4.4. Fertilizer recommendations
Sugarcane monocropping over the decades deteriorated nutrient index and soil quality due to causing multi-nutrient deficiency occurs by imbalance fertilization. Hence, targeted yield equations (TYE) ensure balanced fertilization as doses of N, P and K were applied on the basis of initial soil test value under the concept “Fertilizing the soilVs Fertilizing the crop” proposed by Ramamurthy and Bajaj (1969). WZ soils needed greater amount of N than EZ and CZ for both plant and ratoon crop due to excess N mining from the decades resulted depleted soil Na might be due to mismatch between applied and removal of nitrogen (Shukla et al., 2009; Shukla et al., 2017). The greater P and K fertilizers required in plant and ratoon crops grown in EZ soils linked to lower Pa and Ka status caused through surface runoff (Zhao et al., 1988; Li et al., 2007a). However, lower or even negative P2O5 doses required in CZ and WZ soil due to high Pa status occurs by applying excess P fertilizers. The lower K status in EZ soils (87.8% soil sample deficient) liable to required more K2O for achieving 100 Mg cane yield ha-1 as it removed about 280 kg K ha-1 against applied 60 kg K2O ha-1.