THE INFLUENCE OF HUMIC ACID ON TURFGRASS GROWTH AND DEVELOPMENT OF CREEPING BENTGRASS

It is known that leaching of major nutrients occurs from sand based rootzones, particularly, those built to USGA specifications. This can lead to groundwater contamination and economic loss through wasted fertilizer application. Humic Acid (HA) has a high cation exchange capacity (CEC) and a stimulatory effect in turfgrass growth. Creeping bentgrass turf was established from seed (6 g m-2) on an 85% sand and 15% peat, root zone mixture, in commercial 3L ‘Rose”(195 mm) containers under heated glass. Both nitrogen and phosphorus were applied to the turf at four levels (25%, 50%, 75% and Full Hoagland's solution) at ten-day intervals. Humic Acid (HA) was also applied to the turf at the same interval at a rate of 5 L ha^-1. Turf colour, leaf fresh and dry weight, nitrogen and phosphorus content of leaf tissue and leachate were determined. At the conclusion of the experiment, during spring 2003, rooting qualities were visually assessed. Humic acid ephemerally reduced nitrate but not phosphate leaching from the rootzone. It did not affect the nutritional status of the leaf tissue. It was observed to have an effect on root architecture and growth of the growing plant and also the plant’s resistance to drought.