H. Lohrasbi; A. Farrokhian Firuzi
Abstract
Introduction: Wind erosion is one of the most important environmental challenges in arid and semiarid regions which cause soil loss and dust storm. In recent decades, the potential of soil erosion has been recognized as serious threat against soil sustainability. In addition, accelerated soil erosion ...
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Introduction: Wind erosion is one of the most important environmental challenges in arid and semiarid regions which cause soil loss and dust storm. In recent decades, the potential of soil erosion has been recognized as serious threat against soil sustainability. In addition, accelerated soil erosion has led to harmful environmental effects. Therefore, focus on soil erosion outcomes is necessary in order to mitigate its environmental impacts. Understanding interactions between land use management and topographical properties of landscape are important in order to effectively control soil erosion through implementing best management practices (BMPs). Application of mulch is one of the most prevailing scenarios to prevent the erosive soil against wind as an erosive factor in the hotspots. In this regard the type of much is really important because the environmental aspects and the mulch consistency are important factors for production and selection of mulch between several options. Nowadays, sustainable management is one of the most important scopes in order to achieve the aims of human healthy. In this regards the Bagasse of sugarcane and Conocarpus were selected as feedstocks to produce biochars. Biochar is the by-product of anaerobic process which called pyrolysis. The biogases, energy and so on are other outputs of pyrolysis. Another treatment which evaluated in this study was Zeoplant. Zeoplant is a super absorptive material which is able to hold the water in the soil therefore is capable to enhance the water holding capacity of the soil.
Materials and Methods: In this study the effects of biochar of Bagasse from sugarcane, biochar of Conocarpus and Zeoplant in three levels (0, 2 and 4 percentage) and two moisture levels (25 and 50 percentage of FC) and 3 replications in randomized completely design with factorial on physical and mechanical properties of soil as indices of soil erodibility was studied. Soil sampling accomplished from Horalazim marshes and after application of treatment, incubated in tray with the size of 70×30×10 cm for 90 days. After incubations the trays located in wind tunnel in order to simulate wind erosion process under a wind with 15 m/sec speed and 2 m from soil surface. The main measured soil physical and mechanical parameters include mean weight diameter (MWD), penetration resistance (PR), tensile strength (TS), friability index (FI), shear strength, crusting index (CI), soil textural index and organic matter. The statistical analysis was performed using SAS 9.2 software and the mean comparison was accomplished with Duncan test (5 %). In order to draw the graphs Origin 2017 software was used.
Results and Discussion: The soil texture was silty loam (SiL) including 62% silt, 26% clay and 12% sand, therefore the soil was sensitive to wind erosion. Soil organic matter before application of biochars and Zeoplant was around 1.93% and after application increased to 3.78%. Application of these treatments and the period of incubation, enhanced the soil porosity. Generally increasing soil organic matter and soil porosity and decreasing of bulk density are the main factors to increase the soil aggregation. Our results showed that all three treatments in two moisture levels significantly increased soil porosity, tensile strength and field capacity and decrease soil crusting index (P<0.01). Biochar of bagasse and Zeoplant (2%) also significantly increased shear strength whereas biochar of Conocarpus has no significant effect on shear strength. Overall the applied treatments with armoring effect (AE) and increase the soil aggregate stability, diminished the wind erosion.
Conclusion: Our study illustrated that application of biochar is able to improve soil physical and mechanical properties. The main aspect of this positive effect is the specific characteristics and the structure of biochar which showed with SEM (Scanning electronic microscope) images. Moreover, Zeoplant is organic-inorganic treatment and including high potential to absorb the water in the soil. Indeed, the mulching is an effective management strategy to maintain and preserve the soil against wind (as erosive agent) however afterwards a vegetation cover must be grow on the surface. Therefore some treatments such as Zeoplant are essential to hold the water in the soils of arid and semiarid regions because in those areas the water scarcity is one of the main challenges. Based on our results and evaluation of these treatments we found two main processes which are effective to mitigate wind erosion. The first is aggregation process because of organic carbon and organic matter in the soil and the binding between organic and inorganic components. The second one is an armoring effect which is originating from amendments especially biochar lumps on the surface. Finally our results confirmed the application of evaluated treatments to preserve the erosive soil against wind.
