The objectives of field preparation are based on the following principles: Elimination and control of undesirable plants like crop volunteers and weeds to reduce competition with the established main crop;
- Provide favorable conditions for sowing, allowing germination, emergence and good plant development;
- Maintenance of fertility and productivity over the long term by preserving the soil organic matter and avoiding erosion;
- Breaking of hard pans or compacted layers to increase water infiltration through the soil whilst avoiding erosion;
- Facilitating mixing of fertilizers, lime, or agro-chemical products into the soil;
- Incorporation of organic and agricultural residues.
Timely field preparation facilitates timely sowing which ensures higher yield.
Land preparation should ensure that all crop residues, crop volunteers and weeds are completely buried.
Summer ploughing is advantageous to kill the weed seeds and hibernating insects and disease organisms by exposing them to the heat of summer.
Initial ploughing should be carried out at optimum moisture range to get good tilth and should avoid when moisture is in excess.
Number and depth of ploughings depends on weed intensity.
For rainy season crop, with onset of rains in May-June, the field is ploughed once or twice to obtain a good tilth.
Harrowing of soil should invariably followed after each ploughing to reduce the clod size.
After the initial ploughing, the subsequent ploughings and harrowing are carried out when the moisture content of the clods are reduced.
The number of ploughings are to be minimized to reduce the cost of cultivation. However , groundnut likes five tilth.
Tillage operations should be repeated when the weed seeds are just germinated.
When the soils are heavily infested with perennial weeds like Cynodon or Cyperus, deep ploughing is needed.
Field preparation depends on the system of groundnut sowing.
Three systems of groundnut sowing are followed :
sowing on a flat surface, or
- using ridge-and-furrow system, or
- on a broad bed-and-furrow system.
If sowing is done on a flat surface, the land should be leveled after final ploughing using bullock-drawn or tractor-drawn levelers.
In ridge and furrow system, ridges are made using either tractor drawn or animal drawn ridge ploughs. In ridge and furrow system, ridges are made using either tractor drawn or animal drawn ridge plows (Fig.).
Broad beds and furrows are prepared by an animal- drawn ridger (Fig.), mounted on a tool carrier (e.g., Tropicultor or Agribar), or by tractor-drawn implements with ridgers.
Two ridgers may be fastened on a tool bar so that the top of the bed is 1.2 m wide and the distance from the center of one furrow to the center of the next furrow is 1.5 m. The depth of furrows should be 15 cm or more.
After forming the broad bed and furrows, the top of the beds are smoothened and leveled using a chain attached to a wooden frame of a plough (Fig. 1) or wooden-frame leveler mounted on to a tool bar (Fig. 2).
The broad bed-and-furrow system has many advantages over flat sowing.They are:
helps in draining off excess water in the field and soil;
- provides more soil aeration for plant growth;
- greater in-situ moisture conservation;
- easier for weeding and mechanical harvesting.