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    Environmental management perspectives of soil fluoride in New Zealand's agricultural soils : a thesis presented in partial fulfilment of the requirements for the degree of Master in Environmental Management at the Institute of Agriculture and Environment, Massey University, Palmerston North, Manawatu, New Zealand
    (Massey University, 2017) Alborno Jover, Patricia María Ysabel
    The prolonged use of phosphate (P) fertilisers has inherited an accumulation of F in topsoils and it is considered to be building up in most of New Zealand’s (NZ) agricultural soils. New Zealand research into soil F has been hampered by the lack of a reliable and simple test for soil F. The accuracy of different methods to quantify the presence of F in analytical preparations is dependent on interfering elements such as the aluminium (Al) content of the sample. Thecconventional methodology of NaOH fusion with an ion-specific electrode method is considered to be time consuming, expensive and very dependent on the abilities of the operating technician, thus it is not ideal for environmental monitoring. To improve the traditional method, an alternative technique to the standard fusion protocol was developed by the Fertilizer & Lime Centre Research (FLRC), Massey University, and that found that simple extraction of soil with dilute sodium hydroxide four molar (NaOH 4M) consistently reported 80% of the total soil F across volcanic soils. The initial FLRC initial work was further examined in this research to confirm the repeatability of the NaOH extraction technique to quantify soil F in a range of NZ soil orders. Also, to assess the relative accuracy of the NaOH extraction technique across different NZ soil orders by comparing different NaOH concentrations. The main aim was to compare different methods and NaOH concentrations to determine total soil F on a representative range of soil orders collected from 13 agricultural sites with a longterm P fertiliser application background. The variability between soils orders was assessed as a function of soil properties. Furthermore, microbiological analyses were performed to assess the impacts of total F, as determined by NaOH extraction method, on soil microbial activity. This study also provides a discussion on the environmental management implications of the emerging F issue in the NZ pastoral land. The total soil F concentration across seven different soil orders ranged between 152 mg F kg-1 and 708 mg F kg-1. The NaOH extraction method showed significant correlation with the alkali fusion/ISE technique (r>0.92). The accuracy of the F determination is very dependent on interfering elements such as Al/Fe oxy-hydroxide content, and NaOH 10M extraction method showed the lowest variation within allophane-rich soils compared to the 4M and 16M extractions. Results suggest that the NaOH 10M method can be used for wide-scale environmental studies and monitoring programmes across a variety of New Zealand soils, particularly for Allophanic soils. A significant correlation was found between dehydrogenase enzyme activity (DHA) and the labile or total Al and Fe content (r>82), whereas the microbial biomass carbon (Cmic) was positively correlated with the non-labile Al and Fe fraction in soils (r>0.89). These findings indicate that these microbial parameters can be used for environmental monitoring programmes. The DHA can be used to assess the effects of the labile F to microorganisms and the Cmic variable could be used as an indicator of the total F effects to livestock.
