Effects of rice straw biochar and nitrogen fertilizer on ramie (Boehmeria nivea L.) morpho-physiological traits, copper uptake and post-harvest soil characteristics, grown in an aged-copper contaminated soil

Copper (Cu) contamination in soils is becoming a serious problem. Therefore, an experiment in plastic pots was carried out to investigate interactive influence of rice straw BC (BC0:0, BC1:5, and BC2:10% w/w) and nitrogen fertilizer (N-0:0, N-1:140, N-2:280, and N-3:420 kg ha(-)(1)) on plant growth, Cu mobility and phytoavailability to Boehmeria nivea in Cu polluted soil. Results revealed that BC x N fertilizer had significantly (p <= 0.05) increased the growth of B. nivea in terms of biomass, height of plant, diameter of stem and number of leaves. Furthermore, BC x N fertilizer resulted in significant changes in pH, electrical conductivity and cation exchange capacity of soil after harvesting in comparison with control. However, the influence of BC x N fertilizer on soil extractable Cu and Cu uptake by plant varied with levels of N fertilizer. The BC2N1 treatment significantly increased the shoot biomass of B. nivea by 635% (fresh biomass) and 452% (dry biomass), but reduced Cu contents in roots, stems and leaves i.e., 52, 23 and 34 mg kg(-)(1), respectively. Thereby, high dose of BC along with low N fertilizer could be considered as an efficient soil amendment combination for Cu stabilization and higher biomass production of B. nivea in highly Cu contaminated soil.

Automated summary

This study investigated the interactive influence of rice straw biochar and nitrogen fertilizer on plant growth and copper mobility in copper polluted soil. The results showed that high dose of biochar along with low nitrogen fertilizer can effectively stabilize copper and increase biomass production of Boehmeria nivea in highly copper contaminated soil.