How Plant Food is Made in The Soil
The Fertility of The Soil
By far the greater part of the food of the plant comes from the atmosphere, oxygen, carbon dioxide and water, between them furnish most of the material out of which the plant is built.
But it was discovered long ago that something is taken from the soil, and this part althrough small is absolutely indispensable to the growth of the plant. The food furnished by soil is composed of a number of substances the most important of which are Nitrates, Phophates and other salts of Potassium, Calcium, Magnesium,etc
It is convenient to divide these into two groups The Nitrogenous Group such as the Nitraes, and the Mineral Group including the Phosphates of Potassium and other metals.
The Nitrates are derived from organic matter but the mineral food on the other hand comes partly from rock material of the soil.
Nitrates are easily soluble in water and therefore readily washed away, liable to other sources of loss, while the mineral food only suffers slight losses
Five requirements are necessary for the plant, water, air, temperature, food,root growth.
Water. The soil receives water from the rain and from the subsoil but it also loses water by evaporation and drainage. The actual amount present in the soil at any time depends on gains over losses.
The amount of rain fall is important but its distribution is even more so in determing the amount reaching the soil, heavy rains run off the surface while light rain soak in. The temperature and wind are great factors in determing how much stays there.
Air. The harm that results from a water logged soil is not due to excess of water but the exclusion of air. The plant roots and the food making bacteria need air, and air must be allowed excess to all parts of the soil.
Once the excess of water goes the air comes in, such as liming a clay soil laying drains, and breaking a pan of subsoil, therefore have the effect of improving not only water supply but the air supply.
Temperature. The top half inch of soil is hotter than the air in direct sunshine and colder by night, a little below the surface the fluctuation is no greater than in the air while six inches below it is much less. Heat only travels slowly through dry soil and does not effect the subsoil.
Food. The supply of plant food in the soil depends on its mineral compostion. It is a simple matter to increase the supply of plant food by adding fertilisers to the soil.
The amount of Nitrogen may be increased by adding Nitrate of Soda, Sulphate of Ammonia, organic substances farmyard manure, waste products etc or by adding leguminous crops ie peas, beans,the roots release Nitrogen into the soil.
A further connection between the food supply and water, food has to be dissolved in the soil before it can enter the plant. Roots have no power of taking in solid matter they can only take solutions.
Root Growth. No plant does well unless it has ample space for the full development of its roots. It suffers from the restriction of its supply of water and food.
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How plant food is made in the soil
- How plant food is made in the soil
Soil is disintegrated and pulverized rock mixed with animal and vegetable matter.If two soils are formed from the same kind of rock and differ only in the size of the particles the difference is merely a physical one.