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    The effect of land disposal of dairy factory wastes on soil properties : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Soil Science, Massey University
    (Massey University, 1978) McAuliffe, Keith William
    Many New Zealand dairy factories dispose of their wastewater by spray irrigating onto pasture. Little is known, however, about the effects of this disposal on soil properties. Research was undertaken at three pasture disposal sites in order to determine whether certain soil property changes may have occurred as a result of the wastewater treatment. Of particular interest were those properties related to water movement. Laboratory studies using 'undisturbed' soil cores indicated that dairy factory wastewater can impede soil water movement. A single application of simulated whey effluent resulted in approximately a 50% decrease in saturated hydraulic conductivity (K) within two days. This reduction was observed to be caused by a combination of both physical and biological blockage processes. With repetitive doses of effluent a K decrease of over 99% was induced in some cores. Several cores, particularly those containing earthworms, showed signs of recovery, and in some cores the final hydraulic conductivity value was greater than the initial value. Analyses of soil samples from the disposal and control sites at Te Rehunga and Tokomaru suggest that fifteen years of wastewater irrigation have resulted in marked changes in soil physical, chemical and biological properties. Total carbon and nitrogen levels were found to be significantly higher at the disposal site; for the Te Rehunga site, the differences in the organic matter level down to 600mm represented an increase of 250 000 kg ha-1. Water balances for the Te Rehunga and Longburn sites indicate that, in the absence of wastewater, pasture is likely to be water stressed on average for approximately forty days per year. The water balance also shows that deep percolation will be greatly increased by the wastewater application. The period of maximum deep percolation loss is likely to be September to October at both the Te Rehunga and Longburn disposal sites. The major site management problems encountered at the disposal sites examined occurred as a result of poor soil drainage, pasture burning and pasture pulling. An infiltration problem was observed at the Longburn site and the recently established disposal site at Tokomaru, with two major causes of the low infiltration rate appearing to be blockage from the effluent and pugging; these observations illustrate the need for controlling the effluent application rate, the suspended solids level in the wastewater, and the stock grazing pattern, in order to minimise site drainage problems. A drainage problem over the winter-spring period at Te Rehunga was due to a high groundwater table. Pasture burning was observed at all three disposal sites. The pasture pulling problem at Te Rehunga is the only cited example of such a problem occurring at a dairy factory disposal site. Observations made at the established Te Rehunga and Tokomaru disposal sites show that long term spray irrigation of dairy factory wastewater can occur without inducing undesirable soil property changes. It appears as though considerable benefit can be gained from the wastewater irrigation, particularly in reducing the incidence of water stress in the pasture and decreasing the requirement for fertilizer.
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    Remediation of New Zealand sheep dip sites using biochar and phytoextraction technologies : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science, Institute of Agriculture and Environment, College of Sciences, Massey University, Palmerston North, New Zealand
    (Massey University, 2013) Gregory, Samuel
    The practice of sheep dipping, which subjected livestock to inorganic and organic agricultural pesticides to eradicate pests such as lice and keds, is a historic practice; sheep dipping is no longer practiced in New Zealand today. Animals would be submerged in solid structures known as dips containing chemicals such as arsenicals and organochlorines with the leftover solution pumped onto surrounding soil. The use of pesticides such as these is now banned by law due to their persistence in the environment. Today an estimated 50,000 contaminated sheep dip sites exist in New Zealand representing perhaps the countries’ most significant, but understated, environmental challenge. To determine whether this historic agricultural practice had led to contamination of the environment, an investigation into the extent of contamination resulting from sheep dipping at a known historic dip site in Te Mahia, New Zealand was carried out. Characterisation of the site by arsenic soil concentration mapping revealed that 500 m2 of agricultural land has been contaminated with this metalloid and that arsenic exists at varying high concentrations through the soil profile. Environmental risk from these historic pesticides was established by analysing plant and water samples below the dip site. Staple Maori food varieties such as watercress were significantly