Determine Soil Physical Properties Research Articles

Random forest approach to estimate soil thermal diffusivity: Evaluation and comparison with traditional pedotransfer functions

Pedotransfer functions (PTFs) are widely used in science and engineering to calculate soil thermal diffusivity (κ) as a function of soil moisture content and other soil physical properties. However, available data on κ are rather scarce and already developed PTFs suffer from significant uncertainties in applicability and performance. Few studies attempted to systematically review and evaluate these PTFs with large dataset of κ. The objectives of this study were to (1) review and collate currently available PTFs for κ; (2) compile a κ dataset to evaluate performance of these PTFs, (3) build a machine learning (ML) (i.e., random forest-RF) model with three classes of soil physical properties to determine soil physical properties most appropriate to use as predictors for calculating κ, and (4) compare the RF modelling with the traditional PTFs. The correlation coefficient (r), centered root-mean-square (E'), and standard deviation (SD) were used to evaluate the performance of the above PTFs. A total of nine PTFs were synthesized and assessed with a compiled dataset consisting of 998 measurements from 106 soils with a wide range of textures. In general, the PTFs of Lukiashchenko and Arkhangelskaya (2018) (LA2018–1 and LA2018–2) perform the best. While the quadratic equation of Mady and Shein (2018) (MS2018–1 and MS2018–2) showed better performance for coarse and medium textured soil. However, the overall performance of the nine PTFs for predicting κ was not as accurate as RF. RF can satisfactorily calculate κ taking into account sand, silt, clay contents, and soil moisture content as predictors.

Using empirical correlations and artificial neural network to estimate compressibility of low plasticity clays

Consolidation settlement tests are costly and time-consuming, whereas tests for determining soil physical properties can be performed very rapidly and at lower costs. Therefore, it will be very helpful if the soil compression index (CC) can be determined using soil physical parameters. This study investigated correlations between the CC and the physical properties of undisturbed and remolded Tehran clay by performing 125 consolidation tests and through determining the physical properties. Based on the results, the correlations between the CC and dry density (γd), between the CC and initial void ratio (eo), and between the CC and wet density (γw) are valid and have correlation coefficient (R2) of 0.87, 0.87, and 0.89, respectively, for undisturbed Tehran clay. These correlations have been proposed for engineering applications in this area. Furthermore, available empirical correlations were compared with those presented in this study and the results suggested that the low accuracy of some of the available correlations for estimating the CC of Tehran clay soil required accurate evaluations before using them in engineering applications. Moreover, using artificial neural network showed high potential in predicting the CC and have coefficient (R) close to 1.

Changes in soil quality under conservation agriculture practices in West Nusa Tenggara, Indonesia

The main challenge for cultivating upland in semi arid environment as in West Nusa Tenggara, Indonesia is the limited availability of water resources and accelerated deterioration of soil quality. This study evaluated changes in selected soil properties and soil quality 4 years after the implementation of conservation agriculture (CA) practices. The study was conducted at the CA demonstation plots in Gunung Malang Village, Pringgabaya District, East Lombok Regency, West Nusa Tenggara Province. The surface soil texture was loam with slope ranging from 5 to 10%. Two CA Models and one farmer practice (LP) were compared. Within each model three sampling positions were sampled: within the corn planted area (Position A), 0-10 cm from the edge of the corn planted area (Position B), and 10 – 20 cm from the edge of the corn planted area (Position C). Intact soil samples (76 by 40 mm) were taken from the three positions at two depths (100-mm increments) to determine soil physical properties and bulk samples from the surface soil (0 – 15 cm) to determine soil chemical properties in the laboratory. The CA Model had significantly (<em>P</em> < 0.01) lower bulk density (BD), and increase soil organic carbon (SOC) and available P (Av P), while Position had significantly affect only BD. The lowest BD (0.87 ± 0.07 Mg m-<sup>3</sup>) and the highest SOC (1.51± 0.05%) and available pore water (AWC; 18.06 ± 0.76% vol) were found at Position A in CA with permanent pit (PIT). The highest soil quality index was found in Position A followed by Position B and the least was in C indicating that the crop rotation component in CA had relatively small effect on improving soil quality. These results suggested that there is a gradual improvement on soil quality after 4 years of the implementation of conservation agriculture and require longer time than 4 yr to achieve the best soil quality for this semi arid environment

