Abstract
An overlay of cattle manure compost, several centimeters thick, on a lowland soil-column with a depth of 24 cm, and watering at a rate of 39 mm a day resulted in significant reduction of water-percolation in one or two weeks. With watering, large amounts of dissolved or dispersed organic matter and K+ were released from the compost. The K+ was exchanged with Ca2+ in the soil column and the degree of Ca2+-saturation of the organic matter increased with downward movement and the organic matter was retained in the soil. The precipitated or flocculated organic matter with Ca2+ might have clogged the capillary pores of the soil. Formation of bubbles due to biological activities and swelling of soil colloids with increased K+ saturation might also have been involved in the reduction of water-percolation. No significant reduction of water-percolation occurred when an Ap horizon soil of nonallophanic Andisol was placed in the column. Ion exchange of Ca2+ with K+ proceeded less in the nonallophanic Andisol than in the lowland soil. Aggregates are more stable and bulk density was lower in the nonallophanic Andisol than in the lowland soil. These properties were favorable for the nonallphanic Andisol to keep its high water-percolation. Other changes in soil chemical properties were an increase in labile P and a pH rise. The increase in labile P took place in the upper part of the nonallophanic Andisol column due to its high P retention capacity whereas an increase in the labile P was also observed in the lower part of the lowland soil column.
