Innovative Approach to Active Learning

Presentation on a course redesign and project plan given at the American Society of Agronomy Annual Meeting, Cincinnati, OH

Pre-Plant Anhydrous Ammonia Placement Consequences on No-Till Versus Conventional-Till Maize Growth and Nitrogen Responses

With the advent of precision guidance systems, maize (Zea mays L.) farmers in various tillage systems have more options in pre-plant nutrient banding relative to the intended crop rows. Anhydrous ammonia (NH3) placement during pre-plant application is of interest because of concerns for possible ammonia toxicity to maize seedlings when high NH3 rates are applied too close to the seed row and the need to improve plant-nitrogen (N) use efficiencies. Field studies were conducted between 2010 and 2012 near West Lafayette, IN, to compare traditional angled (diagonally) vs. precision-guided parallel NH3 applications (the latter was offset 15 cm from the future row) in no-till and conventional tillage systems. The NH3 was injected to depths of about 12 cm at N rates of 145 and 202 kg N ha−1. Maize was planted with additional starter N (20 kg N ha−1) within 6 d of NH3 application. Neither NH3 application placement resulted in significant maize seedling mortality. Conventional tillage increased mean grain yields across N rates and placement treatments from 10.6 to 11.6 Mg ha−1. Tillage did not impact reproductive-stage leaf chlorophyll content (SPAD), or whole-plant N content at maturity when NH3 was parallel applied, but these plant responses were significantly lower in no-till after diagonal application. Lowering the pre-plant N rate to 145 from 202 kg N ha−1 significantly lowered maize whole-plant biomass and N accumulation at maturity with diagonal application, but not when NH3 was parallel applied

Integrating Spatial Educational Experiences (Isee) – Mapping a New Approach to Teaching and Learning Soil Science

The purpose of the Integrating Spatial Educational Experiences project is to develop the ability of our students to use digital maps: (1) to learn how and why soils and landscapes vary spatially at scales ranging from fields, to counties, states, and globally and (2) to learn how the spatial distribution of soils and landscapes impacts the distributions of land use, and environmental and ecosystem services across various scales. Our immediate audience is undergraduate students in soil, crop, natural resource, and environmental science curricula in colleges and universities, but the products created by this project will have broader uses for outreach to other clientele. Products to support teaching and learning include: (1) a revised and expanded Integrating Spatial Educational Experiences (Isee) web site, (2) maps of soil properties for Indiana, West Virginia, Ohio, Kentucky, Illinois, Wisconsin, and Texas, (3) a community of practice dedicated to Integrating Spatial Educational Experiences in soil science education on STEMEdhub.org, and (4) lessons, worksheets, exercises, and experiences shared with the Isee community of practice

Anhydrous Ammonia Timing and Rate Effects on Maize Nitrogen Use Efficiencies

Current guidance and equipment technologies permit anhydrous ammonia (NH3) to be confidently placed parallel to crop rows in both before- and after-planting situations at shallower depths than traditional applications. Field studies from 2010 to 2012 investigated the effects of pre-plant vs. side-dress NH3 at four N rates (0, 90, 145, and 202 kg N ha−1) on maize (Zea mays L.) grain yield (GY), N recovery efficiency (NRE), and N use efficiency (NUE). All NH3 was injected to a 12-cm depth; pre-plant NH3 was banded parallel to, but approximately 15 cm offset from, intended rows a few days before planting. Side-dress NH3 was applied to mid-row positions at the V6–V7 growth stage. Whole-plant N uptake at maturity was consistently higher with pre-plant application. Highest GY was observed at the highest N rate with side-dress timing in 2011 but with the pre-plant timing in 2012. Relative to side-dress, pre-plant application improved average NRE across N rates from 0.53 to 0.72 kg plant N kg−1 applied N during the 3-yr period. Overall NUE levels in 2012 were 50% lower than in 2010 and 40% lower than in 2011 due to drought, yet NRE doubled and NUE more than tripled with pre-plant relative to side-dress application. This 3-yr study highlights the inability of either one-time NH3 application strategy investigated to consistently have the highest GY and NUE as well as the dominating year-specific influences of both N timing and N rates on NRE