Ali Motamedi Amin, Hasan Ali Khatinzadeh and Mansour Noori
Agricultural Research Department, Karun Agro Industrial, Inc, Shushtar, Iran; alimahohi@yahoo.com
Constraints on sugarcane cultivation in Iran that include a reduced growing period caused by late harvesting, along with spring precipitation and soil moisture levels suggest different nitrogen fertigation in comparison to other regions. The aim of this study was to assess the impact of the type of nitrogen fertigation and its application timing on foliar nitrogen concentration, on cane growth throughout the growth period, and ultimately on the quantitative and qualitative yield of sugarcane. Nitrogen fertilization (urea and UAN fertilizer sources) was started at the beginning of June and compared to application one or three weeks later in a field of CP69-1062. In addition, nitrogen fertilizer with urea as the source (184 kg ha-1 of nitrogen with three monthly installments of 100-150-150 kg ha-1 of urea) was compared with urea-ammonium nitrate (UAN) fertilizer treatment (97 kg ha-1 of nitrogen with three monthly installments of 60-95-95 L ha-1 of UAN fertilizer). The findings indicated that the timing of fertilizer application had a greater impact on the evaluated factors than the type of fertilizer used. In addition, the delay in fertigation led to a decrease in foliar nitrogen concentration. In contrast to urea, the application of UAN fertilizer resulted in a quicker rise (within a week) in nitrogen concentration in sugarcane leaves following fertilization. It appears that in delayed fertigation, timely fertilization has resulted in the conservation of generated tillers, an increase in the quantity of millable cane, and consequently, an increase in both sugarcane and sugar output. The difference in leaf nitrogen levels between the application of UAN nitrogen fertilizer and urea was especially pronounced, particularly in the early weeks after fertilization. This makes UAN a suitable option to solve the nitrogen deficiency in early-maturing sugarcane varieties when faced with delayed fertilization.