Physiological Parameters and Yield of Sugarcane Under Precision N and K Management in Subtropical India

Abstract

A field experiment was conducted to assess the effect of placement and scheduling of N & K fertilizers on crop growth, yield attributes and sugar yield in subtropical India. Experiment was laid out in split plot design keeping two methods of placement of fertilizers (N & K) in main plots (M₁: broadcast method; M₂: band placement method) and four nutrient management schedules in subplots (S₁: recommended dose of N (RDN) + recommended dose of K (RDK) in five splits; S₂: RDN + RDK in six splits; S₃: RDN + RDK in seven splits; and S₄: recommended dose of fertilizer (150 kg N, 26 kg P and 50 kg K/ha). The mean net photosynthetic rate (NPR) during tillering, grand growth and maturity stage was recorded as 15.59 µ mol m⁻² s⁻¹, 15.41 µ mol m⁻² s⁻¹ and 10.18 µ mol m⁻² s⁻¹, respectively. Band placement of fertilizers recorded the higher transpiration rate and stomatal conductance in sugarcane leaves. Band placement of fertilizer increased the leaf area index (LAI) at the grand growth stage to 5.280. Applying N and K in three splits enhanced LAI to 5.637 at the grand growth stage. Placement methods and nutrient management schedules significantly influenced the harvest stage’s total dry matter accumulation (TDMA). Band placement also increased TDMA in sugarcane by 12.99% (31.61 t/ha) compared to broadcasting. However, application of N and K in five splits enhanced TDMA by 29.57% (35.10 t/ha) over three splits. Microbial activities in soil were also determined through microbial biomass C & N and respiration. The higher mean soil microbial biomass carbon (SMBC-180.6 mg CO₂-C/ kg soil/day) was recorded under N and K band placement. About 9.92% higher sugar yield was obtained under band placement than broadcasting (11.57 t/ha). The schedule of fertilizer applications also significantly influenced growth and yield attributes, as well as sugarcane and sugar yields. Splitting five doses of fertilizers brought 18% and 19.26% higher sugarcane and sugar yields, respectively, than three splitting. Thus, it was concluded that the band application of N and K fertilizers in five splits could be recommended for sustaining sugarcane yield and soil quality parameters. In addition, scheduling of N and K (150 kg N and 26 kg P/ha, respectively) applied in five splits (10% basal and remaining at 45, 75, 90 and 120 days after planting), improved the sugarcane growth, yield and sugar yields and proved superior to other schedules in sustaining soil quality parameters in subtropical India.