Long-term fertilization with pig-biogas residues results in heavy metal accumulation in paddy field and rice grains in Jiaxing of China

Abstract

Pig-biogas residue is widely used as organic fertilizer for rice (Oryza sativa L.) in China. To evaluate the risk of heavy metal contamination in paddy soil and rice grains caused by long-term pig-biogas residue fertilization, this study was conducted in paddy fields which had been fertilized continuously with pig-biogas residue for 8 years. We found that pig-biogas residues contained high concentrations of arsenic (As), cadmium (Cd), copper (Cu) and zinc (Zn). As a result, the concentrations of these four metals in paddy soils and rice grains sampled from biogas residue fertilized fields were significantly higher than those from control fields. In addition, in biogas residue fertilized fields, the concentrations of these four metals rapidly increased in the tillage layer compared with those in deep soil layers, and biological availability was significantly higher than in control fields. Moreover, we found that the accumulation of these four metals in paddy soils and rice grains increased in the second year compared with the first year. To reduce heavy metal accumulation in rice grains, we screened for rice genotype among 20 local rice genotypes. We found obvious genotypic differences in grains' accumulation of heavy metals, and identified some rice genotypes which had low accumulation of multiple heavy metals. These low-accumulating genotypes predicate the possibility to reduce heavy metal accumulation in rice grains grown in pig-biogas residue fertilized fields.

Effects of Pig Slurry as Basal and Panicle Fertilizer on Trace Element Content and Grain Quality in Direct-Seeding Rice

“…When Cu and Zn are used as pig feed additives, they can also be found in high concentrations in some animal manures and may be retained in the soil [15,17]. It has been shown that Fe, Mn, Cu and Zn in rapeseed increases with increasing biogas slurry application [38].…”

Genotypic and Environmental Variations in Grain Cadmium and Arsenic Concentrations Among a Panel of High Yielding Rice Cultivars

“…Phytoremdiation has been tested in small scale field trials (Murakami et al, 2009; Mandal et al, 2012; Deng et al, 2015), but its applicability to cleaning up large areas of contaminated paddy soils remains uncertain. Selection of cultivars accumulating low levels of Cd or As represents a feasible and practical option because there exist large genetic variations among rice cultivars in the accumulation of these metals and metalloids in grain (Norton et al, 2012a; Duan et al, 2012; Kuramata et al, 2013; Pinson et al 2015). For example, Norton et al (2012a) conducted six field trials in Bangladesh, China and USA over 2 years and found there was a 3–34 fold variation in grain As concentration among c. 300 rice accessions (Norton et al, 2012a).…”

Comprehensive Risk Assessment of Applying Biogas Slurry in Peanut Cultivation

“…The long-term application of large amounts of biogas slurry will likely cause serious soil heavy metal accumulation. Duan et al found that after application of biogas slurry for 8 years, the concentration of As, Cd, Cu, and Zn was significantly higher than those in the control (46). Chen et al showed that the fungal community composition of paddy soils treated with excessive rates of biogas digestate for a long time was affected by changes in the chemical properties and heavy metal contents (47).…”