How Microorganisms Can Restore Nutrients and Flavour in Vegetables

New research now shows how this trend can be reversed.

An international team of researchers has demonstrated that the nutrient content of vegetables can be increased substantially when farmers replace chemical fertilisers with organic nutrients and carefully selected microorganisms. The findings almost suggest a return to the “old” vegetable flavour remembered by grandparents’ generation, while fundamentally challenging standard practice across many fields.

Vegetables today: high yields, fewer nutrients

Vegetable production has changed profoundly over the past 80 to 90 years. High-yield varieties produce enormous harvests, but this comes at a cost: they contain fewer minerals and valuable plant compounds than they once did. The new data analysis indicates losses of 25 to 50 per cent in the original nutrient density of many varieties.

The decline is particularly concerning for minerals that are already scarce in many areas. Compared with historical figures, modern vegetable varieties sometimes show dramatic reductions:

• Sodium: down by around 52 per cent
• Iron: down by around 50 per cent
• Copper: down by around 49 per cent
• Magnesium: down by around 10 per cent

The researchers describe this as a gradual problem: people consume enough calories to feel full, yet remain inadequately supplied with micronutrients. This contributes to so-called “hidden hunger”, which affects more than two billion people worldwide.

How chemical fertilisers “starve” the soil

The central criticism is not aimed at vegetables themselves, but at the way fields are farmed. For decades, many sites have relied chiefly on mineral fertilisers and intensive cultivation methods. As a result, soils gradually lose their biological diversity.

The researchers refer to “starved soils”: rich in nutrient salts, but depleted of life.

Soil microorganisms – bacteria, fungi and single-celled organisms – play a key part in supplying plants with nutrients. They break down organic matter, unlock nutrients and improve soil structure. When these microbes are absent, nutrients are less readily available. Artificial fertiliser may allow a plant to grow quickly and tall, but it develops lower levels of secondary plant compounds and minerals.

Microorganisms as “bio-fertilisers”

The study from India, published in 2025, addresses precisely this issue. On trial fields, the researchers largely replaced chemical fertilisers with organic sources such as farmyard manure and vermicompost. They also deliberately introduced so-called plant growth-promoting microorganisms into the soil.

These organisms are known technically as “Plant Growth Promoting Microorganisms”. They mainly include soil bacteria, such as certain rhizobacteria, which work closely with plant roots.

What these microbes specifically do

• They fix gaseous nitrogen from the air, making it available to plants.
• They release poorly available soil minerals, including phosphorus and trace elements.
• They enhance soil structure, allowing it to retain water more effectively.
• They help plants cope better with heat, drought and other stress factors.

In the researchers’ view, these microbes function as a kind of “living fertiliser”: they supply nutrients without the drawbacks of exclusively chemical fertilisation, while also building soil fertility over the long term.

Significantly more minerals in vegetables

For consumers, the most compelling aspect is what ends up on the plate: what does this approach mean for the nutrient content of vegetables? The trials revealed a clear advantage over conventional cultivation using chemical fertiliser alone.

Zinc, iron and calcium increased by as much as a third or more in vegetable crops fertilised with organic and microbial inputs.

The study reports, among other findings:

• Zinc: up 48.48 per cent
• Iron: up 31.70 per cent
• Calcium: up 23.84 per cent

These minerals are essential for blood formation, the immune system, bone development and numerous metabolic processes. Higher levels in vegetables could noticeably improve nutrient intake for populations, especially where supplements are expensive or difficult to access.

More secondary plant compounds, more flavour

Alongside minerals, the researchers paid particular attention to secondary plant compounds. These substances, including flavonoids and phenols, are involved in numerous protective processes in the body and, among other functions, help defend against free radicals.

The new cultivation system also performed strongly in this respect. Examples from the trial crops include:

• Potatoes: 45 per cent more flavonoids and 49 per cent more total phenolic compounds
• Onions: 27 per cent more flavonoids and 31 per cent greater antioxidant capacity
• Legumes such as peas and black-eyed beans: marked increases in antioxidants and vitamins

Of particular relevance in everyday life, the study assessed not only laboratory results but also flavour, aroma and texture – the qualities consumers directly experience. In these organoleptic tests, vegetables produced with organic and microbial inputs came out ahead. The measured flavour score rose by up to 27.9 per cent.

More nutrients in the laboratory, more flavour in the mouth: the new cultivation system scores on both levels.

Why “hidden hunger” is so dangerous

Most people think of hunger as an empty stomach. Far more widespread, however, is a quiet lack of vitamins and minerals. Those who mainly eat calorie-dense but nutrient-poor foods may appear full from the outside while suffering deficiencies internally.

This form of undernourishment contributes to tiredness, greater susceptibility to infections, difficulty concentrating and, in the longer term, chronic illnesses. If staple foods such as potatoes, beans or onions once again provide higher amounts of iron, zinc or antioxidants, that could make a difference to millions of people without requiring them to fundamentally change their eating habits.

What this means for farming and consumers

For farmers, the study sends a clear message: placing greater emphasis on organic fertilisation and microbial soil life not only creates humus-rich soil, but also produces more valuable vegetables. Compared with purely mineral fertilisation, this can combine yield, nutrient content and sensory quality.

For consumers, this has several implications:

• Organic farms that use compost, manure and diverse crop rotations may offer a nutrient advantage.
• Local farms that focus on improving soil are interesting not only for climate reasons, but also for personal nutrient intake.
• Long storage periods, lengthy transport and heavy processing can reduce nutrient benefits again – freshness remains a crucial factor.

How to apply parts of the principle in your own garden

Even those with only a small vegetable garden or balcony can put some of the study’s findings into practice:

• Compost instead of complete fertiliser: turn kitchen waste and garden cuttings into compost, then work it into beds.
• Vermicompost: small worm composters provide highly nutrient-rich humus for container plants and raised beds.
• Mulching: a thin layer of leaves, straw or grass clippings protects the soil and feeds microbes.
• No permanent waterlogging, no bare soil: both harm soil life and reduce fertility in the long run.

Products containing soil bacteria or mycorrhizal fungi, available commercially, can provide further support when establishing living soil. They cannot replace a compost heap, but they can help at the outset, for example on depleted or newly created plots.

Risks, limitations and unanswered questions

However promising the results may be, not every growing area can be converted completely overnight. Building up organic matter takes years. During that period, farmers must safeguard yields and remain economically viable. In poorer regions, there is also the question of whether sufficient high-quality organic material is available.

Legal requirements matter too, including rules governing manure use near groundwater protection areas. Clear strategies are needed to ensure that greater use of organic fertilisers does not create new environmental problems, such as nutrient leaching.

In addition, microbial products vary greatly in composition and quality. Not every formulation is suited to every soil or climate. The study makes clear that trials must be planned carefully before recommendations are rolled out on a large scale.

Why looking at the soil is worthwhile

The new data bring attention to an issue that has long received too little consideration: life in the soil. For future food security, it will not be enough to focus solely on yields per hectare. What will matter is how nutrient-rich harvested foods are and how reliably the growing system functions over time.

When healthy eating is discussed today, the conversation quickly turns to superfoods, shakes and supplements. The study is a reminder that a potato or a handful of peas can already achieve a great deal – if the soil they come from is alive and well supplied.