scholarly journals Effect of Plastic Film Residue on Vertical Infiltration Under Different Initial Soil Moisture Contents and Dry Bulk Densities

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1346
Author(s):  
Junhao Cao ◽  
Pengpeng Chen ◽  
Yupeng Li ◽  
Heng Fang ◽  
Xiaobo Gu ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Water ◽  
Initial Moisture Content ◽  
Comprehensive Treatment ◽  
Burial Depth ◽  
Plastic Film ◽  
Wetting Front ◽  
Factors Affecting ◽  
Pollution Area

In arid and semi-arid regions, plastic film mulching can effectively improve crop yield, but with the increase of service life, a lot of residual plastic film (RPF) remains in the soil. The application of a RPF to a soil will alter soil moisture processes, and thus, affect the soil water distribution and its effectiveness. A quadratic regression orthogonal design was used to study the effects of initial moisture content (IMC), dry bulk density (DBD), residual plastic film content (RPFC), and the burial depth of RPF on the migration time of wetting front (MF), moisture content (MC), and accumulative infiltration (AI) of a test soil. It was found that IMC, DBD, and RPFC were the main factors affecting MC, MF, and AI, while the burial depth of RPF had no significant influence. The order of influence for the factors affecting MF was IMC > DBD > RPFC, while the order of influence for the factors affecting MC and AI was DBD > IMC > RPFC. RPFC was parabolic in relation to MF, MC, and AI, when it was in the range of 50–100 kg/hm2, while within the same range MC and AI reached a maximum and MF reached a minimum. The analysis of the interactive responses revealed that when the DBD was greater than 1.29g/cm3, the MF initially decreased and then increased with the increase of RPFC. When the RPFC was more than 100 kg/hm2, the MF initially increased and then decreased with the increase of the DBD. When the DBD was larger than 1.31 g/cm3, the AI initially increased and then decreased with the increase of RPFC. It was apparent that the RPF not only had a blocking effect on the wetting front, but also affected the water flow. When the RPFC was between 50 and 100 kg/hm2, the soil MC was significantly increased. It was suggested that the RPF pollution area should increase the mechanical recovery of plastic film, standardize the use and recycling of agricultural RPF, optimize the planting model, and establish a recyclable model for the treatment of RPF pollution, and it was proposed that the RPFC remaining after recovery of the RPF should be less than 50 kg/hm2.This study can prove the law of soil water movement in the residue film pollution area and provide reference and solution ideas for the comprehensive treatment of residue film pollution in farmland.

scholarly journals Effect of Organic Matter and Initial Moisture Content on Water Transmission Characteristics of Alfisols of Assam

Agropedology ◽  
2019 ◽  
Vol 27 (1) ◽  
Author(s):  
M. K. Nayak ◽  
◽  
D. K. Patgiri ◽  
T. C. Baruah ◽  
◽  
...  
Keyword(s):  
Organic Matter ◽  
Moisture Content ◽  
Soil Water ◽  
Initial Moisture Content ◽  
Mean Diffusivity ◽  
Wetting Front ◽  
Transmission Parameters ◽  
Increase With Increase ◽  
Water Diffusivity ◽  
Water Transmission

A study was conducted to study the effect of organic matter and initial moisture content on water transmission behaviour of three texturally different Alfisols. Saturated hydraulic conductivity showed a variable increase with increase in organic matter. Soil water diffusivity D (θ) showed an irregular trend with increasing levels of organic matter while sorptivity (s) increased with increasing levels of organic matter, penetrability (P) of wetting front decreased. Weighted mean diffusivity did not show any particular trend amongst the treatments, however, it was found to be higher in treated soils as compared to untreated control. Specific water capacity increased with increasing levels of organic matter, while capillary conductivity (k) did not show any definite trend. All the water transmission parameters except sorptivity were found to be increased with an increase in initial moisture content. Diffusivity was in general higher at lower initial moisture content indicating that soil water diffusivity was greatly influenced by initial moisture content. Prediction of D (θ) was, by and large, satisfactory in coarse textured soils and inconclusive in case of K (θ) relation in most of the soils.

scholarly journals Numerical investigation of wetting front migration and soil water distribution under vertical line source irrigation with different influencing factors

2021 ◽  
Author(s):  
Yanwei Fan ◽  
Liangjun Ma ◽  
Hujun Wei ◽  
Pengcheng Zhu
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Water Content ◽  
Influencing Factors ◽  
Line Source ◽  
Vertical Line ◽  
Initial Water Content ◽  
Wetting Front ◽  
Simulation Results ◽  
Soil Wetting

