Determining a precise nitrogen fertilizer requirement for maize in a particular field and year has proven to be a challenge due to the complexity of the nitrogen inputs, transformations and outputs in the nitrogen cycle. Remote sensing of maize nitrogen deficiency may be one way to move nitrogen fertilizer applications closer to the specific nitrogen requirement. Six vegetation indices [normalized difference vegetation index (NDVI), green normalized difference vegetation index (GNDVI), red-edge normalized difference vegetation index (RENDVI), triangle greenness index (TGI), normalized area vegetation index (NAVI) and chlorophyll index-green (CI_green)] were evaluated for their ability to detect nitrogen deficiency and predict grain maize grain yield. Strip trials were established at two locations in Arkansas, USA, with nitrogen rate as the primary treatment. Remote sensing data was collected weekly with an unmanned aerial system (UAS) equipped with a multispectral and thermal sensor. Relationships among index value, nitrogen fertilizer rate and maize growth stage were evaluated. Green NDVI, RENDVI and CI_green had the strongest relationship with nitrogen fertilizer treatment. Chlorophyll Index-green and GNDVI were the best predictors of maize grain yield early in the growing season when the application of additional nitrogen was still agronomically feasible. However, the logistics of late season nitrogen application must be considered.

Silt loam soils in the mid-southern United States are prone to soil erosion, crusting, and general soil degradation. A field experiment was established at three field sites in northeast Arkansas to evaluate the effect of cover crop and tillage management on cash crop yield and the physical properties of soil health, specifically infiltration rate and aggregate stability. Cover crop management included cereal rye, wheat and crimson clover, and a winter fallow. Tillage management included tillage and no-tillage. During the two-year study, yield was not significantly influenced by different tillage treatments. The cover crop treatment had greater yield than the no-cover crop treatment (5091 vs. 4264 kg ha⁻¹) at one site in one of the years. Water infiltration was significantly improved with cover crops compared to with no-cover crops, with a 52% and 64% increase at Walcott and Magnolia, respectively. Soil aggregate stability was significantly improved with no-tillage as compared with tillage in both years at Walcott, with a 16% and 58% increase in 2015 and 2016, respectively. Both cover crop and tillage management can have significant impacts on soil physical properties in a short period of time.

Competency-based assessments are a common tool used to increase retention and understanding for students in university courses. This analysis of competency assessments in an upper-level soil science course focuses on both the measurable, quantitative impact of the use of competency assessments on student learning as well as the qualitative student perceptions of their use when a compulsory mastery of the assessment was required. This study utilizes data from two years of the course over which the competency assessments and mastery of the content on the assessment to a required 100% was introduced to examine the impact on student learning. Quantitatively, the results of the study are mixed as a result of the compulsory mastery of the content. However, through focus groups, students expressed value and an appreciation of the competency assessments in learning and retaining course material. This analysis expresses the importance of not only the measurable impact of teaching practices, but also the perception of those practices by students.