Effects of carrot growing on volcanic ash soils in the Ohakune area, New Zealand

Effects of intensive carrot production on soils derived from young volcanic ash were determined at Ohakune, New Zealand. Erosion rates (derived from caesium-137) and key soil physical and chemical properties were determined in 3 fields with differing management history (6 and 16 years cropping) or topography (sloping and flat).Caesium-137 areal activity in cropped fields ranged from 90 to 2034 Bq/m2, compared with a reference value under long-term pasture of 602 Bq/m2. Mean areal activity was lower than the reference value in 2 sloping fields, but not in a flat field. Net erosion rates were low in both sloping fields (–16 and –5 t/ha.year), but within each field there was a wide range of erosion and deposition rates (–109 to +293 t/ha.year in Field 1 and –145 to +514 t/ha.year in Field 2). These very high rates imply total soil losses up to 238 mm and deposition up to 670 mm, consistent with observed elevation differences between the cropped fields and adjacent fields in long-term pasture and with topsoil depth variation from 145 to 1165 mm. Tillage erosion and deposition rates are high (up to c. 40 t/ha.year) but water erosion is the dominant mechanism of soil redistribution.Cropping has reduced organic matter and aggregate stability, increased bulk density in the lower part of the topsoil and subsoil, and increased aggregate size. Hydraulic conductivity was higher in the topsoil and lower in the subsoil under cropping than it was under pasture. However, it would not limit soil water movement as it was higher than typical rainfall intensities. Compacted wheel tracks were the primary control on runoff and erosion as they have low infiltration rates (4 mm/h) compared with carrot beds (853 mm/h).

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Surface erosion assessment in the South-Canterbury downlands, New Zealand using 137Cs distribution

Soil Research ◽

10.1071/sr9950787 ◽

1995 ◽

Vol 33 (5) ◽

pp. 787 ◽

Cited By ~ 18

Author(s):

LR Basher ◽

KM Matthews ◽

L Zhi

Keyword(s):

New Zealand ◽

Mean Value ◽

Slope Position ◽

Surface Erosion ◽

The South ◽

Erosion And Deposition ◽

Erosion Rates ◽

Land Use Types ◽

Radionuclide Tracer

Redistribution of the radionuclide tracer 137Cs was used to examine the pattern of erosion and deposition at two sites with contrasting long-term land uses (pasture and cropping) in the South Canterbury downlands, New Zealand. There were clear differences between the two land use types in variation in 137Cs concentrations and areal activity, erosion rates and topsoil depth variability. Erosion and deposition have resulted in greater variability and lower mean levels of 137Cs areal activity under cropping (46.3 mBq cm-2) than pasture (55.0 mBq cm-2). At the cropping site, erosion and deposition roughly balanced with the mean value over all sampling sites, suggesting no net soil loss, but considerable redistribution of soil within paddocks. At the pasture site results suggested slight net deposition. There was evidence for both sheet/rill and wind erosion being important in soil redistribution. While there was no difference in mean topsoil depth between pasture and cropping, there were significant differences with slope position. At the pasture site, there was little variation of topsoil depth with slope position, except for swales which tended to be deeper, whereas at the cropping site there was considerable variation in topsoil depth with slope position. Topsoil depth was a poor indicator of erosion status.

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Soil erosion rates under intensive vegetable production on clay loam, strongly structured soils at Pukekohe, New Zealand

Soil Research ◽

10.1071/sr01116 ◽

2002 ◽

Vol 40 (6) ◽

pp. 947 ◽

Cited By ~ 2

Author(s):

L. R. Basher ◽

C. W. Ross

Keyword(s):

