Soil water behaviour in response to changes in soil structure (original) (raw)
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Water
The conversion from conventional tillage (CT) to no-tillage (NT) of the soil is often suggested for positive long-term effects on several physical and hydraulic soil properties. In fact, although shortly after the conversion a worsening of the soil may occur, this transition should evolve in a progressive improvement of soil properties. Therefore, investigations aiming at evaluating the effects of NT on porous media are advisable, since such information may be relevant to better address the farmers’ choices to this specific soil conservation management strategy. In this investigation, innovative and standard methods were applied to compare CT and NT on two farms where the conversion took place 6 or 24 years ago, respectively. Regardless of the investigated farm, results showed negligible differences in cumulative infiltration or infiltration rate, soil sorptivity, saturated hydraulic conductivity, conductive pores size, or hydraulic conductivity functions. Since relatively small dis...
CATENA, 2014
The purpose of this study was to research the influence of four different tillage practices [T1: Conventional tillage (moldboard plow+disk harrow+combined harrows+precision seeder); T2: Reduced tillage-I (cultivator+combined harrows+precision seeder); T3: Reduced tillage-II (rotary power harrow+precision seeder) and T4: No-till (no-till seeder)] on bulk density, total porosity, penetration resistance, field capacity, field water content and the infiltration rate of a loamy soil in a semi-arid region with a cool climate and an annual mean temperature of 5.6°C. In particular, the effectiveness of the no-till practice was investigated. Since 1999, the experimental field has been tilled by the above-mentioned tillage practices and also applied a crop rotation (vetch-winter wheat-fallow) in dry conditions. We made assessments of selected soil properties according to the data during the sowing-germination period of winter wheat only in 2012 autumn. Therefore, the number of germinated seedlings of winter wheat was also evaluated. The data of this study carried out in three replications were statistically analyzed using the ANOVA and the regression technique. The results indicated that the tillage treatments affected soil properties and wheat germination. The highest values in all examined parameters except for total porosity were obtained under the no-till practice for top soil layer of 30 cm. As was expected, the no-till treatment had the highest bulk density and provided the lowest total porosity. Generally, the plots tilled by conventional practice had the lowest values. Similar results were obtained for the top soil layer of 0-10 cm, which is seedbed. The penetration resistance measured to a depth of 30 cm in 5 cm increments increased as polynomial with increasing the soil depth in all treatments. The infiltration rate decreases as a function of elapsed time could be described by the Kostiakov equation. Also, significant linear relationships were obtained for penetration resistance-bulk density, field capacity-bulk density and field capacity-penetration resistance. Although no-till treatment improved the hydraulic properties of soil, it had no positive effect on the soil physical properties. However, the linear relations with high correlation coefficients between penetration resistance and bulk density with field capacity at the no-till showed that soil physical and hydraulic properties revealed that they are connected to each other. According to the results of our study it could be concluded that the no-till practice increased winter wheat germination due to higher water content.
