Abstract
The purpose of this investigation is to clarify the effect of farmyard manure (FYM) on the distribution of nodule formation and nitrogen-fixing activity in the root systems of soybeans. Soybeans were grown in plastic faced-root boxed supplied with FYM of different quality and size, by two methods. The results obtained were as follows. 1) Nodule formation and nitrogen fixation of soybean was more markedly decreased by whole layer application that by row application of FYM with high available nutrients: however, there were few differences in distribution patterns on nodule formation and nitrogen-fixing activity in the root systems. 2) The application of washed FYM with low available nutrients (W-FYM) resulted in the increase of nodule formation and nitrogen fixation and the enlargement of their distribution in root systems, irrespective of application methods. Moreover, the effectiveness was more strongly recognized in the whole layer application than in the row application 3) Soybean root penetrated into W-FYM placed in soil as row application while it almost did not penetrate into FYM. 4) the improvement of nodule formation and nitrogen fixation, and the enlargement of their distribution patterns were obtained by the application of granular FYM of large size (10-20 mm in diameter) compared with that of granular FYM of small size (2-4 mm in diameter). 5) It became apparent from this root box experiment that nodule formation, nitrogen fixation, and their distribution patterns in soybean root systems were remarkably influenced by the quality, size, and application method of FYM.
