اثر کود فسفر و ترکیب‌های هیدروکسید دوگانه لایه‌ای بر پایه بیوچار و هیدروچار بر ماده خشک و غلظت نیتروژن، فسفر و پتاسیم گیاه ذرت

بیوچار و هیدروچار مواد جامد کربنی هستند که از کربونیزه‌شدن زیست‌توده‌های آلی تولید می‌شوند. بیوچار با گرماکافت زیست‌توده‌های خشک اما هیدروچار با کربونیزه شدن گرمآبی زیست‌توده‌های خشک و یا مرطوب تولید می شود. در این پژوهش، بعد از تولید بیوچار و هیدروچار از چوب سیب، با ترسیب ذرات هیدروکسید دوگانه لایه‌ای (ldh) بر روی سطوح بیوچار و هیدروچار، به‌ترتیب ترکیب‌های ldhبیوچار و ldhهیدروچار ساخته شد و هر گرم از این ترکیب‌ها به‌ترتیب با 51 و 47 (میلی‌گرم فسفر بارگذاری شد (ldhpبیوچار و ldhpهیدروچار). سپس با استفاده از یک آزمایش گلخانه‌ای به‌صورت فاکتوریل در قالب طرح پایه کاملاً تصادفی با 3 تکرار، اثر بیوچار، هیدروچار، ldh، ldhبیوچار، ldhهیدروچار، ldhpبیوچار و ldhpهیدروچار در حضور و عدم حضور کود مونوکلسیم فسفات بر وزن شاخساره و ریشه خشک، غلظت نیتروژن، فسفر و پتاسیم شاخساره و غلظت فسفر و پتاسیم ریشه ذرت بررسی شد. نتایج نشان داد که بیوچار نسبت به هیدروچار دارای درصد عملکرد و خاکستر، ph و ec بیشتری بود و غلظت عناصر مورد بررسی به‌جز نیتروژن در بیوچار بیشتر از هیدروچار بود. با مصرف کود فسفر در خاک، وزن شاخساره و ریشه خشک در تمام سطوح اصلاحگر به جز ldhpبیوچار و ldhpهیدروچار نسبت به تیمار بدون اصلاحگر افزایش یافت. بیشترین وزن شاخساره و ریشه خشک گیاه در تیمارهای ldhpبیوچار و ldhpهیدروچار و کم ترین وزن شاخساره و ریشه خشک در حضور ldh به‌دست آمد. مصرف کود فسفر در حضور ldhبیوچار و ldhهیدروچار باعث افزایش معنادار غلظت فسفر شاخساره و ریشه ذرت شد اما بر غلظت نیتروژن و پتاسیم شاخساره اثر معنادار نداشت و غلظت پتاسیم ریشه را در حضور بیوچار و ldhبیوچار و در شاهد کاهش داد. بیشترین غلظت فسفر شاخساره و ریشه و بیشترین غلظت نیتروژن شاخساره در دو تیمار ldhpبیوچار و ldhpهیدروچار مشاهده شد. کود فسفر با بیوچار، هیدروچار، ldhبیوچار و ldhهیدروچار در افزایش وزن شاخساره و ریشه خشک و غلظت فسفر شاخساره و ریشه گیاه برهم‌کنش هم‌افزایی ولی با ldh، ldhpبیوچار و ldhpهیدروچار برهم‌کنش ناهمسازی داشت. بنابراین، مصرف بیوچار، هیدروچار، ldhبیوچار و ldhهیدروچار به‌همراه کود فسفر و ترکیب‌های ldhpبیوچار و ldhpهیدروچار بدون مصرف کود فسفر برای کشت ذرت در شرایط مشابه می‌تواند پیشنهاد شود.

Effects of layered double hydroxide functionalized biochars and hydrochars on dry matter and N, P and K concentrations of corn

