Biochar in Lebanese soil: nutrient retention before and after

Irrigation water disappears quickly through light, low-organic-matter soil; heavier soils seal after rain; fertilizer applied to the root zone does not necessarily remain there long enough for the crop to use it. In the Bekaa, where seasonal water stress can shape the entire production cycle, this is not a minor efficiency problem. It affects yield stability, input costs, and the farm’s ability to meet the increasingly specific expectations of export markets.

Biochar soil amendment benefits on Lebanon farms begin with a simple change in the soil’s physical architecture. Produced from agricultural waste through pyrolysis, biochar adds a porous, carbon-rich material that can hold water and nutrients in places where ordinary mineral soil would allow them to drain away. It is not a universal substitute for fertilizer, compost, or good irrigation management. Its value lies in changing how those inputs behave after they reach the soil.

From Lebanese agricultural waste to a functioning soil amendment

Biochar is made by heating biomass in an oxygen-deficient or low-oxygen environment. Crop residues, pruning waste, and certain forms of woody material can be converted through this process into a stable carbon-rich product with a network of internal pores.

That production method matters because ordinary burning destroys much of the material’s potential value. Pyrolysis instead transforms part of the biomass into a more persistent structure. The result is not simply ash and not simply compost. Compost is biologically active organic matter that continues to decompose and feed soil organisms. Biochar is more structurally stable, with a porous surface that can remain in the soil for a much longer period.

In Lebanon, LU Environment—co-founded by Dr. May Issa after the USAID DAWERR Ideathon—developed biochar from local agricultural waste and evaluated it under Lebanese soil and environmental conditions. The significance of this work is practical: a soil amendment should not be judged only by results from distant climates or highly controlled research plots. Feedstock, pyrolysis temperature, soil texture, irrigation patterns, and application rate all influence performance.

A biochar made from woody pruning residues will not behave exactly like one made from crop stalks. Nor will the same material perform identically in a sandy coastal soil and a heavier soil in the Bekaa Valley. These differences affect pore structure, nutrient content, pH, and the way the amendment interacts with existing soil minerals.

For a cooperative, this creates two linked opportunities:

• agricultural residues can become an input rather than a disposal problem;
• the resulting amendment can be returned to fields where water and nutrient losses are already limiting production.

That circularity is useful, but it should not be confused with automatic sustainability. The biomass must be clean, the pyrolysis process must be controlled, and the final material must be characterized before it is spread across productive land. Painted wood, treated timber, contaminated residues, or mixed waste can introduce unwanted compounds. A local source is not automatically a safe source.

What changes in the soil?

Before biochar is incorporated, a degraded field may show several familiar symptoms:

• water infiltrates too quickly through coarse soil or runs off compacted ground;
• soluble nutrients move below the active root zone after irrigation or heavy rain;
• fertilizer efficiency declines, encouraging repeated applications;
• roots encounter a narrow zone with little stable organic matter;
• the soil alternates between saturation and rapid drying.

After incorporation, the intended change is not a dramatic new layer of black material. The amendment works at a much smaller scale. Its pores create additional surfaces where water, dissolved nutrients, and microbial activity can be held close to roots.

A reported 5% biochar amendment can increase soil water-holding capacity by up to 50% under relevant conditions. That figure should be read as a possible result, not a Lebanese guarantee for every field. Soil texture, biochar properties, and placement determine whether the change is modest or substantial.

Biochar does not make a drought-prone field independent of water. It gives the soil more places to hold the water that is already being applied.

How porous structure improves nutrient retention

The most important chemical change is linked to cation exchange capacity, or CEC. CEC describes the soil’s ability to hold positively charged nutrient ions and make them available for exchange with plant roots. A soil with greater CEC can retain nutrients such as potassium, calcium, magnesium, and ammonium more effectively than a soil with limited exchange sites.

Biochar contributes in two ways. First, its porous microstructure increases the physical surface available for interaction. A gram of biochar can have a surface area exceeding 2,000 square feet because of its internal pore network. Second, the surfaces of biochar can develop chemical characteristics that attract and hold nutrient ions.

