Uncertainties in the measurement of soil water content caused by abrupt soil layer changes, when using a neutron probe

Soil Research ◽  
1988 ◽  
Vol 26 (1) ◽  
pp. 87 ◽  
Author(s):  
DJ Wilson
Keyword(s):  
Neutron Source ◽  
Thermal Flux ◽  
Soil Layer ◽  
Soil Parameters ◽  
Soil Systems ◽  
Neutron Probe ◽  
Detector Geometry ◽  
Real Value ◽  
Measured Water ◽  
Relative Count Rate

Multigroup diffusion code calculations have been made to model the changes in the thermal flux distribution as a fast neutron source passes through an interface between two soil systems. By integrating this flux over the volume of a detector attached to the source, a relative count rate can be determined for different source positions with respect to the interface. Water densities determined from these count rates and calibration curves can be seriously in error near the interface. The magnitude of these errors depends upon the soil parameters, the detector geometry, and the proximity of the soil strata to the neutron source and detector. Unless the soil structure is well known, it would be unwise to rely on water measurements closer than about 25 cm to a soil discontinuity. It two soils merge over 30-40 cm, it is likely that the measured water density will not deviate far from the real value.

scholarly journals Water requirements of avocado in Israel. I. Tree and soil parameters

1977 ◽  
Vol 28 (5) ◽  
pp. 859 ◽  
Author(s):  
D Kalmar ◽  
E Lahav
Keyword(s):  
Coastal Plain ◽  
Irrigation Schedule ◽  
Soil Layer ◽  
The Other ◽  
Soil Parameters ◽  
Irrigation Season ◽  
Salt Accumulation ◽  
Water Requirements ◽  
Neutron Probe ◽  
Annual Water

The effect of different irrigation intervals on the avocado tree was tested during the years 1968–1974 in the northern coastal plain of Israel. The objectives of this experiment were: (a) to make measurements of soil and plant parameters to help understand mechanisms of response to irrigation; and (b) to establish the most suitable irrigation schedule for highest yields of export quality fruit. The trial consisted of four irrigation treatments, at intervals of 7, 14, 21 and 28 days; the respective average annual water applications were 8890, 7450, 6680, and 5940 m3/ha. The cultivars Ettinger, Fuerte and Hass were tested in five replications in randomized blocks. Soil moisture consumption was estimated by using a neutron probe and tensiometers. Most of the water consumption was from the upper 60-cm soil layer. With the 7-day interval, the calculated daily loss from the soil profile was greater throughout the whole irrigation season than with the other intervals. The least salt accumulation occurred under the long interval treatments since the large amounts of water supplied at each irrigation leached the salts continuously. Reduced intervals between irrigations resulted in increased trunk growth and increased tree size. It is concluded that with a 21-day interval the vegetative growth of producing trees was restricted and therefore relatively smaller trees with easier fruit picking and delayed orchard thinning were obtained.

scholarly journals The Relationship between Soil Electrical Parameters and Compaction of Sandy Clay Loam Soil

Agriculture ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 114
Author(s):  
Katarzyna Pentoś ◽  
Krzysztof Pieczarka ◽  
Kamil Serwata
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Susceptibility ◽  
Precision Agriculture ◽  
Soil Compaction ◽  
Soil Layer ◽  
Soil Parameters ◽  
Soil Electrical Conductivity ◽  
Electrical Parameters ◽  
Management Zones ◽  
Additional Information

Soil spatial variability mapping allows the delimitation of the number of soil samples investigated to describe agricultural areas; it is crucial in precision agriculture. Electrical soil parameters are promising factors for the delimitation of management zones. One of the soil parameters that affects yield is soil compaction. The objective of this work was to indicate electrical parameters useful for the delimitation of management zones connected with soil compaction. For this purpose, the measurement of apparent soil electrical conductivity and magnetic susceptibility was conducted at two depths: 0.5 and 1 m. Soil compaction was measured for a soil layer at 0–0.5 m. Relationships between electrical soil parameters and soil compaction were modelled with the use of two types of neural networks—multilayer perceptron (MLP) and radial basis function (RBF). Better prediction quality was observed for RBF models. It can be stated that in the mathematical model, the apparent soil electrical conductivity affects soil compaction significantly more than magnetic susceptibility. However, magnetic susceptibility gives additional information about soil properties, and therefore, both electrical parameters should be used simultaneously for the delimitation of management zones.

scholarly journals Intercropping cover crops with a poplar short rotation coppice: Effects on nutrient uptake and biomass production

