Farmyard manure alone and combined with immobilizing amendments reduced cadmium accumulation in wheat and rice grains grown in field irrigated with raw effluents

Abstract

Cadmium (Cd) stress is a serious concern in agricultural soils worldwide whereas little is known about the impact of farmyard manure (FYM) alone or combined with limestone, lignite and biochar on Cd concentrations in plants. Wheat was grown in Cd-contaminated field amended with control (T1), FYM @ 0.1% (T2), FYM + limestone @ 0.05% each (T3), FYM + lignite @ 0.05% each (T4), FYM + biochar @ 0.05% each (T5) and subsequent rice was grown without additional use of amendments. Soil application of amendments increased straw and grain yield and thousand grain weight being maximum in FYM + limestone treatment. Wheat and rice straw yield increased by 19% and 10% in T3 than control respectively. Photosynthetic pigments increased with the supply of amendments than control. Amendments decreased Cd concentration, total Cd uptake in straw and grains and Cd harvest index of both crops and the maximum reduction in these parameters was recorded with where FYM + limestone (T3). Cd concentration in wheat and rice straw decreased by 78.5% and 65% in T3 than control, respectively. The highest benefit to cost ratio was obtained in FYM + limestone (T3). Ammonium bicarbonate - diethylenetriamine penta acetic acid (AB-DTPA) extractable Cd of the post-harvest soil reduced whereas Cd immobilization index and soil pH increased with the supply of all treatments than control being maximum in T3. The present study revealed that field management with FYM + limestone increased plant yield and reduced Cd concentrations in grains.