1,721,017 research outputs found
Changes in carbon and nitrogen stocks following conversion of plantation forest to dairy pasture on Vitrands (Pumice Soils), New Zealand
Full text linkBetween 1990 and 2010 some New Zealand plantation forests underwent deforestation to establish dairy farms. The main area of land-use conversion to pasture is to the north of Lake Taupo in the Central North Island (Figures 1 and 2). Pinus radiata (radiata pine) plantations were established in the late 1920s-early 1930s because the Vitrands (Pumice Soils) predominant in the Central North Island were deficient in Co and other trace elements, causing a fatal stock disease in sheep and cattle known as ‘bush sickness’. Bush sickness was subsequently rectified in the mid-1930s with the regular addition of Co, so pastoral farming became viable. The high price of milk solids has recently led to renewed interest in dairying. Recent studies have shown carbon can accumulate following deforestation and establishment of pasture (Fearnside and Barbosa, 1998; Murty et al. 2002; Hedley et al. 2009). However, more information on the rate of accumulation of carbon after deforestation is needed. Increases in soil carbon can improve physical and chemical soil properties, and is an important store of global carbon
Impacts of conversion from forestry to pasture on soil physical properties of Vitrands (Pumice Soils) in central North Island, New Zealand
Full text linkTens of thousands of hectares of land have been converted from plantation forest to pasture in the central North Island of New Zealand between 2000 and 2010. The land use change was driven by the perceived better long term returns from dairy farming compared with forestry. Pumice Soils (NZ Soil Classification, equivalent to Vitrands in Soil Taxonomy) in the central North Island are formed on pumice deposited mainly from the AD 232 ± 5 Taupo volcanic eruption. The texture of Pumice Soils (Figure 1) varies from silt to coarse gravel and they have weak structure and erode easily when disturbed. Water holding capacity may be low but increases as the organic matter content of the topsoil is built up
Human,climatic and oceanographic influences on the marine environment of Pohnpei, Federated States of Micronesia
No full textFile PB200200 could not be included in folder EFR1. Full data available on disc with print copy held at the University of Waikato Library.Coral reefs and marine resources are culturally, as well as economically, vital to Pohnpei, situated in the Federated States of Micronesia (FSM). Farming and fishing are the main sources of livelihood for most Pohnpeian communities. Pohnpei has eleven Marine Protected Areas (MPAs) where nine are situated in the Pohnpei Island Lagoon and two MPAs on the outer low-lying atolls. Like many other Pacific Island countries Pohnpei is on the verge of creating more MPAs. However, the marine environment continues to be significantly threatened by human and natural influences. The recognised threats are yet to be methodically investigated.
This thesis used a combination of sediment, coral, fish, climatic, and oceanographic data, and focused on the Pohnpei Lagoon, examining a range of natural and human issues in the marine environment both at the local level (focusing on that within the Pohnpei Lagoon) and regional level (focusing on the western Pacific region).
Evidence from historical, archaeological, and modern experience has influenced various marine impacts that have altered the coastline and the marine environment of the Pohnpei Lagoon. Humans have greatly impacted on the coral diversity and fish populations in the Pohnpei Lagoon by over-fishing and contributing to accelerated sediment inputs. My study findings shows that that increased sea surface temperature (SST) caused by El Ni o events is not the only cause of coral bleaching, but also cooling of SST, and other human factors. However, when corals bleach they recover by symbiont shuffling . This is an ingenious way in which corals host one or more varieties of their zooxanthelle (Symbiodinium symbiont clades) that are more tolerant of the stress caused by increased SST and human factors.
The recognised natural climatic variability, particularly the El Ni o/Southern Oscillation (ENSO), may pose a significant threat to the Pohnpei Lagoon. El Ni o events are associated with: a change in trade winds and stronger wind gusts attributed to typhoons; lower rainfall causing drought; a decrease in SST attributed to cooling of the marine environment; increase of salinity in marine estuaries affecting development and recruitment of marine species communities; and a steep fall in sea level exposing corals to other elements. The various on-going human threats and El Ni o-like conditions have caused giant clams (Tridacna gigas) to become extinct, have endangered herbivorous fish populations, and caused coral bleaching by cooling of SST.
