TOOLS AND EQUIPMENT FOR LAND DEVELOPMENT, TILLAGE AND SEEDBED PREPARATION

Land development is the costliest operation in farming. It involves jungle clearance, soil opening with deep tillage equipment, moving soil from high to low spots, making farm roads, field bunding and leveling .etc. These operations require use of self propelled and heavy equipment such as crawler tractors with heavy duty ploughs and dozers, high horsepower tractors with dozing arid hoeing attachment, crapers, ditchers, chisel ploughs, subsoilers, terraces, levelers etc.

The tillage operations, defined as mechanical manipulation of soil, are performed to achieve the desired seed bed to provide optimum environment for seed germination and plant growth. Seedbed preparation for sowing / planting of different crops is done through primary and secondary tillage operations.

Seedbed Preparation for Upland Crops

The optimum seedbed preparation for raising upland crops, involves the following unit operations:

i. Loosening of soil

This is done to achieve a desired granular soil structure for a seedbed and to allow rapid infiltration and good retention of moisture, to provide adequate air exchange capacity within the soil and to minimize resistance to root penetration and shoot growth. Local plough (Hat) and blade harrow (Bakhar) are traditional implements used for loosening of soil. These are simplest tools designed to break the topsoil and multi-passes are carried out to prepare seedbed. Mould board plough, disc plough, soil stirring plough, ridger plough, tool frames/carriers with mouldboard plough or tillage sweeps, etc. are improved implements designed for breaking soil. Ploughs are used to break soil and invert furrow slice to control weeds, etc.

ii. Clod size reduction

Clod breaking operation is required to produce a granular soil structure in the final seedbed.Tine cultivator and disc harrow are used for breaking of clods. Generally these are operate after one pass of mouldboard plough or ridger plough. Direct harrowing or cultivator operation is also performed when the fields are clean and free from plant residues of previous crop. Clod crushers, patela harrow, etc., are very effective for clod crushing under favorable soil moisture conditions but their effect is confined to soil surface only. Power driven implements like rotavators disintegrate the clods over a wide range of soil moisture and provide uniform and fine size clods or aggregates in seedbed.

iii. Clod sorting

Operation of tools with narrow tines such as comb harrow and spike tooth harrow, in loosened soil, produces a sorting effect, bringing larger clods and aggregates on surface. The sorting effect increases with increasing forward inclination of tines and share width and decreasing speed and soil moisture. Large size clods on the surface are recommended because of their stability under rainfall, which helps in reducing soil erosion.

iv. Compaction and consolidation

Wide, backward inclined implements compact soil as well as break clods in top surface of soil. Direct compaction at seed depth can best be achieved using narrow press wheels/discs. Planking is widely used to compact the soil at the surface.

v. Smoothening

Smoothening of seedbed is required for proper operation of sowing machines, better distribution of irrigation water and quick disposal of excess rainwater. Smoothening can be best achieved by using wide backward inclined blades, such as leveling boards, floats and patela harrow with closely spaced shallow working narrow tines. Wooden plank, patela harrow, are recommended for smoothening operation.

Land Preparation for Rice Transplanting

Puddling of soil generally refers to breaking down soil aggregates at near saturation into ultimate soil particles and is one of the common operations in low land rice fields. It is normally done after initial ploughing and allowing about 50 to 100 mm of standing water in the field. However; in low land condition the farmers often flood the field prior to ploughing and puddling to weaken the mechanical strength of the soil. Retention of standing water on the rice field helps weed control and oxidation-reduction. Such conditions help achieving nutrient balance,and a soft soil suitable for transplanting rice seedlings. Puddling helps retain standing water in the rice field by producing fine soil particles that reduce soil porosity, thus reducing percolation losses of nutrients. Puddling is also beneficial because it controls weeds, levels the soil surface and provides a homogenized puddled tilth. Puddling must be done when there is standing Water in the field. Puddling is done with an animal or tractor drawn implement (puddler) such as ploughs, comb harrow, patela puddler, ladder puddler and rotary puddler. The degree of puddling is however, dependent on the type of puddler and on intensity of puddling. .Rotary puddlers generally are better than ploughs because their rotary motion continuously changes the direction of the shear stress and therefore matches the weakest fracture plane within a clod.

Further the rotary puddlers tend to compact the sub soil, chop and press down organic matter and require relatively low draft as compared to ploughs. 

Tillage Requirements under Different Agro-climatic Conditions

Optimum tillage to achieve maximum crop yields with minimum energy consumption should be the aim of seedbed p reparation. A good seedbed is generally considered to imply finer particles and greater firmness in the vicinity of seeds. The depth up to which tillage operations disturb the soil can classify the operation as shallow, medium or deep. The depth of tillage depends on the crop and soil characteristics and also on the source of power or energy available.

In arid and semi arid areas with high averages oil temperature and dry spells,t here is a need to break the soil, which becomes very hard. A pointed tool like chisel or bar point are used on country plough to break soil without inverting or disturbing crop residue, in order to collect and store rain water and reduce wind erosion and evaporation losses. Under such conditions Lister plough, rigid tine cultivator, duck foot sweeps and other similar equipment are useful and can be operated for one or two passes. Under black soil regions (vertisols) of Madhya Pradesh, Maharashtra,.Gujarat and Andhra Pradesh, soils dry up and develop deep cracks during hot summer weather, and hence ploughing is not very essential. Mould board ploughing may be done once in 3 to 4 years to destroy weeds. For such soils shallow cultivation by a blade harrow or sweep cultivator is sufficient to prepare a good seedbed, when weeds are under control. Continuous operation of mould board for few years may be required to control the weeds.

In humid areas,i t is desirable to have deep tillage accompanied by soil inversion and burying of crop residues.T his helps in enhancing  nitrogen fixation in soil and  corporation of biomass.

In dry land areas tillage requirements are mainly linked with improved moisture intake and retention, reduced evaporation and checking of weed growth. Studies have indicated that increased infiltration rate and higher crop yields can be achieved under dry land conditions by performing deep tillage by mould board plough.

In brief, the recommendations are to do shallow or medium tillage in most conditions. For weed control and increased storage of rain water deep tillage is recommended. Summer ploughing with mould board plough, once in two to three years, to invert the soil, is also recommended.