Optimized drip-fertigation levels for improved water productivity and profitability of capsicum cultivation under polyhouse in Himachal Pradesh, India

In this study, experiments were conducted to evaluate the efficacy of varying drip-fertigation levels in terms of soil moisture distribution, soil water stock, yield and water productivity of capsicum (Capsicum annum L.) cultivation under polyhouse. The study comprised two levels of drip irrigation (I_0.4 and I_0.8 corresponding to 40% and 80% of cumulative pan evaporation, respectively), and four fertigation levels (F₅₀, F₁₀₀, F₁₅₀ and F₂₀₀ representing 50%, 100%, 150% and 200% of the recommended dose of fertilizer, respectively) alongside farmers’ practice and a recommended practice. Initial averaged discharge of 2.39 L h^-1 and a uniformity coefficient averaging 99%, indicated excellent moisture distribution. Soil moisture distribution determined at different intervals, indicated saving of water to the tune of 40%-60% in I_0.4 as compared to I_0.8 and I_1.0 with all drip irrigation treatments exhibiting minimal depletion across soil depths. Yield assessments indicated that increasing drip irrigation level from I_0.4 to I_0.8 and fertigation from F₅₀ to F₂₀₀ increased the marketable yield significantly (p<0.05). The significantly higher water use efficiency (13.94 g m^-2 mm^-1) was recorded under I_0.4 irrigation level, indicating the challenge of achieving both higher water use efficiency and higher yield at the same time. Fertilizer expense efficiency (157.90 g g^-1) was significantly higher with I_0.8F₅₀, underscoring the benefits of fertigation. Economic analysis showed that treatment I_0.8F₂₀₀ yielded the highest gross returns (228.15 Rs. m^-2) and benefit-cost ratio (5.86) emphasizing the economic viability of capsicum cultivation under optimized irrigation and fertigation levels.