Effect of Activated Carbon Application on the Growth and Yield of Soybean in the Field of Continuous Beans Cropping

Abstract

To investigate the participation of allelopathy in the injury by continuous cropping of soybean, we seeded lettuce in the field where soybean had been cropped for 0, 1, 2, 3 and 5 years, and examined the growth of the lettuce plants. The lettuce growth was inhibited by continuous soybean cultivation and adding activated carbon to the soil alleviated the inhibition. However, the effect of the activated carbon decreased as the duration of continuous cropping increased. Therefore, the growth-inhibitory activity of the soil was considered to increase with increasing duration of the continuous cropping. In the analysis of the root-zone soil, we could not observe any significant differences in pH and nutrient elements, which suggested that the main factor causing injury by continuous soybean cropping might be allelopathy. Hence, we investigated the effect of adding activated carbon to the field where five been cultivars, ‘Tachinagaha’, ‘Enrei’, ‘Tamadaikoku’, ‘Komaki-dadacha’ and ‘Natsunokoe’ had been cultivated continuously. The growth reduction of soybean by continuous cropping of ‘Tachinagaha’, ‘Tamadaikoku’ and ‘Natsunokoe’, was significantly alleviated by the addition of activated carbon.