Although high SSTs are normally blamed for coral bleaching, the last major bleaching event in Pohnpei (2002) was likely to be due to a reduction in salinity (freshwater runoff and lower sea level), and there has been strong recovery. However, decreasing water temperatures rather than increases of SSTs may contribute to coral bleaching in the Pohnpei Lagoon and the Micronesian region. The Micronesian region appears to have suffered relatively few episodes of regional coral bleaching events. This is due to the Western Pacific Warm Pool (WPWP) where sea surface temperatures exceed 29 C but also where various feedback mechanisms limit the maximum SSTs.
The management aims of Pohnpei's MPAs are to move forward, while still respecting traditional practices. However, a lack of scientific monitoring, technical support and funding restricts our understanding of human and natural influences on the existing MPAs and the Pohnpei Lagoon. With respect to our policy makers the findings of the present research have implications on the future work in Pohnpei's marine environment and for policy makers, to make more-informed decisions before establishing new MPAs.
My key recommendations were: 1.) Integrate coral and fish monitoring during and after El Ni o events to understand El Ni o effects on the Pohnpei environment. 2.) Undertake herbivorous fish investigation into their populations inside and outside the MPAs. 3.) Do not cut down vegetation along coastline areas, as it prevents erosion 4.) Investigate Symbiodinium coral clades in Pohnpei Lagoon and the outer low-lying atolls
Environmental Assessment of the Effects of Leachate Irrigation and Seepage from the Paokahu Landfill, Gisborne, New Zealand.
No full textPaokahu landfill operated near Gisborne from 1977 to 2002. About 1 million cubic metres of mixed domestic and industrial (predominantly food processing) wastes were disposed of at the site. The Paokahu landfill is located on the Poverty Bay Flats on low lying flat ground, which was originally the base of a tidal lagoon. A 300m wide band of costal dunes separates the landfill from the Poverty Bay coast. The landfill covers an area of approximately 20 Ha and is unlined but fully capped. Leachate is collected in a cut-off drain which surrounds three quarters of the landfill. Disposal of the leachate is by spray irrigation onto the landfill cap with 13,000 - 15,000 m3 of leachate irrigated annually. The site is currently used for grazing sheep.
The overall aim of this study was to improve our understanding of the effect that Paokahu landfill is having on the environment and to determine if the current management practices are sustainable. Specific objectives were to collate and review all the groundwater and leachate monitoring data held by Gisborne District Council to determine if the landfill was affecting the local groundwater and to investigate the effect of leachate irrigation on the landfill cap's soil and vegetation.
The groundwater monitoring data showed the local groundwater was generally affected by salt water intrusions giving the groundwater high anion and cation concentrations. There was no evidence of a leachate plume originating from the landfill and no conclusive evidence of leachate contamination in any of the groundwater monitoring bores.
The leachate had a high electrical conductivity (mean = 9350 Scm-1) and high soluble salts content (mean values, Na = 845 gm-3, K= 496 gm-3, Ca = 240 gm-3, Mg = 127 gm-3, Cl =1346 gm-3). Heavy metals were present in low concentrations and Semi Volatile Organic Compounds were no longer present in the leachate. Cation and anion concentrations were generally higher in the groundwater than in the leachate. The main risk to groundwater quality from leachate contamination was from ammonical nitrogen and nitrate.
