Proof from tomatoes that biofertilizers increase yields—minus the environmental costs (Anthropocene Magazine)
Excerpt from this story from Anthropocene Magazine:
Using eco-friendly fertilizers instead of synthetic chemicals produces high quality tomato crops with competitive yields, a team of Italian scientists has shown.
Their new study considered two groups of fertilizer alternatives: a nutrient-rich algae-infused concoction; and fertilizers made with symbiotic root microbes like fungi and bacteria that fix nutrients from the soil to increase crops’ uptake. These alternatives, known broadly as ‘biofertillizers’, can be made without the emissions-intensive process required to make conventional synthetic fertilizers, and can significantly reduce crops’ need for these chemical additives in the first place.
The researchers tested their alternatives on tomato fields in Italy, where they subjected growing tomato plants to different combinations of the two: some tomatoes received one of two fertilizers through drip irrigation, containing a mix of growth-promoting fungi or bacteria; some were treated with the algae infusion; and others received a combination of both microbial and algal fertilizers. In each case, the fertilizer-treated crops were compared with tomatoes that had received no fertilizers at all.
Of all the fertilizers, the second microbial mixture containing a combo of root-colonizing fungi and bacteria produced the tallest and bushiest tomatoes, with the largest root mass. The symbiotic root-colonizing behavior of the microbes in this treatment seem to have supported denser, deeper-reaching roots, which can help plants snare more nutrients—and may also help plants to access deeper water sources in times of drought, the researchers say.
The success of that microbial mixture was exceeded only by tomato plants that received it in combination with the algal fertilizer, which was applied to plants as a growth-promoting spray, rich in amino acids, and vitamins. In those tomatoes plants, not only did this combo exceed all growth parameters, but it also produced striking yields: these double-treated crops generated 67.2 tons of tomatoes per hectare, compared to the 30.3 tons per hectare produced when researchers applied the microbial fertilizer on its own—and almost threefold more than the 26 tons per hectare from tomato plots that received no fertilizers at all.
What’s more, the combination of microbial and algal fertilizers also produced the highest number of marketable fruits, with fewer green and rotten fruits than in those plants that received just one fertilizer treatment or none, the researchers found. Interestingly, they noticed that microbial fertilizers led to larger and sweeter tomatoes, while the algal fertilizers were associated with redder fruits. “We were fascinated by the idea that an environmentally-friendly approach like this could produce such strong results,” the scientists say.