New Zealand ◽

Vegetable Production ◽

Clay Loam ◽

Erosion And Deposition ◽

Deposition Rates ◽

Erosion Rates ◽

Soil Redistribution ◽

Structured Soils ◽

Soil Erosion Rates ◽

Tillage Erosion

Rates of soil redistribution by water and tillage erosion were determined in 3 fields under long-term continuous vegetable production on clay loam, strongly structured soils derived from volcanic ash at Pukekohe, South Auckland, New Zealand. Erosion and deposition rates were estimated using a mass balance model to convert variation in 137Cs areal activity within the fields to estimates of erosion and deposition. Caesium-137 areal activity in cropped fields ranged from 171 to 2144 Bq/m2, compared with a reference value under permanent pasture of 774 Bq/m2. There was a characteristic pattern of 137Cs distribution within each field, with differences between the fields related to variation in topography. Lowest values of 137Cs were found in the upper parts of each field and highest values towards the base of each field. In all 3 fields there was a net loss of 137Cs, ranging from 13 to 32%, with an average over the 3 fields of 18%. Net rates of soil loss from the fields were 30, 11, and 7 t/ha.year. However, within the fields there was a much wider range of both erosion (up to 92 t/ha.year) and deposition (up to 100 t/ha.year) rates. Most of the soil redistribution is caused by water erosion, with tillage erosion accounting for 10-20% of the soil redistribution. The soil redistribution rates were 2 orders of magnitude higher than sediment export measured at small catchment scale. Soil erosion rates are not reflected in variation in topsoil depth, because frequent tillage and incorporation of organic residues maintains a uniform topsoil depth, but soil deposition rates are closely related to topsoil depth.

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Erosion rates of the New Zealand Southern Alps reflect long-term tectonics and transient climate

10.5194/egusphere-egu21-6571 ◽

2021 ◽

Author(s):

Duna Roda-Boluda ◽

Taylor Schildgen ◽

Hella Wittmann-Oelze ◽

Stefanie Tofelde ◽

Aaron Bufe ◽

...

Keyword(s):

New Zealand ◽

Strike Slip ◽

Southern Alps ◽

Fault System ◽

Tectonic Deformation ◽

Seismic Cycle ◽

Erosion Rates ◽

Alpine Fault ◽

Oblique Convergence

The Southern Alps of New Zealand are the expression of the oblique convergence between the Pacific and Australian plates, which move at a relative velocity of nearly 40 mm/yr. This convergence is accommodated by the range-bounding Alpine Fault, with a strike-slip component of ~30-40 mm/yr, and a shortening component normal to the fault of ~8-10 mm/yr. While strike-slip rates seem to be fairly constant along the Alpine Fault, throw rates appear to vary considerably, and whether the locus of maximum exhumation is located near the fault, at the main drainage divide, or part-way between, is still debated. These uncertainties stem from very limited data characterizing vertical deformation rates along and across the Southern Alps. Thermochronology has constrained the Southern Alps exhumation history since the Miocene, but Quaternary exhumation is hard to resolve precisely due to the very high exhumation rates. Likewise, GPS surveys estimate a vertical uplift of ~5 mm/yr, but integrate only over ~10 yr timescales and are restricted to one transect across the range.To obtain insights into the Quaternary distribution and rates of exhumation of the western Southern Alps, we use new 10Be catchment-averaged erosion rates from 20 catchments along the western side of the range. Catchment-averaged erosion rates span an order of magnitude, between ~0.8 and >10 mm/yr, but we find that erosion rates of >10 mm/yr, a value often quoted in the literature as representative for the entire range, are very localized. Moreover, erosion rates decrease sharply north of the intersection with the Marlborough Fault System, suggesting substantial slip partitioning. These 10Be catchment-averaged erosion rates integrate, on average, over the last ~300 yrs. Considering that the last earthquake on the Alpine Fault was in 1717, these rates are representative of inter-seismic erosion. Lake sedimentation rates and coseismic landslide modelling suggest that long-term (~103 yrs) erosion rates over a full seismic cycle could be ~40% greater than our inter-seismic erosion rates. If we assume steady state topography, such a scaling of our 10Be erosion rate estimates can be used to estimate rock uplift rates in the Southern Alps. Finally, we find that erosion, and hence potentially exhumation, does not seem to be localized at a particular distance from the fault, as some tectonic and provenance studies have suggested. Instead, we find that superimposed on the primary tectonic control, there is an elevation/temperature control on erosion rates, which is probably transient and related to frost-cracking and glacial retreat.Our results highlight the potential for 10Be catchment-averaged erosion rates to provide insights into the magnitude and distribution of tectonic deformation rates, and the limitations that arise from transient erosion controls related to the seismic cycle and climate-modulated surface processes.&#160;&#160;

