Drought and harsh environment of deserts have made the stakeholders to do whatever possible to combat desertification. MULCHing, using low quality oil materials of oil refineries, is a routine procedure in Iran to stick shifting sands together, which of course has his own criticism. The effect of oil MULCH versus other methods of sand stabilization has been tested using a split design experiment. Oil MULCH, two water absorbent materials, Belgium and French, and a Chine's MULCH and 4 seed, Calligonum comosum, Cyperus conglomeratus, Smirnovia iranica and Haloxylon aphyllum were tested in the experiment. Results show that efficiency of oil MULCH is meaningful, at level of 1% and 5%.

Wind erosion is considered a major global environmental problem. Sands torms cause serious damages to municipal, industrial and agricultural areas. MULCH is one of the most common materials for soil stabilization, which mitigates wind erosion and dust formation. In this research different combinations of organic (waste press mud, beet vinasse dunder and compost) were used in combination with clay as a stabilizer. Sandy soil from the Dejgah plain, the Provice of Fars, was used as the erodible material. Experiments were carried out in a completely randomized desing (CRD) with 14 treatments (organic MULCH type). The MULCHes were sprinkled on plots of 50×30×1 cm sand. The thickness and mechanical properties of the MULCHed layear, namely the: shear strength, penetration resistance, and wind erodibility of the treatments were measured. Based on the analysis of variance (ANOVA), the effects of MULCH type on thickness, penetration resistance, and shear strength of surface soil were highly significant (p<0. 05). Based on comparison of means with the Duncan's multiple range test, the M1 treatment with 25g compost+100g vinasse+100g clay had the highest thickness, penetration resistance, shear strength and the lowest amount of wind erodibility. Due to the biodegradability and economic justification (lower operating cost than petroleum and polymeric MULCHes), the organic MULCH was recognized as the best combination for stabilizing sandy soils.

MULCHing is one of the methods of sand movement control to prepare condition for permanent fixation. Oil MULCHes have been used in Iran. Because of high cost and negative environmental impacts of oil MULCHes, changes in MULCHes type and MULCHing methods is vital. Therefore, for the first time in Iran, different combinations of cement and lime were examined as stabilizer. Sandy soil from the Yazd-Ardakan plain is used as bed treatment and Portland cement were used as the MULCH in this research. The treatments were prepared using different ratios of the above mentioned materials. One liter of water was added to each MULCH combinations and were sprinkled on the plot of 100 cm (length) × 30 cm (width) ×4 cm (height) sands. A completely randomized design is used as research plan with three repeating. Physical parameters, such as thickness, compressive strength, which are created by MULCHes, and wind erodibility of the treatments were measured. The measured data were analyzed using SPSS statistical software. Results show that by increasing the amount of cement, soil crust resistance increases. The combination MULCH of cement 400 gr, sand 800 gr, and lime 10 gr is selected as the best treatment, because it can be prepare optimum physical conditions for sand dune fixation. In addition, the cost of field cement MULCHing estimated 30% lower than oil MULCHing.

