Levels of Lead, Copper, and Zinc in Cabbage (Brassica oleracea sp.) and Lettuce (Lactuca sativa sp.) Grown on Soil Amended with Sewage Sludge

Abstract

The study focused on levels of selected heavy metals (Pb, Zn, and Cu) in sewage sludge, soil, and in lettuce and cabbage grown on sewage sludge amended soil. Also, the effect of sewage sludge on soil properties (pH, soil organic matter, and soil conductivity) was studied. Three treatments were used based on nitrogen application rates of the sewage sludge: 100, 150, and 200 kg N/ha for lettuce while 160, 210, and 260 kg N/ha for cabbage. A pot experiment was conducted with pots arranged in a completely randomized design and under local climatic conditions. The study revealed that soil organic matter content and conductivity increased significantly with increasing nitrogen application rates. Levels of heavy metals in the soil increased significantly with increasing application rates. The controls for both plants recorded the lowest heavy metal uptake. Cabbage had an uptake of 0.48 ± 0.13, 1.36 ± 0.23, and 2.60 ± 0.29 mg/kg for Pb, Zn, and Cu, respectively, while lettuce had 0.34 ± 0.19, 1.35 ± 0.31, and 2.30 ± 0.14 mg/kg uptake for Pb, Zn, and Cu, respectively. Highest metal uptake was recorded at the highest application rate in both plants (0.66 ± 0.17, 2.66 ± 0.09, and 4.33 ± 0.14 mg/kg for Pb, Zn, and Cu, respectively, for cabbage and 0.54 ± 0.01, 2.24 ± 0.17, and 3.88 ± 0.19 mg/kg of Pb, Zn, and Cu, respectively, for lettuce). The uptake of Zn and Cu was significant, while Pb uptake was insignificant for both plants. Yields increased significantly with increasing application rates. The study provides information on yield enhancement resulting from cultivating plants on soil amended with sewage sludge and the associated health risk implication.

A comparison of selected heavy metals in soils mixed with domestic and industrial sludges and assessment of effects of the sludge pollutants on oxidative stress markers of the African kale (Brassica oleracea var acephala) grown using sewage sludge manure

“…The nutrients and other organic matter in the sludge likely contributed to the enrichment of the soil and provision of nutrients to the plants resulting in enhanced plant growth. The findings are supported by the work of Fei-Baffoe et al (2021), who also reported increased yields of cabbage and lettuce in plants that were grown using sludge as fertiliser. Abdul Khaliq et al (2017) also reported a study which is in line with the results.…”

“…Literature has shown that pollutants from sludge can potentially leach into crops (Olowoyo and Mugivhisa, 2019). A transfer of heavy metals from dumpsite soil to plants grown on this soil was recorded by Obasi et al (2017) and Fei-Baffoe et al (2021) also reported an accumulation of heavy metals in plants grown on soil treated with sewage sludge. Nunes et al (2021) observed a collection of heavy metals and other pollutants on vegetables grown on soil treated with sludge.…”

Agronomic Productivity and Organic Fertilizer Rates on Growth and Yield Performance of Cabbage (Brassica oleracea var. capitata L.) in Northwestern Ethiopia

“…The yield was reduced because of the overhead application of farmyard manure fertilizer of five tons for all bud number treatments. Previous studies reported that many vegetables showed a significant yield improvement due to the application of organic fertilizers [ 51 ]. Additionally, farmyard manure has a high organic carbon content and macro and small nutrients, such as N, P, K, Ca, Mg, and Fe, which are permanently essential for crop growth [ 52 ].…”

Assessment of the health risk of some heavy metals in cabbage grown on dumpsite at Hanwa in Zaria, Kaduna State, Nigeria

“…The high levels of these heavy metals in the vegetable grown within the study area are at high risk to the consumers with time unless an urgent step is taken by relevant agencies. The high levels of heavy metals in the vegetable samples from the study area most likely attributed to anthropogenic activities in the area including the use of chemical fertilizers and/or the release of untreated solid wastes (Bernard, 2021).…”