Difference between residue components

[Carlos Alberto Arnillas]

Hello

I am trying to understand the transformations that can occur to the biomass once a plant is dead. So far, I found a few variables that seem strongly related but I don't fully understand how they relate to each other. 

STD: Standing crop residue in t ha-1. (reported in the .SAO and .SAD files)

CVRS: Aboveground crop residue in t ha-1. (not reported in the output files but defined in the theoretical documentation)

RSD: Flat crop residue in t ha-1. (exported either by layer in the DCN file or only for the top layer in the .SAD file)

Besides that, we have BIOM which is split in aboveground (STL) and below ground (RW). And yield (YLDG for grains and YLDF for forage)

Conceptually, what is the difference between STD and CVRS? Also, how is the mass transferred between these compartments? when would that happen?

For instance:

- once a plant dies the belowground biomass is transferred from RW to the different layers of RSD (is this right?). However, it is unclear to me what happens with STL... a part goes to yield, and the rest goes to STD, CVRS or RSD?

- Under some conditions, a part of STL become STD (e.g.,during winter). Does it later become CVRS or RSD?

- What is the impact of tillage on these biomass compartments?

Thanks for your help!

Carlos Alberto

[Jaehak]

STD is standing dead biomass. RSD is crop residue on the surface or in soils. RSD can be incorporated into soil for degradation via tillage or biological mixing. STD turns to STD after a ploughing operation or slowly over time without management. CVRS is surface cover that includes STD and RSD used for estimating USLE cover factor. 

 -once a plant dies the belowground biomass is transferred from RW to the different layers of RSD (is this right?). However, it is unclear to me what happens with STL... a part goes to yield, and the rest goes to STD, CVRS or RSD?

  This is answered above.

- Under some conditions, a part of STL become STD (e.g.,during winter). Does it later become CVRS or RSD?

  Yes, STL -> STD -> RSD. 

- What is the impact of tillage on these biomass compartments?

 A tillage operation accelerates the incorporation of standing dead biomass into soils and decomposition.

[Carlos Alberto Arnillas]

Thanks Jaehak