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The long-term conservation of forest diversity in New Zealand

Pacific Conservation Biology ◽

10.1071/pc950077 ◽

1995 ◽

Vol 2 (1) ◽

pp. 77 ◽

Cited By ~ 16

Author(s):

John Ogden

Keyword(s):

New Zealand ◽

Land Surface ◽

Alpha Diversity ◽

Forest Diversity ◽

Forest Reserves ◽

Introduced Plants ◽

Wide Range ◽

Average Loss ◽

Endemic Flora

The largely endemic flora of New Zealand is a remnant of the Cretaceous flora of Gondwana, supplemented by later additions from Australia and the tropics. Semi-natural plant communities cover about 50% of the country, and a scheme for the protection of supposedly representative areas is in place. Existing reserves do not adequately reflect the patterns of plant species diversity. Many are modified by introduced animals and alien plants. The latter are being actively introduced into New Zealand at the rate of c. 11 species per year. Measures of diversity are discussed and the broad pattern of (gamma) diversity and endemicity in the country is described. A comparison is made between (alpha) diversity levels in Beech Nothofagus solandri var. cliffortioidesand Kauri Agathis australisforest. Within each of these two forest types there are similar levels of alpha-diversity over a wide range of latitude. Altitudinal alpha-diversity trends indicate an average loss of 3.4 species per 100 m of altitude. This can be accounted for by the reduction of land surface area with increasing altitude on conical or ridge-shaped mountains. The altitudinal data emphasize the importance of the lowlands in the conservation of bio-diversity. The Holocene history of the forests in New Zealand suggests that the concept of "representativeness" is flawed: forest varies continuously in time and space. It may be possible to create some "living museums" of the past biota of New Zealand, but unless there are radical changes in our ability to eradicate animal pests and introduced plants, the composition of mainland forest reserves in the lowlands will change dramatically over the next few centuries. Conservation effort on saving endangered birds may have been at the expense of long-term "habitat" survival on the mainland.

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COMPARISON OF MEASURED SOIL 137-CESIUM LOSSES AND EROSION RATES

Canadian Journal of Soil Science ◽

10.4141/cjss87-017 ◽

1987 ◽

Vol 67 (1) ◽

pp. 199-203 ◽

Cited By ~ 54

Author(s):

R. G. KACHANOSKI

Keyword(s):

Atmospheric Deposition ◽

Soil Loss ◽

Accurate Method ◽

Soil Samples ◽

Deposition Rates ◽

Southern Ontario ◽

Erosion Rates ◽

Soil Losses ◽

Runoff Plots

Atmospheric deposition rates of 90Sr and analysis of soil samples from non-eroded sites indicated base levels of total soil 137Cs were approximately 2700 Bq m−2 in southern Ontario in 1985. Measured 137Cs losses (1965–1976) from long-term runoff plots were significantly correlated to measured soil losses during the same period. Monitoring temporal changes in soil 137Cs should be an accurate method of estimating soil loss in southern Ontario. Key words: Soil loss, 137Cs, Ontario, runoff plots

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Denudation rates derived from spatially-averaged cosmogenic nuclide analysis in Nelson/Tasman catchments, South Island, New Zealand

10.26686/wgtn.17008099.v1 ◽

2021 ◽

Author(s):

