Conservation tillage not only conserves soil but also conserves soil moisture and maintains fertility of the soil by adding organic matter to it.
Conservation Tillage:
The need of the hour to attain the goal of sustainable development
-Dr. Arvind Singh
Tillage aims to create a soil environment favourable to plant growth. Tillage is the physical, chemical or biological soil manipulation to optimize conditions for germination, seedling establishment and crop growth. Soil manipulation can alter fertility status markedly and the changes may be manifested in good or poor performance of crops. Tillage operations loosen, granulate, crush or compact soil structure changing soil properties such as bulk density, pore size distribution and composition of the soil atmosphere that affect plant growth.
Tillage operations are grouped into two types i.e. primary tillage (ploughing) and secondary tillage. Primary tillage is opening of the compacted soil with the help of different ploughs. It is practised mainly to open the hard soil and to separate the topsoil from lower layers. However, lighter or finer operations performed on the soil after primary tillage is known as secondary tillage. This type of tillage practice in which soil is opened using ploughs followed by harrowing and planking is known as conventional tillage.
As far as conventional tillage is concerned it is not only time consuming, laborious and expensive but often leads to soil erosion. To overcome the problems of conventional tillage, an alternative system of tillage has emerged which is known as conservation tillage. Tillage practices that leave significant amounts of residue on the soil surface during the entire year are known as conservation tillage. In fact, it is crop production systems involving the management of surface residues. Conservation tillage is economical in comparison to conventional tillage. Economic factors contributing to interest in conservation tillage include:
1. High costs of fuel, labour, tractors and other equipment.
2. High equipment inventories and maintenance costs.
3. Ability to use land at risk of erosion for more intensive crop production.
4. The opportunities offered for more intensive cropping, avoiding long fallow periods because of greater water conservation.
Conservation tillage can reduce soil loss up to 99% over conventional tillage. In most cases, it reduces soil loss by 50% over conventional tillage. Furthermore, conservation tillage maintains the organic matter content of the soil and prevents the removal of nutrients from the soil by rainwater. Conservation tillage also causes an increase in microbial and earthworms population in the soil. The other advantages of conservation tillage include:
(i) Maintains the productivity of upland soils by reducing erosion.
(ii) Maintains a favourable soil temperature.
(iii) Increases the water holding capacity of the soil.
(iv) Improves water use efficiency; and
(v) Increases the nutrient use efficiency.
Types of Conservation Tillage:
(1) Stubble mulch tillage: It refers to tilling of soil in such a way that plant residue or other materials are maintained to cover the soil surface. It is also referred to as mulch farming, trash farming, mulch tillage and ploughless farming. Any form of tillage that results in plant residues being maintained on the soil surface could be classified as stubble mulch tillage. Disk type or other implements incorporate some residues into the soil when unusually large amounts are retained on the surface and leave some on the surface to reduce erosion.
In stubble mulch tillage primary tillage is done generally 12-15 cm deep. Subsequent tillage is done at successively shallower depths. It is adaptable to all types of soils. However, coarse-textured soils require more surface residues to control wind erosion than fine-textured soils. Hence wind erosion is controlled more easily with stubble mulch tillage on fine-textured soils than on coarse-textured soils. Soil erosion by water is controlled easily in coarse-textured soils because of rapid water infiltration in them. Therefore, fewer surface residues would be required on coarse-textured soils to control erosion by water.
The stubble mulch is better adapted to arid and semi-arid climatic regions than humid and sub-humid regions. However, in dry areas it lowers the nitrification (conversion of ammonia to nitrate), thereby prevents overstimulation of plant growth thus improves water fertility balance. In this type of conservation tillage, the rate of organic matter decline is low.
(2) Minimum tillage: The concept of minimum tillage has emerged in the United States of America. The immediate cause for introducing minimum tillage was the high cost of tillage due to steep rise in the oil prices in 1974. Minimum tillage refers to minimum soil manipulation necessary for crop production under existing soil and climate conditions.
