Department of Soil Science, College of Agriculture, Shiraz University, Shiraz, Iran.
Department of Water Engineering, College of Agriculture, Shiraz University, Shiraz, Iran.
Sci Rep. 2024 Nov 3;14(1):26541. doi: 10.1038/s41598-024-77700-3.
Low organic matter content is one of the main constraints in arid and semiarid regions. This constraint and its negative influences on soils and plant growth may be alleviated by biochar (BC). Furthermore, improving soil physical and hydraulic attributes by application of biochar has received increased attention. Therefore, in the present study, the effects of sugarcane bagasse-derived biochar on the structural stability, water availability, and pore-size distribution (PSD) of three texturally different calcareous soils collected from different agro-climatologically regions were examined during a long-term experiment. Low and high-temperature biochars, produced in a muffle furnace by the traditional slow pyrolysis method at 300 °C (BC300) and 600 °C (BC600) were evaluated. Pots (15 kg) were filled with three different silty-clay Inceptisols (SCInc), silty-clay-loam Alfisols (SCLAlf), and loam Aridisols (LArid) soils mixed with 0 (control), 1, 2, and 3 w/w% of BC300 and BC600 during 540 days of incubation. The high energy moisture characteristic (HEMC) data was modeled using a modified van Genuchten function to quantify aggregate stability through stability ratio (SR) and structural stability index (SSI). The plant available water (PAW), least limiting water range (LLWR), and integral water capacity (IWC) were calculated with two matric suctions (h) of 330 cm for field capacity (FC) and 15,000 cm for permanent wilting point (PWP). Then the integral energy (EI) values were calculated (EI). Results indicated that the incorporation of 3 w/w% biochar significantly (p < 0.01) increased SR (35 to 100%) and SSI (21 to 28%) indices in all three soils. Biochar significantly increased modal suction (MS) in LArid soils (5 to 158%); whereas, decreased MS of the other soils (3 to 43%). MS, SR, and SSI of BC300 and BC600-treated soils were not significantly different. PAW, LLWR, and IWC significantly decreased in the SCInc (18 to 61%, 8 to 44%, and 6 to 35%) and SCLAlf (8 to 44%, 18 to 35%, and 20 to 47%) soils and increased in LArid (4 to 54%, 3 to 61%, and 24 to 111%) soil with increasing biochar doses. There were no changes in EI in biochar-treated LArid soil where PAW, LLWR, and IWC increased. Biochar increased EI across the studied soil from 1% to 3.38 folds, thereby increasing the gradient of water potential to absorb the available water. Soil and soil-biochar mixtures exhibited heterogeneous and multimodal pore-size distribution (PSD). Biochar promoted the PSD peaks related to water-transmitting pores in SCInc and SCLAlf soils while decreased in LArid soil. In conclusion, results indicated that among the applied levels of biochar, the application of 3 w/w% biochar is suggested as a suitable way to improve soil physical behavior and structural stability.
低有机质含量是干旱和半干旱地区的主要限制因素之一。这种限制及其对土壤和植物生长的负面影响，可以通过生物炭（BC）得到缓解。此外，通过应用生物炭来改善土壤物理和水力特性的做法受到了越来越多的关注。因此，在本研究中，通过一项长期实验，研究了从不同农业气候区采集的三种质地不同的钙质土壤中，甘蔗渣衍生的生物炭对结构稳定性、水分可用性和孔径分布（PSD）的影响。在马弗炉中，通过传统的慢速热解方法在 300°C（BC300）和 600°C（BC600）下制备了低温和高温生物炭，并对其进行了评估。在 540 天的培养期内，将 15 公斤的花盆装满三种不同的粉质粘土始成土（SCInc）、粉质粘土-壤土淋溶土（SCLAlf）和壤土旱地（LArid）土壤，同时添加 0（对照）、1、2 和 3 w/w%的 BC300 和 BC600。使用修正后的 van Genuchten 函数对高能量水分特征（HEMC）数据进行建模，通过稳定性比（SR）和结构稳定性指数（SSI）来量化团聚体稳定性。利用两个基质吸力（h）为 330 cm 的田间持水量（FC）和 15,000 cm 的永久萎蔫点（PWP）计算有效水分（PAW）、最小限制水分范围（LLWR）和积分水分容量（IWC）。然后计算积分能量（EI）值。结果表明，在所有三种土壤中，添加 3 w/w%生物炭可显著（p < 0.01）提高 SR（35%至 100%）和 SSI（21%至 28%）指数。生物炭显著增加了旱地土壤的模态吸力（MS）（5%至 158%）；而其他土壤的 MS 则降低了（3%至 43%）。BC300 和 BC600 处理的土壤的 MS、SR 和 SSI 没有显著差异。PAW、LLWR 和 IWC 在 SCInc（18%至 61%、8%至 44%和 6%至 35%）和 SCLAlf（8%至 44%、18%至 35%和 20%至 47%）土壤中显著降低，在旱地土壤中（4%至 54%、3%至 61%和 24%至 111%）增加，随着生物炭剂量的增加。在 PAW、LLWR 和 IWC 增加的生物炭处理的旱地土壤中，EI 没有变化。生物炭使研究土壤的 EI 从 1 倍增加到 3.38 倍，从而增加了吸收可用水的水势梯度。土壤和土壤-生物炭混合物表现出不均匀的多峰孔径分布（PSD）。生物炭促进了 SCInc 和 SCLAlf 土壤中与输水孔相关的 PSD 峰值，而在旱地土壤中则降低了。总之，结果表明，在所应用的生物炭水平中，建议添加 3 w/w%的生物炭是一种改善土壤物理行为和结构稳定性的合适方法。
