Maintenance of soil fertility is a great problem to our farmers. Cultivation of particular crop year after year in the same field decreases the soil fertility. To increase the soil fertility, it is necessary to check the loss of nutrient and to increase the nutrient content of soil. The following things must be properly followed for increasing the fertility of soil.
Proper use of land
Good yield of crop is not possible if we cultivate any crop in any land. So it is necessary to select the crop which is suitable for a particular land. Practical experience will be helpful in this regard. The crop should be cultivated on the basis of the nature soil. As for example, cultivation of paddy is best suited in low land clay soil.
Good tillage is necessary to bring the soil in suitable condition for the production of crops. Tillage makes the soil loose and friable. Weeds and stubbles of previous crops ploughed under by tillage are turned into organic matter. As a result, the physical, chemical and biological change of soil takes place which is necessary for the maintenance of soil fertility.
If we cultivate the particular crop year after year in the same field, the particular nutrients of soil become exhausted and the fertility of soil is decreased. For this, different crops should be cultivated in a year.
Control of weeds
Weeds compete with crop plants for water, space, light and mineral matter. Weeds grown on a particular land absorb the plant nutrient and make the soil unfertile. For this, to maintain and improve the soil fertility, it is necessary to control the weeds in times.
Maintenance of optimum moisture in soil
Optimum moisture in the soil is essential for the proper growth of crops. The quantity of soil moisture in more or less amount hampers the growth of crop. Excessive water in the soil causes the losses of nutrient b leaching and as a result, the fertility of the soil decreases. So it is essential to conserve the soil moisture which is helpful in the conservation of soil fertility.
Control of soil erosion
Some of the nutrient especially nitrogen, remains on the upper layer of the soil is removed by in any means, the fertility of the soil decreases. So it is essential to conserve the soil moisture which is helpful in the conservation of soil fertility.
Cultivation of green manuring crops
If we cultivate green manuring crops i.e. leguminous crop such as daincha – Sesbania aculeate, sunhemp – Crotalaria juncea, cowpea – Vigna catjang etc. and non-leguminous crops such as oat – Avena sativa, maize – Zea mays, jowar – Sorghum vulgare, bajra – Pennisetum triphoideum etc. in the field and turned under the soil by ploughing, the organic matter and nitrogen in case of leguminous crop increases in the soil and thereby the fertility of soil increases. The leguminous crop fix nitrogen from air with the help of nitrifying bacteria (i.e. Rhizobium) living in root nodule of that crop. Addition of those crops increases the organic matter and nitrogen content of soil. As a result, the fertility of soil is increased.
Application of manures
Manure is organic in nature. Application of manures i.e. plant origin (oil cakes, compost, farm yard manure etc.) and animal origin (i.e. cow dung, urine, bone meal etc.) increases the organic matter in the soil and thereby the fertility of soil is increased.
Cultivation of cover crops
Cover crops such as cowpea, sweet potato (Ipomea batatus) etc. make a cover of the surface of the soil which reduces the soil erosion and leaching loss of nutrients from the soil. As a result, the fertility of soil is conserved.
Removal of excess water
Removal of excess water from the soil is very much essential. Otherwise, nutrients are lost by the process of leaching. Besides this, aeration is also inhibiting the microbial activity and mineralizations of nutrients do not take place properly. So it is essential to remove excess water from the soil to maintain soil fertility.
Application of fertilizers
Manure contains fewer amounts of nutrients. So we should apply fertilizer to meet the requirement of plant. Applications of fertilizer do not increase the fertility of soil. But it is possible to meet the demand of plant through the fertilizer application.
Maintenance of proper acidity alkalinity of soil
Acid and alkali soils are not suitable for the cultivation of all crops. In acid soil, iron, aluminium and manganese remain in unavailable form. It is essential to reclaim the acidity and alkalinity of soil to maintain the fertility of soil. Lime is applied for reclamation of acid soil and gypsum is applied for the reclamation of alkali soil.
Role of organic matter in Soil:
- Organic matter is the store house of food for the plant. The major plant nutrient namely nitrogen, phosphorus and potassium remain in organic matter and the nutrient releases throughout the year which becomes available to plants.
- Organic matter helps to improve and conserve the fertility of soil.
- Organic matter imparts a dark colour of the soil and thereby help to maintain soil temperature.
- Organic matter improves soil structure by enhancing the granulation of soil particles. As a result, clay soil becomes porous and aeration and movement of water improved. On the other hand, water holding capacity of sandy soil increases.
- The plant nutrients remain in insoluble and complicated state in organic matter. As a result, loss of nutrient by rain water or other natural agencies becomes minimum.
- Organic matter increases cation exchange capacity (CEC) of the soil. Thus it prevents the loss of nutrient by leaching and retains them in available form.
- Organic matter increases the water holding capacity of the soil. This is specially important in case of sandy soil.
- Organic matter makes the soil porous and thus help in proper aeration.
- Organic matter serve as a store house of food for the soil microorganism. They make the plant nutrient available to plants.
- Organic matter increases the availability of phosphorus by locking up the calcium, iron and aluminium which are responsible for phosphate fixation.
- Organic matter increases the buffering capacity of soil. Buffering cheeks rapid chemical changes in soil pH and in soil reaction.
- Organic mulching helps to conserve the soil moisture.
- Organic acid released from decomposing organic matter helps to reduce alkalinity in soils.
- Organic matter reduces the undesirable properties of clay soil like cohesion and plasticity. It makes the clay soil friable and make it easy for cultivation.
- Organic matter reduces the loss of soil by wind erosion and reduces the surface run-off and makes soil water more available to plants.
- Soil becomes inert without organic matter and plant cannot grow well in that soil.
1Balaganesh B*., 2Muthukrishan R and 3Pradeesh Kumar T
1,2 Dept. of SS&AC, Vanavarayar Institute of Agriculture, Manakkadavu, Pollachi – 642 103
3, Dept. of Agronomy, Tamil Nadu Agricultural University, Coimbatore – 03