Jian Liu


(+47) 464 22 528

Ås - Bygg O43

Oluf Thesens vei 43, 1433 Ås (Varelevering: Elizabeth Stephansens vei 23)


I am a soil scientist working on agricultural effects on the environment and crop production. By combining experimentation, modeling and data synthesis approaches and collaborating with scientists, students and stakeholders in a wide range of areas, I study agricultural nutrient and water quality management at various spatial and temporal scales, and extend my research to soil health, crop production, greenhouse gas emissions and generally sustainable agriculture.

My research and collaboration interests include:

  • Agricultural impacts on the environment
    • Water and nutrient leaching and runoff, and soil erosion
    • Gas emissions
    • Field and watershed monitoring and modeling
  • Soil fertility and health
    • Nutrient cycling
    • Crop production
  • Best management practice assessment and implementation
    • 4R nutrient stewardship (fertilizers, manure and soil nutrients)
    • Soil (tillage, and biochar and other amendments), crop (crop rotation, catch crop and crop residue), water and livestock management
  • Other general areas
    • Climate impact mitigation and adaptation  
    • Sustainable agriculture
    • International collaborations   

I obtained my Ph.D. in soil science with a focus on phosphorus and water quality management from the Swedish University of Agricultural Sciences (SLU) in Uppsala, Sweden. Before joining NIBIO, I had conducted research at SLU, and in China (Northwest Agricultural and Forestry University, and Chinese Academy of Agricultural Sciences), United States (Pennsylvania State University, and U.S. Department of Agriculture – Agricultural Research Service), and Canada (University of Saskatchewan, and University of Manitoba).

Selected awards:

  • Water Security Research Excellence Award, University of Saskatchewan, 2022.
  • Outstanding Associate Editor Award, Journal of Environmental Quality, 2021.
  • Outstanding Associate Editor Award, Journal of Environmental Quality, 2020.
  • 2nd Prize for Outstanding Scientific Papers (Agricultural & Forestry Subject), Chinese Association for Science and Technology, 2017.

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We conducted a study over four rice seasons to assess the effects of dairy manure application on water loss, nutrient leaching, and rice yield compared to chemical fertilization. Water input, soil water storage, water percolation, plant growth, and yield data were recorded under triplicate field lysimeters that received either chemical fertilizers or organic manure. The lysimeters received alternate wetting and drying irrigation (5-cm after 3 days (2018 Aman season), 6 days (2019 Boro and Aman seasons), and 9 days (2020 Boro season) of ponded water disappearance) in addition to rainfall (37.5, 33.1, 40.9, and 47.4 cm, respectively). Leachate and ponded water samples were analyzed for nitrogen (N) species (NH+4 - N and NO−3 - N) and available phosphorus (P) content. Manure application increased soil water storage by 1.2–4.4 cm/m but did not affect percolation loss (44–64% of water input) in silt loam soil. The chemical fertilization had significantly higher leaching concentrations of nutrients (NO−3 - N at 0.75–3.6 mg/L and P at 0.02–0.15 mg/L) in several leaching events in the last three seasons than the manure treatment (NO−3 - N at 0.75–3.2 mg/L and P at 0–0.21 mg/L). Overall, the manure treatment reduced the leaching load of N and available P by 13% and 23.6%, respectively. The N and P concentrations in the topsoil were higher for the manure treatment. Manure application increased rice yield by 15% and water productivity by 0.07 kg/m3 by augmenting soil water availability during the drying cycles of alternate wetting and drying processes. In addition, recycling manure in soil significantly reduced its environmental pollution compared to other inappropriate disposal methods. However, research needs remain important to adjust manure management options.

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Aims Root traits associated with resource foraging, including fine-root branching intensity, root hair, and mycorrhiza, may change in soils that vary in rock fragment content (RFC), while how these traits covary at the level of individual root branching order is largely unknown. Methods We subjected two xerophytic species, Artemisia vestita (subshrub) and Bauhinia brachycarpa (shrub), to increasing RFC gradients (0%, 25%, 50%, and 75%, v v− 1) in an arid environment and measured fine-root traits related to resource foraging. Results Root hair density and mycorrhizal colonization of both species decreased with increasing root order, but increased in third- or fourth-order roots at high RFCs (50% or 75%) compared to low RFCs. The two species tend to produce more root hairs than mycorrhizas under the high RFCs. For both species, root hair density and mycorrhizal colonization intensity were negatively correlated with root length and root diameter across root order and RFCs. Rockiness reduced root branching intensity in both species comparing with rock-free soil. At the same level of RFC, A. vestita had thicker roots and lower branching intensity than B. brachycarpa and tended to produce more root hairs. Conclusion Our results suggest the high RFC soil conditions stimulated greater foraging functions in higher root orders. We found evidence for a greater investment in root hairs and mycorrhizal symbioses as opposed to building an extensive root system in rocky soils. The two species studied, A. vestita and B. brachycarpa, took different approaches to foraging in the rocky soil through distinctive trait syndromes of fine-root components.