Submitted to: International Society of Sugar Cane Technologists Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/14/2005
Publication Date: 5/23/2006
Citation: Morris, D.R., Perdomo, R., Powell, G., Montes, G. 2006. Fertilizer N as a factor to prevent sugarcane yield decline in organic soil[abstract}. International Society of Sugar Cane Technologists Proceedings. p. 9.
Technical Abstract: Sugarcane is usually replanted 3 yrs on organic soils in Florida due to yield decline. Literature has reported yield decline may result from a depletion of available soil nutrients. We hypothesized that successive planting, increases soil C/N ratio which allows soil microbes to immobilize inorganic N to create N deficiency. A field experiment was conducted for 2 yrs on an organic soil to determine if fertilizer N reduces yield decline in sugarcane. Treatments were 2 fields (a field previously planted to rice henceforth called fallow and a field previously planted to sugarcane henceforth called successive) and 5 fertilizer N treatments (ranging from 56 to 224 kg N ha-1) plus a 0 N control. Fertilizer N did not prevent yield decline in fallow or successive fields. Fresh cane yields declined 6 and 10% in fallow and successive fields, respectively. However, sucrose yield was only reduced in the successive field (7%). The decline was not due to reduced stalk populations as stalk population increased from year 1 to year 2. Reduced cane yields resulted from decreased stalk wts over time. Root mass, length, and surface area densities near the plant were also reduced in both field types after the last harvest indicating potential disease. But, visual observations of roots did not indicate the presence of a disease. Soil insects were not at threshold levels to cause yield reductions. Soil C/N ratios were not affected by N fertilization, but were increased over the 2-yr period from 14 to 16 and 15 to 17 in the fallow and successive fields, respectively. Our data suggest that sugarcane yield decline on organic soils may be related to pathogenic or autotoxic factors rather than N deficiency due to immobilization.