Temporal variations of the hydraulic conductivity characteristic under conventional and conservation tillage

Geoderma ◽  
2020 ◽  
Vol 362 ◽  
pp. 114127 ◽  
Author(s):  
Janis Kreiselmeier ◽  
Parvathy Chandrasekhar ◽  
Thomas Weninger ◽  
Andreas Schwen ◽  
Stefan Julich ◽  
...  
1993 ◽  
Vol 264 (5) ◽  
pp. H1575-H1581 ◽  
Author(s):  
D. A. Williams ◽  
V. H. Huxley

Bradykinin, a vasodilator, increases permeability to macromolecules in postcapillary venules. Recent studies indicate that vasodilators elevate water flux from frog mesenteric capillaries. Thus we hypothesized that bradykinin would also increase transcapillary water flux. Arteriolar (ac), true (tc), and venular (vc) capillaries were identified within the microvascular network of frog mesentery. Each capillary was cannulated in situ and perfused with control (frog Ringer and 10 mg/ml bovine serum albumin) and then bradykinin test (10(-7) M) solutions. Hydraulic conductivity (Lp) increased across the network (1.8, 5.3, and 11.0 x 10(-7) cm.s-1.cmH2O-1 for ac, tc, and vc, respectively). Bradykinin test Lp normalized to control (LpBKN/LPC) was elevated threefold (n = 37). Lp for ac (n = 12) was elevated 3.5-fold and oscillated with time. Lp for tc (n = 13) increased fivefold within the first 5 min of exposure and then dropped. Lp for vc (n = 12) was not different from control. Location- and time-dependent responses of Lp indicate that capillaries forming microvascular networks have individual responses to bradykinin.


1998 ◽  
Vol 78 (4) ◽  
pp. 643-648 ◽  
Author(s):  
J. J. Miller ◽  
N. J. Sweetland ◽  
F. J. Larney ◽  
K. M. Volkmar

Conservation tillage is increasing on the Canadian prairies and its long-term effect on soil physical properties warrants investigation. Tension infiltrometer measurements were conducted on conventional tillage (CT), minimum tillage (MT) and no-till (NT) loam to clay loam soils in southern Alberta to determine if 26 yr of conservation tillage (MT, NT) modified the unsaturated hydraulic conductivity, K(ψ), relative to CT. Tillage of CT and MT plots was performed using a wide-blade cultivator. Measurements were performed on tillage treatments that were replicated on two adjacent parcels of land, with readings taken at the west parcel (Site 1) in 1993 and at the east parcel (Site 2) in 1994. Infiltration rates were determined at water potentials (ψ) of −0.3, −0.6 and −1.5 kPa. The K(ψ) values at −0.3, −0.6, −1.0 and −1.5 kPa (equivalent circular pore diameters of 1000, 500, 300 and 200 µm, respectively) were estimated from infiltration data using the nonlinear regression method of Logsdon and Jaynes. Tillage had a significant (P < 0.10) effect on K(ψ). Geometric mean K(ψ) values for NT (12.8 × 10−8 m s−1) were significantly (P < 0.05) lower than for CT (21.9 × 10−8 m s−1), but there was no significant difference between MT (13.6 × 10−8 m s−1) and CT, or between MT and NT. Although there was no significant tillage × site-year interaction (P > 0.10) for K(ψ), there was a trend for higher K(ψ) values at −0.6, −1.0 and −1.5 kPa in CT than MT and NT for Site 1 in 1993 compared to Site 2 in 1994. This trend was consistent with a shorter lag time between the most recent tillage event and subsequent infiltration measurements in CT for Site 1 in 1993 (1–16 d) compared with Site 2 in 1994 (28–45 d). Key words: Tillage, tension infiltrometer, unsaturated hydraulic conductivity


2021 ◽  
Vol 13 (15) ◽  
pp. 8177
Author(s):  
Mahran Sadiq ◽  
Guang Li ◽  
Nasir Rahim ◽  
Majid Mahmood Tahir

An improved understanding of the effect of conservation tillage on soil physicochemical quality indicators is obligatory to manage and conserve soil in a climate change scenario. Tillage strategies change soil physicochemical characteristics, consequently modifying crop yields. Conservation tillage is generally used to improve the soil physicochemical characteristics globally. However, the impact of conservation tillage on different soil depths under wheat cultivation is not well documented. A 3-year study was conducted using a randomized complete block design (RCDB). The objective of this research was to specifically study soil physicochemical indicators (soil bulk density, porosity, hydraulic conductivity, water content, temperature, nitrogen, phosphorous, potassium, C:N ratio, pH) and (crop yield) in conventional tillage (CT), straw incorporation into the conventionally tilled soil (CTS), no-tillage (NT), and stubble-retention to the no-tilled soil (NTS) measures under wheat monocropping system across different soil layers. Averaged over 0–40 cm soil layer, the results depicted scarce differences among the tillage practices regarding soil bulk density, porosity, water content and hydraulic conductivity. CT increased soil temperature over conservation tillage systems. Overall, conservation tillage improved soil total nitrogen, available phosphorous, total potassium, C:N ratio and yield than CT, whilst it decreased soil pH. We conclude that NTS and CTS are the best strategies to enhance soil health under wheat mono-cropping system conditions.