The leachate irrigation had caused an increase in soil cation concentrations particularly Na in the landfill cap. However, the soil Exchangeable Sodium Percentage of 1.5 - 2.9, leachate Sodium Adsorption Ratio (6.5) and Electrical Conductivity of (4317 S cm-1) and silty soil material of the landfill cap indicated that soil swelling and dispersion was unlikely to occur in irrigated areas of the landfill cap. Dispersion index testing supported this conclusion with no significant increase in aggregate dispersion under the irrigated areas of the landfill compared to the non-irrigated areas. Soil metal concentrations were low and there was no significant difference in soil heavy metal concentrations between the irrigated and non-irrigated areas of the landfill cap. Leachate Mn concentrations (mean = 1.39 g m-3) were high enough to be potentially toxic to plants, but the soil pH (7.4) and Ca (46.7 me/100g) content mean that Mn toxicity is unlikely to occur. Leachate irrigation appears sustainable under current conditions
Soil and permafrost distribution, soil characterisation and soil vulnerability to human foot trampling, Wright Valley, Antarctica
No full textSoils and shallow permafrost in Wright Valley, Antarctica were mapped at a scale of 1:50 000 to depict their spatial distribution, and sampled to determine the main drivers for the soil classification.
In the cold desert of Wright Valley the Gelisol order of Soil Taxonomy was used to classify the soils. Soils on younger surfaces, associated with Lower Wright Glacier, Upper Wright Glacier and alpine glaciers, contain massive ice within 100 cm of the soil surface and are classified as Glacic Haplorthels or Glacic Haploturbels where there is field evidence of cryoturbation. As a generalization, at either end of the valley, soil moisture recharge from moist coastal air masses (eastern end) and blowing snow drifts maintain the depth to permafrost in which ice-cement occurs at 70 cm, are classified as Salic or Typic Anhyorthels or, where there is field evidence of cryoturbation, Anhyturbels.
While mapping soils in Wright Valley, the distribution and nature of the shallow permafrost were also investigated. Three classes of permafrost were established to coincide with definitions or conditions within Soil Taxonomy viz: permafrost with ice-cement at 70 cm, and massive ice.
A definition for a petrosalic horizon is proposed based on the properties of a salic horizon and the indurated nature of petrocalcic/petrogypsic horizons. The horizon is likely to occur only in the cold desert climate zones of Antarctica.
A rapid method to determine soil vulnerability to human foot traffic was developed. As vulnerability is the product of disturbance and rehabilitation, the method is based on the disturbance of 10 foot prints at a site multiplied by a soil rehabilitation factor based on the soil weathering stage. Although fine-grained aeolian sands are easily disturbed they also rehabilitate rapidly in the windy conditions of Wright Valley. In contrast, old stable soils have a tight cobbly desert pavement with reddish desert varnish and often show less foot print disturbance. When cobbles are overturned, however, fresh rock with thick salt accumulations and without desert varnish is exposed. It takes much time for the desert varnish to re-establish.
The spatial distribution of Soil Taxonomy soil classes, nature of the permafrost and soil vulnerability to human traffic are presented as three separate maps at 1:50 000 scale and as live GIS files
Evaluation of land in Wairoa District for potential horticultural development
Full text linkThe Wairoa District, on the East Coast of the North Island of New Zealand has less horticultural development than areas to the north and south. The objective of this study was to provide information to help inform landowners who may wish to invest in horticulture which could improve the economic situation of the district.
Field work involving local scale climate mapping and soil characterisation of areas with potential for horticulture in Wairoa District was completed in 2017. Constructed climate and topographical maps with existing soil maps were evaluated against known crop growth requirements to produce crop potential maps identifying areas with potential for crop production. Horticultural crops included in this study include kiwifruit, apples, cherries. Alternative crops include hemp and poppies.
Between mid-April – 31 October 2017, 45 portable iButton temperature loggers were deployed throughout Land Use Capability classes 1-3 in the Wairoa District and were set to record hourly temperature. When regressed against nearby climate stations, long term (18 -26 years) temperature datasets were derived from the short term iButton datasets. MODIS satellite images were also analysed to help identify areas prone to frost. From the long-term datasets local scale chill hour, growing degree days and October frost risk maps were constructed for the Wairoa District. For the central area from Wairoa to Frasertown, chill hours were estimated to range between 600 – 900, growing degree days 1300 – 1400 and October frost risk less than 25%.
