Effects of Soil Media and Fertilization on Container Grown Hibiscus and Panax Plants

Because of the relatively little work accomplished in Hawaii, and the pressing demands for information concerning media for nursery plant production, an experiment was designed to study some of these problems. Hibiscus and panax plants were grown in nine soli and amended soli mixes. Combinations of two levels of soil, organic amendments (peat or wood shavings), and inorganic amendments (cinders or perlite), were used in making the mixes. Two fertilization levels were also used, and data were taken at 2.5 months and 5.0 months. A randomized block design was used. Grade and growth of plants were determined at both dates. At 5.0 months infiltration rates, water-holding capacity, available water, and bulk density data were also taken. Statistical analysis of these properties was carried out for the high fertility portion of the experiment. Statistical analyses were also carried out on the differences in grade and growth of both species at both observation dates due to different fertility levels. Few significant differences in grade or growth of these two species were detected at 2.5 months. At 5.0 months several significant differences were apparent in grade and growth. No consistent effect of soil treatment on grade and growth of these two species at the two observation dates was apparent. When grade or growth was affected by soil treatments, the lower percentage of soil was always better than the higher percentage of soil, and amended soil was always better than soil alone. There were several significant differences in the physical properties of the different soil media. Infiltration rate and available water were higher in amended soil than in soil alone. Bulk density and water-holding capacity were lower in amended soil than in soil alone. There were several significant differences in these properties due to percentage of soil, inorganic amendments, and organic amendments as well as several significant interactions between components of the media. Water-holding capacity was highest in mixes with the higher percentage of soil. Peat mixes had significantly higher bulk densities than did wood shaving mixes. Grade and growth of plants grown at the high level of fertility were almost always greater than grade and growth of plants grown at the low fertility level. Many differences were found especially in the physical properties of the mixes. Though the physical properties differed no treatment seemed to suffer on this account. The differences in growth and grade were relatively minor, and would probably be less important as a determining factor than the cost of the media