News Update on Soil Moisture Research: Dec – 2019

Regions of Strong Coupling Between Soil Moisture and Precipitation

Previous estimates of land-atmosphere interaction (the impact of soil moisture on precipitation) are limited by a scarcity of observational data and by the model dependence of computational estimates. To counter the second limitation, a dozen climate-modeling groups have recently performed an equivalent highly controlled numerical experiment as a part of a coordinated comparison project. this enables a multimodel estimation of the regions on Earth where precipitation is suffering from soil moisture anomalies during hemisphere summer. Potential benefits of this estimation may include improved seasonal rainfall forecasts. [1]

Relationship between soil respiration and soil moisture

Microbial activity is suffering from changes within the availability of soil moisture. We examined the connection between microbial activity and water potential during a silt loam soil during four successive drying and rewetting cycles. Microbial activity was inferred from the speed of CO2 accumulating during a sealed flask containing the soil sample and therefore the CO2 respired was measured using gas chromatography. Thermocouple hygrometry was wont to monitor the water potential by burying a thermocouple within the soil sample within the flask. Initial treatment by drying on pressure plates brought samples of the test soil to 6 different water potentials within the range -0.005 to -1.5MPa. Water potential and soil respiration were simultaneously measured while these six soil samples slowly dried by evaporation and were remoistened fourfold. [2]

Soil moisture retrieval from space: the Soil Moisture and Ocean Salinity (SMOS) mission

Microwave radiometry at low frequencies (L-band: 1.4 GHz, 21 cm) is a longtime technique for estimating topsoil moisture and sea surface salinity with an appropriate sensitivity. However, from space, large antennas (several meters) are required to realize an adequate spatial resolution at L-band. So on reduce the matter of putting into orbit an outsized filled antenna, the likelihood of using antenna synthesis methods has been investigated. Such a system, counting on a deployable structure, has now proved to be feasible and has led to the Soil Moisture and Ocean Salinity (SMOS) mission, which is described. the most objective of the SMOS mission is to deliver key variables of the land surfaces (soil moisture fields), and of ocean surfaces (sea surface salinity fields). The SMOS mission is predicated on a dual polarized L-band radiometer using aperture synthesis (two-dimensional [2D] interferometer) so on achieve a ground resolution of fifty km at the swath edges including multiangular acquisitions. [3]

High-resolution simulation and validation of soil moisture in the arid region of Northwest China

Soil moisture plays a crucial role in land-atmosphere interactions, agricultural drought monitoring, and water resource management, particularly across arid regions. However, it’s challenging to simulate soil moisture of high spatial resolution and to guage soil moisture at fine spatial resolution in arid regions in Northwest China thanks to considerable uncertainties in forcing data and limited in place measurements. Then, the info set was wont to produce the 1 km high-resolution atmospheric forcing datasets and to drive the Community Land Model version 3.5 (CLM3.5) for simulating spatiotemporally continuous topsoil moisture. [4]

Adjustment of Sampling Grids for Soil Penetration Resistance, Bulk Density, and Soil Moisture Mapping

There is still a scarcity of data within the literature regarding the sampling grid size and its effect on the accuracy of soil attributes spatial variability mapping. Thus, this study aimed to guage the influence of various sampling grid sizes regarding accuracy for soil penetration resistance (SPR), soil bulk density (SBD) and soil moisture (SM) spatial variability characterization, also because the correlation between these attributes. The study was conducted during a 5.7 ha Red Yellow Latosol area in Januária, Minas Gerais state, Brazil. Soil samples were taken at the 0.00–0.20 m layer, employing a regular sampling grid of 20×20 m. (145 points). Other two grids (41 and 21 points) were derived by deleting lines or lines and points from the initial grid. [5]

Reference

[1] Koster, R.D., Dirmeyer, P.A., Guo, Z., Bonan, G., Chan, E., Cox, P., Gordon, C.T., Kanae, S., Kowalczyk, E., Lawrence, D. and Liu, P., 2004. Regions of strong coupling between soil moisture and precipitation. Science, 305(5687), (Web Link)

[2] Orchard, V.A. and Cook, F.J., 1983. Relationship between soil respiration and soil moisture. Soil Biology and Biochemistry, 15(4), (Web Link)

[3] Kerr, Y.H., Waldteufel, P., Wigneron, J.P., Martinuzzi, J.A.M.J., Font, J. and Berger, M., 2001. Soil moisture retrieval from space: The Soil Moisture and Ocean Salinity (SMOS) mission. IEEE transactions on Geoscience and remote sensing, 39(8), (Web Link)

[4] High-resolution simulation and validation of soil moisture in the arid region of Northwest China
Xianyong Meng, Hao Wang, Ji Chen, Mingxiang Yang & Zhihua Pan
Scientific Reports volume 9, (Web Link)

[5] Nogueira Martins, R., Rodrigues de Oliveira, A., Thália Silva Machado, L., Lima dos Santos, F. F., Cunha Siqueira, W. da and Aparecida de Souza Santos, J. (2018) “Adjustment of Sampling Grids for Soil Penetration Resistance, Bulk Density, and Soil Moisture Mapping”, Journal of Experimental Agriculture International, 24(3), (Web Link)

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