How Do Plants Get Water From the Soil?

Function

Like most other living organisms, plants need water to survive. Without it, normal life-sustaining functions can't continue. Their placement within the soil makes it possible for water to enter plants through their root systems and travel upwards from there. Root system designs vary according to the family of flora. Grasses have a high root density within the area of soil in which they're planted. In comparison, vegetables have a low root density, as each only has one root cluster apiece. This density component plays a part in how plants circulate water throughout their systems.

Interestingly enough, plants only use about 1 percent of the water they extract from soil. This 1 percent is used in photosynthesis, where light from the sun is converted into glucose fuel for the organism. The rest of the water evaporates into the atmosphere. Water absorption rates vary according to soil conditions, environmental conditions and the physical makeup of the plant.

Features

With the root system being the main point of contact to a water source, plants have to work against gravity in order to get this life-sustaining element from the roots to the leaves. The route goes from the roots, up through the stem, into the leaves, then into the air. To do this, a certain degree of tension, or pressure, is needed to push the water through. Amazingly, the strongest pressure comes from the air environment that surrounds the plant. As such, water moves from the low-pressure force of the root system to the high-pressure force of the surrounding air.

Most plant roots further improve their ability to get water by growing root hairs on their surface. These hairs work to increase the root's surface area throughout the soil. Since it's the root tips that play an active role in absorption, they're also able to cultivate new cell formations. This is what makes it possible for roots to grow deeper into the soil.

Effects

While it makes sense to assume that plant roots just naturally absorb water like sponges, this is not the case. Instead, a number of chemical reactions must take place in order for water to actually move into the root's cells. These cells receive sugars from the plant's leaves and salts from the surrounding soil. The sugars and salts contained within the cells are what draw water inside the roots. From there, the water is pulled upwards into the plant by similar chemical reactions and by a suction effect from the leaves. This suction effect is caused by the evaporation process that takes place along the leaves' cells.

Through a combination of root growth, air pressure and chemical reactions within individual plant cells, water is absorbed into the roots and circulated throughout the plant body. In effect, all the parts of the organism work together to ensure needed water supplies are made available.

Resources

• Soil Plant Water Relationships
• Plant Root Systems