Nitrogen management of shallow Florida histosols for sugarcane production

Sugarcane production in Florida occurs mainly in artificially drained Histosols of the Everglades Agricultural Area (EAA). Nowadays, the nitrogen (N) mineralization of these soils is the main source of N to the plants, however, depending on environmental conditions and the restricted soil depth of these organic soils, N availability might be limited for crop establishment and growth. The aims of this study were to analyze N concentration in sugarcane leaf and in the soil, while evaluating the influence of external N input application on sugarcane yields and sugar content, to determine the effectiveness of the current N recommendations for shallow organic soils of the EAA. To address the issue, a small plot trial was conducted in the 2017/2018 crop season, in two commercial sugarcane fields in south Florida Histosols. The experiment consisted of gradual increasing doses of N from control, 56, 112 and 168 kg N ha(-1 )year, applied as ammonium nitrate. We evaluated N levels in the soils and the leaves, chlorophyll index (SPAD) measurements, and sugar and biomass yields. Our results indicated that the N application did not affect the N leaf concentration and yield components did not have any improvement with N application. We concluded that the current recommendation of no N application is still accurate for these shallow soils, since the N mineralization is still sufficient in the supply of the nutrient.