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This pot experiment aimed to investigate the influence of rice straw biochar (BC 0, 1, and 3%, w/w) and organic manure (OM 0, 1, and 2%, w/w) addition on the growth, nutrient and cadmium (Cd) uptake of forage soybean in 10 mg Cd kg−1 contaminated soils. Compared with non-biochar treatments, biochar decreased shoot biomass, height and nitrogen (N) contents. Organic manure markedly increased the shoot biomass, shoot phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) concentration, and root N, P, Ca contents without biochar addition treatments, while in the case of 3% biochar, there were no significant effects on N, K, Ca, and Mg contents of shoot and root among organic manure treatments. In comparison with other treatments, the minimum Cd content of shoots and roots both occurred in the treatment of BC3%+OM2%, while shoot Cd content reached the maximum value in OM2% treatment. Thus, these results suggested that organic manure addition can elevate forage soybean yield and nutrient content, while biochar had no positive effects. High biochar (3%) addition in combination with highest dose of organic manure (2%) can decline the Cd content of soybean and contribute to the agricultural product safety. [ABSTRACT FROM AUTHOR]

The purpose of the study was to examine biochar amendment, phosphorus (P) fertilizer and arbuscular mycorrhizal fungi (AMF) on the yield, nutrient and cadmium (Cd) absorption of Lolium multiflorum in acidic soil. It was shown that mycorrhizal inoculation had no positive influence on the plant shoot biomass and the contents of nitrogen (N), P, potassium (K), calcium (Ca) and magnesium (Mg) in plants at all biochar and P level treatments. Irrespective of mycorrhizal inoculation and P level, biochar amendments markedly elevated the soil available P and K uptake in plant tissues. In contrast, biochar significantly decreased the translocation factor of plants, soil exchangeable Cd, and acid and neutral phosphatase activities, regardless of the mycorrhizal inoculation and P fertilizer. Without P fertilization, biochar amendments significantly promoted shoot P content, while biochar amendments significantly reduced shoot P content when P fertilizer was applied. Without biochar application, P fertilizer application significantly promoted the biomass and N uptake of shoots in both AMF inoculation treatments, while P fertilizer increased these only in the presence of biochar and mycorrhizal inoculation. The increased N content induced by the biochar amendment elevated the shoot N:P ratio and alleviated the N deficiency with P fertilizer input. Thus, we concluded that the addition of biochar and P fertilizer showed more positive effects on the promotion of growth and nutrient uptake of L. multiflorum than AMF grown in acidic Cd-contaminated soils. Image 1 • AMF had no positive influence on shoot biomass and nutrient uptakes. • Biochar markedly elevated soil P level and plant K uptake. • Biochar decreased translocation factor. • Biochar increased shoot N:P ratio with P fertilization. • Biochar and P fertilizer had more positive effects on ryegrass than AMF. [ABSTRACT FROM AUTHOR]

Abstract The synergistic effects of arbuscular mycorrhizal fungi (AMF) inoculation and biochar application on plant growth and heavy metal uptake remain unclear. A pot experiment was carried out to investigate the influence of AMF inoculation, biochar and cadmium (Cd) addition on the growth, nutrient and cadmium uptake of Medicago sativa , as well as soil biological and chemical characteristics. In comparison to the non-Cd pollution treatment, Cd addition significantly decreased mycorrhizal colonization, biomass, and N, P, Ca and Mg contents of shoots and roots in the absence of biochar. Biochar amendment did not increase mycorrhizal colonization at either Cd levels. Regardless of the biochar amendment, AMF inoculation significantly promoted contents of N and P in plant shoots grown in the Cd-contaminated soils. Nevertheless, in the presence of Cd pollution, biochar dramatically elevated the biomass and N, P, K and Ca contents of plant tissues in both AMF inoculation treatments. Biochar addition significantly reduced soil DTPA-extracted Cd. The treatments with AMF inoculation and biochar amendment showed the lowest shoot Cd concentrations and contents, highest plant tissue N and P contents in the Cd addition group. These results suggested that combined use of AMF inoculation and biochar amendment had significant synergistic effects not only on nutrient uptake but also on the reduction in cadmium uptake of alfalfa grown in Cd-polluted soil. Graphical abstract Unlabelled Image Highlights • AMF only promoted N and P uptake of plant shoots. • Biochar facilitated N, P, K and Ca contents of plants grown in Cd-contaminated soils. • Biochar was more effective at increasing plant nutrient uptake. • Both AMF and biochar could decrease plant Cd concentration. [ABSTRACT FROM AUTHOR]

An incubation experiment is conducted at 20 °C for 30 days to explore the influence of biochar, nitrogen, and their interactions on CH4, CO2, and N2O emissions, as well as C and N variations in soils with milk vetch and rape residue amendment or in soils without plant residue. Both the biochar and nitrogen additions had negative effects on the cumulative CH4 and CO2 emissions in the presence of milk vetch and rape residues. Regardless of the biochar and nitrogen addition, the CH4 and CO2 emissions from soils amended with milk vetch residue are the highest, followed by those from soils amended with rape residue and those from soils with no plant residue. With the N application, N2O emissions from soils amended with rape residue are significantly higher than those from soils without plant residue, whereas the N2O emissions from soils amended with milk vetch residue are significantly lower than those from soil without plant residue. DOC is positively related with CO2 emissions. NH4+N, NO3−N, and TIN are also positively correlated with N2O emissions. In soils with the N fertilizer application, milk vetch residue, and biochar decreases the global warming potential, whereas rape residue increases the global warming potential. The results indicate that milk vetch residue in combination with biochar could benefit greenhouse gas mitigation and should be recommended for agricultural practices at high nitrogen level. In contrast, rape residue incorporated with biochar should be applied cautiously, especially in N abundant soils. [ABSTRACT FROM AUTHOR]

