Soujit Kumar, Warin Akhtar, Subhasish Saikia, Tanmee Deori, Bishakha Hazarika, Dibyani Chanda and Bhabana Das
Abstract
Earthworms are one of the key soil macro-organisms that keep the soil fertile and healthy, for which they are also referred to as ecosystem engineers. Nitrogen-containing fertilizers are one of the most common fertilizers used in agriculture to improve crop yields. But they have a negative impact on soil biodiversity. This review article summarizes the current knowledge regarding physiological and behavioural responses of earthworms to nitrogen-based fertilization with focus on its short-term and long-term impacts on earthworm survival, reproduction, activity, and its related ecosystem services. Results show that even low concentrations of nitrogen fertilizers such as urea, ammonium nitrate, ammonium sulfate, calcium ammonium nitrate (CAN), anhydrous ammonia, diammonium phosphate (DAP), potassium nitrate (NK), and ammonium hydroxide (AH) can cause organic matter turnover and earthworm activities, over- and/or long usage causing increased mortality, suppression of reproduction, burrowing behavior, and soil microbial community. These negative effects on soil health can be mitigated strategies including, slow-release fertilizers, urease inhibitors, organic amendment, and use of nano-fertilizers. This review reveals the knowledge gap that exists between field-based studies with a long-term duration that integrate functional traits of earthworms in nutrient management frameworks to limit trade-offs between agricultural productivity and preservation of soil biodiversity. From this review, itâs clear that there is lack of integrated research and so there is the need to conduct more long-term studies and find ways to know how earthwormsâ functions can be used in nutrient management to support healthy soils and better harvests.