From four representative soil types, horizon samples were taken to determine the soils physical properties including each horizons Total Available Water Holding Capacity (TAWHC). Horizon TAWHC for each soil type were summed to give TAWHC to 1 meter which along with 21 years of estimated daily rainfall and potential evapotranspiration were used in a soil water balance model to estimate seasonal crop irrigation requirements. Irrigation estimates for kiwifruit compared well against published values ranging between mean 204 – 247 mm.
The crop potential maps with seasonal crop irrigation estimates can enhance a land owner’s ability to make informed decisions resulting in economic benefit to whanau, community and the Wairoa District
Soil recovery on landslides in hill country at Whatawhata Research Station, western Waikato, New Zealand
No full textMy thesis investigates soil recovery following landsliding in steepland and hill country on part of the Whatawhata Research Station, 25 km west of Hamilton, North Island, New Zealand. Underlain mainly by Mesozoic greywacke, six landslides were studied, ranging in activation time from pre-1953 to 2014. On the basis of geomorphological analysis the landslides were divided into five zones: shear zones (mean of 25 % of landslide area), intact accumulation zones (20 %), transition zones (40 %), and re-deposition zones (15 %), plus an adjacent control zone. Soil physical and chemical properties including: solum depth, A horizon depth, particle size, and soil dry bulk density, along with, soil C, N, P, and pH were determined for each zone of each landslide.
Soils were well-developed in the control and intact accumulation zones and least recovered in the shear and re-deposition zones. Mean A horizon depths ranged from 2 cm in the shear and re-deposition zones to 7 cm in the transition zones, 17 cm in the intact accumulation zones, and 20 cm in the control. Mean solum depths ranged from 24 cm in the shear zones, 91 cm in the intact accumulation zones, 72 cm in the transition zones, 90 cm in the re-deposition zones and >100 cm in the control zones.
The differences between zones within the landslides were greater than the differences between landslides. The controls had higher (P<0.05) C contents than any of the zones within the landslides, and the intact accumulation zones had higher (P<0.05) C contents than the shear, transition or re-deposition zones. Mean soil C contents ranged from 8.2 % in the controls through 5.4 % (intact accumulation zones), 4.2 % (transition zones), 3.2 % (re-deposition zones) to 2.6 % in the shear zones.
Similarly to C, the total N was higher in the controls than the other zones (P<0.05). Mean N content ranged from 0.2 % in the shear zones, 0.3 % in the transition and re-deposition zones, 0.5 % in the intact accumulation zones to 0.7 % in the control zones.
The C:N ratio was consistent across all zones in all six landslides and controls, ranging from 11 to 16. There were no significant differences in the C:N ratio between zones of the landslides or with landslide age.
Soil Olsen P was lower (P<0.05) in the shear and re-deposition zones than the control, intact accumulation, and transition zones. There were no significant differences in Olsen P between the intact accumulation, transition, and control zones. Soil pH was generally low (4.8 to 5.6) across all zones in all six landslides and soil dry bulk density was variable. Thus soil pH, dry bulk density, and Olsen P were not correlated with soil recovery and development.
Overall the shear zone occupied <25 % of the landslide area, was the slowest zone to recover, and was the least productive. The intact accumulation, transition, and re-deposition zones generally consisted of about 75 % of the landslide area, and once stabilised were expected to be relatively productive
Optimising the effectiveness of sediments retention ponds for Waikato soil materials
No full textCurrent Waikato sediment retention pond design is based on guidelines developed by the Auckland Regional Council. As soils in the Auckland and Waikato Regions are different, there is a need to investigate the effectiveness of sediment retention ponds in retaining sediments from Waikato soil materials. The objectives of this study were to:
i) do a comparison between pipette, hydrometer and lasersizer methods for determining soil particle size and to characterise the sand, silt and clay in a range of Waikato soil materials,
ii) evaluate turbidity and suspended solid concentration between the inlet and outlet of sediment retention ponds, and
iii) investigate the use of chemical treatment (flocculants) in assisting sediment settling.
