Mechanical Transplanting of Rice

Wet-bed mat-type nursery:

• • Before preparing the nursery, the field should be ploughed, puddled and levelled. After puddling leave the field to settle for 24 hours. Once the soil is settled, prepare a raised bed 50m in length, 1.5m in width and 15cm in height, for raising the seedlings to transplant in one hectare area of the main field. Leave the bed to settle for 36-48 hours. Thereafter, settle the bed with a plank. Also prepare a 60-cm wide channel all around the bed.
• • Now take a 1.5m wide and 50m long polythene sheet, fold it into 8-10 layers and perforate randomly with an ice prick or thick-handled needle. Cover the bed with this perforated polythene sheet, and remove the air bubbles beneath the sheet. Put the iron frame over the plastic sheet. Keep the required FYM/compost in the channel and mix with soil (4 parts wet soil + 1 part FYM/compost). Spread this mixture on the plastic sheet inside the 0.5-inch thick iron-frame. Make sure the soil and FYM mixture is free from clods, stones, twigs etc. Now spread the sprouted seeds at 40 kg/ha uniformly on the top of the soil layer. Repeat all above-said steps till the whole bed of 1.5 m x 50 m is completed. Now cover the seeds by a thin layer of straw or banana leaves for 2-3 days to avoid seed displacement, or removal by birds, and to minimize the pre-flooding moisture-need by restricting evaporative water-loss. Remove the cover 2-3 days after emergence of seedlings. Seedlings will be ready for transplanting in 15-20 days in Sali season and in 20-25 days in Boro/early Ahu season, when they attain 15-18-cm height. .

Dry-bed mat-type nursery

Preparation of soil FYM/compost mixture

• The crushed and sieved soil free of weed-seeds, having particle size less than 5 mm, is mixed with FYM in a 4:1 ratio.
• The FYM is also crushed to ensure a homogeneous mixture.
• The mixture should be free from stone or any other foreign object, which otherwise may damage the paddy transplanting machine’s finger.

Plough and level the field before bed preparation. Puddling is not required. Prepare a raised nursery bed of 50m length, 1.5m width and 15 cm height. Collect soil from a weed-free field and sieve it using a 2mm-mesh sieve to get clod-free soil. Mix FYM with sieved soil free from clods, stones, twigs etc. in a ratio of 4 parts soil to 1 part manure. It will be best to mix the soil on a polythene sheet. Follow the rest of the steps as indicated under wet-bed mat-type nursery preparation.

Water Management and Nutrient Supplement

For the initial four days, water should be sprinkled on the covered bed so that the soil remains wet. After four days, when the roots are well anchored to the soil, the covering is removed. Now controlled flooding can be done, through peripheral channels/furrows to a level up to the top of the raised bed. The free turbulent flow of water should be avoided, or it may loosen the root anchorage. Nutritional requirements usually met by soil FYM mixture supplemented with 250 g powder of NPK (15:15:15) @ 75 sq. m nursery area, can help in faster growth and early transplanting.

Nursery Bed Cutting

Seedlings become ready for transplanting in 15-20 days during Sali season and 20-25 days during Boro/early Ahu season, when they attain 15-18-cm height. Stop flooding the nursery 20 hours before transplanting for better stability of mat, and anchoring of roots while transplanting. The mats are then cut into pieces of convenient size to be used for transplanter. The mass production of mat nursery can be done by advance planning and the same bed or the same plastic sheet can be used twice or thrice in a season, if taken as a business.

Machine Transplanting:

While transplanting, maintain saturation level or 1-2-cm of standing water in the field. Puddle the field well before transplanting so that soil in the field is settled properly. The soil should be puddled 1-2 days before the machine transplanting. Under freshly puddled conditions, soil cannot make a strong grip on the seedlings. Even excess standing water (>2cm) at the time of transplanting, will loosen the soil grip on the seedlings.

• Drain out excess water from the field for better operation and root anchoring. It will be better to irrigate the field 24 hours before transplanting for smooth operation of the machine. This also leads to better anchorage; thus, having lesser load of manual gap filling.
• 15-20-day old seedlings are transplanted. Optimum depth of planting of the seedlings is very important. Shallow depth risks uprooting of seedlings with a mild flow of water or wind. Whereas excessive depth results in sinking of the planted seedlings, thereby creating the risk of rotting and/or poor tillering. The planting depth can be set at the desired depth simply by sliding the lever handle.
• There should not be standing water in the field for a week after transplanting.
• Before cutting the mat pieces, ensure that the nursery is dry. Use a sharp sickle/knife to cut the mats in desired size, based on the seedling platform of the paddy transplanter used.
• While transporting to long distance, make sure that the nursery-mats do not dry out.
• Place the cut mat pieces on the bunds at two opposite ends of the field in the direction of transplanting for the ease of loading.
• Before start of transplanting, make sure that all mechanical fingers of the transplanting machine are in working condition.
• Transplanting should be started by leaving the space equal to the width of the transplanter at four sides of the field near the bunds.

