This monitoring period(January to April 2018) covers the overwintering stages of winter crops, and the sowing of summer crops: maize, rice, soybean, and spring wheat.

In general, crop condition described by the national NDVI profiles is below average. For the whole country, RAIN (315 mm) was 5% above average, while temperature (4.6°C) was below  (-0.8°C), and radiation (RADPAR) significantly so (-6%). The biomass production potential was 9% below average.

Dry weather prevailed in the major winter wheat areas; in the Southern Plains and California RAIN was -12% and-19% below average, respectively, which in turn resulted in 22% and 6% below average biomass production potential. In another major winter wheat areas, RAIN in the Northwest was 1% above the average, temperature up 0.2°C and RADPAR below average by a significant 9%.

Almost all major winter wheat states suffered serious precipitation deficit problems. RAIN in Kansas, Oklahoma, Texas, California, Oregon and Nebraska was 58%, 15%, 14%, 19%, 22%  and 27% below the average, respectively. Dry weather also prevailed in Iowa, Illinois and Missouri states, where RAIN was 17%, 6% and 10% below the average. Water stress caused the marked drop in BIOMASS of major winter wheat states, including Kansas (-49%), Texas (-17%), California(-6%), Oklahoma (-23%), and Nebraska (-17%). 

Drought is also responsible for the significant CALF drop in major winter crops regions such as the Southern Plains (-24%) and the Southwest(-34%). The performance of crop growth condition was also far below the average with maximum VCI (VCIx) reachng only 0.55 in the Southern Plains.

NDVI profiles indicated that the water deficit resulted in a significant decline of NDVI below average for the whole country after the middle of January. A negative NDVI trend was observed in the whole Southern Plains after the middle of February. Until the end of April, crop growth condition in almost regions was below the average.

Considering the drought and significant decline of CALF in the major winter crop regions, below average crop production is currently estimated by CropWatch for the USA. 

Regional analysis

Based on cropping systems, climatic zones, and topographic conditions, 11 sub-national agricultural regions was distinguished for the USA. They are listed in the tables below.  However, considering the timing of the season only three will be described in detail, namely the  Southern Plains, Northwest and California.

The most important winter wheat region of United States, the Southern Plains suffered drought during this monitoring period. RAIN, temperature and RADPAR were 12%, 1.1℃, and 4% below the average. In Kansas, the most important winter wheat State, RAIN was 58% below the average, which has affected the growth of winter wheat. Unfavorable weather condition resulted in below average crop condition in the Southern Plains, with maximum VCI (VCIx) estimated by CropWatch not to exceed 0.55. In the north-western areas, VCIx was below 0.5, indicating bad crop growth condition.

The weather condition in the Northwest was better than the Southern Plains: RAIN (237 mm) was average, and temperature was 0.2 ℃ above the average, while RADPAR was significant 9% below the average. In this region, Oregon State suffered serious drought with RAIN 22% below the average. The CALF was a marked 19% below the average which  would entail reduced production.  Below average crops and production are expected in this region.

The crop condition in California was also below the average. This region was also dominated by dry weather: RAIN was 19% below the average, Temp was average, while the  RADPAR was 5% below. The biomass accumulation potential was 6% below the average.

图.X 1_4_USA

图.X Crop condition development graph based on NDVI_United States

图.X Maximum VCI

图.X Spatial distribution of NDVI profiles

图.X Crop condition development graph based on NDVI_Southern Plains

图.X Crop condition development graph based on NDVI_Northwest

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图.X Crop condition development graph based on NDVI_California

图.X Crop condition development graph based on NDVI_California