Delineating the various agroclimatic zones of Kerala & identifying the cropping patterns for the different zones

Abstract

An investigation was carried out for delineating the various agroclimatic zones of Kerala and for identifying the cropping patterns for the different zones. Meteorological data were collected from 100 stations in Kerala. Soil and crop data were collected for the whole state. The agroclimatic features of Kerala were studied. The water balance elements and indices of 14 representative stations in the state were computed and presented on annual basis. Six moisture availability regimes (MAR) were proposed and delineated following the guidelines of Hargreaves (1971 & 1975). Twenty agroclimatic zones were identified by superimposing the six moisture availability regimes over seven soil groups. The zones are (1) Dry-Forest loam (AF1), (2) Semi dry-Red loam (BR1) (3) Semi dry-Laterite (BLa), (4) Semi dry-Alluvium (BA1), (5) Semi dry-Black soil (BBs), (6)Semi dry-Forest loam (BF1), (7) Sub humid-Red loam (CR1), (8) Sub humid-Laterite (CLa), (9) Sub humid-Alluvium(CA1), (10)Sub humid-Saline (CSa), (11) Sub humid-Forest loam (CF1), (12) Humid-Laterite (DLa), (13) Humid-Alluvium (DA1), (14) Humid-Greyish Onattukara (DGo). (15) Humid-Saline (DSa) (16) Humid-Forest loam (DF1), (17) per humid-Laterite (ELa), (18) per humid-Forest loam (EF1), (19) Wet-Laterite (FLa) and (20) wet-Forest loam (FF1). Twelve cropping patterns of the state were also identified. Suitability of the existing cropping patterns for the agroclimatic zones were examined. It is found that the cropping patterns existing in almost all the agroclimatic zones are suitable to the zones. Coconut is not suitable for BBs zone and the eastern part of the BLa zone, while rubber is not congenial for the zone BF1. Mango and jack are not suitable for the high altitude areas of DF1zone. Coconut, tapioca and cocoa are suitable only up to 900 m above M. S. L. in the zone EF1. In FLa zone rubber grows well up to 600 m above M. S. L, while cardamom is better for higher elevations. Tapioca is not suitable for areas 800 m above M. S. L in the zone FF1. The important crops except tapioca are unsuitable for AF1 zone. It is felt that a detailed study with a denser network of meteorological stations is necessary for examining the suitability of crops to the zone CF1. Crops such as millets with low water requirement should be given more importance in the zones like BBS and AF1. Dry (A) type MAR demands great care of crops at least for six dry months. Perhumid (E) and Wet (F) types of MAR demand proper drainage for crops except rice. Proper soil conservation measures have to be taken up when tapioca is grown on the slopes, especially of the sub humid (C), Humid (D), perhumid (E) and wet (F) types of moisture availability regimes.