scholarly journals Field spatial and temporal patterns of soil water content and bulk density changes

2006 ◽  
Vol 63 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Luís Carlos Timm ◽  
Luiz Fernando Pires ◽  
Renato Roveratti ◽  
Robson Clayton Jacques Arthur ◽  
Klaus Reichardt ◽  
...  
Keyword(s):  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Surface ◽  
Temporal Patterns ◽  
Temporal Changes ◽  
Spatial And Temporal Patterns ◽  
Wetting And Drying ◽  
Wetting And Drying Cycles

Soil water content (theta) and bulk density (rhos) greatly influence important soil and plant processes, such as water movement, soil compaction, soil aeration, and plant root system development. Spatial and temporal variability of theta and rhos during different periods of the year and different phases of crops are of fundamental interest. This work involves the characterization of spatial and temporal patterns of theta and rhos during different climatic periods of year, aiming to verify whether there are significant temporal changes in rhos at the soil surface layer when submitted to wetting and drying cycles. The field experiment was carried out in a coffee plantation, Rhodic Kandiudalf soil, clayey texture. Using a neutron/gamma surface probe, theta and rhos were measured meter by meter along a 200 m spatial transect, along an interrow contour line. During the wet period there was no difference of spatial patterns of theta while during the dry period differences were observed, and can be associated to precipitation events. It was also observed that there are rhos temporal changes at the soil surface along the studied period as a consequence of the in situ wetting and drying cycles.

scholarly journals Spatial-and temporal-patterns of global soil heterotrophic respiration in terrestrial ecosystems

2019 ◽  
Author(s):  
Xiaolu Tang ◽  
Shaohui Fan ◽  
Manyi Du ◽  
Wenjie Zhang ◽  
Sicong Gao ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Temporal Patterns ◽  
Heterotrophic Respiration ◽  
Spatial And Temporal Patterns ◽  
Carbon Loss ◽  
Global Land ◽  
Global Soil ◽  
Soil Heterotrophic Respiration

Abstract. Soil heterotrophic respiration (RH) is one of the largest and most uncertain components of the terrestrial carbon cycle, directly reflecting carbon loss from soil to the atmosphere. However, high variations and uncertainties of RH existing in global carbon cycling models require an urgent development of data-derived RH dataset. To fill this knowledge gap, this study applied Random Forest (RF) algorithm – a machine learning approach, to (1) develop a globally gridded RH dataset and (2) investigate its spatial- and temporal-patterns from 1980 to 2016 at the global scale by linking field observations from the Global Soil Respiration Database and global environmental drivers – temperature, precipitation, soil water content, etc. Finally, a globally gridded RH dataset was developed covering from 1980 to 2016 with a spatial resolution of half degree and a temporal resolution of one year. Globally, the average annual RH was 57.2 ± 0.6 Pg C a−1 from 1980 to 2016, with a significantly increasing trend of 0.036 ± 0.007 Pg C a−2. However, the temporal trend of the carbon loss from RH varied with climate zones that RH showed significant increasing trends in boreal and temperate areas, in contrast, such trend was absent in tropical regions. Temperature driven RH dominated 39 % of global land and was mainly distributed at a high latitude. While the areas dominated by precipitation and soil water content were mainly semi-arid and tropical areas, accounting for 36 % and 25 % of the global land, respectively, suggesting variations in the dominance of environmental controls on the spatial patterns of RH. The developed globally gridded RH dataset will further aid in understanding of the mechanisms of global soil carbon dynamics, serving as a benchmark to constrain global vegetation models. The dataset is publicly available at https://doi.org/10.6084/m9.figshare.8882567 (Tang et al., 2019a).

