After a brief overview of the agro-climatic and agronomic conditions in China over the reporting period (section 4.1), Chapter 4 describes the situation by region, focusing on the seven most productive agroecological zones (AEZs) of the east and south (4.2): North-east China, Inner Mongolia, Huanghuaihai, Loess region, Lower Yangtze, Southwest China and Southern China. Additional information on the agro-climatic indicators for agriculturally important Chinese provinces is listed in table A.11 in Annex A.

4.1 OVERVIEW

Agro-climatic conditions were slightly below average in China from October 2019 to January 2020, with rainfall and radiation deficits by 4% and 1%, respectively. Temperature was 0.8℃ above the average. Low rainfall but relative high temperatures and close to average radiation resulted in the average potential biomass. Due to the complexity and variability of climatic conditions in China, weather conditions vary over different agroecological zones. Temperatures in seven agroecological zones of China were all above average, ranging from 0.6℃ to 1.2℃. Lower Yangtze and Southern China suffered from water shortage, with 17% and 31% lower rainfall compared to average. Drier conditions may potentially hamper the sowing and early growth of crops after winter. Since potential biomass is a synthetic indicator taking rainfall, radiation, and temperature into consideration, potential biomass in Lower Yangtze was still above average due to the agreeable conditions of radiation and temperature, while potential biomass in Northeast China was still above average due to the relatively high temperatures.

Rainfall departure clustering and temperature departure clustering show detailed spatial and temporal patterns. Rainfall in 58% of the total agricultural area was generally average, and mainly located in Northern China, Northeast China, and western parts of Southwest China. Other regions in China went through some fluctuation in rainfall. Excessive rainfall occurred mainly in early October, early January, and late January mainly in Central China, Southern China, southern parts of Northern China and eastern of Southwest China. Interestingly, the variations of temperature were quite consistent in the three clustered regions, with temperatures above the average in most of the time during the monitoring period.

More than ten provinces had large rainfall anomalies such as Henan (+54%), Guangdong (-53%), and Chongqing (+52%). The largest positive temperature anomalies (in excess of 1.0°C) were recorded in eleven provinces such as Jiangsu (+1.6℃), Jiangxi (+1.5℃) and Anhui (+1.4℃). If the situation of above average temperature still continues into the next monitoring period (January to April), snow may melt early and facilitate early sowing of spring crops.

Winter wheat cultivated across northern China is going through the hibernation period, while there was nearly no crop in Northeast China and Inner Mongolia. The significantly above average CALF in Huanghuaihai and Loess Region could be a result of advanced development of winter crops thanks to the higher than average temperature. CropWatch will keep watching at the agro-climatic and agronomic conditions in the following bulletins.

Table 4.1. CropWatch agroclimatic and agronomic indicators for China, October 2019 to January 2020, departure from 5YA and 15YA

Figure 4.1. China spatial distribution of rainfall profiles, October 2019 to January 2020

Figure 4.2. China spatial distribution of temperature profiles, October 2019 to January 2020

Figure 4.3. Cropped and uncropped arable land over winter crops producing provinces, by pixel, October 2019 to January 2020

Figure 4.4. China maximum Vegetation Condition Index (VCIx), by pixel, October 2019 to January 2020