Effect of Anhydrous Ammonia on Cane Yield, Nematodes and Eldana

Anhydrous ammonia has higher concentrations of nitrogen (82% N) than urea (46% N), is usually more economical, has lower labour requirements for application and is less prone to volatilisation. It has also been shown that ammonia has nematicidal properties. It would be of great benefit to the sugar industry if anhydrous ammonia could be applied as both a fertiliser and as a nematicide for the sugarcane crop. Three field trials (one plant crop and two ratoons) were conducted to compare the effects of four different rates of anhydrous ammonia and urea (82, 120, 196, 260 kg N/ha) on the yield of sugarcane, nematode populations and eldana numbers. These were compared to the ‘control treatment’ of 120 kg N/ha of urea as well as a ‘best management treatment’ of 120 kg N/ha of urea with a nematicide (Temik®, 20 kg/ha), usually recommended for sandy soils. Sugarcane yields (tc/ha and t ERC/ha) in plots treated with ammonia were mostly greater than those of plots treated with urea. Anhydrous ammonia treatments generally had lower ERC% (cane quality) values than the urea treatments. In two of the trials, plots of sugarcane treated with ammonia had greater stalk borer damage than plots treated with urea. Compared with urea, treatment with ammonia reduced the number of Meloidogyne (root-knot nematode) and total numbers of nematodes in the soil in one of the trials.