The effects of soil bulk density, clay content and temperature on soil water content measurement using time-domain reflectometry

2003 ◽  
Vol 17 (18) ◽  
pp. 3601-3614 ◽  
Author(s):  
Yuanshi Gong ◽  
Qiaohong Cao ◽  
Zongjia Sun
2000 ◽  
Vol 80 (1) ◽  
pp. 3-11 ◽  
Author(s):  
D. L. Spittlehouse

Forest soils often contain many large coarse fragments making it difficult to insert probes to measure soil water content. The ability of time domain reflectometry (TDR) to give reliable measurements of water content in soil with up to 40% coarse fragments was evaluated at a site in the southern interior of British Columbia, Canada. A commercial time domain reflectometer was used with 0.3-, 0.5- and 0.75-m-long probes to measure soil water content of the profile and layers within the profile. A probe had a shorting diode at the surface and two 3-mm-diameter stainless steel rods inserted vertically, 30 mm apart, as the waveguide. Diverging rods or profile discontinuities resulted in erroneous readings that required a review of the recorded signals and recalculation the travel time. Soil physical and hydrologic soil properties were determined and the soil calibrated for TDR. An accuracy of ±0.02 m3m−3 was obtained with measurement of soil bulk density and minimizing probe and travel time errors. Variation in water content between probes reflected the variability in coarse fragment content; however, the ranking of the probes stayed constant with time and rates of change were similar between probes. One standard deviation on the measured change in the volume of water between measurement days for the 0 to 0.5 m depth was ±6 mm (n = 20), equivalent to 0.012 m3m−3. Measurements of water content of the layers had one standard deviation of 0.02 m3m−3. Key words: Time domain reflectometry, forest hydrology, soil water content, water balance


2021 ◽  
pp. 126389
Author(s):  
Marco Bittelli ◽  
Fausto Tomei ◽  
Anbazhagan P. ◽  
Raghuveer Rao Pallapati ◽  
Puskar Mahajan ◽  
...  

Soil Science ◽  
2010 ◽  
Vol 175 (10) ◽  
pp. 469-473 ◽  
Author(s):  
Zhaoqiang Ju ◽  
Xiaona Liu ◽  
Tusheng Ren ◽  
Chunsheng Hu

2019 ◽  
Vol 15 (No. 1) ◽  
pp. 47-54 ◽  
Author(s):  
Mxolisi Mtyobile ◽  
Lindah Muzangwa ◽  
Pearson Nyari Stephano Mnkeni

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.


Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1005 ◽  
Author(s):  
Lucia Toková ◽  
Dušan Igaz ◽  
Ján Horák ◽  
Elena Aydin

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.


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