Impacts of Organic and Inorganic Fertilization on Coconut Productivity, Fruit Quality and Soil Health

Abstract

Coconut (Cocos nucifera L.) is a high-value perennial crop essential to global tropical and sub-tropical agriculture, but its yield potential is frequently limited by imbalanced soil nutrition and unsustainable management practices. Hence, this study investigated the efficacy of the combined application of organic and inorganic fertilizers on coconut growth, yield, quality, and soil fertility in order to determine the suitable fertilization strategy. The field experiment was conducted over two consecutive years in a Completely Randomized Design with five treatments and three replicates, using 16-year-old palms of the coconut cultivar 'BARI Narikel-2'.The treatments were viz. T₁ (RDF): N₄₅₀P₁₂₀K₁₀₀₀S₅₀Zn₂₅B_6.8 g per plant_, T₂ (150%RDF+CD): N₆₇₅P₁₈₀K₁₅₀₀S₇₅Zn_37.5B_10.2 g plant^-1+10 kg cowdung (CD) plant^-1_, T₃ (125%RDF + CD): N₅₆₃P₁₅₀K₁₂₅₀S_62.5Zn_31.25B_8.5 g plant^-1+30 kg CD plant^-1, T₄ (FP): N₂₀₀P₇₀K₃₀₀ g plant^-1+20 kg CD plant^-1 and T₅: Control (without fertilizer). Parameters measured included growth characteristics, annual nut count, fruit size, copra quality, nut yield, soil health indicators etc. Results revealed that treatment T₃ significantly improved coconut growth, yield and quality metrics. The highest nut yield (115 kg plant^-1) was achieved in T₃, representing a 195% increase over the control and a 67.9 % increase over farmer practice (T₄). This yield was primarily driven by a higher single fruit weight (1.70 kg) and an increased number of fruits plant^-1 (75.5). Additionally, T₃ enhanced meat thickness (12.8 mm), total soluble solids (7.25 ⁰Brix), vitamin C (3.23 mg/100g) and protein content (12.0%). Regarding soil health, T₃ increased organic carbon by 10% and total nitrogen by 11%. This treatment was also highly economically viable, yielding a gross return of 108 US$ and a gross margin of 77.6 US$ per plant. Correlation analysis and PCA confirmed a strong positive correlation between growth and yield parameters and the fruit quality traits of coconut. Therefore, results suggest that the fertilizer strategy T₃ (N₅₆₃P₁₅₀K₁₂₅₀S_62.5Zn_31.25B_8.5 g plant^-1+30 kg CD plant^-1) optimizes the physiological yield potential, improves fruit quality, and sustains soil fertility, offering a climate-resilient solution for sustainable coconut management.