Sustainable intensification of pigeon pea-turmeric intercropping to optimize turmeric population density for enhancing productivity, and economic profitability

Abstract

Achieving sustainable intensification of cropping system to meet rising food and nutritional demands remains a significant challenge in many developing countries, particularly where smallholder farmers cultivate highly constrained landholding. In such contexts, intercropping offers a sustainable and promising strategy for maximizing production and resource-use efficiency from small plots of land. This three-year study evaluated different intercropping patterns of pigeon pea ( Cajanus cajan ) and turmeric ( Curcuma longa ) to determine their suitable population densities, yield advantages and economic profitability. The experiment, conducted over three consecutive years, included six treatment combinations: T 1 = four rows of turmeric between two rows of pigeon pea; T 2 = three rows of turmeric between two rows of pigeon pea; T 3 = two rows of turmeric between two rows of pigeon pea; T 4 = one row of turmeric between two rows of pigeon pea; T 5 = sole turmeric; and T 6 = sole pigeon pea. A randomized complete block (RCB) design with three replications was used. Several indices were employed to evaluate system performance, including the land equivalent ratio (LER), competitive ratio (CR), monetary advantage index (MAI), replacement value of intercropping (RVI), and system productivity index (SPI). The findings indicate that turmeric grown under the T₁ intercropping system produced a slightly higher rhizome yield (20.71 t ha⁻¹) than sole turmeric (20.61 t ha⁻¹). In T₁, turmeric experienced reduced photosynthetic photon flux density (PPFD) values of 54.34 and 33.09 µmol m⁻² s⁻¹ at 160 and 200 days after planting (DAP), respectively, compared with higher PPFD levels of 245.62 and 225.60 µmol m⁻² s⁻¹ in sole turmeric. These results suggest that moderate shading combine with increased plant density in the T₁ system may enhance turmeric productivity. Pigeon pea yields ranged from 2.81 and 3.18 t ha -1 across treatments, with the highest yield (3.18 t ha⁻¹) recorded in the sole-cropping system. Although, pigeonpea yields declined by about 2–13% under intercropping, this reduction was compensated by the additional turmeric yield. Among all treatments, the T 1 intercropping system delivered the greatest overall benefits, achieving the highest pigeon pea equivalent yield (PEY) of 17.31 t ha⁻¹, a LER of 1.89, a gross margin of 547150 Tk ha⁻¹, a MAI of 407129 Tk ha⁻¹, a RVI of 13.35, and a SPI of 6.01, along with a benefit-cost ratio (BCR) of 2.72. These findings highlight the potential of pigeon pea-turmeric intercropping as an effective strategy for improving land use efficiency and substantially enhancing the profitability of smallholder farming systems in tropical and subtropical regions.