Abstract
Insect feces are a new kind of biological organic fertilizer. Little is known about the influences of insect feces on rice growth and heavy metal migration from soil to rice plant. In this study, the effects of different amounts (CK (0%), T1 (2%), T2 (4%), T3 (6%), and T4 (8%)) of black soldier fly larvae (BSFL) feces on the rice growth and the migration/accumulation of heavy metals (Cd and Pb) were investigated by pot experiments within 2years. The application of insect feces remarkably increased the contents of soil pH, organic matter, ammonium nitrogen, available phosphorus, and potassium. Meanwhile, the insect feces application reduced the weak acid-soluble contents of soil Cd and Pb by 8.3-56.8%, but increased those in the oxidizable (by 22.4-165.7%) and residual (by 1.8-225.6%) states. Except for the T4 treatment in the first year, all fertilization treatments increased the rice yield (up to 43.7% and 195.5% higher than those of CK within 2years). Moreover, the insect feces application reduced the contents of Cd (8.3-66.7%) and Pb (6.4-61.8%) in different parts of rice. Under the same treatment, the metal contents in each part of rice in the second year were lower than those in the first year. The insect feces application decreased the absorption coefficients (24.4-57.5%) and secondary transport coefficients (3.6-44.1%) of Cd and Pb by rice plant. The findings implied that the insect feces might act as effective organic fertilizers for rice plants as well as reducing heavy metal accumulation in rice plants growing in polluted soil.
Highlights
The cultivated land area polluted by heavy metals in China is about 20 million km2, due to the massive discharge of industrial "Three Wastes", sewage irrigation and unreasonable use of pesticides and fertilizers
The application of insect feces remarkably increased the contents of soil pH, organic matter, ammonium nitrogen, available phosphorus and potassium
Because Cd and Pb in the paddy soil exceeded the Chinese soil environmental quality risk control standard for soil contamination of agricultural land (GB 15618 − 2018), the present study focused on the impact of insect feces on the migration of these two heavy metals
Summary
The cultivated land area polluted by heavy metals in China is about 20 million km, due to the massive discharge of industrial "Three Wastes", sewage irrigation and unreasonable use of pesticides and fertilizers. What is more serious is that soil heavy metals will migrate into plants as plants grow (Wang et al 2019). These metals may eventually enter human bodies through food chain and pose a hazard to human health (Li et al 2020a). Among the numerous soil heavy metal remediation technologies, the application of organic fertilizers to passivate metal activities has been widely used to reduce the metal harm to crops due to the advantages of low cost and simple implementation (Fellet et al 2011; Meng et al 2018; Tang et al 2015). Organic fertilizers can increase soil fertility and promote crop growth
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
