DRIS norms chart for cardamom (leaf). Figure 5.1 Foliar diagnostic norms for optimizing cardamom production.
138 V. Krishnakumar and S.N. Potty 6.3 Method and time of application
Root spread of cardamom, which is the feeding zone, should be taken into consideration while fertilizer application is made. Lateral spread of roots of a full bearing 8-year-old plant was found to have 80 per cent of its roots in a zone of 25 cm radius, 14 per cent in a zone of 25—50 cm and only 6 per cent of them are seen in 50—75 cm zone. Vertically cardamom roots penetrates only up to 40 cm (Khader and Sayed, 1977). Further studies conducted at the Indian Cardamom Research Institute (Nair, 1988) also showed that roots of cardamom are confined to a shallow depth. Nearly 70 per cent of roots were seen in the top 5 cm depth. Horizontally only 10 per cent of the roots forage an area 120 cm away from the clump. Therefore for the maximum efficiency of applied fertilizers it would be necessary to apply them at a radius within 50 cm and being a surface feeder, deep placement of fertilizers is not advisable. Before application of fertilizers, if the panicles are spreading on the ground, they are to be kept coiled encircling the base of the plant and the mulch removed. Fertilizers may be applied around the plant base in a circular band of width 15 cm, leaving about 30 cm from plant base and incorporated in the soil by using a hand fork (Fig. 5.2a,b). Mulching should be followed immediately after incorporating fertilizers. Panicles may then be released and spread on the ground for Malabar types to facilitate honeybee movement for better pollination and setting of the capsules.
Cardamom growth is influenced by seasonal conditions, especially rainfall pattern. Vegetative buds emerge from the bases of tillers almost throughout the year. However, majority of vegetative buds are produced after the rainy period (Sudharshan etal., 1988). It was also observed that the linear growth of tiller increases with the onset of southwest monsoon and growth rate slows down with cessation of rain. Peak flowering and fruit set period coincide in cardamom and nearly 70—90 per cent of flower production was recorded between May and August. Hence for efficient utilization of fertilizers, time of application is very important. Applications of fertilizers in May and later in September are found to be the best (Pattanshetty and Nusrath, 1973). However, under irrigated conditions, tiller initiation and panicle initiation are continuous processes and hence more split applications are beneficial.
Cardamom is cultivated under shade tress, and hence complete utilization of applied fertilizers by cardamom may not take place because of root interference. For yielding cardamom plants, soil-cum-foliar application will be an effective method. Soil application of fertilizers in two rounds during May—June and August—September and subsequent applications through foliage during September, November and January are recommended (Srinivasan et al, 1998).
George (1990) reported that in Guatemala, almost all growers fertilize cardamom. There are different fertilizer mixtures available there. One such fertilizer mixture is 15:15:15, which is marketed under brand name Barco Vikingo. Another mixture which contains calcium and magnesium in addition to NPK is 18:6:12:4:0.2 with the brand name of Agrovet SA. Fertilizer application starts from the second year of planting with 2 oz per plant. This is gradually increased to 3 oz in the third year and 4 ounces from the fourth year onwards. Some planters add 1 oz of urea over and above this normal fertilizer application. The recommended dose is applied 2—4 times a year (George, 1990).
When cardamom is cultivated with controlled, artificial shade, a fertilizer dose of 100:25:100 kg NPK/ha is recommended (Korikanthimath etal, 1998b).
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