Abstract Vertical line source irrigation (VLSI) is an underground irrigation method suitable for deep-rooted plants. Understanding the characteristics of the soil wetting body of the VLSI was the key to designing this irrigation system. On the basis of experimental verification of the reliability of the HYDRUS simulation results of VLSI under the conditions of soil texture (ST), initial water content (θi), line source buried depth (B), line source diameter (D) and line source length (L), numerical studies of the migration law of the wetting front of VLSI and the distribution characteristics of soil moisture were performed. The wetting front migration (WFM) was mainly influenced by ST, θi, D and L (P < 0.05), while B had little effect on WFM (P > 0.05). The shape of the soil wetting body changed little under different influencing factors. The water content contour was approximately ‘ellipsoidal’ around the line source. The soil moisture near the line source was close to the saturated moisture content. The moisture content around the line source gradually decreased outward, and the contour lines gradually became dense. According to the simulation results, a prediction model of multiple factors influencing the migration process of the VLSI wetting front was established. The predicted value was in good agreement with the measured value. The results of this research could provide a theoretical basis for further optimizing the combination of VLSI and irrigation elements.

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 Study on Variation of Surface Runoff and Soil Moisture Content in the Subgrade of Permeable Pavement Structure

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Lijun Hou ◽  
Yuan Wang ◽  
Fengchun Shen ◽  
Ming Lei ◽  
Xiang Wang ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Water ◽  
Surface Runoff ◽  
Rainfall Intensity ◽  
Soil Moisture Content ◽  
Asphalt Pavement ◽  
Infiltration Rate ◽  
Runoff Coefficient ◽  
Flood Peak

The self-designed indoor simulated rainfall device was used to rain on five types of pavement structures with 4 types of rainfall intensity (2.5 mm/min, 3.4 mm/min, 4.6 mm/min, and 5.5 mm/min). The effect of rainfall intensity on the surface runoff, the relation between the subgrade soil moisture content changes, and the influence of initial soil water content on rain infiltration rate are studied. The test results show that the surface runoff coefficient of densely asphalted pavement is greater than 90% in drainage pavements and it has little influence on the reducing and hysteresis of the flood peak. The surface runoff coefficient of large-void asphalt pavement (permeable) is less than 40%. Although the large-void asphalt pavement (permeable) can reduce a small amount of surface runoff, it has no obvious effect on the reduction and hysteresis of the flood peak. In semipermeable pavement, with the increasing of the thickness of base (graded gravel), the surface runoff coefficient decreases at different rainfall intensities, parts of the surface runoff are reduced, and the arrival of flood peaks is delayed. In permeable roads, almost no surface runoff occurred. As time continued, the soil moisture content quickly reached a saturated state and presented a stable infiltration situation under the action of gravity and the gradient of soil water suction. As the initial moisture content increases, the initial infiltration rate decreases and the time to reach a stable infiltration rate becomes shorter. The drier the soil, the greater the initial infiltration rate and the higher the soil moisture content after infiltration stabilization. Permeable roads can greatly alleviate the pressure of urban drainage and reduce the risk of storms and floods.

scholarly journals Effects of Rain Intensity and Initial Soil Moisture on Hydrological Responses in Laboratory Conditions

2015 ◽  
Vol 29 (2) ◽  
pp. 165-173 ◽  
Author(s):  
Abdulvahed Khaledi Darvishan ◽  
Kazimierz Banasik ◽  
Seyed Hamidreza Sadeghi ◽  
Leila Gholami ◽  
Leszek Hejduk
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Sandy Loam ◽  
Initial Moisture Content ◽  
Hydrological Responses ◽  
Laboratory Conditions ◽  
Initial Soil Moisture ◽  
Erosion Processes ◽  
Initial Soil

Abstract Although the possibility of measuring and analysing all parts of the rainfall, infiltration, runoff, and erosion process as a natural hydrologic cycle in field conditions is still one of the more unattainable goals in the hydrological sciences, it can be accomplished in laboratory conditions as a way to understand the whole process. The initial moisture content is one of the most effective factors on soil infiltration, runoff, and erosion responses. The present research was conducted on a 2 m2 laboratory plot at a slope of 9% on a typical sandy-loam soil. The effects of the initial soil moisture content on the infiltration, runoff, and erosion processes were studied at four levels of initial soil moisture content (12, 25, 33, and 40 volumetric percentage) and two rainfall intensities (60 and 120 mm h-1). The results showed a significant (p ≤ 0.05) correlation between rainfall intensity and downstream splash, with r = 0.87. The results reflected the theory of hydrological responses, showing significant (p ≤ 0.05) correlations with r =-0.93, 0.98, -0.83, 0.88, and 0.73 between the initial soil moisture content and the time-to-runoff, runoff coefficient, drainage as a part of the infiltrated water, downstream splash, and total outflow sediment, respectively.

