Evaluating the Impacts of Humic Acid Applied with Nitrogen Fertilizer on Corn Growth and Soil Quality in South Dakota.

ABSTRACT

The integration of inorganic fertilizers with Humic Acid (HA) may be an effective way to improve crop yields and maintain soil health. However, little is known about the evaluation of HA applied with nitrogen (N) fertilizer on corn (Zea mays L.) growth and soil properties in South Dakota. The objectives were to evaluate the impacts of HA applied with N fertilizer on corn yield, corn stem height and diameter, and the selected soil properties. The experiment was a split-plot in a randomized complete block design with 4 replications at the SDSU Southeast Research Farm, near Beresford, South Dakota. The six fertilizer treatments were established in 2013 for evaluating corn yield. Another 12 fertilizer treatments were established in 2014 and 2015 for assessing corn growth, yield, and soils quality. The results showed that most treatments of the HA applied with N fertilizer significantly influenced corn yield and stem diameter and height. The treatments did not significantly impact wet aggregate stability (WAS), carbon to nitrogen (C: N) ratio, and bulk density (ρ_b) of soil. However, HA significantly impacted the soil pH, electrical conductivity (EC), soil organic matter (SOM), soil organic N (SON), and water soluble ammonia (NH₃) in soils under some treatments. The findings indicate that the appropriate fertilization of HA applied with N fertilizer may increase corn yield and reduce the cost of fertilizer application, and improve soil quality.