Variability of soil water content and bulk density in a sugarcane field

Soil Research ◽  
2002 ◽  
Vol 40 (4) ◽  
pp. 604 ◽  
Author(s):  
T. T. Tominaga ◽  
F. A. M. Cássaro ◽  
O. O. S. Bacchi ◽  
K. Reichardt ◽  
J. C. M. Oliveira ◽  
...  
Keyword(s):  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Management Practices ◽  
Soil Surface ◽  
Harvest Management ◽  
Soil Water Retention ◽  
Harvest Residues ◽  
Sugarcane Crop

The change in management practices of the sugarcane crop in Brazil, from the traditional trash burning before harvest to the new practice that leaves harvest residues on the field after harvest, can lead to alterations in the water regime and also in soil compaction levels. In this study a neutron-gamma surface gauge was used to monitor spatial and temporal variabilities of soil moisture and density in a experimental sugarcane area submitted to 3 harvest management practices: (i) mulched crop with harvest residues, (ii) crop with bare inter-row, and (iii) crop with ash residues from trash burning before harvest. Variability of soil water content and bulk density was studied using geostatistical tools and analysis of variance was used to compare averages. Autocorrelations and semivariograms indicate a spatial dependence of soil water contents, which were higher in the presence of trash residues left on the soil surface after harvest. The average difference between treatments (i) and (ii) was about of 15%, indicating the beneficial mulching effect with respect to soil water retention. Differences between (ii) and (iii) were much smaller.

scholarly journals Spatial and temporal patterns of soil water content in an agroecological production system

2017 ◽  
Vol 74 (5) ◽  
pp. 383-392 ◽  
Author(s):  
Hugo Hermsdorff das Neves ◽  
Maria Gabriela Ferreira da Mata ◽  
José Guilherme Marinho Guerra ◽  
Daniel Fonseca de Carvalho ◽  
Ole Otto Wendroth ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Production System ◽  
Temporal Patterns ◽  
Spatial And Temporal Patterns

Using soil surface gray level to determine surface soil water content

2010 ◽  
Vol 53 (10) ◽  
pp. 1527-1532 ◽  
Author(s):  
YuanJun Zhu ◽  
YunQiang Wang ◽  
MingAn Shao
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Surface Soil ◽  
Soil Surface ◽  
Gray Level

Root effects on soil water and hydraulic properties

Biologia ◽  
2007 ◽  
Vol 62 (5) ◽  
Author(s):  
Horst Gerke ◽  
Rolf Kuchenbuch
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Hydraulic Properties ◽  
Soil Hydraulic Properties ◽  
Soil Hydraulic ◽  
Root Effects

AbstractPlants can affect soil moisture and the soil hydraulic properties both directly by root water uptake and indirectly by modifying the soil structure. Furthermore, water in plant roots is mostly neglected when studying soil hydraulic properties. In this contribution, we analyze effects of the moisture content inside roots as compared to bulk soil moisture contents and speculate on implications of non-capillary-bound root water for determination of soil moisture and calibration of soil hydraulic properties.In a field crop of maize (Zea mays) of 75 cm row spacing, we sampled the total soil volumes of 0.7 m × 0.4 m and 0.3 m deep plots at the time of tasseling. For each of the 84 soil cubes of 10 cm edge length, root mass and length as well as moisture content and soil bulk density were determined. Roots were separated in 3 size classes for which a mean root porosity of 0.82 was obtained from the relation between root dry mass density and root bulk density using pycnometers. The spatially distributed fractions of root water contents were compared with those of the water in capillary pores of the soil matrix.Water inside roots was mostly below 2–5% of total soil water content; however, locally near the plant rows it was up to 20%. The results suggest that soil moisture in roots should be separately considered. Upon drying, the relation between the soil and root water may change towards water remaining in roots. Relations depend especially on soil water retention properties, growth stages, and root distributions. Gravimetric soil water content measurement could be misleading and TDR probes providing an integrated signal are difficult to interpret. Root effects should be more intensively studied for improved field soil water balance calculations.

scholarly journals Tillage and crop rotation effects on soil carbon and selected soil physical properties in a Haplic Cambisol in Eastern Cape, South Africa

2019 ◽  
Vol 15 (No. 1) ◽  
pp. 47-54 ◽  
Author(s):  
Mxolisi Mtyobile ◽  
Lindah Muzangwa ◽  
Pearson Nyari Stephano Mnkeni
Keyword(s):  
South Africa ◽  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Crop Rotation ◽  
Soil Bulk Density ◽  
Crop Rotations ◽  
Soil Porosity ◽  
No Till

