Soil and Plant Interrelations

Soil provides four needs to the plant; 1) A supply of water 2) Supply of essential nutrients 3) Supply of Oxygen 4) Support for the plant root system. Optimum soil composition must be 25% water, 25% air, 45% mineral matter and 5% organic matter. The soil water is held within the soil pores and together with its dissolved salts makes up the soil solution which is very important as a medium for supplying nutrients to the growing plants

Plant rootlets and root hairs are in intimate contact with the soil colloids (particles) present in the soil solution. Ions are exchanged between the soil colloids and the soil solution. Nutrient uptake by the plants’ roots takes place at the surface of the soil colloids surfaces and through the soil solution proper. Ions are interchanged between the soil colloids and the soil solution. Movement of ions takes place between the plant root surfaces and soil colloids and also between the plant root surfaces and soil solution.

The soil solution is the most important source of nutrients for absorption by plant roots. Since it is very dilute, as the plants deplete the nutrients from the soil solution. It must be replished by the soil particles (colloids). The solid phase of soil releases mineral elements into the soil solution partly by solubilization of soil minerals and organic matter, partly by solution of soluble salts, and partly by cation exchange

Soil versus Hydroponics

There is no physiological difference between plants grown plants grown hydroponically and those grown in soil. In soil both organic and inorganic components must be broken into inorganic elements, such as calcium, magnesium, potassium, phosphorus, iron etc. before they are available to plants. These elements adhere to the soil particles and are exchanged into the soil solution where they are absorbed by the plants.

In Hydroponics the plant roots are moistened with the nutrient solution containing these elements. The subsequent mineral uptake by plants is the same (depicted in green color in the chart) Learn more…

soil versus hydroponics