Methods of irrigation

Among the various methods of irrigation viz., surface irrigation, sub-surface or trench irrigation and overhead irrigation or sprinkler irrigation, the last one is ideally suited in cardamom plantations.

7.1.1 Sprinkler irrigation

Overhead irrigation with sprinkling unit is found well suited for cardamom on account of its several advantages over other irrigation methods. Cardamom is grown on hill slopes with undulating topography and for such land, sprinkler irrigation can provide uniform water supply. The plantation can be irrigated without excessive loss of water due to surface run off or conveyance loss as the rate of application of water can be well regulated with sprinklers (John and Mathew, 1977; Saleem, 1978; Anonymous, 1985; Bambawale, 1980; Vasanth Kumar and Sheela, 1990). This will also avoid puddling, leaching and runoff that are common with other methods of irrigation. The humid atmosphere required for the successful growth and production of cardamom can be created by overhead sprinkling. Frequent light sprinkling can be done on soils of poor water-holding capacity. Irrigation equivalent to a rainfall of 4 cms, every 15 days would be quite sufficient for cardamom crop.

Installation of a sprinkler system should be processed after a careful survey of the area for an efficient and economical design. There should be a perennial source of water nearby. Sprinkler systems are designed to meet specific requirements, which may vary from one plantation to another depending on the lay of the land, area to be irrigated and source of water. The pumping site should be selected in a convenient place so as to cover the entire area with minimum number of pipes. Portable units are more economical to use, but operation costs are a little higher compared to the permanent system. The main line and laterals can be made portable so that they can be moved easily from one position to another.

Considering the high felt-need for a systematic study of the sprinkler irrigation system on cardamom, an investigation was conducted by Vasanthkumar and Sheela (1990) in Idukki district of Kerala state. Field experiments were conducted for two consecutive years (1982—83) and were laid out in split plot designs with two main plots viz., irrigated and non-irrigated (control) and three sub plots viz., three varieties of cardamom (Malabar, Mysore and Vazhukka). The results showed that the mean number of panicles produced per clump showed significant difference between the two main plots, irrigated and non-irrigated. Var. Vazhukka produced the highest number of panicles per clump, in the irrigated treatment (114.6) as against the non-irrigated treatment plots (90.8). Var. Mysore showed the lowest panicle production, in non-irrigated treatment plots (51.8). All the cultivars produced more flowers in plants that received sprinkler irrigation (3048, 1894 and 3756 respectively in Malabar, Mysore and Vazhukka) compared to the non-irrigated plants (1624, 1275 and 2068 respectively). The levels of irrigation did not significantly influence the fruit set per clump. The effect of sprinkler irrigation was in reducing the immature shedding of cardamom capsules, which was rather high in the non irrigated plots in all the three cultivars (26.4, 26.3 and 27.6 per cent respectively in Malabar, Mysore and Vazhukka). Capsule shedding was comparatively low in the irrigated plots (14.5, 14.9 and 11.7 per cent respectively in the three cultivars). Panicles of the irrigated plants showed faster growth, the effect being more pronounced in the var. Vazhukka (155.8 cm as against of 98.4 cm in the non-irrigated plants). Even in the var. Mysore, which normally produced shorter panicles, sprinkler irrigation increased the panicle length up to 73.8 cm whereas the non-irrigated plants produced shorter panicles (54.0 cm). The percentage of capsules that reached final maturity, was significantly influenced by sprinkler irrigation in all the three varieties, Malabar, Mysore and Vazhukka showed 61.3, 55.8 and 62.5 per cent respectively in the irrigated plots; the corresponding figures in the non irrigated plots were 50.6, 46.9 and 52.7 per cent.

Yield of capsules was almost double in the irrigated plots compared to the non-irrigated plants (Table 4.5). Essential oil content of capsules was more in the irrigated plants on dry weight basis. The mean values for the irrigated and non-irrigated plots were 10.2 and 8.2 per cent respectively, the highest was in the irrigated plot of var. Mysore (12.2 per cent) and the lowest in the non-irrigated plot of var. Malabar (7.1 per cent).

7.1.2 Drip irrigation

Drip irrigation is also becoming popular in cardamom plantations where water is scarce. It is a method of watering plants frequently with a volume of water just sufficient for the crop, there by minimizing losses such as deep percolation, runoff and evaporation. Water is applied to plant bases by using small diameter plastic lateral lines with devices called drippers (Fig. 4.7). This system applies water slowly in drops and keeps soil moisture within the desired range for plant growth. Flow of water through the drippers are so adjusted that two-three litres of water is discharged per hour. As water is applied directly to the plant basins and the interspaces are not irrigated, less quantity of water is used in this method. Application of 10-15 l of water per plant per day would be sufficient for cardamom. If cultivation is done on contour, this system can be practiced without any difficulty. Water from small farm ponds can be drawn in this system without pumping. If necessary, pumping can also be done from the lower down tanks, as the quantity of water required to each plant will be very less in this system. Drip irrigation has 80-95 per cent efficiency (Kurup, 1978).

Initial cost of drip irrigation equipment is considered to be its limitation for large-scale adoption. Cost of the unit per hectare depends mainly on the spacing. The investment for drip irrigation equipment for cardamom will be more in Karnataka where closer spacing is adopted than in Kerala and Tamil Nadu. Approximate cost for a drip irrigation unit would be around Rs. 25,000-Rs. 47,000 per hectare.

Figure 4.7 A young plantation maintained by drip irrigation.

Table 4.5 Effect of sprinkler irrigation on yield components and yield

Cultivars Extension growth of Percentage of Fresh weight of Dry weight of Essential oil content of panicles (cm) to the total capsules matured capsules (g) capsules (g) capsules (dwb)

flowers borne

Cultivars Extension growth of Percentage of Fresh weight of Dry weight of Essential oil content of panicles (cm) to the total capsules matured capsules (g) capsules (g) capsules (dwb)

flowers borne

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  • Charles
    How to install sprinkler system for cardamon?
    4 years ago

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