contaminated with arsenic while water samples taken from the stream below the dip returned spiked arsenic concentrations. Based on this, it was justified that arsenic/organochlorine contamination would need to be managed to reduce their effect on these food sources. The design of a coupled remediation strategy using phytoextraction and biochar was utilized to reduce remediation times and is the basis of this thesis. Contaminated soil from the site was removed and amended with two types of biochar produced from willow feedstock. These biochars, known as 350°C and 550°C biochar were added into the soil at application rates of 30 t ha-1 and 60 t ha-1. During a series of 180 d glasshouse trials, the phytoextraction of arsenic into Lolium perenne (ryegrass) shoot tissue was analysed along with growth parameters of shoot and root biomass and corresponding response to arsenic at the molecular level. In soil; microbial activity, soil bacterial community, organochlorine concentration, and element dynamics were analysed as a function of biochar amendment. Soil microbial activity, analysed using the dehydrogenase assay (DHA), was significantly increased (P<0.01) under all biochar treatments compared to the control after 180 d during two glasshouse trials. Metagenomic analysis of the soil bacterial community revealed that biochar amended soils were selecting for bacterial species such as Chryseobacterium, Flavobacterium and Dyadobacter and the family Pseudomonadaceae which are known bioremediators of hydrocarbons. This resulted in isomers of the organochlorine hexachlorocyclohexane (HCH), particularly alpha-HCH and gamma-HCH (lindane), undergoing 10-fold and 4-fold reductions in soil concentrations respectively (2.2 mg kg-1 and 0.4mg kg-1) compared to the control (25 mg kg-1 and 1.6 mg kg-1 respectively). Amendment of soil with both biochars also caused a significant reduction (P<0.01) in soil DDT levels. Biochar promoted a 2-fold increase in shoot dry weight (DW) and a 3-fold increase in root DW after 180 d during one glasshouse trial while during the second trial only ryegrass root biomass was significantly increased as a function of biochar amendment. This increase was attributed, at least in part, to the fertility value of biochar. No negative effect of biochar amendments on ryegrass germination was observed. All biochar amendments resulted in significant increases in arsenic concentrations within ryegrass shoot material. Through extrapolation, 350°C biochar amended soils was estimated to have the potential to increase ryegrass sward DW growth by 0.68 t ha-1 compared to ryegrass grown on unamended soils and would correspond to an increase in the extraction of total arsenic by 14,000 mg ha-1 compared to unamended soils and in doing so decrease soil remediation times by over 50 %. Increased arsenic uptake as a function of biochar amendment resulted in increased enzymic activity of components of the antioxidant pathway including SOD and APX in most biochar treatments but across all treatments a reduction in GPX activity was observed. Analysis of specific metabolites utilizing metabolomics also suggest a definitive metabolite profile under biochar amendment compared to contaminated control ryegrass samples. However, there was no significant difference (P<0.05) in chlorophyll content in response to the total arsenic concentration in ryegrass shoot tissue grown on contaminated soil. The observed increases in activity of SOD, APX and steady CAT activity is suggested to be efficiently catalysing the production of harmful ROS in this soil. A 6-month field investigation into the effect of biochar amendment on the extraction of arsenic into a high biomass crop (Salix sp) resulted in significant increases of arsenic in stem biomass as a function of biochar amendment. When data was extrapolated to predict results of a long-term field trial and scale under willow treatment (stem) it was calculated that over 67.7 g of arsenic could be extracted in soils amended with 350°C biochar compared to 5.9 g extracted under control treatment. This could result - assuming a similar rate of extraction with time - in levels of arsenic concentration in soils reaching background concentrations in as little as 6 years, a reduction in remediation times of 92%.
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    Sorption and movement of ionic and non-ionic pesticides in selected soils of New Zealand
    (Massey University, 1994) Baskaran, Sundaram
