Esha Mukherjee, Amity University Noida
Monocultures now dominate arable land, with enormous swaths of land dedicated to a single, high-yielding elite variety. However, planting only one type of crop on the arable ground has its drawbacks: these regions are easy prey for fungal and insect pests, posing a threat to agriculture. Farmers must utilize resistant types as well as a variety of pesticides to keep pests at bay. Mixed cultures have the potential to replace monocultures. Rather than planting broad swaths of land with only one species or variety, multiple species or varieties are planted alongside one another. Mixed cultures are uncommon in arable farming due to a lack of research into this strategy, particularly from an agricultural standpoint. Plants from mixed cultures, by contrast, produced more leaves or stems than those from monocultures, researchers found.
Mixed cultures are based on the ecological concept that ecosystems with higher biodiversity can execute their duties more successfully. These functions include preserving soil fertility, managing water balance, and promoting plant productivity. Plant fitness is determined by resource allocation to reproduction. In the agricultural environment, this feature, known as harvest index, influences how plant biomass is converted to seed production and, as a result, financial revenue from a variety of main staple crops. Plant variety has been shown to increase plant biomass, however, the benefits of plant diversity on crop seed yield are equivocal and depending on the production syndrome.
Greater yield from mixing just two crops:
The experiment showed that annual primary production increased in two- and four-species mixtures compared to monocultures when the diversity of crop plants was increased, resulting in higher overall plant biomass and, to a lesser extent, higher seed yield. The disparity in reactions to variety was attributable to a lower harvest index in mixtures for the eight crop species evaluated, presumably because their common cultivars were designed for maximum performance in monoculture.
The researchers used wheat, oat, quinoa, lentil, lupin, flax, and fake flax (an oilseed similar to rapeseed) as well as coriander to explore mixes of two or four distinct crops from eight different species. The seeds of the various species were the only ones used. In alternate, parallel rows, the plants were seeded 12 cm apart. Compared to monocultures, mixed-culture crops had a larger seed mass. They also calculated the biomass of plants based on their above-ground growth. The results speak for themselves: even a mix of two species boosted output by 3% in Spain and 21% in Switzerland when compared to monoculture farming. The yield boost was as high as 13 and 44 percent in Spain and Switzerland, respectively, where the researchers sowed four species together.
A change in agricultural practice is, however, required if mixed cultures are to gain ground. Machines should be able to harvest multiple crops and simultaneously separate the various harvest products, among other things. While crop diversification is a long-term measure of agricultural intensification, using currently available cultivars may limit higher seed yield advances. Hence, it is suggested that regional breeding programs for crop types be utilized in combinations that take advantage of crop species complementarity.
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Reference:
- Chen, J., Engbersen, N., Stefan, L., Schmid, B., Sun, H., & Schöb, C. (2021). Diversity increases yield but reduces harvest index in crop mixtures. Nature Plants. https://doi.org/10.1038/s41477-021-00948-4
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