Soil and Tillage Research, 2001
In the absence of irrigation, the cultivation of cereals in semi-arid zones provides a poor yield. To study the consequences of fallow tillage on the soil structure and hydraulic properties, we conducted an experiment from 1991/1992 to 1997/1998 using various techniques (chisel or disc plough, early or late tillage) on a calcisol of the high plateaus of eastern Algeria. In the middle of the tilled horizon (between 8 and 25 cm depth), we measured the near-saturated hydraulic conductivity at four soil water tensions (or potentials) using multidisc in®ltrometers, and quanti®ed the morphology of the macropore space using image analysis. Results indicated that tillage increased soil conductivity mainly at low water potential (0.06 and 0.3 kPa). This increase was more signi®cant with the chisel (1:84 Â 10 À5 m s À1 at 0.06 kPa) than with the disc plough 1:25 Â 10 À5 m s À1 , but was attenuated during the crop cycle. Signi®cant differences appeared between tillage treatments for surface macroporosity (5.1% for chisel, 1.1% for disc), pore-space morphology (thin cracks separating compact aggregates under disc, loose ®ne soil assemblage separating smaller aggregates under chisel) and porosity distribution pattern (equivalent diameter of the macropores varied from 1 mm under disc to more than 2±3 mm under chisel). Analyses of porosity distributions indicate a possible relationship between the structure of the surface horizon and soil hydraulic properties. Durum wheat grain yield varied from 1.08 to 2.85 t ha À1 during the 7-year trial. Grain yield under shallow tillage was signi®cantly higher than under disc plough treatment during wet years. Tillage-date varied across seasons and early tillage effect was more apparent when the fallow season was less rainy. #
Soil structure changes induced by tillage systems
Soil and Tillage Research
Structure represents one of the main soil physical attributes indicators. The soil porous system (SPS) is directly linked to the soil structure. Water retention, movement, root development, gas diffusion and the conditions for all soil biota are related to the SPS. Studies about the influence of tillage systems in the soil structure are important to evaluate their impact in the soil quality. This paper deals with a detailed analysis of changes in the soil structure induced by conventional (CT) and no-tillage (NT) systems. Three different soil depths were studied (0-10, 10-20 and 20-30 cm). Data of the soil water retention curve (SWRC), micromorphologic (impregnated blocks) (2D) and microtomographic (mCT) (3D) analyses were utilized to characterize the SPS. Such analyses enabled the investigation of porous system attributes such as: porosity, pore number and shape, pore size distribution, tortuosity and connectivity. Results from this study show a tri-modal pore size distribution (PSD) at depths 0-10 and 10-20 cm for the soil under CT and a bi-modal PSD for the lower layer (20-30 cm). Regarding the soil under NT, tri-modal PSDs were found at the three depths analyzed. Results based on the micromorphologic analysis (2D) showed that the greatest contribution to areal porosity (AP) is given by pores of round (R) shape for CT (52%: 0-10 cm; 50%: 10-20 cm; 67%: 20-30 cm). Contrary to the results observed for CT, the soil under NT system gave the greatest contribution to AP, for the upper (0-10 cm) and intermediate (10-20 cm) layers, due to the large complex (C) pore types. For the mCT analysis, several types of pores were identified for each soil tillage system. Small differences in the macroporosity (MAP) were observed for the 0-10 and 20-30 cm between CT and NT. A better pore connectivity was found for the 0-10 cm layer under NT. 2016 Elsevier B.V. All rights reserved.
Tillage Effects on the Spatial and Temporal Variations of Soil Water
Soil Science Society of America Journal, 1990
The objective of this study was to examine the effect of tillage on the spatial and temporal variability of soil water content of the surface layer (0-0.2 m) under a corn (Zea mays L.) crop. Soil water content was measured nondestructively every 1 to 2 d in fall moldboard (CT), 1-yr no-tillage (SNT), and longer term (>15 yr) notillage (LNT) plots using permanently placed time domain reflectometry (TDR) transmission line probes. The plots are located near Guelph, ON, Canada on a Typic Hapludalf (loam) soil. Sampling sites were in the corn row, directly between corn rows (interrow), and halfway between the row and interrow (quarter row). Systematic spatial differences in soil water content, within and between tillage treatments, were observed throughout the entire growing season. Large differences between CT and both LNT and SNT early in the season were attributed to increased evaporation in CT caused by spring secondary tillage. The drying rate in the LNT interrow position was much lower than the CT and SNT interrow drying rates. Soil water recharge from rainfall was distributed systematically in space because of canopy interception and subsequent stemflow. Crop residue on the soil surface of the no-till treatments intercepted a significant amount of rainfall and reduced soil water recharge by 14 and 35% in the SNT and LNT treatments, respectively. The tillage treatments affected the temporal dependence of the spatial variability of soil water and the spatial dependence of the temporal variability. A GENERAL PURPOSE OF TILLAGE is to create a favorable soil environment. Soil water content is an important aspect of the soil environment of the plant. Tillage can have a major influence on soil water content through its effect on infiltration, surface runoff, evaporation, and water availability to plants. No-tillage has been defined as a method of planting crops that requires no seedbed preparation other than