This reduces the chance that every soluble nutrient follows irrigation water downward. The process is not the same as locking nutrients away permanently. Properly functioning soil should retain nutrients while still allowing roots and soil organisms to access them. The benefit is a slower, more controlled nutrient cycle rather than a single pulse followed by rapid leaching.

The distinction matters for farms using soluble fertilizers. If the soil loses nutrients quickly, increasing the fertilizer dose can become an expensive response with environmental consequences. More input does not correct a soil structure that cannot retain it. Biochar may improve the efficiency of the existing fertility program, but the response still depends on the fertilizer type, timing, irrigation volume, and crop root system.

Nutrient retention before and after biochar

This is also where the question of carbon sequestration in Lebanese agriculture becomes more concrete. Carbon stored in a relatively stable form is not the same as carbon that decomposes rapidly in the soil. Biochar can contribute to longer-term carbon storage while also altering soil water and nutrient dynamics. Yet the climate value depends on the entire chain: how the biomass was sourced, how efficiently it was pyrolyzed, what emissions were produced during processing, and whether the material genuinely improves field performance.

Improving soil water retention with biochar

Water retention is often the most visible reason farmers become interested in biochar. Lebanon’s Mediterranean climate combines winter rainfall with a dry growing season, so the timing of water matters as much as the total amount available. A field may receive adequate rainfall over the year and still experience severe crop stress when moisture is absent during flowering, fruit expansion, or other sensitive growth stages.

Biochar can help by creating small internal reservoirs. Water enters the pores and remains available for gradual release rather than moving immediately through the soil profile. In selected trial conditions, biochar has reduced irrigation needs by up to 37%. Again, this is a conditional result. It does not mean every Lebanese orchard can simply reduce irrigation by the same proportion after one application.

The effect is influenced by soil texture:

• In coarse, sandy soils, biochar may improve water retention by adding storage capacity where drainage is otherwise rapid.
• In heavier soils, its value may depend more on improving pore balance and reducing the severity of wet-dry fluctuations.
• In compacted ground, biochar cannot replace physical remediation, drainage design, or the correction of traffic-related compaction.
• In orchards, placement near active feeder roots may matter more than broadcasting the amendment across areas with little root activity.

The practical question is not whether biochar holds water in isolation. It is whether the root zone remains moist for longer without becoming poorly aerated. Excess water can be as damaging as drought because roots require oxygen. An amendment that improves one part of the pore system but creates poor drainage will not build resilient soil.

Application for Lebanese orchards

Perennial crops present a different management problem from annual vegetables. An orchard has an established root architecture, permanent rows, and a longer period over which an amendment can influence soil conditions. At the same time, deep incorporation can damage roots, and surface application alone may not place biochar where the most active roots are feeding.

A cautious orchard approach would begin with a limited trial area rather than a whole-farm application:

1. Select a representative block. Include the soil texture, slope, irrigation system, and crop age that best reflect the wider orchard.

2. Characterize the starting soil. Record texture, pH, organic matter, irrigation frequency, and available nutrient levels before amendment.

3. Use a known biochar material. Document the feedstock and production process, and avoid material of uncertain origin.

4. Compare treated and untreated rows. A control area is essential because rainfall, crop load, and irrigation changes can otherwise be mistaken for biochar effects.

5. Combine the amendment with a fertility plan. Biochar is not a complete nutrient package, and it should not be treated as one.

6. Track the season, not just the first week. Measure soil moisture, plant response, fertilizer use, and irrigation intervals through the crop cycle.

For cooperative farms, this type of side-by-side trial has another advantage. It creates a shared evidence base. Members can compare results under similar management instead of relying on broad claims made for different climates or feedstocks.

Biochar versus compost: the useful answer is often both

The comparison between biochar and compost is sometimes presented as a contest. In practice, they perform different jobs.

