Biological Farming: 5 Methods With Evidence

Biological farming is a way of growing crops and raising livestock that relies on living systems to do the work. Soil microbes, legumes, compost, cover crops and the natural enemies of pests supply nutrients and keep pests in check, so the farm needs fewer synthetic fertilizers and pesticides. It is also called bio farming or biological agriculture. It is not the same as certified organic farming, although the two share most of their methods.

This guide explains the five core biological farming methods: compost and organic matter, cover crops and green manure, biological pest control, biofertilizers and nitrogen-fixing legumes, and crop rotation with mulch and careful water use. For each method we show what the research and official data say, with the source and its date. You will also find three charts and a calculator that tests whether a legume cover crop pays for itself in nitrogen on your own field.

What is biological farming?

Biological farming treats the soil as a living system. The farmer feeds the soil life, and the soil life feeds the crop. In practice that means adding organic matter, keeping the ground covered, rotating crops and encouraging the insects, fungi and bacteria that work for the farmer.

There is no single legal definition of biological farming in the United States, Canada, the UK, the EU or Australia. That is the main difference from organic farming. Organic is a certified label with fixed rules on which inputs are allowed. Biological farming is a set of methods. A biological farmer may still use a small amount of synthetic fertilizer or a targeted pesticide when the soil or a pest outbreak needs it. The goal is to use fewer inputs and to use them better, not to follow a label.

Many people also ask “what is a bio farm?” A bio farm is a farm run on these principles. In several European languages, “bio” is the everyday word for organic food, so in Germany or France a “bio” product usually means certified organic. In English-speaking markets, “biological farming” usually means the wider, method-based approach described here.

The word “biologicals” is also used in a narrower sense. It refers to products made from living organisms or natural materials: microbial inoculants, biostimulants and biopesticides. These products are one part of biological farming, but the approach is much wider than buying products.

Biological farming vs organic and conventional farming

The table compares the three approaches on the points farmers ask about most often. It is a general guide; individual farms vary a lot.

Because biological farming has no label, its value comes from lower input costs, better soil and steadier yields, not from a higher sale price. That makes record keeping important. You need to know whether a practice is paying off on your own fields.

Why biological farming matters now

Several pressures push farmers to look at biological methods. Fertilizer prices swing sharply from year to year. Some weeds and insects have become resistant to common pesticides. Long periods of tillage and bare soil have lowered soil organic matter in many fields, which reduces how much water the soil can hold.

Biological methods address these problems at the source. A soil with more organic matter holds more water and nutrients. A field with a living cover between cash crops loses less soil to wind and rain. A farm with healthy populations of natural enemies sees fewer pest outbreaks, and sprays less often when they do occur. The University of Maryland Extension notes on organic matter describe how organic matter improves soil structure, water holding and nutrient supply over time.

The methods are also a way to manage risk. A farm that depends on one input or one pesticide is exposed when that input becomes expensive or stops working. Spreading the work across several biological tools makes the system less fragile. For a wider view of these practices, see our guide to new sustainable agriculture farming practices.

How common is biological farming?

There is no census count of “biological farms”, because the term has no legal definition. Two numbers give a good picture instead: the area under cover crops, a core biological practice, and the area under certified organic management. In the US, cropland planted to cover crops rose from 15,390,674 acres in 2017 to 17,985,831 acres in 2022, a 17% gain, according to the USDA Economic Research Service chart on the 2022 Census. That is still only 4.7% of US cropland.

Chart

US cropland planted to cover crops

Million acres, Census of Agriculture years

The growth was faster in the five years before. Cover crop acres rose by 5.1 million, or 50%, between the 2012 and 2017 Census, according to the farmdoc daily analysis of the 2022 Census. Texas had the most cover crop acres in 2022 (1.55 million) and Iowa was second (1.28 million). The same analysis notes that a federal crop insurance discount for cover crops was in place for 2022 and may have raised the acres reported that year.

