Organic amendments: effects on cereals growth and cadmium remediation

Abstract

Cadmium (Cd) is one of the toxic metals that adversely affect plant growth. Organic amendments may not only enhance nutrient status of soil, but they may also form complexes with Cd and reduce its availability to plants. This experiment was conducted to determine whether organic amendments (compost and biogas slurry) could stabilize/extract Cd and alleviate the adverse effects of Cd on the growth of two cereals, wheat and maize. Organic amendments along with four varying levels of Cd (0, 5, 20, 50 mg kg -1 soil) were prepared with soil. Effect of these amendments on tolerance indices, root/shoot dry biomass, tissue Cd concentration, Cd uptake and translocation were studied. Biogas slurry caused maximum increase in tolerance indices of wheat and maize (100-112 and 117-133 %, respectively, as compared to control), whereas compost caused significant increase in their dry biomass. Negative correlation between root dry biomass of wheat (r = -0.37) and maize (r = -0.53) to Cd revealed its suppressive effects. Dry biomass of plant correlated with organic amendments in wheat (r = 0.83-0.98), whereas weak correlation was observed in maize (r = 0.30-0.40). Compost significantly reduced Cd uptake in wheat and maize; however, it increased Cd translocation in plants. Based on the results of this study, root was the major sink of Cd when soil was amended with or without organic amendments. Biogas slurry removed 97 % Cd from artificially polluted water after 13 h at pH 6. The additions of compost in soil and biogas slurry in wastewater are recommended to stabilize/extract Cd.

The influence of humic substance on Cd accumulation of phytostabilizer Athyrium wardii (Hook.) grown in Cd-contaminated soils

“…In addition, in this work, the application of the humic substances enhanced Cd remediation efficiency of A. wardii. The RF values in underground part of ME, which increased from 0.73 to 0.91 %, were apparently higher than those of NME and common crops, such as wheat and green bean (Prapagdee et al 2014;Ahmad et al 2015). These results indicated that ME possessed greater ability of root remediation with the increasing application of the humic substances.…”

“…Several types of organic amendments have effectively reduced metal bioavailability in amended soils and their uptake by plants. For instance, compost produced from fruit peels significantly (P ≤ 0.05) reduced Cd concentration in wheat and maize (Ahmad et al 2015). Horse-and sheepmanure compost reduced Cu and Zn concentrations in shoots of Brassica juncea and metal bioavailability of Cu and Zn in soil.…”

“…are known to improve soil fertility and certain physical-chemical properties by adding essential nutrients and enhance the microbial community of soil (Ahmad et al 2015;Nawab et al 2015). Compost produced from different green waste sources (plant leftovers, pine bark, etc.)…”

“…However, studies about organic amendments not only focus on being a way to improve soil fertility but also are proposed for the remediation of heavy metal contaminated soils. Organic amendments have been used to either mobilize or immobilize heavy metals in contaminated soils (Ahmad et al 2015;Khan et al 2015). For the mobilization, metals are released into the soil and subsequently removed through native plant species.…”

Potential of some soil amendments in reducing leaching of fipronil to groundwater

“…Hence it is important to restrict the leaching of this insecticide to prevent groundwater contamination. Organic amendments are known to improve soil structure and fertility by adding essential nutrients and increasing the microbial community in the soil (Ahmad et al 2015). Organic matter also plays an important role in the retention of pesticides in soil.…”