Isaac Madsen

Isaac Madsen
  • PhD Student
  • Washington State University
  • Crop and Soil Sciences


Bill Pan

Thesis or Dissertation Citation: 

Madsen, J. 2017. Nitrogen-plant-soil interactions at the root-rhizosphere, cropping system, and national scales. Washington State University PhD Dissertation.

Research Focus: 

Nitrogen loss from irrigated cropping systems

Research Abstract: 

The transport and transformation of N at all scales is of paramount importance to humans. Not only is N crucial for our survival, being a central building block in protein, but N can also be toxic when found in high concentrations in the wrong locations. This work focuses on the importance of the place of N at three distinct scales. 1.) At the seedling root system scale we examined the effects of the concentration of N on causing symptoms of root toxicity, and found increasing ammoniacal-N to increase the symptoms of toxicity to roots. 2.) At the field scale, cover cropping and reduced tillage where assessed for their potential to decrease soil NO3- leaching and increase of N exportation efficiency. 3.) At the national scale a research project database was used to assess the amount of research that has gone into the development of best management practices.


Isaac Madsen is originally from Portland, OR. Although not originally from an agricultural background he has a life long interest in agriculture, food systems, as well as basic plant and soil science. He is passionate about the rhizosphere and producing videos of roots growing.

Publications and Presentations: 

Pan, W., Madesn, I., Bolton, R., Graves, L., Sistrunk, T. 2016. Ammonia/ammonium toxicity root symptoms induced by inorganice and organic fertilizers and placement. Agronomy Journal. 108(6): 21875-2492.