◽

Abby Jade Burdis

Keyword(s):

New Zealand ◽

Dynamic Environment ◽

Low Frequency ◽

Short Term ◽

Erosion Rates ◽

Cosmogenic Nuclide ◽

Denudation Rates ◽

Conventional Methods

New Zealand’s tectonically and climatically dynamic environment generates erosion rates that outstrip global averages by up to ten times in some locations. In order to assess recent changes in erosion rate, and also to predict future erosion dynamics, it is important to quantify long-term, background erosion. Current research on erosion in New Zealand predominantly covers short-term (100 yrs) erosion dynamics and Myr dynamics from thermochronological proxy data. Without competent medium-term denudation data for New Zealand, it is uncertain which variables (climate, anthropogenic disturbance of the landscape, tectonic uplift, lithological, or geomorphic characteristics) exert the dominant control on denudation in New Zealand. Spatially-averaged cosmogenic nuclide analysis can effectively offer this information by providing averaged rates of denudation on millennial timescales without the biases and limitations of short-term erosion methods. Basin-averaged denudation rates were obtained in the Nelson/Tasman region, New Zealand, from analysis of concentrations of meteoric ¹⁰Be in silt and in-situ produced ¹⁰Be in quartz. The measured denudation rates integrate over ~2750 yrs (in-situ) and ~1200 yrs (meteoric). Not only do the ¹⁰Be records produce erosion rates that are remarkably consistent with each other, but they are also independent of topographic metrics. Denudation rates range from ~112 – 298 t km⁻² yr⁻¹, with the exception of one basin which is eroding at 600 - 800 t km⁻² yr⁻¹. The homogeneity of rates and absence of a significant correlation with geomorphic or lithological characteristics could indicate that the Nelson/Tasman landscape is in (or approaching) a topographic steady state. Millennial term (¹⁰Be-derived) denudation rates are more rapid than those inferred from other conventional methods in the same region (~50 – 200 t km⁻² yr⁻¹). This is likely the result of the significant contribution of low frequency, high magnitude erosive events to overall erosion of the region. Both in-situ and meteoric ¹⁰Be analyses have the potential to provide competent millennial term estimates of natural background rates of erosion. This will allow for the assessment of geomorphic-scale impacts such as topography, tectonics, climate, and lithology on rates of denudation for the country where many conventional methods do not. Cosmogenic nuclides offer the ability to understand the response of the landscape to these factors in order to make confident erosion predictions for the future.

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Climate Oscillations from Mountain Uplift and Erosion are Damped by Bioactivity

10.5194/egusphere-egu21-13627 ◽

2021 ◽

Author(s):

Dennis Höning

Keyword(s):

Plate Boundaries ◽

Climate Oscillations ◽

Biosphere 2 ◽

Erosion Rates ◽

Wide Range ◽

1D Model ◽

Uplift And Erosion ◽

Steep Slopes

Earth&#8217;s long-term carbonate-silicate cycle is continuously perturbed by processes of mountain building and erosion. Mountain uplift near convergent plate boundaries causes steep slopes, which in turn imply high rates of continental erosion. Erosion rates ultimately affect the weatherability and thereby the regulation of Earth&#8217;s climate. Using a simple 1D-model that includes the outlines processes, I investigate the resulting climate oscillations over timescales from thousands to millions of years. With a simple model of the long-term carbon cycle that includes biological enhancement of weathering and marine biogenic calcite precipitation, I study the role of Earth&#8217;s biosphere in damping these oscillations [1]. I show that both mechanisms play a role: Biological enhancement of weathering damps oscillations mainly on timescales > 1 Ma and marine calcification mainly on shorter timescales. Altogether, the results indicate that Earth&#8217;s biosphere contributes to a stable climate over a wide range of timescales.In the context of anthropogenic emissions, a dramatic elevation in the atmospheric CO2 and related temperature is known to damage Earth&#8217;s biosphere [2] and may even trigger runaway processes [3]. The results presented here indicate that a damaged biosphere may furthermore cause the Earth system to react more sensitive to oscillations from geological forcing and may also affect climate recovery.References:[1] H&#246;ning 2020, Geochem. Geophys. Geosyst. 21(9), e2020GC009105 [2] Sully et al. 2019, Nat. Comm. 10, 1264 [3] Lenton 2013, Annu. Rev. Environ. Resour. 38, 1-29

