Sri Lanka cultivates mainly maize and rice in rotation. The main Maha season extends from October to December or March (depending on location) mostly in the east. Much of the west has bimodal rainfall with the second Yala season centered around March-June. The monitoring period covers the entire growth and harvesting season of main Maha rice and maize, as well as early sowing season of Yala rice and maize. According to the CropWatch monitoring results, crop condition was below average during January to April.

Nationwide, rainfall dropped 31% below average, while temperature and radiation were near average (-0.1℃ and 4%, respectively). As shown by agronomic indices, the fraction of cropped arable land (CALF) remained comparable with the 5-year average. Low precipitation in the country may have had a negative influence on Maha crops and resulted in low biomass (BIOMSS -23%). The crop condition development graph based on NDVI displayed an unfavorable situation during the whole period. Crop condition dropped below average since January and reached minimum during mid-April. Similar conditions also occurred in sub-national regions as described below.  Poor performance of NDVI profiles may be related to dry climate over the country.

Spatial heterogeneity was significant throughout the country according to NDVI clusters map and profiles. 17.1% area of the cropland displayed good crop condition during January to April, mainly distributed in scattered areas in Colombo to Galla, Kurunegala, Kandy, Nuwara Eliya and Badulla. 45.2% area of the cropland, distributed in the same areas as  above, enjoyed average conditions before mid-February and slowly declined since then. The remaining cropland showed negative departures at different times and locations. 21.4% of cropland was below average since mid-February around Puttalam, Anuradhapura, Trincomalee and Polonnaruwa. 7.4%, scattered in north-eastern areas, deviated far from average in February. In addition, 8.9% of the cropland (between Anuradhapura and Trincomalee) showed negative values during the whole period. The maximum VCI map displays a mostly fair situation with low values distributed in south-western regions and high values occurring throughout the country. 

Regional analysis

Based on the cropping system, climatic zones and topographic conditions, three sub-national agro-ecological zones (AEZ) can be distinguished for Sri Lanka. They are the Dry zone, the Wet zone, and the Intermediate zone.

There is little difference between the three AEZs in terms of agronomic indices. The CALF for the three sub-national zones is almost the same and shows full cropping. VCIx values are above 0.95 for the Dry zone and the Intermediate zone, and somewhat lower (0.89) for the Wet zone. The BIOMSS indices, however, displayed different decreases: 28%, 12% and 26%, respectively.

The Dry zone is the largest of the three AEZs and located in the eastern half of the country (from north to south). The agro-climatic conditions show that rainfall fell 45% compared with average, while both temperature and radiation were near. Crop condition of the zone was below average during almost the whole period, akin to the nationwide situation

The Wet zone covers the smallest area (in the south-west) as well as the “most favorable” agro-climatic condition among AEZs. Rainfall was below average by 9% and temperature and radiation were respectively close to average and above (+0.1℃ and +7%). Indicators were near average before mid-March and deteriorated since then but crops are nevertheless assessed as average.

In the Intermediate zone agro-climatic indicators are close to national values. The rainfall decreased by 32% and both temperature and radiation are slightly above average. According to the NDVI development graphs, crop condition is near average.

Figure 3.21. Sri Lanka crop condition, January 2019 - April 2019

(a) Phenology of major crops

(b) Crop condition development graphbased on NDVI

(c) Maximum VCI

(d) Spatial NDVI patterns compared to5YA  (e) NDVI profiles

(f) Crop condition development graphbased on NDVI(Dry zone (left) and Wetzone (right))

(g) Crop condition development graphbased on NDVI (Intermediate zone)

Table 3.50. Sri Lanka agroclimatic indicators by sub-national regions,current season's values and departure from 15YA, January 2019 - April 2019

Table 3.51. Sri Lanka agronomic indicators by sub-national regions,current season's values and departure from 15YA/5YA, January 2019 - April 2019