Adoption is not one-way. A 2024 study in Choices magazine found that some counties dropped cover crops while others took them up. Without those losses, US cover crop area would have grown by 4.9 million more acres between 2017 and 2022, and the drop-outs were more widespread than in 2012 to 2017. Farmers who stop often cite cost, extra work at planting time or a poor first year. That is a good reason to start small and measure.

Organic farming is the best-measured form of biological agriculture. The FiBL and IFOAM release of February 2025 put world organic farmland at 98.9 million hectares at the end of 2023, up 2.6% on the year, or 2.1% of all farmland. Australia led all countries with 53 million hectares. FiBL’s 2026 yearbook again puts the world total at nearly 99 million hectares.

In the US, the USDA NASS 2021 Organic Survey highlights counted 17,445 certified organic farms in 2021, up 5% from 2019, with 4.9 million certified acres, down 11% from 2019. Certified organic sales reached $11.2 billion in 2021, up 13% from 2019. California led in farms, land and sales.

Chart

Organic farmland by region

Million hectares at the end of 2023, the four regions with figures in the release

The 5 biological farming methods at a glance

Each method has its own section below with the evidence behind it. The methods work best together: compost feeds the soil life that cover crops and rotations keep alive, and healthy plants are easier to protect with biological pest control.

Method 1: Compost and organic matter

Compost is decomposed plant and animal material. When it goes onto a field, it adds organic matter, a slow-release supply of nutrients and a large population of microbes. Manure, crop residues and green waste can all be composted. Good compost is dark, crumbly, and smells of soil rather than ammonia.

Organic matter does several jobs at once. It binds soil particles into crumbs, which lets air and water move through the soil. It holds water like a sponge, so crops last longer between rains. It also holds nutrients in a form that roots can take up, and it feeds the earthworms, fungi and bacteria that recycle nutrients. The University of Maryland Extension notes that organic matter must be added again and again, because soil life keeps breaking it down.

How to use compost well

• Test the compost. Ask for nutrient content, carbon-to-nitrogen ratio and salt level. A high salt level can harm seedlings.
• Count its nutrients. Compost releases only part of its nitrogen in the first year. Count it in your nutrient plan so you do not over-apply.
• Watch phosphorus. Fields that get manure or compost year after year can build up high phosphorus levels, which can wash into streams. A soil test every two to three years shows the trend.
• Use the right material. Fully finished compost is safer around crops than raw manure. Food-safety rules limit how close to harvest raw manure can be applied on produce farms.
• Start on the poorest field. Compost has the largest effect on low-organic-matter soils, such as eroded knolls or sandy patches.

Compost is bulky and costly to haul, so it pays best close to where it is made. Many farms make their own from manure and crop residues. Others buy municipal compost in bulk. Either way, keep a record of what went where, so you can compare yields and soil test results later.

▶ Why soil organic carbon matters for soil structure, water and long-term yields. · 12:28

Method 2: Cover crops and green manure

A cover crop is a crop grown to protect and improve the soil rather than to sell. It fills the gap between two cash crops, often over winter. A green manure is a cover crop that is cut and worked into the soil while it is still green, so its nutrients return to the soil quickly.

▶ A short, plain-English look at seven practices that protect soil and water. · 4:34

Cover crops fall into three main groups. Grasses such as cereal rye, oats and wheat produce a lot of residue, hold soil well and take up leftover nitrogen so it does not leach away. Legumes such as hairy vetch, crimson clover, red clover and winter peas fix nitrogen from the air. Brassicas such as radish and mustard have deep taproots that can break up compacted layers. Many farmers sow a mix to get several benefits at once.

The nitrogen benefit of legumes can be large. The SARE chapter on cover crops says hairy vetch, crimson clover, red clover and Austrian winter peas may supply over 100 pounds of nitrogen per acre to the next crop if they grow to flowering. Other legumes may supply much less. The amount depends on the species, how long the crop grows and how much biomass it makes.