Sifat Fisika Tanah dan Produktivitas Kelapa Sawit (Elaeis Guineensis Jacq.) Di Lahan Gambut Pada Tinggi Muka Air Tanah Yang Berbeda

This study aims to determine soil physical properties and palm oil productivity in different of water levels (TMA) in peatland. This study conducted in palm oil plantation area in PT. Tabung Haji Indo Plantation Indragiri Hilir Regency, and Laboratory of Soil Science Faculty of Agriculture, University of Riau. This study was carried out started from July until October 2017 by using survey method. Sampling Location conducted by purposive sampling, and sampling point was determined by stratified random sampling. Analysed data used analyse of variance, followed by further test by Duncan’s new multiple range test level of 5%. Parameters observed in physical properties ware bulk density, porosity, water content of maximum occupied capacity, particles size distribution, and palm oil productivity. The result of this study showed that peatland with water levels (20-40) cm (TMA1) showed higher water content of maximum occupied capacity than water levels (>40-60) cm (TMA2), and >60 cm (TMA3). Peat soil with water level TMA2 owned bulk density, the particle size (≤63 µm) higher compared to TMA1 and TMA3. Peat soil with TMA3 showed higher porosity compared to TMA1 and TMA2. Peat soil TMA1 showed higher palm oil productivity compared to TMA2 and TMA3. Palm oil productivity TMA2 and TMA3 showed lower compared to TMA1 is caused by Ganoderma attack.

Within cropping season changes in soil physical properties under no-till in Southern Brazil

Although opening a narrow furrow for seed placement and fertilizer application is the only mechanical disturbance in soils under no-till (NT) production systems, the persistence of effects associated with that disturbance on physical properties throughout the growing season has not been widely quantified. This study tested the hypotheses that soil physical properties within the row (R) differ from those in the interrow (IR) zone under long-term NT, and that the disturbance effects on soil in the R zone persist during the soybean (Glycine max) growing season. The objective of this study was to determine soil physical properties under R and IR zones under NT soybean. Thirty undisturbed samples in each zone were obtained during the growth cycle at 15, 52 and 115days after sowing. Soil properties monitored were bulk density (BD), total porosity (TP), soil water content and air-filled porosity at field capacity (FC and εa, respectively), air permeability (Ka), pore continuity index (K1) and saturated hydraulic conductivity (Ksat). There were significant differences in all soil physical properties among R and IR zones when measured 15days after sowing (DAS). At the 52 and 115 DAS samplings, K1 and Ksat did not differ between R and IR positions, but significant differences persisted for BD, FC, εa, Ka and TP. BD in R and IR remained different during the soybean growing season. Despite that, the large difference for BD found in 15DAS (1.34 and 1.04Mgm−3 for IR and R, respectively), tended to disappear, resulting in values of 1.15 and 1.07Mgm−3 for IR and R at 115DAS, respectively. A long-term NT soil thus had different physical properties at R versus IR over a short term after sowing. Soil resilience was evident even over a short term, improving soil physical quality at IR position. The large contrast in soil physical parameters between R and IR positions was observed right after sowing, gradually decreasing over time and no longer being detectable by the end of the growing season.