Introduction: As one of the most significant environmental problems in recent decades, wind erosion has caused environmental pollution throughout the world (Shojaei et al., 2019; Aliabad et al., 2019; Alipour et al., 2016). ), inflicting damages to nearly 500 million hectares of land worldwide per year (equivalent to 46. 4% of the world's degraded lands) (Rand et al., 2015). On the other hand, the presence of large areas of running sands, wind erosion-inflicted damages, and problems regarding the use of oil-based MULCHes, highlights the necessity of using nature-friendly MULCHes. This study, therefore, sought to investigate the effects of lignocellulosic nanomaterials and lignocellulosic micromaterials on shear strength of soft sands and to the positive and negative effects of such MULCHs in that regard so that the most appropriate composition and extent of those MULCHs could be identified in terms of increased shear strength of sand particles. Materials and methods: To conduct this study, a sample of sandy soil with 89% sand particles was collected from the Isfahan’ s sand dunes (Rig Boland of Kashan) in the central Iran. Bagasse paste is used to make lignocellulose materials. Using blade mills and super disk mills, bagasse paste is transformed into lignocellulosic micromaterials and nanomaterials. Moreover, the Black liqueur is a paper industry’ s waste that is used as an adhesive element. To investigate the effect of lignocellulose nanomaterials and lignocellulose micromaterials on soft sands’ shear strength, nano and microparticles each with 0. 3% concentration at three levels (2. 5, 5 and 10 g/L in 0. 3 m2 soil), Black liqueur with 1% concentration at the level of 10 g/L in 0. 3 m2 soil, a combination of Nano lignocellulose (NL) and Black liqueur (BL) in three levels (2. 5, 5 and 10 g/L at 0. 3 m2 of soil), composition of Micro-lignocellulose (ML) and black liqueur at three levels (2. 5, 5 and 10 g / L in 0. 3 m2 soil), the control sample and all treatments in one-later and two-layer thickness were sprayed on the surface of the sand. Furthermore, shear blades were used to measure the adhesion of the MULCHes under saturated and dry conditions. Results: In saturated mode, the maximum shear strength of the double-layer microlignocellulose was found to be 10 g/0. 3m2, with the shear strength increased to 13. 6 kN/m2 compared to the control sample (zero), followed by double layer-microlignocellulose at 5 g/0. 3m2 (8 kN/m2) level, double layer-nanolignocellulose at 10 g/0. 3m2 (7 kN/m2) level, and the combination of single-layer microlignocellulose plus Black liqueur at 10 g/0. 3m2 level (7 kN/m2). It was also found that the lowest shear strengths belonged to single-layer treatments of NL (at all levels), ML (2. 5 and 5 g/0. 3m2), and the combination ML + BL (2. 5 g/0. 3m2), as well as double-layer treatments of the combination of NL + BL (at all levels), and 2. 5 g/0. 3m2 ML + BL. In the dry mode, the maximum shear strength belonged to double-layer NL + BL MULCH at 10 g/0. 3m2 level, with its shear strength increased by 39 kN/m2 compared to the control sample (zero), followed by double-layer ML at 10 g/0. 3m2 (36. 33 kN/m2), and a combination of double-layer ML + BL (33. 33 kN/m2), respectively. The study’ s findings indicated that there was no significant difference between these three types of MULCHes in terms of shear strength at 5% confidence level, while the results of the mean comparison between these three types of MULCHes and the control sample showed a significant difference in terms of shear strength (P <0. 05). Table (7): Shear strength of different MULCHes in both saturated and dry conditions One Layer Double Layer Black Liqueur control (water) lignocellulose lignocellulose + Black Liqueur lignocellulose lignocellulose + Black Liqueur Saturation level 2. 5 5 10 2. 5 5 10 2. 5 5 10 2. 5 5 10 One Layer Double Layer Nano 0 0 0 1 4 3 1 6 7 0 0 0 3. 3 0. 3 0 Micro 0 0 0. 66 0 3 7 1. 33 8 13. 6 0 3. 6 6 Dry Nano 0 5 26 1 4 22 1 16 26 0 7 39 1 0 0 Micro 0 0 5 0 1 13 1 14 36 2 15 33. Discussion and Conclusion: As mentioned above, the amount of shear strength increased in the dry mode compared to the saturation one. Therefore, it seems that the passage of time and dryness of the sandy bed have increased the efficiency and strength of the MULCH. While the findings of some studies have indicated a significant correlation between the soil’ s shear strength and time, other studies have proven the opposite. Moreover, this study found that the paper layer created by the spray of NL on the sand’ s surface increased the resistance to sand retardation as well as surface resistance to sinking. Therefore, it appears that the morphologic structure of NL which is comprised of long hole-less nano strings increased both abrasion and strengths. According to the study’ s findings, the minimum amounts of shear strength belonged to the treatments of 2. 5 gr/0. 3m2 NL, ML, ML+BL, 5 gr/0. 3m2 of single-layer ML, the combination of NL+BL, and double-layer BL, with the results of the mean comparison between these treatments (minimum shear strength) and the control sample proving no significant difference between them in terms of shear strength (P <0. 05). The results of the study also showed that while a seemingly integrated layer had been created on the sand surface via the addition of those MULCHs, limited suspensions may have prevented proper adhesion of the sand particles, leading to the easy disintegration of the particles. Therefore, it is recommended that these types of MULCHes be tested in the natural field first, and should they produced favorable results, be used for the stabilization of the running sands.