Speaker: Kunal Das, Graduate Assistant, Department of Statistics, Iowa State University

Title: How to Collect Data on Agricultural Nutrient Management Practices: Survey Results from Iowa

Abstract: In response to the 2008 Gulf Hypoxia Action Plan, the Iowa Department of Agriculture and Land Stewardship partnered with the College of Agriculture and Life Sciences at Iowa State University to create the Iowa Nutrient Reduction Strategy (INRS) aimed at assessing and reducing nutrients in Iowa waters and the Gulf of Mexico to reduce, mitigate, and control hypoxia and improve overall water quality in the Mississippi River Basin. In this presentation we will discuss how survey sampling methodologies can be used efficiently to reach such goal of nutrient reduction plans based on the finite sample data collected in Iowa. The two-stage procedure employed initiates with a sampling methodology of randomly selecting 150 individuals out of 580 agricultural retailers across all eight MLRAs(Major Land Resource Areas) using the Local Pivotal Method(LPM) to ensure a balanced sampling scheme. The survey is unique in that questionnaires related to the crop production amount and quantities of different nutrition products used(like Fall anhydrous ammonia, manures, etc.) are sent to the retailers rather than the farmers to avoid a high proportion of non-responses. Once the data are collected across all MLRAs, the average, as well as the standard errors for the percentage of total land where different categories of nutrients are used, is also being extrapolated to the entire state to help policymakers chalk out their nutrient-reduction plans for the succeeding crop years. This entire procedure has been performed for Iowa over the last six crop years, starting from 2017 to 2022, and we are hoping to continue the collaboration in the future as well, with the state of Illinois now on board. To wrap up, We will present some of the findings regarding land use for different nutrients for all these years, and their uncertainty estimates for visualization.