A field study on heavy metals phytoattenuation potential of monocropping and intercropping of maize and/or legumes in weakly alkaline soils

Abstract

The study focused on the phytoattenuation effects of monocropping and intercropping of maize (Zea mays) and/or legumes on Cu, Zn, Pb, and Cd in weakly alkaline soils. Nine growth stages of monocropping maize were chosen to study the dynamic process of extraction of heavy metals. The total content of heavy metals extracted by the aerial part of monocropped maize increased in a sigmoidal pattern over the effective accumulative temperature. The biggest biomass, highest extraction content, and lowest heavy metals bioaccumulation level occurred at physiological maturity. Among the different planting patterns, including monocropping and intercropping of maize and/or soybean (Glycine max), pea (Pisum sativum), and alfalfa (Medicago sativa), the extraction efficiency of Cu, Zn, Pb, and Cd varied greatly. Only intercropping of maize and soybean yielded relatively higher extraction efficiency for the four metals with no significant difference in the total biomass. Moreover, the heavy metals concentrations in dry biomass from all the planting patterns in the present study were within China's national legal thresholds for fodder use. Therefore, slightly polluted alkaline soils can be safely used through monocropping and intercropping of maize and/or legumes for a range of purposes. In particular, this study indicated that intercropping improves soil ecosystems polluted by heavy metals compared with monocropping.

Dynamic changes of rhizosphere soil bacterial community and nutrients in cadmium polluted soils with soybean-corn intercropping

“…The concentrations of ACd in IS and IC groups were significantly different from those in corresponding monoculture from day 40, and the differences of ACd concentrations between the monocultures and intercropping systems gradually decreased with cultivation time, which may be due to the roots of the intercropped plants secreting numerous organic acids and consequently altering the mobility of soil Cd in the intercropping systems [ 39 , 40 ]. However, there were significant differences in ACd concentration between IS and S, which indicated that the soybean activated the soil Cd [ 41 ] . Consequently, the results showed that the soybean–corn intercropping system altered the cadmium concentrations in cadmium-polluted soil.…”

A review of green remediation strategies for heavy metal contaminated soil

“…Additional information obtained from (Fässler et al, 2010;Mench et al, 2018;Song et al, 2019a is a secondary aim (Burges et al, 2018;Meers et al, 2010). Profitable crops, rather than hyperaccumulators, are grown in contaminated land, which can be used for various purposes such as bio-energy production, animal feeding and soil fertility improvement after harvesting (Burges et al, 2018;Fässler et al, 2010;Zhu et al, 2016). Phytomanagement provides much wider site benefits, including the generation of renewable energy, greenhouse gas mitigation, water flow management and landscape reservation (Table 3, Figure 6).…”

The effects of monoculture and intercropping on photosynthesis performance correlated with growth of garlic and perennial ryegrass response to different heavy metals

“…In the present study, IC is shown to increase concentrations of Cd, Cr and Pb in plant organs while also contributing to total biomass. The heavy metals (Cd, Cr and Pb) in soil from the experiment affected the biomass yield, which was independent of the concentration of heavy metals and varied among different crop systems and plant species [ 35 ]. Generally, Cd, Cr and Pb do not function as nutrients in plants and seem highly toxic to many organisms in the ecosystem, including microorganisms and plants [ 36 ].…”

“…Dry pot soil samples were grounded using an agate mortar and digested into boiling aqua regia for 2 h. The digested sample were adjusted to 50 ml with distilled water. Heavy metals analysis was done by using the Perkin Elmer AAS [ 35 , 36 ]. Bioavailable heavy metals in the soil were extracted using EDTA [ 36 ].…”