You can estimate the nitrogen a cover crop will release from two numbers: how much dry matter it produced, and its nitrogen content. The Oregon State University guide PNW 636 gives the method. The chart below shows the table SARE adapted from it. A cover crop with only 1% nitrogen, like a mature cereal, releases almost none in the first season. A lush legume with 3.5% nitrogen releases about 37 pounds per ton of dry matter.

Tips for cover crop success

• Plant early. A cover crop sown soon after harvest grows more before winter and gives more benefit.
• Match the species to the goal. Pick a legume for nitrogen, a grass for erosion control and weed suppression, a brassica for compaction.
• Plan termination. Decide how you will end the cover crop: rolling, mowing, tillage, winter kill or a herbicide. Allow time before planting the next crop.
• Sample before you cut fertilizer. Clip a square of cover crop, dry and weigh it, and send a sample for a nitrogen test.
• Check program rules. Conservation programs and crop insurance have rules on cover crop planting and termination dates. Check with your local office before you plant.

Use the calculator below to test whether the nitrogen from a legume cover crop covers its seed and planting cost on your field. The example values are set near break-even. Replace them with your own numbers and today’s nitrogen price.

Chart

Nitrogen a cover crop releases, by its nitrogen content

Estimated available N to the next crop, pounds per ton of cover crop dry matter

Try the numbers for your own farm below.

Method 3: Biological pest control

Biological pest control uses living organisms to keep pests below the level where they cause economic damage. There are three main approaches. Conservation means protecting the natural enemies already on the farm, for example by planting flowering strips and avoiding broad-spectrum sprays. Augmentation means buying and releasing natural enemies. Classical biological control means bringing in a natural enemy from a pest’s home range, which is done only by government agencies after careful testing.

Natural enemies include predators, parasitoids and pathogens. Lady beetles, lacewings and predatory mites eat aphids, mites and other soft-bodied pests. Tiny parasitoid wasps lay eggs inside pests. Some beetles are reared and sold for release. The UC IPM page on the mealybug destroyer says releases of 500 of these beetles per acre are recommended in spring in California citrus where mealybugs have been a problem.

Biopesticides

Biopesticides are pest control products made from natural materials such as bacteria, fungi, plants and certain minerals. The EPA page on biopesticides says there were 390 registered biopesticide active ingredients as of 31 August 2020. The EPA usually needs less data to register a biopesticide, and new biopesticides are often registered in less than a year, against more than three years on average for a conventional pesticide.

The best-known example is Bt, the bacterium Bacillus thuringiensis. The National Pesticide Information Center fact sheet on Bt explains that each Bt toxin is specific to a group of insects: Bt kurstaki and Bt aizawai control caterpillars of moths and butterflies, while Bt israelensis controls the young of mosquitoes, flies and gnats. Because Bt has to be eaten to work, timing the spray to when young larvae are feeding matters a lot.

Other biological products use fungi such as Beauveria bassiana against insects, or Trichoderma species and Bacillus strains against some soil-borne plant diseases. Results vary with weather, timing and the product. Always read the label, follow it exactly, and check that the product is registered for your crop and your state or country.

Biological control within integrated pest management

Biological control works best inside integrated pest management (IPM). EPA’s integrated pest management principles set out four steps: set action thresholds, monitor and identify pests, prevent problems, and control them when needed. The EPA points out that seeing a single pest does not always mean control is needed.

In practice, scout fields every week in the growing season, learn to tell pests from beneficial insects, and record counts. Spray only when counts pass the threshold for your crop. When you do spray, pick the most selective product that works, so the natural enemies survive. For a look at the pests Midwest growers face most, see our page on common crop pests in Illinois.

▶ Organic ways to control thrips, and how satellite crop monitoring helps spot problem areas. · 13:24

Method 4: Biofertilizers and nitrogen-fixing legumes

Biofertilizers are products that contain living microbes. The microbes make nutrients easier for the crop to get. They do not add many nutrients themselves. The main groups are nitrogen-fixing bacteria, phosphorus-solubilizing microbes and mycorrhizal fungi.