    There is a growing concern about the persistence of pesticide residues in soils and their subsequent movement to groundwater and surface water. Sorption of pesticide by soil particles is one of the key processes affecting the fate of pesticides in soil. The overall objective of this research was to examine the sorption and movement of ionic (2,4-D, atrazine and metsulfuron methyl) and non-ionic (phorate and terbufos) pesticides in a range of allophanic and non-allophanic soil materials of New Zealand. Firstly, the methods of measuring pesticide in the soil solution were evaluated. The results suggested that radiotracer techniques can be used to measure low concentrations of pesticide in the soil solution during sorption studies. Based on this, the sorption and movement of pesticides was examined using 14C-labelled compounds. Complete recovery of 14C pesticide residues in soils was achieved by direct extraction of soils with a scintillation cocktail, which contained an organic solvent. The effect of drying soils on the sorption and leaching of an inorganic anion (phosphate; P) and organic pesticides (2,4-D and phorate) was examined using field-moist, freeze-dried, air-dried and oven-dried soil samples. Compared to field-moist and freeze-dried, both air-drying and oven-drying of soil increased the sorption of P, but decreased the sorption of pesticides. Solubilization of organic carbon during air-drying and oven-drying may have increased the accessibility of P to sorption sites on the mineral surfaces and thereby increased the sorption. In contrast, the addition of water soluble organic carbon bound onto pesticides in solution and decreased the apparent sorption onto the soil; thereby increasing leaching. Pesticide sorption was measured in a range of allophanic and non-allophanic topsoil and subsoil samples using a batch equilibrium technique. In general, pesticide sorption, as measured by the distribution coefficient (Kd), increased with an increase in octanol-water partition coefficient (Kow) of the pesticide and followed the order: terbufos > phorate > 2,4-D > atrazine > metsulfuron methyl. The Kd values increased with increasing organic carbon content of the soils and when the sorption was normalised to organic carbon (Koc) there was less variation in Koc values between the soils. Removal of organic carbon decreased the sorption of pesticides and the effect was more pronounced with non-ionic than with the ionic pesticides. The results suggest that organic carbon is the principal sorbent for non-ionic pesticides, whereas clay is also contributing to the sorption of ionic pesticides. Multiple regression models were developed to predict pesticide sorption based on soil properties. The existing empirical equations based on Kow values gave unsatisfactory predictions of pesticide sorption in the soils examined. The contribution of different particle size fractions of soils to sorption and desorption of pesticides was examined using two soils with contrasting characteristics. The Kd values decreased in the order: clay > silt > sand. Organic carbon accounted for most of the variation in Kd values between the particle size fractions, and the removal of organic carbon decreased the Kd values of the pesticides. Following four successive extractions with 0.01 M CaCl2,65-90% and 22-75% of the initially sorbed ionic and non-ionic pesticides, respectively were released from the particle size fractions. Greater amounts of pesticides were released from the soil fractions from which organic carbon had been removed than from natural soil fractions and the difference was greater for the non-ionic than the ionic pesticides. Experiments were conducted to examine the effects of different sources of added carbon (peat, sludge, mushroom compost, pig manure and poultry manure), and dissolved organic carbon (DOC) on the sorption and movement of pesticides in soils. Added carbon sources increased the sorption of pesticides and followed the order: peat > sludge > pig manure > mushroom compost > poultry manure. The differences in the effect of carbon addition on the sorption of pesticides may be related to the differences in their effect on DOC and pH of the soil. Premixing DOC with the pesticide solutions decreased the pesticide sorption whereas premixing DOC with soil increased the pesticide sorption. Column studies showed that pesticide mobility was enhanced by the presence of DOC. Column leaching experiments were conducted to examine the movement of pesticides through repacked soil cores (step-function and pulse inputs) and intact cores (step-function input) using two soils with different pesticide sorption capacities. In repacked soil columns, the step-function experiments showed a symmetrical breakthrough curve (BTC) for a non-sorbed solute (3H20) with a sigmoidal shape, whereas there was an asymmetrical BTC with extensive tailing for a sorbed solute (2,4-D). In the pulse experiments the leaching of pesticides decreased with an increase in the Kd values and leaching decreased in the order: terbufos > phoratc > 2,4-D > atrazine. The results from the intact core experiments suggested that both the sorbed (2,4-D) and non-sorbed (3H20) solutes move preferentially through macropores such as worm holes and root channels. The convection-dispersion equation (CDE) either with an equilibrium or a bicontinuum non-equilibrium sorption process was used to simulate the measured effluent BTCs obtained by simultaneous displacement of 3H20 and 2,4-D. The CDE with an equilibrium sorption process failed to simulate the BTC for 2,4-D in repacked and intact soil columns; whereas the CDE with a bicontinuum non-equilibrium sorption process provided a good description of the experimental data. Both chemical (intraorganic matter diffusion) and physical (preferential flow) processes are involved in the non-equilibrium sorption during the movement of pesticides in soil.