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Accuracy and Uncertainty Evaluation of Measuring the ISO Long-Term Conductivity of Proppants

10.2118/205940-ms ◽

2021 ◽

Author(s):

Roman Vysotskiy ◽

Galina Makashova ◽

Vladimir Radaev ◽

Alexey Yudin

Keyword(s):

Reference Value ◽

Raw Material ◽

Silica Sand ◽

Conductivity Measurements ◽

Laboratory Measurements ◽

Conductivity Data ◽

Natural Sand ◽

Testing Procedures ◽

Wide Range

Abstract One of the critical factors in planning a hydraulic fracturing treatment is proppant selection. Conductivity is an important property for ensuring efficient reservoir stimulation. Conductivity data obtained during laboratory measurements help determine which proppant to use. ISO provides standard testing procedures and methodology for measuring the long-term conductivity of proppants but does not document expected measuring uncertainty. This paper addresses accuracy and uncertainty estimation of ISO 13503-5 conductivity measurements. For the purposes of this study, three proppant samples were used. Two identical samples of high-strength ceramic proppant (HSP) and one sample of natural silica sand were distributed among six laboratories that participated in this study. The resulting data from measuring conductivity and permeability of the samples were used to calculate repeatability and reproducibility in terms of standard deviations in accordance with ISO 5725-2. Uncertainty of measuring the ISO long-term conductivity of proppants was calculated in accordance with ISO 21748. The evaluation shows that conductivity and permeability values of ceramic proppant and natural sand measured by the ISO 13503-5 method have quite high interlaboratory uncertainty. Uncertainty of conductivity is from 19 to 100% depending on closure stress for values of conductivity from 3000 to 200 md-ft respectively. Uncertainty of long-term conductivity measurements increases dramatically while conductivity decreases. At the same time, internal evaluation of uncertainty in measuring conductivity within one laboratory resulted in approximately 15% as reference value of uncertainty for a single laboratory and never exceeded 30% in given conductivity range. ISO 13503-5 prescribes testing procedures; however, it does not provide information about measurement uncertainty. This information is essential for comparing different proppants to enable reasonable selection criteria for a job, to identify proppant property inconsistency and quality decline over time due to changes in production process or raw material, or to resolve discrepancies in different laboratory measurements. Uncertainty values were estimated for a wide range of conductivity data and different proppant types.

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Examining erosion in New Zealand over millennial timescales using in-situ 10Be and 14C

10.5194/egusphere-egu2020-9309 ◽

2020 ◽

Author(s):

Duna Roda-Boluda ◽

Taylor Schilgen ◽

Maarten Lupker ◽

Wittmann Hella ◽

Prancevic Jeff ◽

...

Keyword(s):