A LABORATORY STUDY ON THE EFFECTS OF SOIL MOISTURE CONTENT, TEXTURE, AND TIMING OF LEACHING ON N LOSS FROM TWO SOUTHERN ALBERTA SOILS

1982 ◽  
Vol 62 (2) ◽  
pp. 407-413 ◽  
Author(s):  
T. G. SOMMERFELDT ◽  
C. CHANG ◽  
J. M. CAREFOOT
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Sandy Loam ◽  
Wetting Front ◽  
N Losses ◽  
Initial Soil Moisture ◽  
N Removal ◽  
Southern Alberta ◽  
Initial Soil

A column study was conducted to determine the effects of soil texture, initial soil moisture content and timing of leaching on N removal from two irrigated soils of southern Alberta. Pelleted NH4NO3 fertilizer (0.639 g N per column = 336 kg∙ha−1) was applied to Lethbridge loam (Leth L) and Cavendish fine sandy loam (CV FSL) at three initial levels of soil moisture: air dry (AD), 0.5 field capacity (0.5 FC), and wet (W, 25 cm suction). Leaching began immediately after the fertilizer application or was delayed 1 wk. Water was applied in 1400-mL (7.6 cm depth) increments every 2nd day for a total of 33 600 mL (175 cm depth). The leachate was collected, measured, and analyzed for NH4-N and NO3-N. The soil was analyzed for N content before and after leaching. More N was leached from CV FSL (0.600 g) than from Leth L (0.521 g). Responses to initial soil moisture were similar for both soils; the NO3-N concentration peak followed the advancing wetting front more closely in the AD than in the W systems and leaching losses were greatest from the 0.5 FC treatment. Delayed leaching did not significantly affect the amount of N leached. N losses, other than from leaching, were greatest in the W and AD treatments, in the AD treatment these losses were attributed to volatilization and, in the W soils, to denitrification.

Some factors affecting compacted clay swelling

1970 ◽  
Vol 7 (1) ◽  
pp. 79-91 ◽  
Author(s):  
A. Yevnin ◽  
D. Zaslavsky
Keyword(s):  
Moisture Content ◽  
Volume Change ◽  
Empirical Equation ◽  
Clay Soil ◽  
Initial Density ◽  
Initial Moisture Content ◽  
Swelling Pressure ◽  
Compacted Clay ◽  
Factors Affecting ◽  
Applied Loading

Volume change after saturation was determined on specimens of a statically compacted clay soil. It was found that density after swelling increases linearly with increasing initial density, initial moisture content, and increasing logarithm of applied loading pressure. An empirical equation with five coefficients and a constant, found with the aid of a computer, represents the results with a coefficient of correlation close to 1. An equation for the swelling pressure was also obtained from this equation. Results of specimens which consolidated did not fit the lines obtained for swelling. The relationships obtained were explained by the influence of particle reorientation and moisture content on swelling tendency.

scholarly journals Factors affecting nitrogenase activity (C2H2 reduction) associated with sorghum and millet estimated using the soil core assay

1983 ◽  
Vol 29 (8) ◽  
pp. 1063-1069 ◽  
Author(s):  
S. P. Wani ◽  
P. J. Dart ◽  
M. N. Upadhyaya
Keyword(s):  
Soil Moisture ◽  
Seasonal Variation ◽  
Moisture Content ◽  
Soil Temperature ◽  
Diurnal Variation ◽  
Host Plant ◽  
Soil Moisture Content ◽  
Nitrogenase Activity ◽  
Soil Core ◽  
Factors Affecting

Factors affecting nitrogenase activity associated with sorghum and millet roots have been studied. Plants grown in iron cores in the field and then assayed had significantly higher activity than plants cored at the time of assay. Mechanical disturbance during transportation of the cores reduced the activity significantly. Any delay between cutting off the plant top and injecting C2H2 gas led to a reduction in the level of nitrogenase activity determined. Diurnal variation in nitrogenase activity was noted but was not correlated with soil temperature. Most activity occurred at the end of the photoperiod. Seasonal variation in nitrogenase activity of plants was observed and was correlated with the ontogenetic development of the host plant, being most at flowering. A low but significant correlation existed between soil moisture content and nitrogenase activity associated with the plant.

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