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A study entitled “Secondary and micronutrient management for enhanced productivity under open precision farming in southern coastal plain (AEU 1)” was conducted at College of Agriculture, Vellayani during 2023 - 2024. The objective of the study was evaluation of different secondary and micronutrient sources in open precision farming with graded doses of NPK in southern coastal plain (AEU 1) using chilly as the test crop.
The experiment was laid out in a split plot design with twenty treatments and three replications at farmer’s field in Kanjikuzhi, Alappuzha (AEU 1). The main plot treatments consisted of comparison of graded dosages of NPK recommendations followed by Adhoc precision farming practice of KAU (2013) and conventional nutrient management (KAU 2016). They were F1 – 75% of the recommended dose of fertilizer (RDF) through fertigation (158:36:207 NPK kg ha-1), F2 – 100% RDF through fertigation (210:48:276 NPK kg ha-1), F3 – 125% RDF through fertigation (263:60:345 NPK kg ha-1), and F4 – Nutrient management in conventional agriculture given through fertigation (75:40:25 NPK kg ha-1). The sub plot treatments assessed the impact of secondary and micronutrients on growth characteristics of chilli. They were S1- soil application of sulphur at the rate of 25 kg ha-1 based on soil test value, S2- foliar nutrition of 0.5 per cent Sampoorna KAU multimix for vegetables, S3 and S4 were foliar feeding of 0.25 and 0.5 per cent of multinutrient mixture comprising 5% MgSO₄.7H₂O, 0.1% ZnSO₄.7H₂O, and 0.1% borax and S5- water spray. Fertigation was given in 40 splits at three-day intervals, while foliar nutrition was applied three times at 15, 30 and 45 days after transplanting.
The results revealed that the tallest plants at 120 days after transplanting were observed with 125 per cent of KAU Adhoc precision farming recommendation (F3) combined with 0.5 per cent Sampoorna foliar spray (S2). This treatment also recorded the highest number of branches. The shortest fruit-set duration (34.33 days) was achieved with 100 per cent of KAU Adhoc precision farming recommendation combined with Sampoorna foliar spray (F2S2), while the maximum root length of 42 cm was noticed in 125 per cent of KAU Adhoc precision farming practise with 0.5 per cent

multinutrient mixture (F3S4).
The maximum yield per plant was achieved with the F3 treatment (2.01 kg) in the main plot and S4 treatment (1.90 kg) in the subplot. Treatment F3S2 recorded the highest fruit weight and total soluble solids (TSS), while F2S2 maximized ascorbic acid levels. Oleoresin content was highest in the subplot receiving a soil application of sulphur at 25 kg ha-1.
Total nitrogen, Phosphorus, manganese, copper, and boron uptake showed no significant interaction effects, but the highest uptake of potassium, sulphur, and zinc occurred with F3S2, and maximum calcium and iron uptake was noted with F2S2. Additionally, magnesium uptake was enhanced by 125 per cent of KAU Adhoc precision farming nutrient recommendation and 0.5 per cent foliar feeding of multinutrient mixture (F4S4).
The F3S2 treatment demonstrated the highest leaf area index and benefit-cost (B:C) ratio. The interaction effect on relative agronomic efficiency and relative apparent nutrient recovery was not significant.
This study suggests that applying 125 per cent of KAU Adhoc precision farming nutrient recommendation (263:60:345 kg ha-1 of NPK) combined with 0.5 per cent Sampoorna foliar nutrition (F3S2) significantly improves yield, nutrient uptake, B:C ratio and quality of chilly. Hence this nutrient management approach can be recommended for precision agriculture on sandy clay loam soils for future research.