The effects of tillage and crop rotation on the soil carbon, the soil bulk density, the porosity and the soil water content were evaluated during the 6<sup>th</sup> season of an on-going field trial at the University of Fort Hare Farm (UFH), South Africa. Two tillage systems; conventional tillage (CT) and no-till and crop rotations; maize (Zea mays L.)-fallow-maize (MFM), maize-fallow-soybean (Glycine max L.) (MFS); maize-wheat (Triticum aestivum L.)-maize (MWM) and  maize-wheat-soybean (MWS) were evaluated. The field experiment was a 2 × 4 factorial, laid out in a randomised complete design. The crop residues were retained for the no-till plots and incorporated for the CT plots, after each cropping season. No significant effects (P &gt; 0.05) of the tillage and crop rotation on the bulk density were observed. However, the values ranged from 1.32 to1.37 g/cm<sup>3</sup>. Significant interaction effects of the tillage and crop rotation were observed on the soil porosity (P &lt; 0.01) and the soil water content (P &lt; 0.05). The porosity for the MFM and the MWS, was higher under the CT whereas for the MWM and the MWS, it was higher under the no-till. However, the greatest porosity was under the MWS. Whilst the no-till significantly increased (P &lt; 0.05) the soil water content compared to the CT; the greatest soil water content was observed when the no-till was combined with the MWM rotations. The soil organic carbon (SOC) was increased more (P &lt; 0.05) by the no-till than the CT, and the MFM consistently had the least SOC compared with the rest of the crop rotations, at all the sampling depths (0–5, 5–10 and 10–20 cm). The soil bulk density negatively correlated with the soil porosity and the soil water content, whereas the porosity positively correlated with the soil water content. The study concluded that the crop rotations, the MWM and the MWS under the no-till coupled with the residue retention improved the soil porosity and the soil water content levels the most.

scholarly journals Effect of Biochar Application and Re-Application on Soil Bulk Density, Porosity, Saturated Hydraulic Conductivity, Water Content and Soil Water Availability in a Silty Loam Haplic Luvisol

Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1005 ◽  
Author(s):  
Lucia Toková ◽  
Dušan Igaz ◽  
Ján Horák ◽  
Elena Aydin
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Bulk Density ◽  
Relative Increase ◽  
Saturated Hydraulic Conductivity ◽  
Soil Drought ◽  
Silty Loam

Due to climate change the productive agricultural sectors have started to face various challenges, such as soil drought. Biochar is studied as a promising soil amendment. We studied the effect of a former biochar application (in 2014) and re-application (in 2018) on bulk density, porosity, saturated hydraulic conductivity, soil water content and selected soil water constants at the experimental site in Dolná Malanta (Slovakia) in 2019. Biochar was applied and re-applied at the rates of 0, 10 and 20 t ha−1. Nitrogen fertilizer was applied annually at application levels N0, N1 and N2. In 2019, these levels were represented by the doses of 0, 108 and 162 kg N ha−1, respectively. We found that biochar applied at 20 t ha−1 without fertilizer significantly reduced bulk density by 12% and increased porosity by 12%. During the dry period, a relative increase in soil water content was observed at all biochar treatments—the largest after re-application of biochar at a dose of 20 t ha−1 at all fertilization levels. The biochar application also significantly increased plant available water. We suppose that change in the soil structure following a biochar amendment was one of the main reasons of our observations.

Modelling leaching and recharge in a bare transitional red-brown earth ponded with low salinity water in summer

1994 ◽  
Vol 34 (7) ◽  
pp. 1085 ◽  
Author(s):  
L Cai ◽  
SA Prathapar ◽  
HG Beecher
Keyword(s):  
Hydraulic Conductivity ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Profile ◽  
Soil Surface ◽  
Saturated Hydraulic Conductivity ◽  
Rate Dependent ◽  
Water And Salt Movement ◽  
Winter Fallow

A modelling study was conducted to evaluate water and salt movement within a transitional red-brown earth with saline B horizon soil when such waters are used for ponding in summer. The model was calibrated using previously published experimental data. The calibrated model was used to evaluate the effect of depth to watertable, saturated hydraulic conductivity, and ponding water salinity on infiltration, water and salt movement within the soil profile, and recharge. The study showed that when initial soil water content and the saturated hydraulic conductivity (Ks) are low, infiltrating water will be stored within the soil profile even in the absence of a shallow watertable. Once the soil water content is high, however, recharge will be significant in winter, even if there is no net infiltration at the soil surface. Infiltration rates depend more on Ks than the depth to watertable if it is at, or below, 1.5 m from the soil surface. When Ks is high, recharge under ponding will be higher than that under winter fallow. Subsequent ponding in summer and fallow in winter tend to leach salts from the soil profile, the leaching rate dependent on Ks. During winter fallow, due to net evaporation, salts tend to move upwards and concentrate near the soil surface. In the presence of shallow watertables, leached salts tend to concentrate at, or near, the watertable.