The most reliable example is rhizobia, the bacteria that live in nodules on legume roots. The University of Hawaii guide to legume nitrogen fixation describes this as a partnership: the plant feeds the bacteria, and the bacteria turn nitrogen from the air into a form the plant can use. Beans, peas, alfalfa and clovers can meet much of their own nitrogen need this way.

Rhizobia are specific. Each group of legumes needs its matching strain. If a field has not grown that legume for years, or ever, the right bacteria may be missing. That is why seed of soybeans, peas, lentils, alfalfa and clovers is often treated with an inoculant before planting. Inoculant is cheap compared with fertilizer and is one of the best-proven biological inputs.

Checking whether nodules are working

• Dig up a few plants about four to six weeks after emergence. Do not pull them, or the nodules will stay in the soil.
• Wash the roots gently and look for nodules, usually small round lumps on the main and side roots.
• Cut a few nodules open. A pink or red inside means they are fixing nitrogen. White, green or brown means they are not.
• Few or no working nodules can point to a missing strain, very acid soil, waterlogging or high soil nitrate.

Mycorrhizal fungi and other microbial products

Mycorrhizal fungi form links with the roots of most crops. They extend the root system and help the plant take up phosphorus and water. Most farm soils already contain these fungi. They are harmed by long fallow periods, heavy tillage and crops that do not host them, such as brassicas. Keeping a living root in the soil most of the year, through cover crops and rotation, often does more than buying a product.

The market for microbial biostimulants is growing fast, and product quality varies. Ask the seller for independent trial results from conditions like yours. Test a new product on strips of the same field, with untreated strips next to them, before using it on the whole farm.

Method 5: Crop rotation, mulch and careful water use

Crop rotation means growing different crops on the same field in a planned sequence. It is one of the oldest biological tools. Many pests and diseases attack one crop family. When a different crop follows, they lose their host and their numbers fall. Rotations that include a legume also add nitrogen, and those with a deep-rooted crop improve soil structure.

A simple rule is to avoid growing the same crop family in the same field two years in a row. Longer rotations of three or four crops, with a hay or pasture phase, give the most benefit to soil and the strongest break in pest cycles. The right rotation depends on your markets, equipment and climate, so start with the crops you can sell.

Mulch

Mulch is any material spread on the soil surface. Organic mulches such as straw, wood chips and crop residues slow evaporation, keep soil cooler in summer, suppress weeds and add organic matter as they break down. In vegetable and fruit crops, mulch also keeps soil off the harvested produce. On large fields, leaving crop residue on the surface with reduced tillage or no-till does a similar job.

Water care

Biological farming and good water management go together. A soil with more organic matter and better structure takes in rain faster and holds more of it. Drip irrigation puts water at the root zone and keeps foliage dry, which can reduce some leaf diseases. Scheduling irrigation from soil moisture readings or weather data, rather than the calendar, avoids both stress and waste.

Vertical and indoor farms use some of the same ideas in a controlled setting, with very precise water and nutrient delivery. Our page on vertical farming lighting in the USA covers that side of the picture.

How to start: a step-by-step plan

Switching a whole farm at once is risky. Most farmers who succeed start with one or two fields and build from there. Here is a practical order of steps.

1. Test the soil. Get a standard nutrient test plus organic matter. Some labs also offer soil health tests that measure biological activity.
2. Pick a test field. Choose a field you know well, with yield records, so you can compare.
3. Add a cover crop. Choose a species for one clear goal, such as nitrogen or erosion control.
4. Fix the rotation. Make sure the same crop family does not follow itself.
5. Start scouting. Set up weekly pest scouting and learn the action thresholds for your main crops.
6. Cut inputs step by step. Reduce nitrogen only where a soil or tissue test and your cover crop sample support it.
7. Keep strips. Leave untreated or conventional strips in the field so you can see the difference.
8. Review after each season. Compare yields, input costs and soil tests, then decide whether to expand.

