By Sotirios Archontoulis and Mike Castellano et.al
One of the largest and least visible sources of nitrogen (N) for Iowa corn is the soil itself. Through N mineralization, soil microbes convert organic N into plant-available forms every day. In many fields, this natural process supplies well over 100 lb N/acre during the growing season.
The Iowa State University FACTS (Forecast and Assessment of Cropping sysTemS) platform estimates soil N mineralization every two days using public weather and soil data and the APSIM cropping systems model. Current estimates (as of July 19) indicate that 2026 is shaping up to be another exceptional year, with soil N mineralization tracking at or above last year's record-setting levels across much of Iowa.
Estimated cumulative soil N mineralization during the 2026 growing season for the nine Iowa Crop Reporting Districts. The 2026 season (red) is compared with 2025 (blue), the 40-year average (black), and individual historical years (gray). Through mid-July, 2026 has generally matched or slightly exceeded 2025, making it another potential record-breaking year for natural soil N supply.
Source : iastate.edu