اثر بیوچار ضایعات درخت خرما بر غلظت عناصر، نسبت جذب سدیم و برخی خصوصیات فیزیکی خاک شور

بیوچار ماده ای غنی از کربن شناخته می‌شود که شرایط پیرولیز، سطح ویژۀ بالایی در آن ایجاد کرده و عملکردهای ویژه‌ای در خاک از خود نشان می‌دهد. در این پژوهش که با هدف بررسی تاثیر بیوچار خرما بر خاک شور انجام شد، بیوچار مورد نیاز از ضایعات هرس خرما در دمای 500 درجۀ سانتی گراد با شرایط اکسیژن محدود به دست آمد. این آزمایش در قالب طرح کاملاً تصادفی با سه تکرار انجام گرفت. بیوچار خرما با درصد وزنی صفر، 0.5، 1، 1.5 و 2 به‌صورت یکنواخت با خاک شور مخلوط گردید و به‌مدت 90 روز با رطوبت ظرفیت مزرعه نگهداری شد. پس از این مدت، نمونه ها هوا خشک شده و ویژگی های شیمیایی و فیزیکی خاک تعیین گردید و مقایسۀ میانگین داده‌ها با استفاده از آزمون دانکن در سطح 5% انجام شد. نتایج نشان داد که افزودن بیوچار شاخ و برگ خرما به خاک به‌طور معنی داری مقدار هدایت الکتریکی خاک، کربن آلی، کلسیم، منیزیم، سدیم، پتاسیم خاک و تخلخل را افزایش داد. درحالی‌که sar و وزن مخصوص ظاهری کاهش معنی‌دار پیدا کرد و بر پارامترهای ph، فسفر، رطوبت ظرفیت مزرعه و چگالی حقیقی تاثیر معنی داری نداشت. کاربرد اصلاح‌کننده‌های آلی مانند بیوچار می‌تواند به‌دلیل داشتن عناصر مختلف و همچنین سطح ویژۀ بالا تاثیر مثبتی بر خصوصیات فیزیکی و شیمیایی خاک داشته باشد.

Investigating the Effect of Palm Tree's Waste Biochar on Concentration of Elements, Sodium Adsorption Ratio (SAR), and Some Saline Soil's Physical Properties

Expanded abstractsIntroduction: Salinity is an important environmental stressor that affects plant growth. In saline soils, plants are subjected to some toxic ions and water shortages. Crop residues are considered major organic agricultural wastes that can be useful for the soil and the plants. Organic matter has positive effects on the soilchr('39')s physical and chemical properties. Converting agricultural wastes to Biochar is an appropriate way to achieve a valuable amendment. Biochar is a carbonrich decompositionresistant product obtained by heating biomass in an oxygenfree chamber, being used for carbon sequestration by applying large amounts of carbon.Moreover, as a highly stable residue in the soil, it has been proven to store atmospheric carbon for hundreds to millions of years. According to different studieschr('39') findings, the application of Biochar can increase the soilchr('39')s waterholding capacity, microbial activity, and nutrient availability. However, its effect on soil properties depends on its source and the extent of its application. As the dependency of Biocharchr('39')s effects on saline soilschr('39') properties in such soils has been underresearched, this study attempted to investigate the effect of palmtree residueschr('39') Biochar on the physical and chemical properties of saline soils. Materials and Methods: the required Biochar was prepared from palm treeschr('39') residues at 500 °C under limited oxygen conditions. This experiment was conducted in a completely randomized design with three replications. Biochar was mixed at 0, 0.5, 1, 1.5, and 2% rates with saline soils and incubated with humidity at field capacity for 90 days. Then, the samples were airdried, and some physicochemical characteristics of the soil were determined. Moreover, the comparison of the means was performed using Duncanchr('39')s test at a confidence level of 95%. Results: The results showed that applying the Biochar obtained from palm trees to the soil significantly increased the soilchr('39')s chemical properties such as electrical conductivity (EC), organic carbon, calcium, magnesium, sodium, and potassium while decreased the sodium adsorption ratio (SAR), and the sodium/potassium ratio. Moreover, while adding Biochar to the soil increased the porosity by 10% and reduced the bulk density by 4%, treatments did not significantly affect pH, available phosphorus, field capacity, and the soilchr('39')s particle density. Furthermore, adding 2%, Biochar increased calcium concentration in soil by 2.08 times compared to that of the control treatment. It was also found that the changes in the soilchr('39')s magnesium calcium were similar and that using more Biochar increased magnesium concentration by 2.88 times compared to what was observed in the control treatment (more than the control treatment). Therefore, the studychr('39')s findings indicated that the available potassium concentration in soil increased significantly following the application of different biochar levels. It was also found that compared to the control treatment, the amount of potassium increased about 12.33 and 18.79 times, respectively, with an increase of biodates in 1.5 and 2% treatments. Moreover, the highest increase in sodium was related to applying a 2% biochar date, which was 49.35% more than that of the control treatment. Finally, using 2% biochar reduced the sodium adsorption ratio by 7.6%. Discussion and Conclusion: This study showed that palm treeschr('39') Biochar improved some saline soil parameters such as SAR, organic matter, and nutrients. Increased EC is due to increased sodium as a destructive factor and other cations such as calcium, magnesium, and potassium as helpful plant nutrients. On the other hand, the sodium to potassium ratio was decreased. Moreover, it was suggested that the potassium was increased more than sodium, and that was why the index was improved. According to the studychr('39')s findings, Biochar increased porosity due to its high specific surface area.Moreover, using 2% biochar treatment increased the saline soilchr('39')s organic carbon by approximately three times. Due to the Biocharchr('39')s low specific gravity, it can be expected that the soilchr('39')s density is decreased by applying Biochar in soil. However, the increase in Biochar did not significantly affect the soilchr('39')s particle density, which is probably due to the low weight of biochar particles versus the high weight of the soilchr('39')s minerals and the amount of Biochar applied. It seems that applying Biochar as an amendment can improve the saline soilchr('39')s properties and that the size of biochar particles may have different effects on changing the soilchr('39')s properties, which can be investigated in future researches.