Macronutrient accumulation and partitioning in sugarcane biomass grown in the Burdekin region

Developing an understanding of how nutrients accumulate and partition in sugarcane is important for fine-tuning fertiliser recommendations to improve nutrient-use efficiency in a profitable, productive and ecologically sustainable farming system. The commercial sugarcane varieties Q253A, Q208A and KQ228A, which are grown in the Burdekin, were sampled several times throughout the growing season to study the accumulation of the macronutrients nitrogen (N), phosphorus (P), potassium (K), sulphur (S), calcium (Ca) and magnesium (Mg) in above- and below-ground biomass. In sugarcane, the accumulation of macronutrients in above-ground biomass peaked by 270 days after planting (DAP). The concentration of these nutrients was monitored from 200 to 365 DAP and showed a general decline in all components from 200 DAP onwards. Sugarcane exhibited three distinct phases of growth, the first being a lag phase, followed by a period of rapid development, and a final phase of sucrose accumulation. A positive relationship between stalk dry matter yield and macronutrient accumulation in above-ground biomass was identified. Below-ground biomass which included roots and stool of Q208 was monitored at 200 and 365 DAP. The concentration of all macronutrients except N remained unchanged or declined over this period. In contrast, N concentration during this period increased significantly. Surface trash biomass for Q253, Q208 and KQ228 was sampled at 365 DAP with macronutrient accumulation compared across the three varieties. Due to the free-trashing characteristics of Q208 it produced considerably more surface trash compared to Q253 and KQ228, consequently this variety accumulated considerably more macronutrients in surface trash. These data provide insights into the key periods of macronutrient uptake and their partitioning in above- and below-ground biomass during sugarcane development.