Abstract

Nitrogen (N) fertilizer and irrigation are important inputs for all managed plant species, especially in arid and semi-arid climates. The interaction between N management and irrigation can lead to more sustainable practices. This is true for both agricultural and urban environments. Precision nutrient management has been widely adopted by producers in recent decades, and water conservation has become an important goal for turfgrass managers. In urban systems, our goal was to evaluate Kentucky bluegrass (Poa pratensis L.) to determine response to three N fertilizer rates and three irrigation rates in all possible combinations. The main and interacting treatment effects were evaluated for daily evapotranspiration (ET), Normalized Difference Vegetation Index (NDVI), and grass height. Irrigation treatments significantly influenced daily ET. The N treatments did not affect daily ET, but the Deficient (50%) N rate resulted in lower NDVI and height measurements regardless of irrigation treatment. Additionally, for excess N fertilization a lack of drought tolerance in plots was revealed when NDVI decreased towards the end of the experimental periods. By the end of the study, a portion of this treatment type seemed to be in dormancy. While fine-tuned N rates will not significantly impact the overall water consumption of a highly irrigated turfgrass lawn, it will increase the overall NDVI for the same water costs. In agricultural systems, one strategy for communicating precision nutrient management approaches is known as the nutrient 4Rs: right timing, right source, right rate, and right place. Ideally, the use of the 4Rs would result in economically maximized crop yield while maximizing resource use and reducing environmental harm. The effectiveness of different 4R management practices is commonly assessed by comparing yield or economic response. However, for irrigated cropping systems in water scarce regions, another way is to evaluate crop water productivity. While there has been research into the relationship between irrigation and N, it has not been examined for irrigated winter wheat, potatoes, and silage corn in a semi-arid area. By using a full factorial experimental design with 18 different treatments of the 4Rs on these crops around Idaho, it is possible to isolate the effects of each practice on yield. From there, it is combined with ET values, both daily and season long, that are found with a water balance equation (P+I=ET+D+R+S) to estimate water consumption for each treatment. Evaluating how nitrogen 4R management practices affect water use, recommendations can be made to make the best use of limited irrigation supply in water-scarce regions.

Degree

MS

College and Department

Life Sciences; Plant and Wildlife Sciences

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2023-08-14

Document Type

Thesis

Handle

http://hdl.lib.byu.edu/1877/etd13369

Keywords

Nitrogen, Irrigation, Kentucky bluegrass, 4R, Precision Fertilizer, Evapotranspiration

Language

english

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