FACTS regional scale results for June 19, 2019

June 19, 2019 10:50 AM
Blog Post

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.

soil water index for Iowa, Illinois, Indiana

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.

soil N mineralization index for Iowa, Illinois, Indiana


Sotirios Archontoulis Professor of Integrated Cropping Systems

Dr. Sotirios Archontoulis is an assistant professor of integrated cropping systems at the Department of Agronomy. His main research interests involve understanding complex Genotype by Management by Environment interactions and modeling various components of the soil-plant-atmosphere continuum. Dr...

Mark Licht Associate Professor

Dr. Mark Licht is an associate professor and extension cropping systems specialist with Iowa State University Extension and Outreach. His extension, research and teaching program is focused on how to holistically manage Iowa cropping systems to achieve productivity, profitability and en...