EGU General Assembly 2020
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Silicon recycling through rice-residue management does not prevent silicon depletion in paddy rice cultivation

Harold Hughes1, Dao Trong Hung1,2, and Daniela Sauer1
Harold Hughes et al.
  • 1Georg-August-Universität Göttingen, Geographisches Institut, Physical Geography, Göttingen, Germany (
  • 2Soils and Fertilizers Research Institute, Duc Thang, Bac Tu Liem, Hanoi 1000, Vietnam

Silicon (Si) is known to have beneficial effects on plants, in particular on rice, which is a strong Si accumulator. Si helps mitigate environmental stresses and nutrient deficits of plants. In some regions, the limited plant-available Si in soils might have detrimental effects on rice cultivation. Crop-residue recycling can help to maintain the amount of plant-available Si in soils. However, the effect of crop-residue management practices on the soil-plant Si cycle and on Si availability to plants remains largely understudied. Here, we contribute to fill this knowledge gap by reporting a study on the effects of three different rice-residue management practices on Si-depleted paddy rice systems from northern Vietnam. The rice-residue management practices were (1) direct incorporation of rice residues into the soils, (2) burning in the field, and (3) use as fodder for animals, followed by composting of the obtained manure, and subsequent application of the composted manure to the field. We analyzed different Si reservoirs in soils and plant-Si contents under these different practices. Our results show a strong correlation between the different soil Si reservoirs and plant Si contents. We found no significant difference with respect to plant-available Si in soils and plant-Si contents between the different management practices. Moreover, our data suggest that Si-depleted rice-cultivation systems proportionally lose Si through grain harvest faster than less Si-depleted systems, because of enhanced relative Si accumulation in the grains. This loss cannot be mitigated by straw recycling. It may be one of the reasons why straw recycling has only a limited effect in the extremely Si-depleted rice-cultivation systems that were analysed in this study. Such information is critical in finding ways to maintain an appropriate level of plant-available Si in cultivated soils.

How to cite: Hughes, H., Trong Hung, D., and Sauer, D.: Silicon recycling through rice-residue management does not prevent silicon depletion in paddy rice cultivation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16603,, 2020.


Display file

Comments on the display

AC: Author Comment | CC: Community Comment | Report abuse

displays version 1 – uploaded on 04 May 2020
  • CC1: Comment on EGU2020-16603, Damien Cardinal, 07 May 2020

    Dear Harold and coauthors

    Thanks for this original and interesting study. How would you explain the inverse relationship you have between the fraction of Si in grain vs. total plant Si content? Can a simple Si transfer explain this (i.e. mass balance is fullfilled)? Could it be possible that the plant "must" accumulate and/or keep a minimum concentration Si in grain to be healthy? Why?



    • AC1: Reply to CC1, Harold Hughes, 07 May 2020

      Dear Damien, 

      This is an excellent question… to which we currently have no clear answer.
      Despite the abundant literature on Si in rice we could not find any previous mention of this phenomenon. However, since the grain is not a part of the plant with a strong transpiration flux, it is likely that this preferential accumulation of Si in the grain (incl. the husk) is also the result of an active process.
      As rice is a strong Si accumulator, actively taking up Si from soil solution (and thus spending energy to take up this Si)  this Si accumulation in the grain should result in some sort of advantage for the plant (a "return on investment" for the energy spent in taking up this Si). 
      As the grain is not a vital part of the plant individual an effect on the plant’s health seems unlikely. But maybe the higher Si content provides a better physical protection to the grain, later resulting in a higher fertility rate. This is still pure speculation, though.
      This is certainly one of the most interesting aspects of our study and I hope this can be studied more in detail in the futur. This is still based on just three datasets, so the first point would be to see if this trend is confirmed by futur studies as, unfortunately, most publications on Si in rice only mention the total Si in plant or the total Si in straw. 

      Best regards,