Organic Iceberg Lettuce Beats Conventional Farming on Profit in Bangladesh Trial

Lettuce may seem like a humble salad ingredient, but a new field trial from Bangladesh suggests that the choices farmers make about seeds and fertilizer can mean the difference between a marginal crop and a genuinely profitable one. Researchers at Gazipur Agricultural University tested three popular lettuce cultivars under both organic and conventional fertilization regimes during the winter season and found that the best-performing combination was not the one with the highest raw yield. Instead, the winning pairing was Iceberg lettuce grown entirely with well-decomposed cow dung, which delivered the strongest economic return despite yielding less than the same cultivar fed with synthetic fertilizers.

The study, published in Innovations in Agriculture, addresses a persistent problem for Bangladeshi growers. Lettuce is rapidly gaining popularity in the country as a nutritious salad vegetable, yet average yields hover around just 4.0 tonnes per hectare, a strikingly low figure compared with Italy at 73.5 tonnes, Japan at 58.6 tonnes, and India at 108.9 tonnes per hectare. The authors attribute this gap largely to inadequate knowledge of modern production practices, including the selection of appropriate cultivars and the optimization of nutrient management, rather than to any fundamental climatic limitation. The crop is well suited to Bangladesh’s Rabi season, the cool winter window when many vegetables thrive.

To untangle how genetics and fertilization interact, the team grew three cultivars, Green Wave, Grand Rapids, and Iceberg, under two systems: an organic regime using only well-decomposed cow dung at 50 tonnes per hectare, and a conventional regime combining that same manure at 15 tonnes per hectare with urea, triple superphosphate, and muriate of potash at 250, 150, and 200 kilograms per hectare respectively. The urea was applied as a top dressing in two equal installments at 12 and 24 days after transplanting. The six treatment combinations were arranged in a randomized complete block design with three replications across eighteen unit plots, each 2 meters by 1.5 meters, with plants spaced 40 centimeters apart within rows set 25 centimeters apart.

Growth measurements were taken at 15, 25, and 35 days after transplanting, capturing plant height, leaf length and breadth, leaf number, and total leaf area per plant. The results revealed significant interaction effects between cultivar and fertilization method for most parameters, meaning that no single fertilization strategy was universally superior. Green Wave grown organically produced the tallest plants throughout the season, reaching 22.52 centimeters at final measurement, and also posted the largest leaf area early on, with 635.68 square centimeters per plant at 25 days after transplanting. This suggests that the slow mineralization of nitrogen in cow dung provided a steady nutrient supply that favored sustained vegetative expansion in that cultivar.

Leaf development told a similarly nuanced story. Green Wave under organic management produced the longest leaves at 25 days after transplanting, measuring 16.71 centimeters, significantly longer than every other treatment. By contrast, Grand Rapids was generally the weakest performer, recording the shortest plants and smallest leaves in several comparisons, and it ultimately yielded among the lowest of the six combinations. Iceberg, meanwhile, started relatively small, with the lowest leaf area at 15 days under conventional fertilization at just 148.00 square centimeters per plant, but accelerated late in the season to reach 722.25 square centimeters, nearly matching the 742.25 square centimeters of organically fertilized Green Wave at final measurement.

When it came to harvest, the yield hierarchy became clear. Iceberg under conventional fertilization produced the highest marketable yield at 31.0 tonnes per hectare, with 0.31 kilograms of leaf per plant and 9.30 kilograms per plot. Iceberg grown organically followed at 27.0 tonnes per hectare, a figure matched by conventional Green Wave and conventional Grand Rapids. The lowest yields came from organic Green Wave at 22.0 tonnes per hectare and organic Grand Rapids at 24.0 tonnes per hectare. The authors note that crisphead types like Iceberg respond strongly to readily available nitrogen, which helps explain their exceptional performance when mineral fertilizers deliver nutrients in immediately plant-accessible forms.

The economic analysis, however, flipped the script. Because organically produced lettuce commands a premium price of 5,583 Bangladeshi taka per tonne compared with 4,624 taka for conventionally grown produce, and because the organic system avoided the cost of synthetic fertilizers, organic Iceberg achieved the highest benefit-cost ratio of 1.84. That combination generated a gross return of 150,741 taka per hectare against production costs of 82,000 taka, leaving a net return of 68,741 taka. Conventional Iceberg came second with a benefit-cost ratio of 1.69, despite its higher yield, because greater input costs and lower prices eroded its advantage. The worst performers economically were the conventional treatments of Green Wave and Grand Rapids, each at 1.47.

These findings align with a broader body of research showing that organic systems can remain profitable even with somewhat lower yields. Earlier studies cited by the authors found that conventional mineral fertilizers rapidly boost soil nitrogen and phosphorus availability, driving higher chlorophyll content, canopy development, and fresh biomass, while compost-based amendments act more slowly but improve soil organic matter and can, when well managed, match or even surpass conventional yields over time. The slow, steady release of nutrients from decomposed manure may also support beneficial microbial activity and improved soil structure, advantages that accrue beyond a single growing season and are not captured by yield figures alone.

The practical message for farmers is that cultivar choice matters as much as fertilization strategy. Iceberg proved the most productive cultivar under both systems, while Green Wave excelled in vegetative traits under organic management. For growers weighing the trade-off between maximum output and maximum return, the study indicates that organic cultivation of Iceberg lettuce offers a sustainable and economically viable pathway, combining lower external input costs, premium consumer prices, and environmentally friendlier practices. As demand for organic vegetables grows in Bangladesh and beyond, matching the right genotype to the right nutrient system could transform lettuce from a marginal crop into a dependable source of farm income.

The research also underscores a caution about overreliance on chemical fertilizers. Excessive nitrogen use can disrupt soil nutrient balance, pollute the soil, and reduce crop quality, threatening long-term productivity. By demonstrating that a fully organic regime can deliver the best financial outcome for a high-value leafy vegetable, the Gazipur team adds to the growing evidence that sustainable intensification is not merely an ideal but a practical, profitable option for smallholder farmers in South Asia.

Subject of Research: Effects of organic versus conventional fertilization on the growth, yield, and profitability of lettuce cultivars in Bangladesh

Article Title: Organic versus conventional fertilization: impacts on growth, yield and profitability of lettuce cultivars

Article References: Akter, N., Nabi, M. N., Chowhan, S., Kayesh, E., Alam, M. S., & Roni, M. S. (2026). Organic versus conventional fertilization: impacts on growth, yield and profitability of lettuce cultivars. Innovations in Agriculture, 9, Article e183987. https://doi.org/10.3897/ia.2026.183987

Image Credits: AI Generated

DOI: 10.3897/ia.2026.183987

Keywords: lettuce, organic farming, conventional fertilization, Bangladesh, crop yield, benefit-cost ratio, cultivar selection, soil health, sustainable agriculture, Lactuca sativa, Iceberg lettuce, agronomy