Soil porosity and water infiltration as influenced by tillage methods
Soil and Tillage Research, 2006
The relations between soil pore structure induced by tillage and infiltration play an important role in flow characteristics of water and solutes in soil. In this study, we assessed the effect of long-term use of various tillage systems on pore size distribution, areal porosity, stained (flow-active) porosity and infiltration of silt loam Eutric Fluvisol. Tillage treatments were: (1) ploughing to
Soil organic matter widens the range of water contents for tillage
Soil and Tillage Research
The effects of soil organic matter on the water contents for tillage were investigated by sampling soils with a uniform texture, but a range of soil organic carbon (SOC) from two long-term field experiments at Highfield in Rothamsted Research, UK and Askov Experimental Station, Denmark. The treatments studied in Highfield were Bare fallow (BF), Continuous arable rotation (A), Ley-arable (LA) and Grass (G); and in Askov: unfertilized (UNF), ½ mineral fertilizer (½ NPK), 1 mineral fertilizer (1NPK), and 1½ animal manure (1½AM). Minimally undisturbed soil cores (100 cm3) were sampled per plot in both locations from 6-10 cm depth to generate water retention data. Soil blocks were also sampled at 6-15 cm depth to determine basic soil properties and to measure soil aggregate strength parameters. The range of soil water contents appropriate for tillage were determined using the water retention and the consistency approaches. SOC content in Highfield was in the order: G>LA=A>BF, and in Askov: 1½ AM>1NPK=½NPK>UNF. Results showed that different long-term management of the silt loam Highfield soil, and fertilization of the sandy loam Askov soil affected the mechanical properties of the soils-for Highfield soil, aggregates from the G treatment were stronger in terms of rupture energy when wet (-100 hPa matric potential) than the BF treatment. As the soil dried (-300 and-1000 hPa matric potentials), soil aggregates from the G treatment were relatively weaker and more elastic than the BF soil. Our study showed, for both Highfield and Askov soils, a strong positive linear increase in the range of water contents for tillage with increasing contents of SOC. This suggests that management practices leading to increased SOC can improve soil workability by increasing the range of water contents for tillage. We recommended using the consistency approach over the water retention approach for determining the range of water contents for tillage because it seems to give realistic estimates of the water contents for tillage.
Water, 2019
Spatial variability of soil properties at the field scale can determine the extent of agricultural yields and specific research in this area is needed. The general objective of this study was to investigate the relationships between soil physical and hydraulic properties and wheat yield at the field scale and test the BEST-procedure for the spatialization of soil hydraulic properties. A simplified version of the BEST-procedure, to estimate some capacitive indicators from the soil water retention curve (air capacity, ACe, relative field capacity, RFCe, plant available water capacity, PAWCe), was applied and coupled to estimates of structure stability index (SSI), determinations of soil texture and measurements of bulk density (BD), soil organic carbon (TOC) and saturated hydraulic conductivity (Ks). Variables under study were spatialized to investigate correlations with observed medium-high levels of wheat yields. Soil physical quality assessment and correlations analysis highlighted some inconsistencies (i.e., a negative correlation between PAWCe and crop yield), and only five variables (i.e., clay + silt fraction, BD, TOC, SSI and PAWCe) were spatially structured. Therefore, for the soil-crop system studied, application of the simplified BEST-procedure did not return completely reliable results. Results highlighted that (i) BD was the only variable selected by stepwise analysis as a function of crop yield, (ii) BD showed a spatial distribution in agreement with that detected for crop yield, and (iii) the cross-correlation analysis showed a significant positive relationship between BD and wheat yield up to a distance of approximately 25 m. Such results have implications for Mediterranean agro-environments management. In any case, the reliability of simplified measurement methods for estimating soil hydraulic properties needs to be further verified by adopting denser measurements grids in order to better capture the soil spatial variability. In addition, the temporal stability of observed spatial relationships, i.e., between BD or soil texture and crop yields, needs to be investigated along a larger time interval in order to properly use this information for improving agronomic management.