Wheat is regarded as the third important staple crop of Nepal in case of production. In 2076/77 the area under cultivation was 707505 hectares with a productivity of 3089 kg/ha. Most of the wheat in Nepal is grown in a rice-wheat cropping pattern which develops many challenges to farmers to escape adverse heat stress and high cost of production. In Nepal, the optimum sowing time for wheat is November (Terai region) to October(hilly region). But, field preparation is delayed after the harvest of rice due to the practice of conventional(old) tillage.
Tillage can be defined as agricultural preparation of soil by mechanical agitation of various types such as digging, stirring, and overturning. Zero tillage can be simply defined as a technique of growing crops without disturbing the soil. It has become a preferred method of land preparation for farmers in Nepal these days.
Zero tillage is a modern technique of land preparation. It decreases the amount of soil erosion and nutrient leaching. Besides, it increases the amount of water that infiltrates into the soil, soil retention of organic matter, and nutrient cycling. These methods may increase the amount and variety of life in and on the soil. It also increases the microbial activity of soil as the crop residue isn’t removed or burnt which creates numerous micropores.
How can we practice zero-till??
The field where the wheat is to be sown needn’t be plowed but the land must be uniform with an adequate amount of moisture so that the seed drill machine can operate properly. The broadcasting method of sowing isn’t recommended in zero-till. If broadcasting is done the seed and fertilizer won’t be uniformly distributed on fields which may create vacant patches. Besides, it requires almost double the dose of fertilizers if done so. If the plot is found to be dry, is recommended pre-sowing irrigation. In case there is high weed infestation in the field farmers should use glyphosate 41% a.i (1 kg a.i per ha) 1 week before sowing.
The seed drill machine should be calibrated properly to calculate the amount of seed and fertilizer needed for sowing. The drive wheel is rotated to measure the weight of seed dropped as per the distance covered(sq.m). The lever needs to be adjusted according to the required amount of seed and fertilizer. The drive wheel helps the drill in dropping seed and fertilizer. In addition, there is a depth control wheel that determines the depth from the ground to sow the seed and fertilizer simultaneously with a standard depth of 5cm. Recommended seed rate is 100kg/ha for zero-till and machine sewing. But, for late sowing and broadcasting seed rate should be high i.e. 120kg/ha. The difference can be clearly understood here. The required amount of seed and fertilizer is placed in a separate box in the seed drill machine. Seed drill machine is found to be more efficient than ordinary tractor plow because a single drive of it with seed drill machine fitted back makes the sowing more scientific with labor cost and yield benefits.
Why zero tillage?
- It revives the natural fertility of soil as crop residues aren’t removed.
- It saves time in land preparation that enables a more timely planting of crops.
- Straw retention on the soil surface reduces weed seed germination and growth.
- It moderates soil temperature and reduces the loss of water through evaporation.
- Labors required for (5-6) time plowing and leveling can be replaced by a simple seed-cum-fertilizer drill.
- No need for burning previous rice crop residue which prevents the release of toxic gases like CO, CO2, and SO2.
- It is about 30% cheaper than conventional methods which require more fuel, effort, and higher cost. Besides, zero-till saves up to Rs 10,000 per hectare.
- Yield loss that is incurred due to terminal heat is no longer a problem.
Zero tillage practice helped farmers to sow their crop in proper time which is really a boon for farmers. The temperature in the month of March rises up to 35 degrees which hinders late sown crops. Due to delay sowing, at this time the grain starts to shrink instead of filling out. Naturally, high temperature results in lower yield. Scientific research has shown that late sowing and an increase in temperature during the physiological maturity phase of the crop can lead to a yield loss of up to 50%. Machine sown wheat is found to have a longer earhead, almost double that of traditional broadcasted wheat. It is so because, in zero tillage, an adequate amount of fertilizer is placed with seed through a seed drill machine. Hence, with zero tillage farmers not only reduce their cost but increase their yield as well.
