Organic amendments for crop production, phosphorus bioavailability and heavy metal immobilisation: a review
Shamim Al Mamun, Shatabdi Saha, Jannatara Ferdush, Tanmoy Roy Tusher, Md. Saiful Islam
Abstract
Repeated and excessive use of inorganic phosphorus fertilisers adversely affects soil fertility, reduces plant phosphorus (P)-use efficiency, increases soil heavy metal concentrations and poses human health risks via food chain interaction. Organic amendments (OAs) are considered as cost-effective and environment-friendly supplement to inorganic P fertilisers that are produced from scarce phosphate rocks. Numerous studies have reported the synergistic and antagonistic effects of OAs on crop production, P solubility and availability, and immobilisation of heavy metals. However, the results of these studies are found to be variable and demand a critical review. This article summarises the environmental and health implications of continuous inorganic P fertilisers application along with a detailed overview of commonly available OAs and their efficacy to stimulate plant growth and yield. Moreover, this review describes the potentiality of OAs to increase the bioavailability of P in soil, discusses how and to what extent these soil amendments can immobilise heavy metals and reduce plant uptake, and finally provides future research directions for organic farming and sustainable agricultural practices.