F. Arzaghi; A. Farrokhian Firouzi; N. Enayatizamir; B. Khalilimoghaddam
Abstract
Introduction: Wind erosion is the most important agent of environmental degradation, poverty of soil, air pollution and the dust spread. Wind erosion is causing a lot of damage to crops, buildings, facilities and vehicles. The first step of the wind erosion control is the stabilization of soil particles. ...
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Introduction: Wind erosion is the most important agent of environmental degradation, poverty of soil, air pollution and the dust spread. Wind erosion is causing a lot of damage to crops, buildings, facilities and vehicles. The first step of the wind erosion control is the stabilization of soil particles. Soil stabilizing methods to control wind erosion can be classified into mechanical, biological and chemical stabilization. Mechanical soil stabilization type is relatively time-consuming and costly. Biological stabilization is a traditional way that exhibits a long-term validity but sandy soil cannot provide essential water and nutrition elements needed by plant. Recently, chemical stabilization such as high-molecular-weight anionic polyacrylamide (PAM) has attracted the attention of researchers because of its advantages in easy and quick construction, and the improvement of the growing conditions for plant. However PAM has been mainly used to control water erosion and there is still little available information regarding the effectiveness of PAM on preventing soil loss by wind erosion. The main objective of this study was to investigate the feasibility of using PAM in wind erosion controlling. Also, effects of PAM on some soil physical and chemical properties and their temporal variability were evaluated.
Materials and Methods: In this study polyacrylamide polymer was used as a restoration of soil and soil structure stabilizer on sandy soil of Azadegan Plain (Khuzestan province, Iran). Consequently, an experiment was conducted as factorial based on completely randomized design with three replicates. The experimental treatments were consist polyacrylamide polymer (PAM) at three levels (0, 0.5, and 1 %), soil moisture at two levels (80% FC and dry) and time duration at three levels (15, 30 and 45 days). The emulsion of PAM was sprayed homogeneously on the soil surface. After passing each time treatment, penetration resistance and some physical and chemical properties of soil was measured. Finally after doing all measurements, the treatment with maximum penetration resistance were selected and the sample was prepared for wind tunnel testing. The wind erosion experiments were conducted in a wind tunnel. Soil samples were located in removable trays. The width and length of the trays was 30 and 100 cm, respectively. The wind erosion experiments were performed under wind velocity of 12 m s−1 according to the actual situation of study area.
Results and Discussion: The results indicated that in comparison to control, soil acidity decreased at both levels of the polymer with increasing time. The decreasing of soil acidity in wet treatments was more than dry treatment. The lowest amount of pH was obtained in the 30-day wet treatment at 1% polymer level. The results show from the 30th day onwards, soil pH increased, which is probably due to the polymer degradation. With passing time, soil electrical conductivity (EC) at both levels of the polymer (0.5 and 1%) increased and decreased respectively after 30 days. These observations are probably because after 30 days the properties of polymer-hydrophilic units gradually decrease and water adsorption was reduced or that soil soluble salts were adsorbed by polymer particles. The results also showed with passing time, Mean Weight-Diameter of Soil Aggregates (MWD) increased and then after 30 days declined. The largest MWD was observed in 30 days treatment at 1% polymer level. After thirty days, its effect has probably diminished due to polymer degradation. Furthermore, the results showed no significant difference of bulk density among treated soil with different level of polymer, but application of polymer caused to decrease bulk density comparison to control. Polymer application increased soil penetration resistance significantly. Using 1% of polymer increased it to 6 kg/m2. The results also indicated that the soil resistance at first increased with time and then decreased significantly. The amount of soil penetration resistance at 45-day was less than 15-day. The results of wind tunnel with a maximum 12 m/s wind velocity showed that application of the polymer reduced the erosion of sands samples to zero.
Conclusion: The research results indicated that PAM application increased soil penetration resistance and MWD. The polymer could improve the structure of soil aggregates and increase the amount of dry-stable aggregates and therefore decrease soil bulk density. Spraying PAM solution on the surface of soil significantly decreased the wind erosion amounts. Therefore, this inexpensive and easily usable polymer can be considered as a soil stabilizer to control wind erosion in arid and semiarid areas.