Ten samples representing a range of Waikato soil materials were collected. Particle size was determined using hydrometer, pipette and lasersizer analysis. The pipette and hydrometer gave similar results. Lasersizer analyses were similar to pipette-hydrometer analyses for six samples. The remaining four samples analysed by lasersizer did not give a close agreement to conventional methods. However, error bars showed that between-sample variability was not large. The pipette was found to be the most reliable method for determination of particle size, however the lasersizer gave fast measurements which were easily repeatable. The soil texture of the ten Waikato soil materials tested ranged from sand to clay.
A rain gauge connected to an autowater sampler was installed at the inlet of two sediment retention ponds, one at SH1 in Piarere and the other at a quarry in Ngaruawahia. Water samples were collected when rainfall reached 2mm in the previous 30 minute period. Samples were analysed for turbidity and suspended solids.
The sediment retention ponds at both sites were effective, reducing suspended solids and turbidity by at least 94%. Water samples collected at Piarere showed a 94% reduction in turbidity (from 558.68 NTU to 35.27NTU) and a 97% declination in suspended solids concentrations (from 2365.63mg/L to 78.41mg/L). Results from water samples collected at Ngaruawahia demonstrated a 97% reduction in turbidity (from 491.33 NTU to 14.46 NTU) and a 95% drop in suspended solids concentration (from 210.43 mg/L to 9.5 mg/L). Flocculants (Polyaluminium Chloride, PAC) were being used at the sediment retention pond at Ngaruawahia.
Further investigation into the effectiveness of flocculants in removing sediments from the water column found that samples 1 and 2 collected from the Ngaruawahia study site and allophanic soil materials do not require treatment with flocculants. The recommended dose of 8 ppm/litre of PAC was sufficient to treat sediment runoff without lowering pH level to a point that might induce aluminium toxicity in aquatic life of downstream rivers and streams for Ngaruawahia 3 and coarse materials of Hinuera Formation. PAC doses of 2.7ppm in the Hamilton Ash materials and 5.3 ppm in Hinuera Formation (fine materials) were sufficient to ensure flocculation. For the Piarere soil materials an 8 ppm PAC dose gave reasonable flocculation and 10.7 ppm PAC further reduced the turbidity after 24 hours
The Occurrence and Causes of Pasture Pulling Under Dairy Farming on Pumice Soils
No full textThe occurrence, and causes, of pasture pulling under dairy farming on Orthic Pumice Soils (Typic Udivitrands) in the central North Island of New Zealand was investigated. Pasture pulling occurs on Pumice Soils, where dairy cows pull clumps of pasture from the soil, thus diminishing pasture production. The overall objective of this study was to investigate the occurrence, and establish the causes, of pasture pulling under dairy farming on Orthic Pumice Soil in the Central North Island, New Zealand.
Fifteen paddocks containing pasture of differing ages were investigated at Pouakani dairy farm near Mangakino. Soil profile descriptions were undertaken, and samples were taken seasonally to monitor root depth and density, soil macrofauna, soil dry bulk density, and penetration resistance. Pasture pulling was monitored every 3 weeks by recording the number and size of pulls in a 4 m² quadrant at five points equally spaced along a transect in 15 paddocks.
Pasture pulling was recorded in all paddocks and occurred throughout the year, but was most common during the late summer and autumn. Up to 80 % of the root biomass was in the 0-5 cm depth. The 5-10 cm depth generally showed increased compaction with higher soil dry bulk density and penetration resistance then the surface soil. Pastures in isolated clumps were more commonly pulled than more evenly spread pastures. There was an interaction between pasture age and size of pulls, with more medium and large sized pulls in the younger (1-3 year old) pastures. Although anecdotal evidence reports worse pulling in younger pastures, we did not find strong evidence for that assertion.
