The Forecast and Assessment of Cropping sysTemS (FACTS) webpage has been updated to include regional scale forecasts. These regional scale forecast cover the three I-states providing weather, soil water, and soil N mineralization information. Additional crop information will become available with future updates.
As of June 19, rainfall is 0 to 7 inches above normal across the I-states and accumulated growing degree day units are lower than normal. The forecast for next week calls for rains across the three-state region with greater rainfall in Indiana and Illinois. For the first time this growing season, the growing degree day accumulation next week will be above normal.
The soil information is a product of APSIM model simulations at a fine resolution. The model runs a water balance every day. The water balance includes the following processes: precipitation, runoff, soil water evaporation, plant transpiration, water flow in tile drainage, deep seepage and capillary rise from shallow water tables. The net product of all these processes is soil water index. A soil water index of 1 is ideal for plant growth but does not allow for field operations with values ranging from 0.8 to 1.2 being optimal for plant growth. Values below 0.75 indicates drought stress can be occurring with greater drought stress the smaller the index becomes. Values above 1.25 indicate the onset of excessive moisture impacts. As of June 19, the water index indicates wet soil conditions in Indiana, Illinois, and parts of eastern Iowa. At lower soil depths the water index is high and could begin to limit corn and soybean rooting depth. For reference, both corn and soybean roots are severely constrained when soil moisture is very close to saturation.
The APSIM model calculates a daily nitrogen balance by considering the following processes: soil N mineralization, crop residue N immobilization, N loss via denitrification and leaching to tile drainage or below the tile lines and crop N uptake. A soil N mineralization index is currently available online and is calculated as ratio of 2019 soil N mineralization divided by the 35-year historical values since May 1. Value of near 1 are near normal soil N mineralization. As of June 19, soil N mineralization is lower than normal years due to cooler temperatures that have been experienced. There are differences across the 3 I-states. Iowa and northern Illinois have about 20% less soil N mineralization compared to southern Illinois and Indiana.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on June 19, 2019. The information contained within may not be the most current and accurate depending on when it is accessed.
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- Integrated Cropping Systems
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