2018 ◽  
pp. 126-133 ◽  
Author(s):  
Nicola Silvestri ◽  
Vittoria Giannini ◽  
Daniele Antichi
Keyword(s):  
Water Content ◽  
Cover Crops ◽  
Dry Matter ◽  
Soil Cover ◽  
Plant Cover ◽  
Central Italy ◽  
Research Work ◽  
Soil Layer ◽  
Soil Parameters ◽  
Short Rotation

The risks of soil erosion and nutrient leaching can be considered appreciable in short rotation coppices especially in the first growth phases because of the absence of any plant cover. The temporary intercropping with legumes or grasses used as cover crops can help to overcome these environmental issues. The present research work aims to evaluate the effects of the introduction of cover crops in a short rotation poplar (Populus deltoides W. Bartram ex Marshall) with two-year harvest cycle. The plantation was located in a Typic Xerofluvent, silty-loam soil of the coastal Central Italy. Two different species of cover crops, Trifolium subterraneum L. (TS) and Lolium perenne L. (LP), were compared along with an untreated control, colonised by spontaneous vegetation (CO). Several plant and soil parameters were evaluated: the above ground biomass and nutrient accumulation for the three different soil cover types, the nitrate and water content in two soil layers (0.00-0.30 and 0.30-0.60 m), the poplar yield and nutrient content in branches and leaves. TS returned to the soil about 70 kg ha–1 of nitrogen at the end of its biological cycle, thanks to the high N content (over 2%) and to the noticeable amount of dry matter produced (3.46 t ha–1 of dry matter). This value was considerably higher than those of the LP (23 kg ha–1 of N) or CO (10 kg ha–1). The different amount of nitrogen returned to the soil affected both nitrate concentration in topsoil (0.00-0.30 m) and accumulation of nitrogen in poplar organs. Concerning phosphorous, the differences among treatments were less evident and the amount of P returned to the soil ranged from 2 (CO) to 10 (TS) kg ha–1. However, the effect of soil cover type on P uptake in poplar was still appreciable. Generally, the soil water content was slightly affected by the soil cover types. Indeed, the differences between the cover crops and the control became significant only in the shallowest soil layer and over the summer season. In the first year, LP induced a significant decrease in poplar yield (10.1 t ha–1 of dry matter) in comparison with TS (14.7 t ha–1) and CO (13.4 t ha–1), whereas in the second year there were no significant differences among treatments due to the weak regrowth of cover crops. These results show how to make it feasible a long lasting coexistence between cover crops and SRC, a clever design of agro-forestry systems is therefore needed.

scholarly journals Soil moisture monitoring at the field scale using neutron probe

2014 ◽  
Vol 51 (3) ◽  
pp. 332-345 ◽  
Author(s):  
J. Kodikara ◽  
P. Rajeev ◽  
D. Chan ◽  
C. Gallage
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Layer ◽  
Calibration Method ◽  
Flow Equation ◽  
Wetting Front ◽  
Wet Season ◽  
Buried Structures ◽  
Neutron Probe ◽  
Moisture Variation

Measurement of the moisture variation in soils is required for geotechnical design and research because soil properties and behavior can vary as moisture content changes. The neutron probe, which was developed more than 40 years ago, is commonly used to monitor soil moisture variation in the field. This study reports a full-scale field monitoring of soil moisture using a neutron moisture probe for a period of more than 2 years in the Melbourne (Australia) region. On the basis of soil types available in the Melbourne region, 23 sites were chosen for moisture monitoring down to a depth of 1500 mm. The field calibration method was used to develop correlations relating the volumetric moisture content and neutron counts. Observed results showed that the deepest “wetting front” during the wet season was limited to the top 800 to 1000 mm of soil whilst the top soil layer down to about 550 mm responded almost immediately to the rainfall events. At greater depths (550 to 800 mm and below 800 mm), the moisture variations were relatively low and displayed predominantly periodic fluctuations. This periodic nature was captured with Fourier analysis to develop a cyclic moisture model on the basis of an analytical solution of a one-dimensional moisture flow equation for homogeneous soils. It is argued that the model developed can be used to predict the soil moisture variations as applicable to buried structures such as pipes.

scholarly journals Stability Reinforcement of Slopes Using Vegetation Considering the Existence of Soft Rock

2021 ◽  
Vol 11 (19) ◽  
pp. 9228
Author(s):  
Chungang Liu ◽  
Huanjun Bi ◽  
Dong Wang ◽  
Xiaoning Li
Keyword(s):  
Factor Of Safety ◽  
Soil Layer ◽  
Soft Rock ◽  
Failure Surface ◽  
Soil Parameters ◽  
Rainfall Condition ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Actual Geometry ◽  
Red Bed

