تاثیر بلند مدت خاک‌پوش ماسه بادی و نانو رس بر خصوصیات فیزیکی شیمیایی و برخی از شاخص‌های فرسایش‌پذیری خاک در مناطق خشک (مطالعه موردی: منطقه نیمروز سیستان)

هدف این پژوهش، بررسی تاثیر خاک‌پوش ماسه بادی و نانو رس بر خصوصیات و شاخص‌های فرسایش‌پذیری خاک است. با آماده‌سازی تیمارهایی متشکل از خاک‌پوش ماسه‌بادی، نانو رس و شاهد در قالب طرح بلوک تصادفی با چهار تکرار، اثرات اقدامات حفاظتی بر ویژگی‌های فیزیکی شیمیایی و برخی شاخص‌های فرسایش در سه عمق 100، 3010 و 5030 سانتی‌متر آزمایش شد. یافته‌ها نشان دادکه درصد رس، سیلت و شن، در لایه سطحی تیمار خاک‌پوش ماسه‌بادی و نانو رس نسبت به شاهد تفاوت معنی‌داری داشت (05/0p<). همچنین نتایج بیانگر افزایش 4/56 درصدی رطوبت خاک در تیمار نانو رس و در مقابل، کاهش 7/43 درصدی آن در خاک‌پوش ماسه‌بادی بود. مقدار اسیدیته، هدایت الکتریکی، نسبت جذب سدیم، سدیم، مجموع کلسیم و منیزیم و کاتیون‌های خاک در تیمارهای نانو رس و خاک‌پوش ماسه‌بادی نسبت به شاهد نیز در اعماق مختلف به‌طور معنی‌دار (05/0>p ) کاهش ولی ماده آلی آنها افزایش یافت. شاخص‌ دلینهیر و دبوت (ddi) در عمق10 -0 سانتی‌متر، در تیمار نانو رس و خاک‌پوش ماسه‌بادی نسبت به شاهد به ترتیب 2/62 و 4/79 درصد کاهش یافت. در اعماق30 10 و 5030 سانتی‌متر، مقادیر این شاخص در تیمار نانو رس به‌طور محسوس کاهش یافت ولی در تیمار خاک‌پوش ماسه بادی تفاوت معنی‌داری نداشت. بررسی تغییرات شاخص پراکنش میدلتون (dr) در لایه سطحی بیانگر کاهش به ترتیب 54 و 50 درصدی در تیمار خاک‌پوش ماسه بادی و نانو رس نسبت به شاهد بود که به تغییر توان واگرایی خاک از کلاس واگرایی زیاد به کلاس معتدل منجر شد. در اعماق 3010 و 5030 سانتی‌متر، مقادیر این شاخص در تیمار نانو رس به‌طور معنی‌دار کاهش یافت و در تیمار خاک‌پوش ماسه بادی بدون تغییر بود. بر اساس نتایج این تحقیق، کاربرد خاک‌پوش ماسه‌بادی و نانو رس به بهبود مشخصه‌های فیزیکی شیمیایی خاک و افزایش پایداری خاکدانه‌ها و در مقابل، کاهش شاخص ناپایداری خاکدانه در خاک منجر شد.

The Long Term Effects of Sand Mulch and Nanoclay on Physicochemical Properties and some Erodibility Index in Arid Areas (Case Study: Nimroze of Sistan Area)

