This report covers the main season (Maha) planting of rice and maize from October to November and their early growth period. According to the CropWatch monitoring results, crop conditions were generally below average for the monitoring period.

During this period, the country experienced the second inter-monsoon during October and November, as well as northeastern monsoon from December to January. At the national level, temperatures were slighly above average (TEMP +0.4°C), while precipitation and radiation were below the 15YA (RAIN -4%, RADPAR -2%). The decrease of rainfall mainly occurred in October, which is the main sowing period. They may have delayed the planting of the crops. The fraction of cropped arable land (CALF) was nearly comparable to the 5YA. BIOMSS was 4% down comparable to the 15YA. As shown on the NDVI development graph, NDVI values were near average in late November and late January but below average for the rest of period. The maximum VCI for the whole country was 0.96.

As shown by the NDVI clusters map and profiles, more than half of the country’s cropland showed significant negative NDVI departure values during the whole period. 17.4% of cropland and 30% of cropland showed a large decline of NDVI values in late December and early January respectively, which may be outliers due to cloud cover. These croplands with negative NDVI departure values were mainly distributed in the north and southwest part of the country. Almost half of the cropland (49.1%) had near-zero NDVI departure values during the whole period. They were distributed in North Western Province, Eastern Province, Uva Province and Southern Province.

Regional analysis

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

In the Dry zone, the recorded RAIN (1005 mm) was 2% above average and amounted to more than 8 mm per day, which was sufficient for the water demand of the growth of maize in this region. TEMP was 0.5°C above average, RADPAR was down by 3% and BIOMSS also decreased by 6% as compared to the 15YA. CALF was near the 5YA level and 99% of cropland was utilized. NDVI followed a similar trend to the whole county. The VCIx for the zone was 0.95. Overall, crop conditions were below average for this zone.

The Wet zone received the highest precipitation among three sub-national regions. RAIN (1422 mm) was down by 12% as compared to the 15YA. TEMP was 0.2°C above average and RADPAR was near average. BIOMSS was comparable to the 15YA and cropland was fully utilized. NDVI values were close to average almost for the whole period except for early January, which could be caused by cloud cover. The VCIx value for the zone was 0.98. Crop conditions were near average for this zone.

The Intermediate zone also experienced sufficient rain (RAIN 1244 mm) with a 8% decrease from the 15YA. TEMP was 0.3°C above average and RADPAR down by 1% compared to the 15YA. With full use of cropland, BIOMSS was 5% below average. The NDVI values were similar to the Wet zone and the VCIx value for this zone was 0.98. Conditions of crops were assessed as slightly below average.

Figure 3.27. Sri Lanka crop condition, October 2020 – January 2021

(a) Phenology of major crops

(b) Crop condition development graph based on NDVI

(c) Rainfall profile

(d) Temperature profile

(e) Maximum VCI

(f) Spatial NDVI patterns compared to 5YA (g) NDVI profiles

(h) Crop condition development graph based on NDVI (Dry zone (left) and Wet zone (right))

(i) Crop condition development graph based on NDVI (Intermediate zone)

Table 3.43 Sri Lanka agroclimatic indicators by sub-national regions, current season's values and departure from 15YA, October 2020 - January 2021

Table 3.44 Sri Lanka agronomic indicators by sub-national regions, current season's values and departure from 5YA, October 2020 - January 2021