Figure 1. N availability throughout the crop cycle.

(A) Soil nitrous oxide flux, soil mineral N (combined NH₄ ⁺ and NO₃ ⁻), and plant shoot N in the 3^rd ratoon of a sugarcane crop fertilised with urea at 200 kg N ha⁻¹ as indicated by the arrow (redrawn from 6 and 11). Dissolved (B) and soluble (C) soil N over the growing cycle of a plant crop fertilised with urea at 110 kg N ha⁻¹ as indicated by the arrow. (B) Dissolved NO₃ ^- and NH₄ ⁺ was measured in soil solution from 0–20 cm depth, and (C) soluble NO₃ ⁻ and NH₄ ⁺ measured in KCl extracts (0–20 cm), data represent mean±standard error n = 5 and n = 3, respectively.