Effects of loosing Aigamo ducks on the growth of rice plants, weeds, and the number of arthropods in paddy fields

Abstract

Aigamo duck farming has been noticed as one of the techniques of environmental conservation agriculture. This study was carried out to investigate the effects of loosing Aigamo ducks on the growth and production of rice plants, the quantity of weeds and arthropods, and the balance of nitrogen (N) in paddy fields by changing the density of the Aigamo ducks. A paddy field was divided into three test plots: a 10‐Aigamo‐duck plot, a five‐Aigamo‐duck plot, and a weeding plot. The results show that the height, number of culms, and yield crops of the rice plants increased more in the 10‐Aigamo‐duck plot and the five‐Aigamo‐duck plot than that of the weeding plot. Millet (Echinochloa oryzicola) remained in both the Aigamo duck plots. The weeding plot was covered with monochoria (Monochoria vaginalis). In both the Aigamo duck plots, the outbreak of total arthropods was lower than that of the weeding plot, but the number of rice plants damaged by grass leaf rollers (Cnaphalocrocis medinalis) was increased. The number of spiders, regarded as useful insects, did not differ that much between the experimental plots. The N content of the soil did not differ as an effect of loosing the Aigamo ducks. The rice plants in the 10‐Aigamo‐duck plot absorbed more N than the rice plants in the other plots.