Biochar is an organic amendment used for soil remediation, there are only a few studies documenting the effects of nitrogen on the role of biochar in contaminated soils. A pot experiment was conducted to investigate the impacts of biochar (0%, 1%, and 2.5%, w/w) and nitrogen (0, 100, and 200 mg N kg−1) on plant growth, nutrient and cadmium (Cd) uptake of Cichorium intybus. N, P, Ca, Mg, and Cd concentrations increased with N level in 0% and 1% biochar treatments. In plants treated with 2.5% biochar, 200 mg N kg−1 addition caused significant reductions of N, P, Ca, Mg, and Cd concentrations in comparison to 100 mg N kg−1 treatments. Nitrogen promoted shoot biomass at all biochar treatments, while biochar had no effect on shoot biomass in 0 and 200 mg N kg−1 addition treatments. Nitrogen also significantly increased N, P, K, Ca, Mg, and Cd contents in the 0% and 1.5% biochar addition treatments. Although soil DTPA-extractable Cd concentration showed the lowest values in 1% biochar in combination with 100 and 200 mg N kg−1 addition treatments, lowest shoot Cd concentration, and relatively high shoot biomass occurred in the 2.5% biochar + 200 mg N kg−1 treatment. Based on these results, biochar application at its highest rate (2.5%) in combination with high N supply (200 mg N kg−1) contributed to both crop yield and agricultural product safety. N input alone might increase the risk of human health, and the optimum N dose should be determined during phytostabilization process. [ABSTRACT FROM AUTHOR]

The objective of the study was to explore the influences of arbuscular mycorrhizae (AM), phosphorus (P) fertiliser, biochar application (BC) and their interactions on Medicago sativa growth, nutrient, Cd content and AM fungi-plant symbioses. Applications of both P fertiliser and BC significantly increased total biomass and P and potassium (K) uptake, regardless of AM. When no P fertiliser or BC was used, the shoot biomass and nitrogen (N), P, and K contents in the +AM treatments were 1.39, 1.54, 4.53 and 2.06 times higher than those in the –AM treatments, respectively. AM fungi only elevated the total P uptake by 44.03% when P fertiliser was applied at a rate of 30 mg P kg−1 in the absence of BC addition. With BC application or high-P fertiliser input (100 mg P kg−1), the soil available P was significantly higher than that in the other treatments, and AM fungi significantly reduced the shoot biomass. The minimum Cd concentration occurred in the shoots of alfalfas treated with BC and high-P fertiliser inputs; this concentration was lower than the maximum permitted concentration in China. Although the BC and high-P inputs could eliminate the positive mycorrhizal response, the results suggested that BC application in combination with high-P fertiliser input could not only increase forage yields but also lower Cd concentrations to meet the forage safety standards by the dilution effect. • Biochar and P fertiliser promoted plant growth. • No biochar and P input, positive mycorrhizal response was observed. • With biochar or high P input, negative mycorrhizal response was found. • Biochar + high P, shoot Cd concentration was below safety standard. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the effects of arbuscular mycorrhizal (AM) fungi, biochar (BC) addition and phosphorus (P) fertilizer applications on the mycorrhizal response, biomass and elemental uptake of Trifolium repens in cadmium (Cd)-polluted soils. The results showed that mycorrhizal colonization were significantly decreased by 100 mg P kg−1 fertilizer input. Moreover, AM fungi, BC addition and P fertilizer significantly increased shoot biomass accumulation at all treatments. In the absence of BC, the nitrogen (N), potassium (K), calcium (Ca) and magnesium (Mg) contents in the shoots were not affected by AM fungi after P fertilizer application, but the P content in the shoots significantly increased in response to AM fungi. In the absence of BC, both AM fungi and P fertilizer significantly reduced the Cd concentrations in the plant tissues as well as the soil diethylenetriaminepentaacetic acid (DTPA)-Cd concentration. These results indicated that the translocation factors (TFs) were influenced only by BC addition and that the roots could accumulate greater amounts of Cd than the shoots. On the basis of the hygienic standard for feed in China, the shoot Cd concentration in white clover was below the maximum permitted Cd concentration (1 μg g−1) across all treatments. Therefore, it is suggested that no negative mycorrhizal-white clover symbiotic relationships were observed and T. repens could be a suitable forage species for planting in soils with low concentrations of Cd contamination when BC and P fertilizer are applied. Image 1 • AMF, biochar and P input increased plant growth at all treatments. • Biochar and P have no negative effects on mycorrhizal response. • Shoot Cd concentration is below the maximum permitted Cd concentration. • White clover is a suitable forage species planted in the low Cd-contaminated soils. Main finding of the work : BC and AMF had synergistic effects on growth of T. repens in Cd-contaminated soils, regardless of P fertilizer. [ABSTRACT FROM AUTHOR]