Fertigation of flue-cured tobacco with a combination of water soluble and straight fertilisers, for enhancing nitrogen and potassium use efficiency
Nutrient application through drip irrigation (fertigation) with water soluble fertilisers, is an established practice to achieve nutrient use efficiency in flue-cured tobacco production. However, there has been a steady price escalation and erratic availability of water soluble fertilisers, in the recent past, which prompts to identify an effective combination of nutrient source, time, dose and schedule of application, to harness myriad advantages of fertigation. The study aims at establishing a combination of water soluble and straight fertilisers, method of application, scheduling application time and dosing of nutrients. Nutrient use efficiency, productivity and quality of flue-cured tobacco, were studied to establish the influence of various nutrient combinations, method, dose and time of application.
Experimental trials were conducted in 2014 and 2015, in irrigated flue-cured tobacco growing tracts of Alfisols in Northern Light Soils (West Godavari District, India). A combination of two water soluble fertilisers - potassium sulphate & potassium nitrate and four straight fertilisers - Single super phosphate, ammonium sulphate, potassium sulphate and urea in different combinations and rates were used for the study. Fertigation treatment combinations were compared with drip irrigation with manual fertiliser application. Nitrogen (N) and potassium (K) at 75% rate, through a combination of urea, potassium nitrate and potassium sulphate resulted in 3353 kg/ha which is similar to the productivity levels achieved with 100% nitrogen and potassium with same combination of fertilisers (3406 kg/ha), indicating a saving of 25% nitrogen and potassium. The practice of fertigation with same combination, also resulted in a significantly higher productivity compared to manual application of fertilisers, with drip irrigation (3143 kg/ha). A grade index of 82 with the above fertiliser combination indicates no significant shift in quality. Similar uptake levels of nitrogen and potassium were recorded at 75% application rate in comparison with nitrogen and potassium uptake of 95 kg and 83 kg respectively, with 100% nutrient dose and no significant changes in chemical characteristics like total alkaloids as nicotine and total sugars were observed.
Application of nitrogen and potassium through fertigation, delivers a dual advantage of nutrient optimisation coupled with enhanced productivity levels, leading to a sustainable tobacco production.