Soil is the anchorage of roots, and repository of nutrients. Soil can be sandy, i.e. having sand in excess and therefore very porous. It can be clayey, which forms lumps and will not conduct water or hold much air. The third category is loamy soil, having sand, clay and humus in same proportion.
Each type of plant has a preference for a particular type of soil. Root vegetables need a soft and loose soil so that their roots can swell nicely. This is provided by humus. Cacti and succulents cannot stand even a little water logging, so the ground should not be rich in clay to retain water.
Ideal Soil is porous enough to allow water to pass through in a few minutes, and then let air enter the pores. The soil must have enough humus to soak in water and nutrients, and make the composition of soil less dense. Small amounts of clay are needed to bind and provide minerals. A good garden soil does not have hard lumps of earth. Lumps are clods of soil compacted by clay and must be broken. After adding sand and manure (beaten to small particles), the soil will become less dense and more crumbly.
Proper soil drainage is an important consideration as it ensures that (a) water reaches deep down to the roots, and (b) there is no water logging (excess water retention) which would displace valuable air from the soil. With sufficient air, roots will be able to breathe well and not rot.
Excess drainage, however, is also to be avoided. Water will simply not remain long enough to provide the roots with moisture over a sustained period.
To test the Drainage of the Ground dig a hole 18 inches deep and as wide. Fill with water. If the water drains out fully in about half an hour's time, the ground soil has reasonably adequate drainage. If not, sand (three mugs to every square metre of land) should be added along with humus. Shrubs and other decorative plants can also be grown on a bed raised about one foot from the ground so that the roots do not grow in the water, logged part of the earth. If the soil is hard and heavy, it may be made lighter by incorporating humus (dead vegetable matter), cowdung manure or compost.
For testing the Drainage of Potted Soil, pour water upto brim. If the water drains through in five to ten minutes the drainage is all right. To correct drainage problem just remove the plant from the pot. Then, carefully, remove as much of the old soil as possible ensuring minimum damage to the roots. Replace with fresh appropriate soil. Keep the plant in shade for a week or so to allow it to recover from root, damage shock.
Preparing the Soil for Planting
For Flower Beds the soil should be dug at least six inches deep. All weeds and stones must be removed. Manure (lumps broken) is incorporated into the soil at the rate of one kg for every square metre of soil in the bed. If the drainage of the soil is not good, sand is added at the same time. It is left for a few days and then again dug up, the soil being loosened all the while, so that it assumes a fine, grainy texture. After that has been done, the bed is ready for planting.
For Trees a hole three feet wide and much deeper is dug. Into the top half of the dug out soil (topsoil), an equal amount of manure and some sand is added, if required. The sapling is planted in this mixture. Shrubs and climbers need the same treatment, but for shrubs, 1.5 feet wide and as deep holes, will suffice.
For Potted Plants the drainage hole of the pot is first checked. If it is narrow, it needs to be made wider. A plastic dish scrubber is then put over the hole, and the pot filled up to half an inch with crocks, pebbles or chips. Another half inch layer of sand is added and then the pot is filled with the soil mixture. Such an arrangement provides sufficient air space, which is vital for root health and easier drainage. Common pot soil mixtures suitable for different plant types are given on the next page.
Regularly Working the Soil is necessary as it breaks up the surface crust allowing better entry of air and irrigation water. Hoeing loosens the roots of the weeds,facilitating their pull-out. Care should be taken that roots of the plants are not hurt while hoeing. A khurpi can be used for the beds and a kitchen fork for the pots. Fortnightly hoeing is beneficial, and fertilizer or manure can be added to the soil, if needed, at the time of hoeing.
Correcting the Soil
In areas of regular heavy rainfall the soil is normally acidic. This is because rainwater is naturally acidic, though mildly so.
The soil can also become too acidic after repeated or heavy application of manure, or soils with a lot of decayed vegetables like grasses, leaves, twigs, etc. This is on account of the humic acid in decayed vegetable matter. Soils can become alkaline if there is too much salt or calcium and low rainfall. Soil acidity is expressed in terms of pH value and can be determined by dipping a pH paper (indicator) into a cup of water to which two tablespoons of the sample soil has been added and then stirred. Color changes on the paper can be matched with the color readout. This reveals the pH. (A friendly pathologist may get you some pH papers). Usually, acidic soils look a little blackish and alkaline soils are hard and cloddish, whereas saline soils are whitish in color.
The best pH range is six to seven (mildly acidic to neutral) for most plants. One kilogram of lime in about four square metres can raise the pH (i.e. alkalise it) by one unit. Unslaked lime should never be used, nor should the plants be overdosed with lime. It should be added only once in two years. The soil can be acidified by applying ammonium sulphate at the rate of 375 grams per four square metres. Using four kilograms of manure will also achieve the same acidifying effect. For saline soils, or soils watered with brackish water (usually coming from shallow wells) gypsum salt can be added. Three tablespoons of gypsum should be added for every square metre of land, or half a spoon per pot. The dosage should be repeated every month. Plants like tomatoes, potatoes, eggplants and most foliage plants grow better in a mildly acidic soil, whereas cabbage, onions, cacti, peas and beans thrive in neutral soil to which lime has been added. Carrots will do well even in saline soils.
Mulching the Soil
A soil cover of dead leaves, grass, or even a black plastic sheet, called mulch, serves many functions. It helps to conserve soil moisture, eliminating the frequent need for watering. It arrests the growth of weeds as the cover prevents entry of light to the soil surface. Leaf mulch has an additional advantage of replenishing micro-nutrients to the soil when the leaves disintegrate into it. Fruit and vegetable peels can also be used to make mulch. Before applying mulch around seedlings ensure they have grown six inches (15 cm.) high.
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