Healthy soil will foster healthy root systems. In order for plants to thrive, their roots must have room to grow and expand so they can access the water and nutrients in the soil. Healthy soil structure consists of pores that roots can penetrate in order to grow to their fullest potential. In dense or hard soils, roots will be unable to expand or reach the nutrients and moisture needed to nourish the plant. Root expansion is at its healthiest in soils without compaction or drainage problems; instead, healthy soil should have a balanced supply of water and soil organic matter, as well as good tilth. If the soil provides sufficient water, nutrients, and an appropriate structure, root systems will expand to their fullest potential, leading to optimal crop productivity.
While a healthy soil can cause healthy roots, the opposite is also true. A strong root system will benefit the structure and nutrient levels of the soil. As the roots grow into the pores of the soil, it will force soil particles together, creating aggregates that stabilize the structure. Plant roots also serve as organic matter in the soil, feeding soil organisms that are vital to soil and plant health. Once plant roots die, they are decomposed in the soil and become humus, another key component to soil health.
Microorganisms in the soil benefit root growth. When soil is alive with microorganisms, the roots will be able to access micronutrients, which cause them to flourish and branch out. Many of the substances produced by microorganisms stimulate roots, much like plant hormones. Mycorrhizal fungi are similarly linked to enhanced root systems. When mycorrhizae colonize roots, their volume is expanded through the fungi’s hyphae, which can reach more than 8cm further than the root itself. The hyphae can absorb nutrients that the root could otherwise not access, which increases both root mass expansion and nutrient efficiency.