Biochar-induced changes in metal mobility and uptake by perennial plants in a ferralsol of Brazil’s Atlantic forest

Abstract

Despite an abundance of short-term studies focusing on biochar's effects on annual plants, the long-term effects of biochar on perennial plants and the effects of the biochar on the mobility and speciation changes of metals/metalloids not limited to main plant nutrients in soils are poorly constrained. This study reports on the amelioration a sloped orthic ferralsol by biochar from Tibouchina wood and the resulting effects on perennial crops and microbiota, including a comprehensive analysis of metals/ metalloids speciation changes. Fields were amended with biochar and urine-amended biochar (2 kg/m 2) and were planted with papaya, banana, and manioc. Soil and plant materials were analyzed using acid digestions, sequential extractions, and 16S rRNA gene sequencing. Biochar applications led to decreased soil acidity, shifted the cation exchange capacity from being Al-influenced to being Mg/K/Ca-dominated, and elevated the concentrations of Mg, K, Ca, Zn, and Ba in soils. The exchangeable/acid-soluble fraction of Ca, P, and S notably increased. The soil microbial biome became more species rich and diverse in the biochar-amended fields. Manioc benefited from biochar applications, demonstrating increased growth, which resulted in generally decreased concentrations of trace elements in most plant parts, however, with an increased total elemental uptake. Urine amendment contributed to higher concentrations of P, S, and K in soils, but did not further increase plant growth. Biochar was shown to be a promising soil amendment for agricultural use of orthic ferralsols of the Brazil's Atlantic forest region, but the accumulation of potentially harmful metals needs to be considered.

The Use of Biochar as a Soil Amendment to Reduce Potentially Toxic Metals (PTMs) Phytoavailability

“…Amending soil with biochar has been practiced for a long time. The high fertility of anthropogenic dark earth soils known as 'Terra Preta de Indio' in the Amazon basin has been related to the high content of charred materials [11][12][13]. Historically, the source of char in these soils has been considered as a disposal of charcoal from domestic fires and the practice of slash and char agriculture by Pre-Columbian Amazonian Indians [11,14].…”

“…In addition to the role of biochar in increasing the C sequestration and influencing the reduction of CO 2 emissions, biochar has been shown to enhance soil quality and to stabilize PTMs [15]. Biochar has a potential benefit for improving soil fertility [16,17], improving soil properties such as pH [11][12][13]18], cation exchange capacity (CEC) and water holding capacity [19], enhancing plant growth [20], and reducing nutrient leaching losses [21]. The significant amount of calcium (and magnesium) carbonate (Ca/MgCO 3 ) in BCs enables them to function as lime materials providing Ca and Mg to plants and neutralizing acidity when applied to acid soils.…”

Efektivitas Biochar Terhadap Ketersediaan Unsur Hara Mikro Pada Ultisol

“…Hasil penelitian ini akan menjelaskan bagaimana dinamika unsur hara mikro pada tanah Ultisol pasca didistribusikan biochar secara merata di dalam tanah. Dimana pada peneliti sebelumnya oleh Gunten et al (2019) menunjukkan bahwa aplikasi biochar dari kayu Tibouchina arborea dosis 20 ton/ha pada tanah Oxisol meningkatkan pH dan konsentrasi K, Ca, Mg, Zn serta menurunkan kejenuhan Al.…”