Soil organic carbon (SOC) – the carbon component of organic matter in soil – is a key driver of soil fertility and plant growth. High SOC improves soil structure, retains moisture and nutrients, and fuels soil microbial processes that release nutrients. In practice, soils with higher SOC tend to produce stronger, more vigorous crops. For example, a global meta‐analysis found that maize and wheat yields rise substantially with higher SOC up to about ~2% organic carbon; in soils below 2% SOC (common in many croplands), increasing SOC can boost maize yields by ~10% and wheat by ~23% on average.

🌾 Nutrient Reservoir and Natural Fertility

• SOC is a major reservoir of plant nutrients (especially nitrogen, phosphorus and sulfur) in organic form. Soil microbes decompose organic matter and mineralize these nutrients, gradually releasing them in plant‐available forms. Thus high‐SOC soils buffer nutrient supply, reducing the need for synthetic fertilizers. Soil organic matter also increases cation exchange capacity (CEC), helping soils retain nutrient ions that would otherwise leach away.

💧 Moisture Memory: Greater Water Availability

• Organic matter has a sponge‐like character. It binds water and raises the soil’s water‐holding capacity, which is especially important in sandy or drought‐prone soils. Even a 1% increase in SOC can raise available soil water by roughly 1.5–2.5 mm per 30 cm of depth. In practical terms, higher SOC means more moisture for crops during dry spells and greater drought resilience.

🏗️ Soil Strength and Root Pathways

• SOC acts like glue, binding soil particles into stable aggregates. Well‐aggregated soils have better porosity and air flow, which promotes deep root growth and efficient drainage. Good structure also reduces crusting and compaction. Soils rich in organic matter resist erosion and allow faster water infiltration, helping crops exploit more nutrients.

🪱 Soil Life and Microbial Activity

• Soil microbes depend on SOC as their energy source. High‐SOC soils support larger and more diverse microbial communities that recycle nutrients and protect plants. Healthy soils with abundant organic matter also foster plant‐growth‐promoting rhizobacteria and fungi, which stimulate root growth and nutrient uptake.

📈 Measured Yield Improvements

• Altogether, these factors translate into higher and more stable yields. In smallholder fields in Ethiopia, wheat yield was strongly correlated with soil organic matter (and especially its organic-N fraction). Farmers observe that well‐fed “humus‐rich” soils produce faster, taller, and more productive plants.