Compost supplies decomposable organic matter and supports microbial activity. It can improve aggregation, contribute nutrients, and help rebuild biological function. Biochar provides a more stable carbon framework with a high internal surface area. It can retain nutrients and water, but fresh biochar may not immediately contain the nutrients a crop needs.

This is why biochar-compost blends are often more promising than either material used alone. Compost can charge the biochar with nutrients and microbial life before or during incorporation. Biochar, in turn, can provide surfaces and protected pores that help retain some of those resources.

Synthesis literature has reported yield increases of up to 155% for biochar-compost mixtures compared with standard applications, while standalone biochar has been associated with increases of up to 43.3% in general studies. These figures come from a broad body of research rather than a single uniform Lebanese field result. They show the potential of combination strategies, not a guaranteed yield response for every crop.

The quality of the blend matters. Fresh biochar may temporarily interact with nutrients in ways that reduce their immediate availability, especially if it is applied without adequate nutrient charging. Mixing it with mature compost can reduce that risk and create a more biologically active amendment. The blend should still be matched to crop needs and soil test results.

A useful way to think about the two materials is:

• Compost feeds the soil biology.
• Biochar helps build a durable habitat and retention system.
• Together, they can improve both short-term biological activity and longer-term soil structure.

That does not eliminate the need for crop rotation, cover crops, residue management, or careful irrigation. Soil health is a system, not a product category.

The strongest case for biochar is not that it replaces other inputs. It is that it can make water, compost, and fertilizer behave more efficiently inside the root zone.

What this means for fertilizer use and export production

Lebanese cooperatives supplying fresh produce to export markets work under two pressures at once. They need reliable yields, and they must increasingly document how crops are produced. Buyers and certification systems may examine fertilizer records, pesticide use, traceability, water management, soil protection, and post-harvest handling.

Reducing fertilizer requirements through better nutrient retention can support that transition, but only if the reduction is documented rather than assumed. A farm should not cut fertilizer rates immediately because biochar has been applied. The correct response is to monitor soil and crop performance, then adjust inputs according to evidence.

A practical record can include:

• the biochar feedstock and batch;
• the application rate and treated area;
• incorporation depth and date;
• compost or fertilizer used alongside it;
• irrigation volume or interval;
• soil moisture observations;
• crop development and yield;
• nutrient analysis before and after the trial.

This record connects soil biology to export certification requirements. It also protects farmers from a common mistake: treating a successful demonstration plot as proof that every field will respond identically.

Biochar can reduce fertilizer requirements and lower overall crop production costs under suitable Lebanese conditions. It may also reduce irrigation demand. But the result depends on the cost of producing or purchasing the amendment, transport distance, spreading method, labor, and the time needed before the benefits become clear. A cooperative that produces biochar from its own clean residues may have a different cost structure from a small farm purchasing a finished product.

The economic calculation should therefore include avoided waste disposal, reduced fertilizer losses, possible irrigation savings, and the cost of quality control. The cheapest material is not necessarily the most economical if it is inconsistent or contaminated.

Climate resilience and nitrous oxide emissions

Soil amendments are often judged only by yield. That is too narrow for farms facing rising climate variability. A resilient field should use water efficiently, retain nutrients, support roots through dry periods, and avoid creating unnecessary emissions.

Under biochar application, nitrous oxide soil emissions have decreased by 30% to 70% in Mediterranean-climate studies. Nitrous oxide is a potent greenhouse gas associated with nitrogen cycling, particularly where soils are wet, oxygen conditions fluctuate, and nitrogen fertilizer is available in excess of immediate plant demand.

The mechanism is not identical in every field. Biochar can alter aeration, moisture distribution, microbial habitat, and nitrogen retention. These changes may reduce the conditions that favor nitrous oxide production, but the outcome depends on the soil and management system. Over-irrigation, excessive nitrogen application, and poor drainage can still create emissions even when biochar is present.

This is another reason to view the amendment as part of a management sequence:

• apply nitrogen according to crop demand;
• avoid irrigating beyond the root zone;
• maintain organic matter through compost and residues;
• reduce compaction;
• monitor soil moisture rather than relying only on fixed irrigation schedules;
• use biochar to improve retention and habitat, not to excuse poor input management.