This study investigates the effectiveness of vegetation reinforcement on the stability of a slope with red-bed soft rock in a slope along the Xining-Chengdu railway, China. Four kinds of vegetation were considered to reinforce the soil and the slope. The rooted soil parameters were determined based on the laboratory tests. A numerical model was developed based on the actual geometry and soil layer distributions. The soils were modeled as elastic perfectly plastic materials and the vegetation reinforcement was represented as addition cohesion of a series of subsoil layers within a given depth. The effectiveness of vegetation on slope reinforcement under both dry and rainfall conditions was investigated regarding this case. The potential failure surface and corresponding factor of safety of the red-bed soft rock slope for those different conditions were analyzed and compared. It has been found that the addition of vegetation increased the safety of slope stability whether the slope is under a dry condition or a rainfall condition, while the increasing proportion of factor of safety due to vegetation reinforcement for this case is very limited. The results and findings in this study are still significant for the practitioner to evaluate the reasonability of vegetation reinforcement.

scholarly journals Input-Output Budget of Nitrogen and the Effect of Experimentally Changed Deposition in the Forest Ecosystems in Central Japan

2001 ◽  
Vol 1 ◽  
pp. 472-479
Author(s):  
Junko Shindo ◽  
Tamon Fumoto ◽  
Noriko Oura ◽  
Hideshige Toda ◽  
Hiroyuki Kawashima
Keyword(s):  
Exchange Resin ◽  
Soil Layer ◽  
Field Measurements ◽  
Ion Exchange Resin ◽  
N Leaching ◽  
Central Japan ◽  
Rooting Zone ◽  
Plant Soil ◽  
Soil Systems ◽  
N Input

To evaluate the current nitrogen (N) status in Japanese forests, field measurements of rainfall, throughfall, litter layer percolation, and soil solution percolation were conducted in a red pine stand (Kannondai) and a deciduous stand (Yasato) located in central Japan. N input via throughfall was 31 and 14 kg ha–1year–1and output below rooting zone was 9.6 and 5.5 kg ha1year–1in Kannondai and in Yasato, respectively. Two thirds of input N were retained in plant-soil systems. Manipulation of N input was carried out. Ionic constituents were removed from throughfall with ion exchange resin at removal sites and ammonium nitrate containing twice the N of the throughfall was applied at N addition sites periodically. SO42–output below 20-cm soil layer changed depending on the input, while NO3–output was regulated mainly by the internal cycle and effect of manipulation was undetected. These Japanese stands were generally considered to have a larger capacity to assimilate N than NITREX sites in Europe. However, N output fluxes had large spatial variability and some sites in Kannondai showed high N leaching below rooting zone almost balanced with the input via throughfall.

Bodenschäden durch Freizeitaktivitäten im Wald: Regeneration durch Einzäunen

2014 ◽  
Vol 165 (1) ◽  
pp. 2-9
Author(s):  
Hans-Peter Rusterholz ◽  
Bruno Baur
Keyword(s):  
Soil Layer ◽  
Ground Vegetation ◽  
Soil Parameters ◽  
Management Tools ◽  
Recreational Activities ◽  
Recreation Areas ◽  
Soil Scarification ◽  
Management Plans ◽  
Vegetation Parameters ◽  
Recreational Use

Soil damage from recreational activities in forests: regeneration by fencing Urban forests are popular recreation areas. Recreational activities, particularly the use of picnic places and playing areas, can cause damages to soil and above-ground vegetation, which in turn negatively affect other forest functions. Forest management plans propose management tools for resolving these conflicts. So far, little is known concerning the restoration success of temporary fencing of heavily impacted forest areas in order to prevent any further recreational use. Here, we report the results of a field experiment designed to examine the effects of fencing and soil scarification upon regeneration of soil and above-ground vegetation in a highly impacted forest in Allschwil, Switzerland. We assessed different soil and vegetation parameters in plots with and without soil scarification in the fenced area in the year before the regeneration experiment was initiated and over the following seven years. In parallel, the same variables were recorded in an undisturbed area and in an area with ongoing recreational use. Our study showed successful regeneration of the formerly degenerated soil and ground vegetation within seven years. In addition, the scarification of the upper soil layer accelerated regeneration of some soil parameters but had no effect on ground vegetation. We conclude that temporary fencing is a useful tool for the restoration of forest soil and vegetation in areas heavily impacted by recreational activities.