1 IntroductionSoil as a bed of life plays an important role in meeting the nutritional needs of human societies. But due to unscientific poisoning, it is eroding and causing problems for humans, especially in arid areas. Today, a significant part of the soil of these areas is out of use and is practically not suitable for agriculture and exploitation. In addition, by destroying the soil structure, conditions are provided for the movement of soil particles under the influence of wind and water, one of the destructive effects of which is the destruction of the environment. Therefore, since soil is the only source of nutrients, its protection not only reduces evaporation, but also prevents salinization of the soil and also improves plant yield and growth. Therefore, improving the physical and chemical properties of soil and increasing its resistance to corrosive agents (water and wind) is essential. One of the important and efficient methods to improve the physical and chemical properties of soil is the use of mulch, which controls the physicchemical and biological degradation of soil. Numerous studies have been conducted to investigate the effect of mulch on the physical and chemical properties of soil in and outside the country. One of the arid and desert areas of the country where the decline of natural areas today has caused environmental degradation and also the expansion of erosion centers is Sistan region which has been exposed to soil degradation due to wind erosion and poor vegetation due to lack of water and soil moisture, which in turn has expanded desert areas. This phenomenon has intensified and spread sandstorms and dust. Therefore, due to the importance of studying soil conservation methods and also the urgent need to provide a suitable model compatible with climatic conditions in Sistan region and achieve a principled and efficient management for sustainable use of soil resources in this region, some research studies are needed. Accordingly, the aim of this study was to investigate the longterm effects of using sandy loam and clay nanoparticles on some physical and chemical properties and soil erodibility indices in one of the erosion centers of Nimroz city in Sistan region. 2 MethodologyThe experiment had been conducted in a randomized complete block design with 3 treatments in 4 replications. The treatments included: nanoclay, sand mulch and witness. In this study, the sand mulch was prepared from windy sediments deposits of the Sistan plain. Also, to prepare nanoclay, sediments from floods that entered Sistan River were used (to pulverize the flood sediments, ball mill were used and to determine the particle size and main elements, DLS and xrf methods were used, respectively). By sampling from each treatment, the physical chemistry characteristics were measured. To study the physical properties of soil, hydrometer method was used and the soil texture was determined. To investigate the chemical characteristics, the soil properties such as organic carbon, acidity (PH), electrical conductivity (EC), sodium absorption ratio (SAR), Na and available P were measured in laboratory. Irrigation of the studied treatments was done by clay method. The pottery used in this research is about 40 cm high and 5 cm in diameter. Sour tea was the plant cultivated in this study. Experimental treatments in this study included: Control treatment, with aerated sand and clay nanoparticles, was coducted in a randomized complete block design with four replications. Statistical analysis of data was performed using SPSS 23 software. The means of the studied parameters were compared using Duncan #39;s multiple range test at the level of 5%. 3 ResultsBased on the results obtained from the particle size distribution, the findings indicated that the percentage of clay, silt and sand at a depth of 0 to 10 cm in the soil of nanoclay treatments and wind sand cover at 5% level significantly differed with the control soil. The highest percentage of sand was in the sandy and nanoclay soil cover treatments, respectively, and the highest percentage of silt was related to the control treatment. Also, the highest values ​​of clay percentage were measured in the nanoclay treatment and the lowest in the windblown sandy soil treatment (p>0.05). Particle size in the surface layer of the findings indicated significant changes in the percentage of silt and clay in the treatment of aeolian sand cover. In the same vein, with the preparation of sandy loam soil, the particle size was mainly in the average sand size (0.3 mm), which during the study period was 12.1 and 7.9% of the particles in the average silt (0.031 mm) and clay with > 0.0039 mm, respectively. In analyzing the amount of the abovementioned parameters in the depths of 1030 and 3030 cm of the soil, the findings showed no significant differences between these variables in the treatments of windblown sand and control condition. However, the values ​​of these parameters in the nanoclay treatment showed a significant difference compared to other treatments. In control treatments, the percentage of sand, silt and clay decreased by increasing depth of the trend. However, in the treatment of aeolian sand cover, except for the percentage of sand, the trend of changes in the percentage of silt and clay increased. Moreover, in the nanoclay treatment, the studied parameters remained unchanged and, in general, the particle size distribution had the same structure in the studied layers. In the study of the percentage of soil saturation moisture in the treatments, the findings indicated that the rate of this parameter is higher in the nanoclay treatment compared to the two treatments and aerated sand cover. The mean values ​​of this parameter in the mentioned treatments were 33.9, 18.9 and 8.6%, respectively, which are significant at the 95% probability level. The trend of changes in this parameter in other sampling depths compared to the control treatment showed a significant difference. In general, its values ​​in nanoclay and sandy loam treatments are higher than the control treatment. In examining the texture distribution of the collected samples, the findings indicated that in the surface layer (0 to 10 cm) the soil texture was in sandy loam sandy loam treatment. 4Discussion ConclusionIn this research, which was conducted for the first time in Nimroz city in the north of Sistan region, the longterm effects of nanoclay and aeolian sand cover on physicochemical properties and some soil erodibility indices were investigated. In examining soil physical properties, the results showed that the percentage of clay, silt and sand under the protective effect of soil in the studied treatments are different. In the surface layer, the values ​​of the studied variables in control, nanoclay and aeolian sand cover treatments were significantly different (P <0.05). In fact, with the use of aeolian sand cover on the soil surface with a particle size of 0.316 mm, the soil texture was changed from loamy to sandy loam class and in other sampling depths that did not use sandy loam underwent no significant difference compared to the control treatment. In nanoclay treatment, although changes in the values ​​of the above variables had no effect on soil texture, there was a significant difference in particle size distribution compared to control and aeolian sand cover at all sampling depths. In addition, the presence of nanoparticles among soil particles for increasing the specific surface area had a significant effect on water absorption and thus increased soil moisture. The increase of 1.2 and 1.6 times soil moisture in nanoclay treatment compared to windblown sandy soil and control treatments showed a significant difference in the 95% probability level. It has already been found that increasing soil moisture due to the presence of clay nanoparticles in the soil increases the total specific surface area and this in turn increases moisture absorption due to hydrophobicity and high moisture absorption of clay in the soil, which is consistent with the results of this study.