Cambodia has gradually entered its wetter season since April, when the harvest of dry-season early rice and dry-season maize were finished. Both the sowing of wet-season early rice and wet-season maize began in May, which was followed by the sowing of floating rice and medium rice starting in June. Soybean had reached maturity at the end of this period.

During this monitoring period, Cambodia experienced wetter and relatively cooler weather conditions. Compared to the 15YA, the precipitation in Cambodia was higher (RAIN +9%) , while the average temperature was slightly cooler  (TEMP + 0.6℃). Abundant precipitation and more sunshine (RADPAR, +6%) with average temperature are generally beneficial to the crop growth and biomass accumulation, which resulted in a higher potential biomass (BIOMSS +5%). As the NDVI profile shows, NDVI kept staying at a 5-year maximum level before mid-April, indicating favorable growth conditions for dry-season rice and dry-season maize. However, the crop NDVI was lower than average in mid-June, which could partly be a consequence of the rainy and cloudy weather, as well as of cloud cover in the satellite images. The spatial assessment of NDVI dynamics revealed four patterns: 1) about 35.8% cropland (in light green color) showed favorable crop conditions during this monitoring period. These regions were mainly located on western Pursat, Kampong Chhnang, and Kampong Speu. 2) Around 27.7% of cropland (in blue and red color) had an above-average NDVI before mid-May, followed by a below-average NDVI, indicating relatively poor conditions for rain-season rice and maize. The sudden decline over the blue-color regions in early July was the result of clouds in the satellite images. 3) Around 26.7% of cropland experienced near average NDVI during the monitoring period, indicating normal crop conditions. These regions were mainly located in the lower Mekong River basin, which is the major crop planting area in Cambodia. 4) About 9.9% of cropland (in dark green color) experienced poor crop conditions, which were mainly located in Banteay Meanchey and southern Takéo.

In conclusion, at the national scale, the agro-climatical indicators imply generally favorable weather conditions and water supply from the Mekong River. Negative departures in the NDVI maps can be attributed to cloud cover in the satellite images. The VCI value was as high as 0.89 and the CALF index slightly increased by 3%, also indicating favorable conditions. All in all, conditions in Cambodia can be assessed as normal. 

Regional analysis

Based on cropping systems, climatic zones, and topographic conditions, four sub-national regions are described below: The Tonle Sap Lake area (agro-ecological zone number 117), a seasonally inundated freshwater lake which is influenced by the inflow and outflow from the Mekong River; the Mekong valley between Tonle Sap and Vietnam border (number 118); Northern plain and northeast (number 119); and the Southwest Hilly region (number 120) along the Gulf of Thailand coast.

For Tonle Sap Lake region, the region experienced 11% higher cumulative precipitation, 0.7℃ lower average temperature, and about 4% higher radiation, resulting in a 3% higher potential biomass. However, the crop NDVI in this region had stayed below average since late-April, which could be the result of increased rainfall. Abundant precipitation may have delayed the sowing of rice and maize, leading to a lower NDVI. As NDVI departure cluster graph shows, the poor crop growth was mainly located in the eastern bank of Tonle Sap Lake (in red color), which only accounts for a small part. In addition, the CALF index is at 96% and the VCIx value is 0.88. The crop growth condition was normal.

For Mekong Valley region, the precipitation was significantly higher by 17%, the average temperature was about 0.4℃ lower, radiation was 7% higher, and abundant precipitation resulted in a higher potential biomass (+7%). NDVI in this region was higher than average before early May, indicating a favorable production for dry-season crops. However, the NDVI declined in mid-June and stayed below average, indicating a relatively poor growth for rainy season crops. The poor condition mainly appeared in the eastern part (in blue and red color) of this region. The CALF index for this region was at 96% and the VCIx value was as high as 0.90. Crop conditions were close to normal.

For Northern plains and Northwest region, the zone had an 2% higher cumulative precipitation, about 0.6℃ lower average temperature, and about 8% higher radiation, resulting in a potential biomass increase by about 5%. Similar to Mekong Valley region, the crop NDVI was above average before mid-May and below average since mid-June. The sowing of rain-season crop may have been delayed by the increased precipitation as well. Furthermore, the NDVI development showed some anomalies, presumably due to cloud cover in the satellite images.  The CALF index in this region is 99% and the VCIx value was as high as 0.93.

For Southwestern Hilly region, the precipitation was 22% above average, the average temperature was about 0.7℃ lower, and the radiation was about 2% higher, resulting in a potential biomass increase in this region that was also about 2% higher. The NDVI pattern was similar to Mekong Valley region and ended in above-average conditions by the end of this monitoring period. The CALF index in this area is as high as 100% and the VCIx index is close to 0.93.

Figure 3.26 Cambodia's crop condition, April - July 2022

(a) Phenology of major crops

(b) Crop condition development graph based on NDVI                  (c) Maximum VCI

(d) Spatial NDVI patterns compared to 5YA                                   (e) NDVI profile

(f) Time series temperature profile (left) and rainfall profile (right)

(g) Crop condition development graph based on NDVI (left) and time series rainfall profile (right) in Tonle Sap Lake region

(h) Crop condition development graph based on NDVI (left) and time series rainfall profile (right) in Mekong valley region

(i) Crop condition development graph based on NDVI (left) and time series rainfall profile (right) in Northern plain and northeast region

(j) Crop condition development graph based on NDVI (left) and time series rainfall profile (right) in Southwest hilly region

Table 3.41 Cambodia's agro-climatic indicators by sub-national regions, current season's values, and departure from 15YA, April- July 2022

Table 3.42 Cambodia's agronomic indicators by sub-national regions, current season's values, and departure from 5YA, April – July, 2022