The carbon story also needs this level of discipline. Biochar can store carbon in a more stable form, but carbon sequestration in Lebanese agriculture is strongest when connected to reduced residue burning, efficient water use, lower nutrient losses, and productive soils that remain in cultivation.

A seasonal transition plan for Lebanese farms

Biochar works best when introduced as a measured soil-building project rather than a single dramatic treatment. The following sequence gives a cooperative or individual grower a practical starting point.

Before the main growing season

Start with soil sampling from the proposed trial area. Record texture, pH, organic matter, and relevant nutrient levels. Map differences between sandy, silty, and heavier sections rather than mixing them into one average result.

At the same time, identify a clean local feedstock. Crop residues and pruning waste may be available, but they should be separated from treated wood, plastics, and contaminated material. If the biochar is produced locally, document the pyrolysis process and retain a sample from each batch.

Choose one representative block and leave an untreated comparison area. The trial does not need to be large to be useful, but it must be managed consistently.

At incorporation

Use a conservative, documented application rather than spreading an unknown quantity across the farm. Where possible, combine the biochar with mature compost or another suitable organic amendment. This helps integrate the material into the soil’s biological cycle.

In orchards, avoid damaging major roots. In annual crops, incorporate the amendment into the active root zone at a depth suited to the crop and soil structure. Do not place all the material in a concentrated band unless the application method and crop make that appropriate.

During the growing season

Track irrigation intervals, visible plant stress, soil moisture, and fertilizer applications. The key comparison is not simply whether plants look greener. It is whether they maintain growth with a more stable water and nutrient supply.

Watch for differences in:

• the time between irrigation events;
• soil moisture after irrigation;
• runoff or crusting after rainfall;
• plant response during heat and drought;
• fertilizer quantities required to maintain crop condition;
• root development where inspection is possible.

Do not reduce fertilizer or irrigation aggressively based on early appearance. Build the adjustment from repeated observations and, where possible, soil and tissue analysis.

After harvest

Compare treated and untreated areas for yield, crop quality, irrigation use, fertilizer use, and production cost. Include labor and transport in the calculation. A biochar trial that improves soil condition but costs more than the farm can recover may still be valuable as a long-term investment, but that decision should be explicit.

Review the results before expanding. If the soil response is weak, investigate the reason. The problem may be unsuitable feedstock, poor placement, insufficient compost, a mismatch between application rate and soil texture, or an irrigation system that overwhelms the root zone.

The long-term measure is fertility, not novelty

Biochar has a credible role in sustainable farming Lebanon, particularly where agricultural residues, drought pressure, and nutrient leaching intersect. Local evaluation through LU Environment shows why field-specific testing matters. The amendment can improve CEC, create porous microsites, increase water-holding capacity, reduce irrigation needs under suitable conditions, and lower fertilizer requirements. When combined with compost, it may produce stronger results than either amendment alone.

But the science also gives farmers a reason to remain cautious. Biochar does not eliminate fertilizer. It does not correct every compacted or saline soil. It does not guarantee the same water-saving percentage across the Bekaa, mountain terraces, and coastal farms. Its performance changes with feedstock, pyrolysis conditions, soil texture, application rate, and crop management.

The practical path is therefore clear: begin with a characterized material, a measured trial, an untreated comparison, and a full-season record. Use the results to refine fertilizer and irrigation programs rather than replacing them with a slogan.

For Lebanese cooperatives, that discipline has value beyond one harvest. Better nutrient retention means fewer inputs lost below the root zone. Better water storage means greater resilience during the dry season. Better records make soil improvements legible to buyers and certification systems. And agricultural waste, when processed responsibly, can return to the field as part of a more stable fertility cycle.

That is the real promise of biochar: not a shortcut to perfect soil, but a practical way to give damaged soil more structure, more memory, and a better chance to hold on to what the crop needs.