Temporal Growth Inhibition of Rice Plant and Growth Recovery Observed under Application of Anaerobically-Digested Cattle Manure

抄録

A field experiment assessing the effect of the annual application of anaerobically-digested cattle manure (ADM), produced at a biogas plant, on paddy rice was conducted. In plots with ADM (MF), the early growth of rice plants, from transplanting to the active tillering stage, was inhibited compared to the plots with chemical fertilizers (CF). This phenomenon was observed over many growing seasons and was especially obvious in nitrogen uptake and leaf area index (LAI). However, after panicle initiation, the growth of MF-treated plants was equal to or superior to CF-treated plants. The grain yield in all the MF plots was 96–105% of that in the CF plots. The inorganic nitrogen content of the soil in the MF plots was higher than that in the CF plots, which was contradictory to the growth inhibition observed in the initial growth of plants in the MF plots. In contrast, the oxidation/reduction potential and pH of the surface soil in MF plots were within the normal range, indicating that these soil factors were not associated with growth inhibition observed in MF plots. Our results implied that rice cultivars with a long growing period that are able to recover from the initial growth inhibition, such as medium or late maturing cultivars, are suitable for paddy rice production fertilized with ADM.