Fertilizer management

The fertilizer recommendation for paddy in Sali season is 60-20-40-5, and in late Boro/early Ahu season it is 60-30-30-5 kg/ha of N-P2O5-K2O-Zn. Nitrogen is applied in 3 equal splits i.e. 1/3 as basal, 1/3 at maximum tillering, and 1/3 at panicle initiation. In addition to this, if submergence occurs during Sali season, 20 kg N and 20 kg K₂O is applied 5-7 days after recession of flood to facilitate regeneration, and boost recovery from flood-shock. The detailed schedule and method of applying all nutrients is given in the table 1 below -

Table 1: Fertilizer doses (kg/bigha) for Sali and Late Boro/early Ahu season

Note:

• Stop urea broadcast, in case Bacterial Leaf Blight symptoms appear.
• Apply ZnSO₄ in soils deficient in zinc, once in three years.
• As far as practicable, drain out standing water before top-dressing of fertilizer.

Weeding

Keep the field weed-free, especially early in the season. Weeds cause most damage in the early crop stage. But later control is also important to prevent seed setting by weeds.

Hand Weeding

First weeding with paddy weeder or hoe, three weeks after transplanting and second weeding with paddy weeder or hoe, six weeks after transplanting

Herbicide Selection

Herbicides should be selected based on present, and even previous weed pressure in the field.

Herbicide application

• Equipment: Given their superior effectiveness, herbicides should only be applied using multi-nozzle sprayer-boom fitted with a flat-fan nozzle. While spraying, the new spray-swath should always overlap 25% of the previous spray-swath margin to ensure uniform application.
• Pre-emergence (PE) Herbicides: Most PE herbicides require moisture at the soil surface at the time of application. Without sufficient moisture, the PE herbicide will not be that much effective.
• Pre-emergence herbicides can be used by splash method in 3-5-cm standing water in the field, preferably within 2-3 days after transplanting.
• Pre-emergence herbicides supplemented with one hand-weeding will be more effective to take care of the germinated weeds, and the weeds emerging later in the season.
• Post-emergence (POE) Herbicides: POE herbicides, if required, should be applied between 20 -25 DAT when weeds attain 2-4-leaf stage. Ensure that there is no standing water in the field; however, the field should have sufficient moisture at the time of POE application.
• Spray volume: Use a spray volume of 300 liters/ha in all herbicide applications.

Select suitable and need-based herbicide(s) from the below given table 2

Table 2: Herbicides, their doses, time of application and type of weed flora they kill in paddy field

DAT= Days after transplanting.

Given below are some of the recommended herbicide-combinations. Depending on weed-flora, follow the application timing and doses as per above table:

• Pretilachlor (PE) followed by Bispyribac-Sodium (POE)
• Pretilachlor (PE) followed by Bispyribac-sodium and Pyrazosulfuron (POE)
• Pretilachlor (PE) followed by Bispyribac-sodium and Pyrazosulfuron (POE) followed by spot hand weeding

Irrigation

In the Sali season, in the absence of rain, application of 5-cm irrigation water 3 days after disappearance of ponding water is recommended in medium and heavy soils.During the Boro season, in the absence of rain, application of 5-cm irrigation water 3 days after disappearance of ponding water is recommended in medium and heavy soils. Alternatively, follow Alternate Wetting and Drying (AWD) technique of irrigation using field water tubes.

Plant protection measures

It is applied, if threshold levels of pests are present in the field. Follow plant protection measures as per state recommendations.

Harvest and post-harvest

• Harvest when 80-85% of the grains attain physiological maturity i.e., visually straw-colored.
• Minimize the time during which the harvested plants remain in the field, and avoid field drying. Make sure that the panicles stay dry.
• Thresh and dry within two days after harvesting. Sun drying is best on a mat or plastic sheet, keeping the thickness of the grain layer at 3 to 5cm.
• Clean thoroughly by winnowing. Store the rice in a cool, dry, and clean area.