mm "cut and carry" treatments, and the LD-DFE 25 mm "grazed" treatment, respectively. Denitrification losses were 0.06, 4.4, 1.69, 19.70, and 7.4 kg N ha⁻¹ yr⁻¹ for Control 25, the LD-DFE 25 "cut and carry" treatments, the LD-DFE 25 mm "grazed" treatment, and calculated "paddock losses", respectively. Isotopic nitrogen studies found that 29.4 and 25.8% of applied LD-DFE nitrogen was immobilised in the LD-DFE 25 and LD-DFE 50 "cut and carry" treatments. The results of this experiment confirm the findings of the previous lactose-rich DFE study, in that the effects of grazing stock are of greater environmental concern than the removal of lactose from the effluent waste stream.