Classification of tillage

1. On season tillage

• Tillage operations are carried out in normal season or main season of planting and intercultural
• operations of any crop are called on season tillage.
• According to the types of implements used and time of operation on-season tillage can be classified under two major headings:

a) Preparatory tillage:

• Tillage operations that are carried out after the harvest of previous crop and before sowing and /
• or planting of succeeding crop are known as preparatory tillage operations.
• Preparatory tillage operations include primary and secondary tillage operations.

i) Primary tillage

• The operations performed for initial cutting or opening and inverting the hard or compact soil,
• (new land or virgin land and cultivated land) to a depth of 10-30 cm.
• It is performed immediately after harvesting of the previous crop or untilled fallow or to bring virgin land under cultivation at the beginning of the new crop season.
• During primary tillage the soil is inverted, weeds are uprooted and stubbles are incorporated into the soil.
• The main objective of primary tillage operation includes deep opening and loosening of the soil to bring about a desirable tilth through heavy equipment like Mould Board (MB) plough or disc plough.
• This operation is done once, twice or thrice per year in normal and settled agriculture and once in 4-5 years in dry land agriculture.

ii) Secondary tillage

• It refers to those operations, which are performed after primary tillage but before and after seed
• placement to prepare a good tilth of soil.
• Pulverization of soil by breaking clods with the help of running harrow, cultivators, plankers, rollers, various types of power-driven implements, fertilizer cum seed drills, pudlers, levelers etc. come under secondary tillage.

b) Inter tillage:

• Tillage operations that are carried out for manipulating the soil after the seed is sown or young plant has emerged are known as inter tillage operations.
• The main objectives of intercultural operations are to control weeds, increase porosity by pulverizing the soil and make dust mulch in the soil surface for reducing the evaporation loss.
• Placement of fertilizers (top dressing), weeding, intercultural hoeing, earthing up etc. are intercultural operations.
• Equipment used during intercultural operations are hoe, spades, cultivators etc.

2. Off-season tillage

• Preparatory tillage operations that are performed during the off season or before the main crop is cultivated is known as off-season tillage.
• It is done for conditioning the soil suitably for the forthcoming main season crop.
• Off season tillage is categorized into four types which are i) post-harvest tillage ii) Summer tillage iii) Winter tillage iv) Fallow tillage.

3. Special Purpose Tillage

• Tillage operation performed to serve special purposes are called special purpose tillage.
• These are: i) sub soiling ii) leveling iii) blind tillage iv) clean tillage v) contour tillage vi) wet tillage vii) minimum tillage, viii) zero tillage and ix) mulch tillage.

i) Minimum tillage:

• Minimum tillage operation is a practice in which the tillage operations are reduced to the minimum number necessary for ensuring good seed bed preparation.
• Tillage number can be reduced by omitting operations which do not give much benefit when compared to the cost and by combining agricultural operations.
• It is easy to adopt in coarse and medium textured soils and is practiced for a period of 2-3 years.

Advantages of minimum tillage:

1. Minimum tillage practices can save a lot of power energy, labour and time and sowing of seeds can be done on time.
2. It is especially of greater importance when harvesting and threshing of one crop coincides with immediate sowing of another crop.
3. This system is found to be an alternative to the conventional tillage system where soils are subject to wind and water erosion, the timing of tillage operation is too difficult, the requirements and cost of energy and labour are too high and performance is insufficient.
4. Minimum tillage practices can improve soil conditions due to decomposition of plant residues in situ.
5. Higher infiltration caused by the decomposition of dead roots.
6. Less resistance to root growth due to improved soil structure.
7. Less soil erosion compared to conventional tillage practices.

Disadvantages

1. Sowing operations are difficult with ordinary equipment.
2. Continuous use of herbicides causes pollution problems and dominance of perennial problematic weeds.
3. Seed germination is lower; more N has to be added because rate of decomposition of organic matter is slow.

ii) Zero tillage

• Zero tillage is a tillage system in which mechanical manipulation of soil is completely avoided and the control of unwanted vegetation is done by using other methods than the mechanical
• It is also called no-tillage or reduced tillage and is done especially in wind and water erosion areas and in the field where timing of tillage operation is too difficult and requirements of energy and labour for tillage are too high.
• Use of herbicides for controlling weeds and mulching on the surface of seed bed is the normal practices in zero tillage.
• In zero tilled soils the structure of soil is homogenous with more number of earthworm, increase organic matter content reduce runoff due to presence of mulches.

Disadvantages of zero tillage

• The seedling establishment in zero tillage is about 20% less than in conventional methods that’s why the seed rate should be increased by 20%.
• This practice reduces labour cost but crowd work into a shorter time period immediately prior to planting.
• Land improvement, reclamation of problem soils, cultivation of tuber, root and rhizome crops that bear economic yield in subterranean parts are seriously affected in the zero tillage system of farming.

iii) Mulch Tillage:

• Mulch tillage involving one or more tillage trips which disturbs the entire soil surface and is done prior to and/or during planting.
• During tillage operation mulch materials, surface clods or crop residues are least disturbed.
• Light and subsurface soil stirring type tillage tools such as chisels, field cultivators, disks, sweeps or blades are common used.