Relation of some Soil Water-transmission Characteristics to some Soil Physical Properties in a Tropical Alfisol

A study was conducted to determine soil physical properties of an Alfisol constituting the soil of a proposed tillage and irrigation water management field laboratory and to relate the physical properties to the water transmission characteristics. The soil was found to be mainly sandy loam on the surface with high infiltration rate and dense concretionary sub-surface layers with low hydraulic conductivity which restricted water movement of water down the profile and facilitated sub-surface lateral movement of water down the slope. Saturated hydraulic conductivity correlated negatively with bulk density (r = -0.239**), clay content (r = -0.290**), gravel content (r = -0.131*); but positively correlated with porosity (r= 0.235**) and sand content (r=0.256**) (r=correlation coefficient;**=significant at ≤ 5% level; * = significant at10% level). The available water content estimated as the water content between the 100cm and15000cm matric tensions was well predicted with a linear multiple regression equation from the bulk density and gravel, sand, silt, clay and organic carbon contents with a co-efficient of determination (R2) of 59.5%. The average 48-hour post infiltration water content in the top 30cm depth was lower than the estimate of water content at field capacity from laboratory-determined water retention at 100cm matric tension. This suggests that irrigation scheduling in the soil based on the laboratory estimate of available water content may overestimate the intervals between irrigation water applications. JARD Vol. 1 2001: pp. 9-22

Capacidade de suporte e compressibilidade de um argissolo, influenciadas pelo tráfego e por plantas de cobertura de inverno

Uma das medidas mais efetivas na prevenção da compactação do solo é a aplicação de pressões inferiores à sua capacidade de suporte de carga, estimada pela tensão de pré-consolidação (σp). Visando a quantificar o efeito de plantas de cobertura de inverno e do tráfego de rodados de trator sobre a σp e sobre o índice de compressibilidade (IC), vem sendo realizado, desde 2002, um experimento em Eldorado do Sul (RS), em Argissolo Vermelho distrófico franco-argilo-arenoso. Os tratamentos, sob semeadura direta, abrangem três coberturas de inverno (pousio, aveia preta e aveia preta + ervilhaca, substituída em 2006 por nabo forrageiro) e duas condições de tráfego (com ou sem tráfego de rodados de trator). No verão, foram semeados milho e soja, em rotação anual. Amostras de solo indeformadas, visando à determinação de algumas propriedades físicas e da σp e do IC, foram coletadas, em junho e novembro de 2006, nas camadas de 0,03-0,06 e 0,12-0,15 m, e equilibradas a diferentes tensões de água. Independentemente da época de avaliação e do tráfego, o pousio resultou nos maiores valores de σp e menores de IC na camada de 0,03-0,06 m. Com menor teor de água no solo, as diferenças na σp entre o pousio e as plantas de cobertura tenderam a diminuir. A realização de sete tráfegos em cinco anos aumentou a σp apenas na superfície do solo, mas não afetou o IC. O uso de plantas de cobertura de inverno, aliado à ausência de tráfego, ao reduzir a densidade do solo e aumentar a macroporosidade, diminuiu a capacidade de suporte de carga e aumentou a susceptibilidade da superfície do solo à compactação.

Atributos físicos de um planossolo háplico sob sistemas de manejo comparados aos do campo nativo

Sistemas de manejo podem influenciar as condições físico-hídricas do solo e a produtividade das culturas. O objetivo deste estudo foi avaliar os atributos físicos de um Planossolo Háplico sob diferentes sistemas de manejo e compará-los com os encontrados no campo nativo. A densidade, a condutividade hidráulica de solo saturado, a porosidade e a agregação foram avaliadas nas camadas de 0,000-0,025; 0,025-0,075; 0,075-0,125; 0,125-0,175; 0,175-0,275 m. O sistema plantio direto e o preparo convencional apresentaram condições físico-hídricas similares, enquanto o solo sob campo nativo proporcionou condições adequadas ao crescimento e desenvolvimento de plantas por apresentar maior condutividade hidráulica, macroporosidade, porosidade total e agregação, e menor densidade do solo. Sugerem-se valores críticos para as plantas, respectivamente de densidade, de condutividade hidráulica saturada, de diâmetro médio ponderado de agregados de 1,56 Mg m-3; 16,18 mm h-1 e 2,49 mm.