Expect a learning period. Soil changes take several years. Some farmers see slightly lower yields in the first seasons while soil life builds up and they learn new timing. Lower input costs can offset part of that. Before major changes to fertilizer or pest programs, get advice from a local agronomist or extension adviser, and check the label and local rules for any product you use.

Costs, risks and limits

Biological farming is not a cure-all. It has real costs and limits, and it helps to know them before you start.

• Seed and labour. Cover crop seed, compost and natural enemies cost money, and planting and terminating a cover crop takes time at busy periods.
• Timing risk. A cover crop that grows poorly gives little nitrogen. A wet spring can delay termination and planting.
• Slower pest control. Natural enemies and biopesticides often act more slowly than conventional sprays, so you need to scout early.
• Variable products. Microbial products vary in quality and in how well they work in different soils and climates.
• No label premium. Unless you certify as organic, crops grown with biological methods usually sell at normal prices.

Financing and insurance can also be affected. Some lenders and insurers now ask about conservation practices. Our pages on crop loans and insurance and carbon footprinting cover those topics. Carbon credit programs pay for some practices in some places, but the rules, prices and payment terms differ a lot, so read contracts carefully and get financial and legal advice before you sign.

Measuring results on your farm

Because biological farming has no label, you need your own evidence. Good records answer the question every farmer asks: is it paying?

• Yield by field and by strip, from a yield monitor or weighed loads.
• Input costs per acre: fertilizer, pesticide, seed, compost, fuel and labour.
• Soil test results every two to three years, including organic matter.
• Pest scouting counts and spray records.
• Cover crop biomass and nitrogen test results.

Satellite images help too. Vegetation indices such as NDVI show how evenly a crop is growing across a field and over the season. You can compare a cover-cropped block with the rest of the field, or spot an area where a pest or water problem is starting. Some growers also use crop records and traceability tools to show buyers how their food was grown; see our page on product traceability.

Data tools can bring these records together. Our article on AI-powered agricultural insights covers how farm data is being used, and developers can find our satellite and weather API documentation. Larger operations that run many machines may also find our page on fleet management useful.

How we checked the numbers

Cover crop acres come from the USDA Census of Agriculture, as reported by USDA ERS and farmdoc daily. Organic figures come from the USDA NASS 2021 Organic Survey and the FiBL and IFOAM statistics for 2023. Nitrogen release values come from SARE and Oregon State University. Pest control facts come from the US EPA, the National Pesticide Information Center and UC IPM. Each figure is given with its year. Each source is listed at the end of the article.

Related pages on our site: sustainable farming practices.

FAQ

What is biological farming in simple words?

It is farming that uses living things, such as soil microbes, legumes, compost and the natural enemies of pests, to feed crops and control pests. The aim is healthy soil and fewer synthetic inputs.

Is biological farming the same as organic farming?

No. Organic farming is a certified label with fixed rules on inputs. Biological farming is a set of methods with no legal definition. A biological farmer may still use some synthetic inputs where tests show a need.

What are the five methods of biological farming?

Compost and organic matter, cover crops and green manure, biological pest control, biofertilizers and nitrogen-fixing legumes, and crop rotation with mulch and careful water use.

How much nitrogen can a cover crop provide?

SARE says productive legumes such as hairy vetch and crimson clover may supply over 100 pounds of nitrogen per acre to the next crop if they reach flowering. Grass cover crops supply much less. Test the biomass and its nitrogen content before cutting fertilizer.

Does biological farming lower yields?

It can in the first seasons, while soil life builds up and farmers learn new timing. Lower input costs can offset some of that. Start on one field, keep comparison strips and judge the results over several seasons.

Are biopesticides safe?

The EPA says biopesticides tend to pose fewer risks than conventional pesticides, but they are still pesticides. Read and follow the label, wear the stated protection and check that the product is registered for your crop.