New Zealand ◽

Erosion Rate ◽

Sediment Flux ◽

Short Term ◽

Sediment Fluxes ◽

Landslide Activity ◽

Erosion Rates ◽

Order Of Magnitude

Landslides are the major erosional process in many orogens, and one of the most sensitive erosional process to tectonic and climatic perturbations. However, it remains extremely difficult to constrain long-term or past rates of landslide activity, and hence their contribution to long-term landscape evolution and catchment sediment fluxes, because the physical records of landsliding are often removed in <102 yrs. Here, we use the in-situ 10Be and in-situ 14C concentrations of recent landslide deposits and catchments from the Fiordland and the Southern Alps of New Zealand to: (a) estimate landslide frequencies over 103-104 yr timescales, which we compare against landslide inventories mapped from air photos (<102 yrs) to estimate changes in landslide activity, (b) quantify catchment-averaged erosion rates, and landslide&#8217;s contribution to those erosional fluxes, and (c) test whether paired 14C-10Be measurements can be used to trace erosional depth-provenance and identify transient erosion rate changes. We show that 10Be concentrations on landslide deposits can be used to estimate landslide recurrence intervals and frequency over 103 yr timescales, and that 14C/10Be ratios reflect the depth-provenance of sediment, and possibly transient changes in erosion rates. The comparison of our 10Be-based long-term landslide frequencies with short-term published inventories suggests that landslide frequencies have increased towards the present by up to an order of magnitude. We compare sediment fluxes inferred from these long- and short-term landslide inventories with sediment flux estimates derived from 10Be catchment-averaged erosion rates, which allows us to examine fluctuations in erosion rate estimates from 101 to 103 yrs timescales.&#160;

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Occurrence and properties of lepidocrocite in some soils of New Zealand, South Africa and Australia

Soil Research ◽

10.1071/sr9850543 ◽

1985 ◽

Vol 23 (4) ◽

pp. 543 ◽

Cited By ~ 27

Author(s):

RW Fitzpatrick ◽

RM Taylor ◽

U Schwertmann ◽

CW Childs

Keyword(s):

South Africa ◽

New Zealand ◽

Iron Oxides ◽

Water Movement ◽

Climatic Conditions ◽

Chloride Ions ◽

Temperate Climate ◽

Hydromorphic Soils ◽

Wide Range ◽

Soil Temperatures

Fifty-one samples, collected from 26 sites in New Zealand, South Africa and Australia, were tested for the presence of lepidocrocite (�-FeOOH) and goethite (�-FeOOH). The samples were predominantly orange-coloured mottles, bands, crusts and pipestems from hydromorphic soils, but also included a placic horizon, iron-rich precipitates from water courses, altered pyrite cubes, and geode-like features in weathered saprolites. The iron oxides were identified and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Lepidocrocite was identified in 49 of the samples, and in 44 was present in concentrations exceeding I%, with the highest being approximately 70%. Crystallinities of the lepidocrocite were assessed from the widths and positions of XRD peaks, and, in some cases, from TEM. Goethite was also present in most samples, and predominated over lepidocrocite in some. In all three countries, the most common occurrence of lepidocrocite was associated with the gleyed soil materials commonly found in wet, poorly drained pseudogley soils (mostly 'humic slope gley') of humid temperate climate. Under these climatic conditions the high degree of water supply, relatively lower soil temperatures, lower evaporation and slower water movement caused reductomorphic conditions. At these sites soil iron oxides are reduced and, on reoxidation, lepidocrocite and goethite are generally formed. The colour generally associated with lepidocrocite in iron-rich segregations in hydromorphic soils is 7.5YR6-7/4-8 Lepidocrocite was also identified in all of the other samples mentioned above. A study of the relative proportions of lepidocrocite and goethite, and the crystallinity of these associated minerals in the various morphological concentrations (profile trends), suggests that their formation is strongly governed by soil microenvironmental factors (pH, Eh, and ionic environment). However, climatic and pedogenic factors such as podzolization and high organic matter contents may modify these mineral phases or induce further transformation. These findings indicate that lepidocrocite occurs in a remarkably wide range of materials and weathering environments. Moreover, the morphology, crystallinity, differential XRD line broadening and line shift of the lepidocrocite, and the commonly associated goethite also vary markedly in the respective materials. This suggests that other factors associated with particular weathering environments, such as those involved in pseudomorphous alteration of pyrite and the influence of chloride ions, may be more important in the formation of lepidocrocite than the conditons associated with hydromorphy. The morphology and characteristics of lepidocrocite and goethite, together with field associations, appear to be useful indicators of soil genesis.

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