Determining soil physical properties by multi-sensor technique

Plant growth and crop yield can be significantly impeded by a number of soil physical parameters including soil water content, mechanical strength and soil electrical conductivity (EC). Therefore, to simultaneously measure these physical parameters along vertical depths in the field, it has been desired for many years. This study focused on developing a multi-sensor system, which contained a cell with three sensors for measuring soil water content, mechanical strength and EC. Additionally a Hall-current sensor was proposed to measure the operating current of a dc-motor, which generated the penetrating force during operating process. Based on the theoretical analysis of the transformation from electrical to mechanical energy, it was feasible to evaluate the soil mechanical strength from the operating current of the dc-motor. In order to verify the performance of the designed system and the theoretical analysis addressed, relevant calibrations and tests were conducted. The results demonstrate that the multi-sensor system could be beneficial and practical for field surveys.

SODICITY AND WATER QUALITY EFFECTS ON SLAKING OF AGGREGATES FROM SEMI-ARID SOILS 1

Aggregate slaking is one of the main mechanisms responsible for the breakdown of aggregates. Exchangeable sodium percentage (ESP) and electrolyte concentration (C) of the soil solution play a significant role in determining soil physical properties and the response of soil clays to dispersion and swelling. However, studies of sodicity and C effects on aggregate stability have yielded inconsistent results. Our objective was to evaluate the effects of sodicity and C on aggregate slaking in soils with different clay contents. Using the high-energy-moisture-characteristics (HEMC) method, we studied aggregate slaking in 56 samples of Israeli topsoils varying in clay content (80-675 g kg -1 ) and ESP levels (0-30). In this method, accurately controlled wetting of the aggregates (i.e., the driving force for slaking) was the only force exerted on the aggregates. Aggregates (0.5-1.0 mm) were placed in a funnel equipped with a fritted disk and, using a peristaltic pump, were wetted either fast (100 mm h -1 ) or slowly (2 mm h -1 ). Two salinity levels were studied: dionized water (DW, C = 0.04 mmol c L-1) and saline water (SW, C = 20 mmol c L -1 ). Thereafter, the aggregates were subjected to stepwise increases in matric potential up to 5.0 J kg -1 to obtain a moisture retention curve that served as the base for calculation of aggregate susceptibility to slaking. The latter was expressed in terms of stability ratio (SR). The SR of low ESP soils increased from 0.298 to 0.751 and from 0.508 to 0.799 for DW and SW, respectively, with the increase in soil clay content from 11.3 to 67.4%. Increase in ESP decreased SR (i.e., enhanced aggregate slaking), whereas use of SW increased SR compared with DW. A triple interaction among ESP, C, and clay content (P = 0.001) in their effect on aggregate slaking suggested that the combined effects of these variables on slaking were complex. Our results suggested that: (i) in soils having inherently low aggregate stability (clay 35%), aggregate slaking decreased upon use of SW only when ESP > 15.

Probe microphone instrumentation for determining soil physical properties: testing in model porous materials: J. M. Sabatier, D. C. Sokol, C. K. Frederickson, M. J. M. Romkens, E. H. Grissinger & J. C. Shipps, Soil Technology, 8(4), 1996, pp 259–274

Probe microphone instrumentation for determining soil physical properties: testing in model porous materials: J. M. Sabatier, D. C. Sokol, C. K. Frederickson, M. J. M. Romkens, E. H. Grissinger & J. C. Shipps, Soil Technology, 8(4), 1996, pp 259–274

Probe microphone instrumentation for determining soil physical properties: testing in model porous materials

An acoustic technique for evaluating soil physical properties is described and tested in model porous materials. A probe microphone is used to measure the acoustic signal attenuation and phase speed. Emphasis is on the probe construction, insertion in soils and reduction of acoustic data to predict tortuosity and an effective air-flow resistivity of the soil. Well-known capillary-tube models of porous materials which incorporate these two porous material properties are used to invert the acoustic data. The probe microphone, associated hardware, data acquisition and analyses are implemented on a personal computer. The system can provide real time prediction of the soil properties in the field. Measurements in three materials: glass beads, washed sand and loess soil are analyzed and discussed. The instrumentation works well in the glass beads and washed sand tested; however, in the loess soil tested some restrictions occur.