This report covers the grainfilling period and harvest of winter-spring rice, followed by planting of summer-autumn rice in the Mekong Delta and the southeast of Vietnam. In the central part, winter rice was also followed by summer rice, but planting took place in April only. In the north, winter-spring rice was planted in January. It will be ready for harvest in May. 

During this reporting period, the total precipitation in Vietnam was slightly above average (RAIN +4%). Between January and March, rainfall was generally slightly below average, but above average in April. Temperatures were also slightly above the 15YA (TEMP, +0.2°C). Early January was cooler than average, but subsequently, temperatures pretty much followed the 15YA. A similar pattern was observed for photosynthetically active solar radiation: it was mostly below average in January and above average thereafter. The estimated biomass was 4% below the 15YA.

Based on the NDVI crop condition development graph, the crops conditions were below the 5YA for the country. The largest negative departure was observed in March. Almost all cropland was cultivated except for some areas in Minh Hai, Soc Trang in the Mekong River Delta, and the southern part of Dong Nai in the South East. There was not any noticeable change in the cropped arable land fraction (CALF). The national average VCIx was 0.91. As to the spatial distribution of NDVI profiles, crop conditions in practically all areas were below average. Mekong River Delta, the Southeastern and Northwestern part of Vietnam had relatively poor crop conditions.

Regional analysis

Based on cropping systems, climatic zones, and topographic conditions, several agro-ecological zones (AEZ) can be distinguished for Vietnam: North Central Coast, North East, Red River Delta, South East, South Central Coast, North West, Central Highlands, Mekong River Delta. 

The North Central Coast recorded an average rainfall of 342 mm, 2% below average, while the temperature was 19.2°C, a reduction by 0.2°C as compared to the 15YA. RADPAR was above average (+7%) and BIOMASS was close to average. Overall, VCIx was 0.94 and CALF was close to average. According to the NDVI-based development graph, crop conditions were below the five-year average

In the North West, the average rainfall was 55% above the 15YA while the temperature was close to the 15YA. Radiation was slightly lower than average (+3%). The potential biomass was above average (+13%) and the VCIx was 0.93. According to the NDVI-based development graph, crop conditions were below the 5YA and recovered to the long-term average in April. Conditions were generally unfavorable for winter rice.  

In the Red River Delta, the average rainfall was 361 mm (RAIN +20%). The temperature was up by 0.4°C and the VCIx was 0.89. RADPAR was above by 4% and BIOMSS was average of the 15YA. According to the NDVI-based development graph, crop conditions were lower than the 5Y average. CALF decreased by 5%. The crop output is expected to be unfavorable.

In the South East, total rainfall was 209 mm, 15% below 15YA. The temperature was 25.7°C, which was -0.5°C cooler than the 15YA. RADPAR was higher than average (+4%). BIOMASS was below average (-13%). According to the NDVI-based development graph, crop conditions were lower than the five-year average, except for April, when they improved to above average conditions. Overall, VCIx (0.87) and CALF (94%) indicated below average conditions in this region.

In the South Central Coast, the average rainfall was about 268 mm, 37% below average, while TEMP was 19.9°C, which was -0.7°C cooler than the 15YA. RADPAR was above average (+7%). BIOMASS was below average (-19%). According to the NDVI-based development graph, crop conditions were lower than the 5YA. VCIx for this region was 0.89 and CALF slightly decreased by 1%.

The average rainfall in the Central Highlands was about 191 mm, 25% below average, while TEMP was 21.6°C, a decrease by -0.6°C, as compared to the 15YA. RADPAR was above average (+6%). BIOMASS was below average (-13%). According to the NDVI-based development graph, crop conditions were near the 5YA. Overall, high VCIx (0.86) and stable CALF expected normal conditions.

In the Mekong River Delta, rain was 281 mm, 10% below the 15YA. The average temperature was 27°C, which was 0.5°C lower than the 15YA. PAR (RADPAR) was higher than average (3%). BIOMASS was below average (-8%). According to the NDVI-based development graph, crop conditions were close to the 5YA only in February, whereas in the remaining months, they were below.  VCIx (0.86) and CALF (86%) indicate moderate conditions in this region.

The North East region recorded the highest rainfall among all the regions, resulting in a positive departure by +37%. TEMP was above average by 0.3°C, and the RADPAR decreased by 3%. CALF in this region did not significantly change and VCIx reached 0.95.

Figure 3.5 Vietnam’s crop condition, January- April 2021

(a). Phenology of major crops

(b) Crop condition development graph based on NDVI

(c) Maximum VCI

e) Spatial distribution of NDVI profiles

(f) Rainfall profiles

(g) Temperature profiles

(h) Crop condition development graph based on NDVI (South)

(h) Crop condition development graph based on NDVI (South Central Coast)

(h) Crop condition development graph based on NDVI (Red River)

(h) Crop condition development graph based on NDVI (North West)

(h) Crop condition development graph based on NDVI (North Central Coast)

(h) Crop condition development graph based on NDVI (Mekong)

(h) Crop condition development graph based on NDVI (Central Highlands)

Table 3.1. Vietnam's agroclimatic indicators by sub-national regions, current season's values and departure from 15YA, January to April 2021

Table 3.2. Vietnam's agroclimatic indicators by sub-national regions, current season's values and departure from 15YA, January to April 2021