2021 ◽  
Author(s):  
Hana Ben Mahrez ◽  
Lilla Tőkés ◽  
John Molson ◽  
Judit Mádl-Szőnyi ◽  
Orsolya Sztanó

&lt;p&gt;This study focuses on the stratigraphic architecture of deltaic and fluvial sand lithologies within the Late Neogene Pannonian basin-fill succession in Hungary, identified from seismic and well data, in order to develop a quantitative hydrostratigraphic classification of the sequence. Hydrostratigraphic divisions are based on the hydraulic conductivity of the rock bodies, which depends on their extent, i.e. the thickness and the spatial distribution, as well as the lateral and vertical connectivity of sand bodies embedded in various muddy lithologies. Thus, we are going to build a simplified 3D lithological model for the uppermost 1500 m of the basin fill succession, that can later be transformed into hydrostratigraphic units and hydraulic conductivity values applied in a numerical flow model. The depositional environments change from deltaic to fluvial and within the fluvial system, the environment alternates between meandering and anastomosing. These intervals will appear as different hydrostratigraphic units in the model.&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;In our work-flow, a merged three-dimensional seismic cube covering an area of approximately &amp;#160;&amp;#160;&amp;#160;50 x 40 km&lt;sup&gt;2&lt;/sup&gt; was analyzed: 7 master horizons and several proportional slices were delineated in different attribute maps (e.g. amplitude, Root Mean Square amplitude, symmetry, similarity). These maps were generated to investigate the seismic geomorphological features and their associated depositional environments. Rock bodies were defined on the planform geometry of seismic attributes. Basic wireline logs (gamma, spontaneous potential, and resistivity) from 237 wells were interpreted simply in terms of sand, mud, and heterolithic muddy-sand, and finally were tied to the seismic cube. Lithology of rock bodies was determined with the help of well data. With this method, sandy deltaic lobes, sandy fluvial channel belts, and the muddy flood plains were identified. Based on the extension and density of sand bodies, percentages of sand vs clay (net-to-gross; N/G) as well as sand connectivity percentages were determined.&lt;/p&gt;&lt;p&gt;Above the deltaic succession, the fluvial depositional setting can be divided into three minor units. These units start with a meandering system, with 500-3600 m wide channel belts and a relatively high N/G. For an interval in the Pliocene about 350 m thick, a transition into an anastomosing river system is observed. This unit is characterized by channels about 100-200 m wide, with significantly lower N/G ratios and less connectedness. In the uppermost part of the succession, large meandering channel belts returned to the area. These changes in river style and paleo-hydrography affect the sand and clay ratio and their connectivity; therefore, definition of previous hydrostratigraphic units must be reconsidered.&amp;#160;&lt;/p&gt;&lt;p&gt;This research is part of a project that has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 810980.&lt;/p&gt;


2021 ◽  
Author(s):  
Kaihua Liao ◽  
Xiaoming Lai ◽  
Qing Zhu

Abstract. The saturated hydraulic conductivity (Ksat) is a key soil hydraulic property governing agricultural production. However, the influence of conversion from conventional tillage (CT) to conservation tillage (CS) (including no tillage (NT) and reduced tillage (RT)) on Ksat of soils is not well understood and still debated. In this study, we applied a global meta-analysis method to synthesize 201 paired observations for soil Ksat from 59 published studies, and investigated factors influencing the effects of conversion to CS on Ksat. Results showed that the Ksat measured by hood infiltrometer, tension disc infiltrometer, and Guelph permeameter produced a similar pattern under CS practices, with non-significant (p > 0.05) increase of 6.6 %, 3.6 % and 4.9 %, respectively. However, conversion to CS significantly (p < 0.05) increased Ksat by 32.0 % for ring infiltrometer, while it decreased Ksat by 3.2 % for constant/falling head (p > 0.05). Soil layer, CS type and soil texture had no significant (p > 0.05) effects on the influence of conversion to CS on the Ksat, but the Ksat under CS showed a greater increase for a longer conversion period (time since conversion). In addition, mean annual temperature (MAT) was found to be an important driver controlling the response of Ksat to tillage conversion at the large scale. These findings suggested that quantifying the effects of tillage conversion on soil Ksat needed to consider experimental conditions, especially the measurement technique and conversion period.


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