Agronomic performance of wheat (Triticum aestivum L.) and fertiliser use efficiency as affected by controlled and non-controlled traffic of farm machinery

Abstract. Controlled traffic farming (CTF) is a mechanization system that confines all load-bearing wheels to permanent traffic lanes, thus optimizing productivity of non-compacted crop beds for given energy, fertilizer and water inputs. This study investigated the agronomic and economic performance of winter wheat (Triticum aestivum L.) grown in compacted and non-compacted soils to represent the conditions of non-CTF and CTF systems, respectively. Yield-to-nitrogen (N) responses were obtained by applying urea (46% N), urea treated with 3,4-dimethyl pyrazole phosphate (DMPP), commercially known as ENTEC^® urea (46% N), and urea ammonium nitrate (solution, 30% N) at rates between 0 (control) and 300 kg ha^-1 N at regular increments of 100 kg ha^-1 N. The results showed that the CTF system increased grain yield, total aboveground biomass, and harvest index by 12%, 9%, and 4%, respectively compared to the crop grown under the non-CTF system (P<0.05). Overall, the agronomic efficiency was approximately 35% higher in CTF compared with non-CTF (≈4 vs. 3 kg kg^-1, respectively). Nitrogen use efficiency (NUE) was approximately 50% higher in CTF compared with non-CTF; however, there was not fertilizer type effect on NUE. On average, the optimal economic nitrogen application rates and corresponding grain yields were 122 kg ha^-1 and 3337 kg ha^-1, and 175 and 3150 kg ha^-1 in the CTF and non-CTF systems, respectively. This work demonstrated that significant improvements in fertilizer-N recoveries may not be realized with enhanced nitrogen formulations alone and that avoidance of (random) traffic compaction is a pre-requisite for improved fertilizer use efficiency.