In minimum tillage system crop residues are maintained for a longer time or throughout the crop season. Thus minimum tillage virtually leads to improved soil conditions and soil moisture conservation. Through this effective conservation, the productivity of land can be maintained for sustained crop yield. Since it involves fewer cultural operations or less intensive soil manipulation, it reduces labour expense, tractor and equipment usage. Moreover, time and fuel energy are also reduced and hence result in more economical crop production. Minimum tillage maintains organic matter in the soil. The loss of nutrients by leaching, volatilization and erosion is reduced.
There are a few disadvantages of minimum tillage. These include lower seed germination, lesser nutrient availability and pest problems. Major types of minimum tillage systems are mentioned below:
(i) Autumn plough: In this system, primary tillage is with the mouldboard plough and secondary tillage is reduced to one shallow cultivation which is followed by levelling the soil by planking at the time of planting. A disk or rotary tiller may be used instead of the field cultivator to produce finer and firmer seedbed. It is widely used on the dark, nearly level, medium to fine-textured clay loam soils.
(ii) Spring plough: In this system, strip seedbed is prepared on soil that was initially ploughed i.e. only 12-24 hours before planting the crop. By planting soon after ploughing, the soil does not dry appreciably and the soil water content at planting would be such that the clods get broken and make the seedbed firm. This system provides greater protection against erosion because residues from the previous crop are maintained on the surface until ploughing.
(iii) Disk and plant: The initial disking is done usually in the autumn followed by one or more disks in spring before planting.
(iv) Strip tillage: Only a narrow band of soil is tilled in this system. A typical tillage zone is about 20 cms wide and 5-10 cms deep.
(3) No-tillage: The no-till system is a specialized type of conservation tillage consisting of a one-pass planting and fertilizer operation in which the soil and the surface resides is minimally disturbed. The surface residues of such a system are of critical importance for soil and water conservation. Weed control is generally achieved with herbicides or in some cases with crop rotation. No-tillage systems eliminate all pre-planting mechanical seedbed preparation except for the opening of a narrow (2-3 cm wide) strip or small hole in the ground for seed placement to ensure adequate seed/soil contact.
The entire soil surface is covered by crop residue mulch or killed sod. Furthermore, in this type of conservation tillage there is improved control of wind and water erosion, increased use of land, improved water conservation, reduced energy requirements, reduced labour requirements and equipment inventories, reduced wear and tear on tractors and equipment and greater net returns.
The disadvantages of non-tillage include the application of higher nitrogenous fertilizers due to slower mineralization of organic matter, the appearance of perennial weeds and an increase in insect pests population.
Equipment for Conservation Tillage Systems:
Under the stubble mulch tillage systems machines with blades, sweeps are used for primary tillage. Subsequent or secondary tillage operations are performed with a sweeping machine, spring tooth cultivator, chisel plough etc. The last tillage operation can be carried out by rod weeder which does shallow ploughing and provides a firm seedbed. Fertilizers can be applied with chisel applicators. Drills with hoe openers are widely used for seeding. Weed control can be done with herbicides.
In minimum tillage, various types of medium to large tractors can be used. Primary tillage can be carried out by mouldboard plough or disk plough or chisel plough, rotary tiller etc. Planting and fertilizer application is similar to that of stubble mulch system. Weed control is done by herbicidal application or cultivation or by hoeing.
In no-tillage systems, a herbicide applicator, fertilizer applicators, a seeding unit and a power source are required. A harvester capable of chopping or uniformly spreading crop residues is also needed. Drills are required for the placement of seeds and fertilizers.
Conclusion:
In conservation tillage since all emphasis is laid on leaving the crop residue on the soil surface, hence this type of tillage is helpful in conserving the soil and soil moisture. Moreover, on decomposition, the crops residue adds organic matter and nutrients to the soil. Thus the conservation tillage avoids soil erosion and maintains the soil moisture and soil fertility. Therefore, conservation tillage is the need of the hour to fulfil the goal of sustainable development.
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Dr. Arvind Singh is M. Sc. and Ph. D. in Botany with area of specialization in Ecology. He is a dedicated Researcher having more than four dozens of published research papers in the journals of national and international repute. His main area of research is Restoration of Mined Lands. However, he has also conducted research on the Vascular Flora of Banaras Hindu University Main Campus, Varanasi (India). Furthermore, he is also an active science writer having more than 10 dozens of published science articles in different periodicals of national repute. His email address is: 
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