A Research Reactor Core Design for Advance Neutron Source

2017 ◽  
Author(s):  
Zeyun Wu
Keyword(s):  
Neutron Source ◽  
Research Reactor ◽  
Cold Neutron ◽  
Thermal Flux ◽  
Thermal Power ◽  
Reactor Core ◽  
Operating Cycle ◽  
Start Up ◽  
Cold Neutron Source ◽  
Pool Type

This paper presents the recent neutronics analysis results of a proposed LEU-fueled research reactor. The main goal of the research reactor is to provide advanced neutron source with a particular emphasis on high intensity cold neutron sources. A tank-in-pool type reactor with an innovative horizontally split compact core was developed in order to maximize the yield of the thermal flux trap in the reflector area. The reactor was designed with 20 MW thermal power and 30-day operating cycle. For non-proliferation purposes, the LEU fuel (U3Si2-Al) with 19.75 wt.% enrichment was used. The estimated maximum thermal flux of the reactor is ∼5×1014 n/cm2-s. The total peaking factor of the start-up (SU) core is ∼2.5. The calculated brightness of the cold neutron source (CNS) demonstrates the superiority of the cold neutron performance of the design.

Analyzing the Excavation of Fluid-Solid Coupling Foundation Pit Based on 3D Numerical Simulation and GA-ANN

2010 ◽  
Vol 171-172 ◽  
pp. 394-398
Author(s):  
An Nan Jiang ◽  
Jun Xiang Wang ◽  
Lin Bo Hou
Keyword(s):  
Numerical Simulation ◽  
Orthogonal Design ◽  
Soil Layer ◽  
Soil Parameters ◽  
3D Numerical Simulation ◽  
Foundation Pit ◽  
Feedback Analysis ◽  
Engineering Construction ◽  
Sample Data ◽  
Bp Neural Network Model

Aiming at the complexity mechanism of foundation pit excavation, the paper proposed a feedback analysis flow combining 3D numerical simulation, orthogonal design, artificial neural networks(ANN) and genetic algorithm(GA). The sample data are produced by numerical simulation based on seepage theory and Biot consolidation theory, reflecting the interaction of hydraulics and mechanics. The BP neural network model is trained by above sample data and is optimized by GA, which can map the relation between soil layer parameters and character monitoring displacements well. Based on the relation, the soil parameters could be identified by GA. The method has been applied to analyze the Suzhou Runjie square foundation pit excavation and the permeability coefficients of soil layers were identified. The fluid-solid coupling process of foundation pit excavation based on inversion parameters are simulated. It indicates that the method can get satisfied precision, which provides guide meaning to specific engineering construction and appraisal.

scholarly journals The Effect of Mineral and Organic Fertilization on Common Osier (Salix viminalis L.) Productivity and Qualitative Parameters of Naturally Acidic Retisol

Agriculture ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 42
Author(s):  
Gintaras Šiaudinis ◽  
Danutė Karčauskienė ◽  
Jūratė Aleinikovienė ◽  
Regina Repšienė ◽  
Regina Skuodienė
Keyword(s):  
Sewage Sludge ◽  
Positive Impact ◽  
Soil Layer ◽  
Biomass Productivity ◽  
Field Trials ◽  
Salix Viminalis ◽  
Soil Parameters ◽  
Soil Productivity ◽  
Mineral Fertilization ◽  
Total N

One of the potential options for sewage sludge as an alternative organic material is the fertilization of energy crops. To evaluate the effect of granulated sewage sludge and mineral fertilization N60P60K60 on common osier’s (Salix viminalis L.) biomass productivity and soil parameters, field trials were held in Western Lithuania’s naturally acidic Retisol (WB 2014; pHKCl 4.35–4.58). After four years of cultivation and dependent on fertilization type, common osier dry matter (DM) yield varied from 49.60 to 77.92 t ha−1. Higher DM yield was related to an increased number of stems/plants. The application of a 90 t ha−1 sewage sludge rate had a significant and positive impact on common osier productivity, as well as on the increment of soil organic carbon, total N, and mobile P2O5 content in the upper 0–30 cm soil layer. The use of both sewage sludge rates (45 and 90 t ha−1) had a similar impact on soil bulk density, water-stable aggregates, and the active soil microbial biomass. Annual mineral fertilization had little effect on the parameters studied. When growing common osier in Retisol, 45 t ha−1 of a single sewage sludge rate was enough to maintain both plant and soil productivity.

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