Tina Karimi

Tina Karimi
  • PhD Student
  • Washington State University
  • Biological Systems Engineering


Claudio Stockle

Thesis or Dissertation Citation: 

Karimi, T. 2012. Revising crop coefficients for Washington State. Washington State University PhD Dissertation, pp. 1-122.

Research Focus: 

Simulation of regional yields and GHG emissions under climate change in PNW

Research Abstract: 

Silicon (Si) levels have a wide range of variation in plant and soil systems depending on abiotic and biotic factors. In the inland Pacific Northwest the predominant cropping system relies on wheat (a Si accumulator). Within this region, studies have shown high levels of total soil Si and evidence of Si compounds becoming potential cementing agents therefore degrading soil quality. The dependence of Si cycling on plant type, environmental factors, and agronomic inputs needs to be assessed in order to determine if introduction of canola (a non-accumulator of Si) could enhance soil quality by reducing the occurrence or severity of soil crusting in comparison to wheat-dominated systems. Both wheat and canola were grown in a greenhouse and upon harvest the wheat residue accumulated between 40–65% more Si than canola. This residue was then used in a laboratory incubation with soil pH as a variable. The results suggest that a higher pH, rather than residue type, was the primary factor positively affecting surface resistance, water soluble Si (Siws), and amorphous Si (Siam). The greenhouse residues were also used in a decomposition study, which showed wheat had a slightly faster decomposition rate compared to canola, consistent with the lower starting C:N ratio of the wheat residue. An additional incubation with applications of amorphous silica (SiO2) confirmed that such v applications positively influence water loss, soil Si, surface resistance, and crust thickness. In addition to the silica treatments, soils from two cropping systems were used: one previously cropped in wheat and the other in canola. The soil previously cropped in wheat had higher soil Siam, surface resistance, and crust thickness compared to the canola system demonstrating the influence crop rotation can have on Si related soil properties. A field survey of Siws, Siam, and surface resistance showed little dependence across cropping systems. As shown from the experiments under controlled conditions, it can be concluded that Si cycling does affect important soil physical properties. The lack of confirmation in the field survey suggests that other factors influence the state of Si in active cropping systems and should be the focus of further research.


I got my bachelor in Agriculture-Irrigation and Drainage Engineering, at Tehran University in Iran (2006). After my graduation I started to attend some professional courses regarding my field of study and later I accepted as a licensed designer and executor of pressurized irrigation systems in the experts' team of Iran Agriculture Ministry (2007). I have worked in three consulting engineers companies as a part time and full time irrigation engineer after my graduation since I was in Iran. In 2010 I came to WSU (WSU) to peruse my education in more broad directions. I got my master's at WSU, Biological System Engineering department in Land, Air, Water Resources and Environmental Engineering field in 2012. My thesis project, titled 'Revising crop coefficients of Washington State', was funded by Washington State Department of Ecology, under the supervision of Dr. Peters. In summer 2012 I joined to the Regional Approaches to Climate Change (REACCH) project, funded by USDA-NIFA,as a temporary employment under Optional Practical Training (OPT)and in the following fall I started PhD in the same department. Now I am part of the REACCH and working in the modeling and LCA team under supervision of Dr. Stockle.

Publications and Presentations: 

Beard, T., Sowers, K., Pan, W. 2016. Phsiology matters: adjusting wheat-based management strategies for oilseed production. Washington State University Extension, issuing body.