Changes between Version 67 and Version 68 of Documentation/TrunkFunctionality4

Timestamp:

2020-11-01T13:42:10+01:00 (4 years ago)

Author:

luyssaert

Comment:

--

Documentation/TrunkFunctionality4

@@ -309 +309 @@
 
 === Nitrogen reserve pools ===
-Describes r6904. As the carbon, the model simulates two non-structural nitrogen pools: labile and reserve. Nitrogen uptake is stored in the labile pool, and after the growth, nitrogen exceeds the calculated potential labile pool moved to reserve nitrogen. Before the r6825, nitrogen limitation during plant growth was estimated using only labile nitrogen, and this resulted in the accumulation of reserve nitrogen. To deal with this issue, the functionality considers reserve nitrogen for estimating nitrogen limitation added to the r6825. The parameter '''use_reserve_n''' controls the functionality along with nitrogen uptake feedback which was added r6869 (See [wiki:TrunkFunctionality4#Rootnitrogenuptake Root nitrogen uptake]).
+Describes r6904. As for carbon, the model simulates two non-structural nitrogen pools: labile and reserve. Nitrogen uptake is stored in the labile pool, and after the growth, nitrogen in excess of the calculated target labile pool is moved to reserve nitrogen. Before r6825, nitrogen limitation during plant growth was rather common but was solely based on the labile nitrogen pool. It was rather common that the labile pool was empty but that at the same time the reserve pool was very well filled. Plant growth experienced n-stress despite having a good amount of N in the reserves. To deal with this issue, r6825 also considers the reserve nitrogen for estimating nitrogen limitation. The parameter '''use_reserve_n''' controls the functionality along with nitrogen uptake feedback which was added r6869 (See [wiki:TrunkFunctionality4#Rootnitrogenuptake Root nitrogen uptake]).
+
 
 === Parameter files ===
@@ -372 +373 @@
 
 === Root nitrogen uptake ===
-Describes r6904. The calculation of root nitrogen uptake in nitrogen_dynamice has two parts. First, the maximum amount of root nitrogen uptake is calculated based on soil chemical properties and long-term root carbon mass. And then, nitrogen uptake is adjusted by the feedback from nitrogen reserve; if the long-term ratio of actual to potential nitrogen reserve pool is over one, then root nitrogen uptake decreases. The uptake does not decrease further than '''p_n_uptake''' of maximum root nitrogen uptake. The adjustment was added due to carbon limitation and too much nitrogen in the plant which was caused by using the reserve nitrogen as possible (See [wiki:TrunkFunctionality4#Nitrogenreservepools Nitrogen reserve pools]), and it is controlled by the parameter '''use_reserve_n''' to y.
+Describes r6904. The calculation of root nitrogen uptake in nitrogen_dynamice has two parts. First, the maximum amount of root nitrogen uptake is calculated based on soil chemical properties and long-term root carbon mass. And then, nitrogen uptake is adjusted by the feedback from nitrogen reserve; if the long-term ratio of actual to potential nitrogen reserve pool is over one, then root nitrogen uptake decreases. The uptake does not decrease further than '''p_n_uptake''' times maximum root nitrogen uptake. The adjustment was added due to avoid carbon-limited growth (evident from too much nitrogen in the plants) which became more common after the code was changed such that the reserve nitrogen was used as much as possible. This setting is described in  [wiki:TrunkFunctionality4#Nitrogenreservepools Nitrogen reserve pools]), and it is controlled by the parameter '''use_reserve_n''' to y. A better use of the reserve nitrogen in the code was implemented after observing that the labile nitrogen pool was empty resulting in n-limited growth whereas the reserve pool was still well filled.