Update:
Final report is downloaded in the file option below
View uploaded report 
Improving Soil Health and Productivity of Sodic Soils
Principal Investigators: Dr. Thomas DeSutter, Dr. Amitava Chatterjee, and Dr. Abbey Wick, Department of Soil Science, NDSU; Maria Breker, M.S. Student, Soil Science, NDSU
Executive Summary
North Dakota has over 4 million acres of sodic soils and producers have difficulty managing them for soybean production. Sodic soils are those that have excess sodium compared to calcium and magnesium. These soils are difficult to manage since, when wet, oftentimes reduce trafficability and, when dry, become very hard and reduce seed germination and root growth. Addition of amendments to combat the negative influences that sodium has on soil is a ‘first choice’ management strategy. The intent of this research was to determine management options that are feasible, cost effective, and promote soil health.
This study used flue-gas desulfurization gypsum (a byproduct from coal combustion), sugar beet waste “spent” lime (mostly calcium carbonate), and potassium-magnesium sulfate (sold as K-Mag fertilizer). Each amendment was applied at three rates at two sites near Delamere, ND that are both mapped as having excess sodium. The rates for the gypsum and spent lime were 5, 15, and 30 tons/acre and the K-Mag was applied at 1, 2.5, and 5 tons/acre. One site was tile drained and the other was only surface drained (no tile). Each site was seeded to alfalfa in 2014 which is being used as a “nurse crop” to better promote long-term soybean production and soil health. The amendments, coupled with alfalfa’s ability to promote soil health, are hypothesized to improve soil function and enhance long-term soil productivity.
Application of amendments, up to 30 tons/acre for flue-gas gypsum and spent lime did not alter alfalfa yield or its quality at either site. The high rate of K-Mag, 5 tons/acre, did reduce alfalfa yield at the non-tiled site, compared to the zero amendment treatment, which was likely due to K-Mag’s high solubility and subsequent increasing of the soil’s electrical conductivity during seed germination. Over time, however, the soil’s electrical conductivity was not different across treatments and their rates of application. The rates of amendment applications were not high enough or their solubilities were too low (gypsum and lime) to see treatment differences in soil %Na (the ratio of Na to Na+Ca+Mg+K) in the 0-6” depth.
A laboratory study using soils from both field sites determined that the spent lime greatly increased soil microbial respiration compared to the other field treatments and rates. The other treatments (gypsum and K-Mag) and their rates of application did not reduce microbial respiration below that of the zero amendment treatment. These results are significant in that the amendments used for sodic soil management most likely will not decrease soil microbial activity.
Improving the health and function of soils is critical for long-term financial and food security. In precipitation-limited regions, such as North Dakota, increasing the health of sodic soils is difficult. However, the use of a nurse crop, such as alfalfa, and amendments may offer improved long-term soil health and soybean productivity.