The global agricultural system faces widespread challenges due to nutrient deficiencies, particularly in phosphorus, nitrogen, and potassium, which are essential for plant growth and crop yields. With global phosphorus reserves facing potential depletion, innovative strategies for its recycling and reuse are critically needed. A recent study published in the Journal of Soil Science and Plant Nutrition by Carol Omara-Ojungu and M. Lukac investigates MicroChar, a novel biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More product, as a solution to enhance phosphorus availabilityPhosphorus is another essential nutrient for plant growth, but it can sometimes be locked up in the soil and unavailable to plants. Biochar can help release phosphorus from the soil and make it more accessible to plants, reducing the need for chemical fertilizers.   More in nutrient-deficient soils, particularly Regosol and Cambisol.

This study aimed to address the gap in research on specific biochar types and their impact on nutrient availability, especially phosphorus. MicroChar is distinct from conventional biochar because it is enriched with organic nutrients and inoculated with a mixed microbial culture of bacteria and fungal spores, produced through co-pyrolysis of biowaste and poultry droppings at 400-600°C. This multi-step process results in a granulated product that is easy to handle and apply in agricultural settings.

The researchers conducted both incubation trials and pot experiments using pea (Pisum sativum L) as an indicator crop to evaluate MicroChar’s effectiveness under optimal soil water and drought conditions. In the incubation experiment, MicroChar addition significantly increased phosphorus concentrations in soil pore water throughout the 20-week period, with a more pronounced effect in Regosol than in Cambisol. For instance, in week 1, Regosol amended with 2% MicroChar (RM2%) showed phosphorus levels of 76.3±20.0 mg.L−1, significantly higher than the Regosol control’s 4.4±3.5 mg.L−1. Similarly, in pot experiments, MicroChar treatments (FB and FB-S) increased soluble phosphorus levels by 320% and 415% respectively, compared to the control under optimal conditions. This sustained enhancement of phosphorus availability directly benefited plant growth under optimal watering.

Under optimal water conditions, pea plants grown with MicroChar exhibited enhanced root, shoot, and pod growth, implying improved phosphorus nutrition. Analysis of pea pods from a second pot experiment confirmed this, with phosphorus content increasing by 60% in FB and 69% in FB-S treatments under optimal conditions compared to the control (2.66 g.kg−1). Even under drought conditions, the FB treatment showed a 44% increase in pod phosphorus compared to the control (3.37 g.kg−1).

However, the study also revealed that drought stress suppressed the overall plant response regardless of phosphorus availability. While MicroChar enhanced phosphorus availability under drought, plants could not fully utilize the additional phosphorus, underscoring the critical interdependence of soil moisture and phosphorus for plant uptake. Despite this, MicroChar application did lead to higher phosphorus tissue concentration in pea plants and helped maintain pigment levels, suggesting enhanced protection against drought-induced stress due to increased enzyme activity.

Overall, MicroChar augmented plant-accessible phosphorus in phosphorus-deficient Regosol, with critical implications for sustainable phosphorus management in agriculture. The ability to reduce soluble phosphorus leachingLeaching is the process where nutrients are dissolved and carried away from the soil by water. This can lead to nutrient depletion and environmental pollution. Biochar can help reduce leaching by improving nutrient retention in the soil.   More can also minimize eutrophication risks. The study suggests that MicroChar could potentially reduce phosphate fertilizer applications by 20-25%. The findings imply that strategic MicroChar application holds significant potential to improve phosphorus use efficiency, reduce reliance on inorganic fertilizers, and contribute to overcoming the global phosphorus challenge. Further trials across diverse soils and climates are essential to extend these findings.

Source: Omara-Ojungu, C., & Lukac, M. (2025). Effects of MicroChar on Phosphorus Availability and Pea Growth. Journal of Soil Science and Plant Nutrition.