This monitoring period covers the wet season in Cambodia, which lasts from May to October. The planting period of wet-season early rice and floating rice ended in July. It was followed by medium rice and late rice, which was completed in September and October, respectively. Harvest of the soybean and wet season maize ended in August and October, respectively.

Cambodia experienced wetter weather than usual during this monitoring period. As shown by the agro-climatic indicators, the precipitation (RAIN +5%) was above the 15YA, which can mainly be attributed to several tropical storms. Both the typhoon Cempakm in July and the tropical storms in September brought strong wind and rain, damaged the crops and decreased the NDVI. This is reflected in the NDVI profiles, although cloud cover in the satellite images can also cause large negative departures in NDVI. Temperatures were near average, and the radiation slightly increased (RADPAR +1%). The estimated potential biomass increased (BIOMSS +2%). The CALF was higher than average by 1% and the VCIx value was at 0.9. Moreover, the NDVI for the country was slightly lower than the average at the end of the monitoring period. All in all, the crop conditions were close to normal in Cambodia. The NDVI of 10.7% (orange color) of the arable land is mainly located in the southeast of Banteay Meanchey and the middle of Kampong Thom. It remained near or slightly below average until mid-August.  For about 25.8% of the cropland, stable and slightly higher-than-average NDVI was observed. These croplands (blue color) were mainly located in Kandal, southern Preyveng, southern Svay Rieng and other areas scattered around the Tonle-Sap. The rest of the croplands (light green, dark green and red color) remained slightly below average for most of the monitoring period. All in all, the crop conditions were below average in the important Tonle Sap Lake area and near average for the rest of the country.

Regional analysis

Based on cropping systems, climatic zones and topographic conditions, four sub-national regions are described below: The Tonle Sap Lake area, 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, Northern plain and northeast, and the Southwest Hilly region along the Gulf of Thailand coast.

For the Tonle Sap Lake area, the rainfall (RAIN) increased by 12% while the temperature  (TEMP) and radiation  (RADPAR) were near average. In addition, the estimated biomass (BIOMSS) grew by 3%. Inflow from the Mekong River remained far below the long-term average, resulting in negative NDVI departures. As a result, the crop condition in this region was estimated below average.

The Mekong valley region experienced relatively dryer weather. The rainfall dropped by 2% (RAIN) and temperature increased by 0.2℃. The radiation was higher than average (RADPAR +1%). This resulted in a biomass estimate that was almost near average. According to the NDVI profile, although the NDVI fluctuated all the time, it recovered to average levels at the end, indicating the crop condition in this region was close to normal.

In the Northern plain and northeast region, the precipitation (RAIN) was 5% higher than average, accompanied by average temperature  (TEMP) and above-average radiation  (RADPAR, +3%). The resulted biomass (BIOMSS) increased by 2%  and the VCIx value reached 0.93, which was the largest for all four regions. Moreover, the CALF stayed at 99%. All the indicators show that the crop growth for this region was good.

The Southwest Hilly region went through a wetter (RAIN, +9%) and slightly warmer period  (TEMP, +0.2℃) compared to the 15YA. Although the radiation decreased (RADPAR -3%), the estimated biomass was near average (BIOMSS, no change). According to the NDVI profile, although the NDVI fluctuated, it recovered to average levels at the end of monitoring period, which indicates normal crop conditions.

Figure 3.26 Cambodia’s crop condition, July-October 2021

(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) Crop condition development graph based on NDVI_Tonle-sap (left) and NDVI_Mekong valley (right)

(g) Crop condition development graph based on NDVI (Northern plain and northeast (left), Southwest Hilly region (right))

(h) Time series temperature profile          (i) Time series rainfall profile

Table 3.43 Cambodia's agro-climatic indicators by sub-national regions, current season's values and departure from 15YA, July- October 2021

Table 3.44 Cambodia's agronomic indicataors by sub-national regions, current season's values and departure from 5YA, July - October 2021