Optimum nitrogen fertilizer rates for corn can vary by more than 100% from field-to-field and year-to-year. This variability is a product of near limitless interactions among crop genetics, management, and environment factors (weather & soil type). Among them, the amount of soil inorganic nitrogen in the soil is one of the most important (Baum et al., 2024).

Optimum nitrogen fertilizer rates for corn can vary by more than 100% from field-to-field and year-to-year. This variability is a product of near limitless interactions among crop genetics, management, and environment factors (weather & soil type). Among them, the amount of soil inorganic nitrogen in the soil is one of the most important (Baum et al., 2024).

Iowa State University Extension and Outreach Field Agronomists have completed their fall survey of subsoil moisture in northwest Iowa. Subsoil moisture sampling in Iowa dates back to February 1954 when ten sites were chosen for soil moisture sampling. In 1959, the sampling increased to 22 locations, and in 1971, 61 locations were sampled. Today, 18 locations are sampled in northwest Iowa.

Iowa State University Extension and Outreach Field Agronomists have completed their fall survey of subsoil moisture in northwest Iowa. Subsoil moisture sampling in Iowa dates back to February 1954 when ten sites were chosen for soil moisture sampling. In 1959, the sampling increased to 22 locations, and in 1971, 61 locations were sampled. Today, 18 locations are sampled in northwest Iowa.

The crops are coming out and it’s ALMOST time for farmers to start making fall nitrogen applications. Remember that soil temperatures should be below 50°F at a depth of 4 inches and continuing to drop before making fall nitrogen applications —ideally, the cooler, the better. It's important for farmers to check the soil temperatures in their specific fields, as many factors can influence them.