Listening this week to speakers on Marjorie Wildcraft’s Home Grown Food Summit has been a real education. If you haven’t taken advantage of this opportunity, visit her website to get details. One of my favorites with some amazing information is Robert Kourik’s talk about Understanding Roots. Here are some of the things he shared.
- Root systems expand much farther than we understand; for years we were thinking that the roots beneath matched the shape of the tree above ground. Research has shown that not to be the case.
- The top two inches of soil has the best stuff and shows 50% more growth than from the next two inches.
- Soil type has a big influence on how roots grow. Roots grow much farther than the drip line; heavy clay soils make tree roots grow not very deep but they may grow 5x farther out.
- Most feeding roots extend past the drip line but like to stay in an aerobic zone to gather nutrients from critters.
- Microorganism populations vary with depth into the soil – aerobic organisms are closer to the surface and anaerobic organisms can be found deeper.
- When planting try not to upheave the soil – break it with a pitchfork, do not turn it upside down. The different microbes will have their life balance upset if they’re moved and it takes sometime for them to recover the populations and continue their work of decomposition, etc.
- Roots grow in different direction in different amounts, for example, roots don’t expand into compressed soil (like walking paths or roads) and will take the direction of least resistance.
- Often more roots grown on the downhill side of a slope.
- The top 1-2 feet are most critical for nutrient and water absorption; different plants can reach farther down, but the percentage obtained for use is greater near the surface.
- Only about 2% of trees have tap roots; some have sinker roots which grow down from roots that have grown out horizontally first and then grow down.
- When planting don’t add soil that’s different from the existing soil the roots will have to grow into.
- Plant on a mound in any soil, but especially clay soils.
- Don’t add more than 4 inches of mulch. Keep the crown above level of soil to get roots to grow away from planting area. Avoid composting near tree trunk to encourage root growth.
- Drip irrigation is more important to be set up past the drip line of trees because as roots age, those roots closer to the trunk become woody and don’t have root hairs to absorb water and nutrients.
- You will be surprised that most plants have more roots than you know and leave lots of them behind in the soil when they’re harvested. Those roots are good to be left in the soil, they condition it and replenish nourishment as they decompose.
Billie Nicholson, Editor