EFFECTS OF SILICATE MATERIALS ON GROWTH AND GRAIN YIELD OF RICE PLANTS GROWN IN CLAY LOAM AND SANDY LOAM SOILS

Abstract

The usefulness of silicate materials in rice cultivation has been reported by a number of authors. However, very little has been done to study recycling of silicon (Si)-rich plant residues, such as the use of rice chaffs as soil amendments. Pot experiments were conducted in a green-house at Gifu University in 1997. In this investigation, powdered rice chaff (Cp) and normal rice chaff (Ch) were mixed in a fertile clay loam soil and an infertile sandy loam soil, with or without a biodecomposer (Wara soil). Calcium silicate was also applied to the soils for comparison. For both types of soils, six treatments were replicated four times giving 48 pots (24 × 2) in total with a randomized complete block design. Rice plants (Oryza sativa L. cv. Hatsushimo) were grown in pots filled with the soils as treated above, and the growth and Si and nitrogen (N) contents in the plants and grain yield were determined. Application of rice chaffs had little effect on plant height, but slightly increased the number of tillers per pot. The total N content of the plants was decreased in the clay loam soil but not in the sandy loam soil, but the Si content in the plants, grown in both soils, was increased. The effect of Cp and Ch on the Si content of plants was significantly enhanced by the addition of the biodecomposer. Both organic and inorganic silicate materials increased the number of grains and the dry weights of grains. The application of Cp together with the biodecomposer was the most effective. Cp could be used instead of inorganic Si fertilizer, providing a sustainable Si recycle system in rice cultivation.