EFFECT OF AN ANIONIC SOIL CONDITIONER ON WATER-STABLE AGGREGATION OF 3 HAWAIIAN SOILS

The primary purpose of soil conditioner application is to enhance a so il's resistance to erosion processes by increasing the water stability of aggregates. In this study, a wrist-action shaker was used to asses s the aggregate stability of three Hawaiian soils treated with an anio nic surfactant soil conditioner (AGRI-SC). Aggregates of 2.00 to 4.00 mm in size were treated with Agri-SC at rates of 1 to 100,000 times th e manufacturer-recommended rate of 0.30 L ha(-1). The manufacturer-rec ommended application rate of Agri-SC was effective for only the most s table soil tested (Kaneloa Oxisol), ineffective for the Lualualei Vert isol, and adversely effective for the Molokai Oxisol. For higher appli cation rates ranging from 10 to 10,000 times recommended, stability of large aggregate fractions increased for the Kaneloa Oxisol. In sharp contrast, the same application rates decreased aggregate stability of the Molokai Oxisol. For the third, least stable soil (Lualualei Vertis ol), Agri-SC was relatively ineffective, except at very high applicati on rates (1,000 and 10,000 times recommend). Finally, at the extremely high application rate of 100,000 times recommended, aggregates for al l soils were peptized. These results suggest that careful attention sh ould be given to the application of soil conditioners with anionic sur factants as active ingredients, for aggregate response to various appl ication rates appears to be soil dependent.