Influences of introducing frogs in the paddy fields on soil properties and rice growth

This paper aims to study the influences of introducing frogs in the paddy fields on soil ecology and rice growth. The 2-year field experiments were conducted in the suburb of Shanghai in 2013 and 2014. No pesticides, herbicides, and chemical fertilizers were applied within the rice growing season to prevent the possible poisonous effects of agrochemicals on frogs. The results indicated that immigrant frogs in the fields could reduce the populations of rice leaf rollers, stem borers, and planthoppers effectively due to frog predation, and could control rice sheath blight indirectly through reducing insects that transmit disease pathogens. The frog treatment could raise soil nutrient status, improve rice growth, and increase the contents of soluble protein, chlorophyll, and soluble sugar in rice leaves to some extent, thus increasing grain yield significantly. Moreover, it also raised soil microbial biomass and enhanced the activities of soil enzymes such as dehydrogenase, catalase, urease, and acid phosphatase. To raise the survival rate of immigrant frogs in the fields, it should be protected from human hunting and chemical poison, and its habitats in the nearby fields should be properly reserved. Introducing frogs in the paddy fields not only showed a potential of pest and disease control but also improved soil fertility and rice growth. Such eco-modified method is beneficial to establish a low-input integrated farming system in the suburb of Shanghai in the future.