Pasture pulling in 2014 at Pouakani dairy farm was not more obviously impacted by insects. Grass population numbers were uniformly low, and black beetle was rarely seen.
Perennial ryegrass was dominant in all paddocks. The paddocks with older, more established pastures contained a higher proportion of other grass species and weeds. Only grass was pulled, other species such as clover, chicory and weeds were not pulled by grazing stock. A pasture pulling index, created to account for the size distribution of the pulls, was more effective at illustrating the seasonal trends associated with pasture pulling than the mean total pulls per quadrat.
Overall, the pasture pulling was not severe at Pouakani Dairy farms in 2014. This study has not discovered one sole cause of pasture pulling at Pouakani dairy farms, but has identified a number of soil characteristics that may be contributing, including; limited rooting depth, low root density in the 5-10 cm depth, increased compaction with depth, less cohesive soil when it has low moisture, and the incidence of pasture growing in clumps
Gaseous emissions (NH₃, N₂O and CH₄) following manure or urea application to soil as influenced by amendments
No full textIncreasing concentrations of greenhouse gases in the atmosphere may contribute to global warming. The three most important greenhouse gases are carbon dioxide (mainly from burning fossil fuels and deforestation), methane (mainly from ruminant animals and waste management) and nitrous oxide (mainly from dung, urine, and nitrogenous fertilisers). Dairy farms contribute to greenhouse gas emissions because of nitrous oxide and methane emissions (Whitehead et al., 2009).
Herd-homes or stand-off pads are increasingly used on dairy farms to minimise soil pugging and compaction. The manure collected from herd-home bunkers or stand-off pads, may be a source of gaseous emissions (NH₃, N₂O and CH₄). Addition of soil or sawdust to manure prior to land application of manure is a potential best farm management practice to minimise gaseous losses.
The specific objectives of the study were to:
1. Determine the optimum flow rate for measurement of ammonia emissions from manure or urea application to soil using a chamber method.
2. Quantify gaseous (NH₃, N₂O and CH₄) emissions from manure or urea after application to soil.
3. Determine the effects of addition of soil or sawdust to manure prior to land application of manure on subsequent gaseous emissions.
4. Determine the effects of surface or incorporated land application of manure or urea on gaseous emissions.
A preliminary experiment was undertaken to determine the optimum flow rate to measure ammonia emissions, from manure or urea after application to soil, using a chamber method. The flow rate experiment was set up in the glasshouse with 3 replications of 9 flow rate treatments. A flow rate of 5 L min-¹ (1 exchange volume min-¹) was determined as the optimum air flow rate to use in the chamber method to measure ammonia volatilisation.
An experiment was undertaken, with 27 pots and 3 replications of 9 treatments, to investigate the effect of soil or sawdust addition to manure on gaseous emissions (NH₃, N₂O and CH₄), when applied on the land surface or incorporated. The physical and chemical properties of the soil, urine, dung, and sawdust were determined in the laboratory.
Addition of sawdust was more effective in reducing ammonia emissions, than addition of soil, to manure prior to land application. The incorporated application of all manure treatments resulted in less NH₃ volatilisation compared to surface application. Total ammonia losses were 51% of the applied N from the surface application and 2% of the applied N from incorporated application of urine and dung with soil, and 15% of the applied N from the surface application and 4% of the applied N from incorporated application of urine and dung with sawdust. Ammonia emissions followed a general pattern of rapid emission on day 2 after the application of the urine and dung to soil followed by a progressive decline over time for both the surface and incorporated application for all the manure treatments applied.
Total N₂O loss of 14% of applied N was observed with incorporated application of manure with sawdust. Most treatments had no net methane emission. Addition of soil and sawdust to manure, prior to application to soil, reduced ammonia emissions and increased nitrous oxide emissions
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