Using satellite data in the Land Surface Model to estimate water availability of arid agricultural region

2020 ◽  
Author(s):  
Eugene Muzylev ◽  
Zoya Startseva ◽  
Elena Volkova ◽  
Eugene Vasilenko
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Availability ◽  
Land Surface ◽  
Land Surface Model ◽  
Soil Surface ◽  
Surface Model ◽  
Heat Regime ◽  
Vegetation Characteristics

&lt;p&gt;The water availability of agricultural arid regions can be assessed at presence using the physical-mathematical model of water and heat exchange between land surface and atmosphere LSM (Land Surface Model) adapted to satellite-derived estimates of meteorological and vegetation characteristics. The LSM is designed to calculate soil water content W, evapotranspiration Ev, vertical heat fluxes and other water and heat regime elements. Soil and vegetation characteristics were used in the LSM as parameters and meteorological characteristics were utilized as input variables.&lt;/p&gt;&lt;p&gt;The case study was carried out for the territory of the Saratov and Volgograd Trans-Volga region (the left-bank part of the Saratov and Volgograd regions) of 66600 km&lt;sup&gt;2&lt;/sup&gt; for the vegetation seasons 2016-2018.&lt;/p&gt;&lt;p&gt;The satellite measurement data from radiometers AVHRR/NOAA, SEVIRI/Meteosat-10, -11, -8, and MSU-MR/Meteor-M No. 2 in visible and IR ranges were thematic processed to built estimates of vegetation index NDVI, emissivity E, vegetation cover fraction B, leaf index LAI, land surface temperature LST and precipitation.&lt;/p&gt;&lt;p&gt;LAI and B estimates were obtained using empirical dependencies on NDVI. The adequacy of the LAI and B estimates obtained from all sensor data was verified when comparing the LAI time behavior built for named vegetation seasons. Errors of determining B and LAI were 15 and 20%, respectively.&lt;/p&gt;&lt;p&gt;Satellite-derived estimates of daily, decadal and monthly precipitation sums for each pixel were obtained using the Multi Threshold Method (MTM) for detecting clouds, identifying its types allocating precipitation zones and determining their maximum intensity. The MTM is based on the developed algorithm of the transition from the assessment of precipitation intensity to the assessment of their daily amounts. Testing of the method was carried out when comparing these amounts with observed at meteorological stations. The probability of satellite-detected precipitation zones corresponded to the actual ones was ~ 80% for all radiometers.&lt;/p&gt;&lt;p&gt;Based on the MTM, computational algorithm to evaluate the LST was developed and verified on the study region data. Comparison of ground-measured and satellite-derived LST showed that the latter estimates for the overwhelming number of observation turned out to be comparable in accuracy with each other and with the ground-based data.&lt;/p&gt;&lt;p&gt;Calculations of water and heat regime elements (being the final products of the simulation) were carried out when replacing ground-based estimates of precipitation, LST, LAI and B in the LSM by satellite-derived ones at each time step in all nodes of the computational grid. The efficiency of such replacement procedures was confirmed by comparing measured and calculated values of W and Ev (the difference between them didn&amp;#8217;t exceed 15% for W and 25% for Ev).&lt;/p&gt;&lt;p&gt;The possibility of using soil surface moisture estimates obtained from all-weather measurements by the scatterometer ASCAT/MetOp in the microwave range when simulating soil water content was also revealed. These estimates may use to set initial conditions for the vertical soil water transfer equation, as well as for calculating evaporation from the soil surface and the subsequent formation of the upper boundary condition for this equation.&lt;/p&gt;&lt;p&gt;As a summary, the described approach can be considered as a method for assessing the water availability for agricultural arid region.&lt;/p&gt;

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