Introduction Phosphorus (P) is an essential element for living organisms. Discharging P from various sources, such as industrial wastewater and agricultural waters, into surface water causes eutrophication and undermines the balance of aquatic ecosystems and imposes many costs due to water quality degradation. In addition, mineral resources of Pfertilizers in the world are unrecoverable and are coming to an end. Therefore, it is very important to develop adsorbents to remove P from contaminated water and then be used as Pfertilizer for surmounting the eutrophication and Pfertilizer exhausting challenges. In the last few years, biochar and hydrochar have been considered as lowcost porous ecofriendly adsorbents with a high surface area and easy to produce and use. Biochar and hydrochar are carbonaceous solids that are produced from the carbonization of biomasses and could be used as adsorbents and soil amendments. However, because of their high negative charge and very low ability to absorb anions, especially phosphate, they cannot be used as phosphate adsorbents. In recent years, several methods have been introduced to change the surface of biochar and hydrochar to increase their anion adsorption capacity. In this respect, the successful results of the production and the use of engineered biochars, such as layered double hydroxides (LDHs) functionalized biochar (LDHbiochar) and LDHhydrochar composites have been provided. Layered double hydroxides (LDHs) are brucitelike compounds with a large specific surface area, high positive charge, and exchangeable interlayer anions. LDHs functionalized biochar and hydrochar composites are environmentally friendly adsorbents for the removal of phosphate from aqueous solutions. Also, Ploaded LDHbiochar and LDHhydrochar composites have the potential application as a Pfertilizer. These composites may increase soil availableP through the slow release of P and can improve soil properties and fertility due to the presence of the biochar and hydrochar in their structure. So, the Ploaded LDHbiochar and LDHhydrochar may affect the availability of soil nutrients and plant growth. Nitrogen (N), P, and potassium (K) are the macronutrients that have a direct and great influence on plants growth. Therefore, the aims of this study were: (I) producing LDHbiochar and LDH hydrochar composites and loading them with phosphate. (II) Investigating the effects of the biochar, hydrochar, LDH, LDHbiochar, LDHhydrochar, the Ploaded LDHbiochar (LDHbiocharP), and LDHhydrochar (LDHhydrocharP) on dry matter and concentrations of P, N, and K in corn shoot and root. Materials and Methods Biochar was produced from applewood feedstock through slow pyrolysis at 600 ºC for 1 h under Argon flow conditions. Hydrochar was produced through hydrothermal carbonization of the applewood feedstock at 180 ºC and 11 bars pressure for 12 h. Then by precipitation of LDH particles on the biochar and hydrochar surfaces, LDHbiochar and LDHhydrochar composites were prepared. The LDH particles were synthesized via a combined fast coprecipitation and hydrothermal treatment route. Each gram of LDHbiochar and LDHhydrochar composites was loaded with 51 and 47 mg P, respectively. Then using a factorial experiment on the basis of completely randomized design with three replications, the effects of biochar, hydrochar, LDH, LDHbiochar, LDHhydrochar, LDHbiocharP, and LDHhydrocharP were studied in presence and absence of monocalcium phosphate fertilizer on corn dry matter and concentrations of N, P, and K in corn shoot and concentrations of P and K in corn root. Results and Discussion The results showed that the biochar had a higher yield and ash percentage, pH and electrical conductivity (EC) as compared with the hydrochar. The concentrations of all studied nutrients in the biochar, except for N, were greater than those of hydrochar and biomass. The P, K, Na, Fe, Mn, and Zn concentrations in biochar and hydrochar were significantly greater than the initial biomass. The application of Pfertilizer increased root and shoot dry matters in all treatments, except for LDHbiocharP and LDHhydrocharP treatments. Biochar and hydrochar had no significant effects on root and shoot dry matter in nonPfertilized treatments and had no significant effects on P and K concentrations of corn root and shoot. However, biochar and hydrochar increased shoot dry matter in Pfertilized treatments. The highest root and shoot dry matters, P concentrations of root and shoot, and N concentration of shoot were obtained in the presence of the LDHbiocharP and LDHhydrocharP, and the lowest root and shoot dry matters of corn were observed in the presence of the LDH. Application of Pfertilizer increased P concentrations of corn root and shoot in the presence of the LDHbiochar and LDHhydrochar but decreased the K concentration of root in biochar, LDHbiochar and no amendment treatments and had no significant effects on N and K concentrations in the shoot. The application of Pfertilizer decreased P translocation factor in presence of the LDHbiochar and LDHhydrochar and had no significant effect on P translocation factor in all other treatments. Using Pfertilizer had no significant effect on K translocation factor in all treatments. Biochar, hydrochar, LDH, LDHbiochar, and LDHhydrochar had no significant effects on P and K translocation factors. The translocation factor of P was greater than 1 in all treatments, except for the LDHbiocharP and LDHhydrocharP treatments. Also, the translocation factor of K was greater than that of P in all treatments. Conclusion Due to the structural similarities between biochar and hydrochar, LDHbiochar and LDHhydrochar, and LDHbiocharP and LDHhydrocharP, the root and shoot dry matter and concentrations of the studied elements in corn root and shoot were not significantly different between the biochar and hydrochar, LDHbiochar and LDHhydrochar, and LDHbiocharP and LDHhydrocharP treatments, respectively. Pfertilizer had synergistic relationships with biochar, hydrochar, LDHbiochar, and LDHhydrochar but antagonistic relationships with LDH, LDHbiocharP, and LDHhydrocharP composites in terms of dry matter and P concentrations in corn root and shoot. So, applications of the biochar, hydrochar, LDHbiochar, and LDHhydrochar accompanied by Pfertilizer and the use of LDHbiocharP and LDHhydrocharP without the application of Pfertilizer can be proposed for corn cultivation under similar conditions.