Add guards for b_lu_hi=0 in N residue removal and NH3 emission

fdm-calculator/CHANGELOG.md

@@ -1,5 +1,11 @@
 # fdm-calculator
 
+## 0.6.1
+
+### Patch Changes
+
+- a9acf19: Fix divide-by-zero in nitrogen balance when b_lu_hi is undefined or 0
+
 ## 0.6.0
 
 ### Minor Changes

fdm-calculator/package.json

@@ -1,7 +1,7 @@
 {
     "name": "@svenvw/fdm-calculator",
     "private": false,
-    "version": "0.6.0",
+    "version": "0.6.1",
     "description": "Calculate various insights based on the Farm Data Model",
     "license": "MIT",
     "homepage": "https://github.com/SvenVw/fdm",

fdm-calculator/src/balance/nitrogen/emission/ammonia/residues.test.ts

@@ -258,4 +258,58 @@ describe("calculateNitrogenEmissionViaAmmoniaByResidues", () => {
             { id: "cultivation1", value: expect.any(Decimal) },
         ])
     })
+
+    it("should return 0 when b_lu_hi is 0", () => {
+        const cultivations: FieldInput["cultivations"] = [
+            {
+                b_lu: "cultivation1",
+                b_lu_catalogue: "catalogue1",
+                b_lu_start: new Date("2022-01-01"),
+                b_lu_end: new Date("2022-12-31"),
+                m_cropresidue: true,
+            },
+        ]
+        const harvests: FieldInput["harvests"] = [
+            {
+                b_id_harvesting: "harvest1",
+                b_lu: "cultivation1",
+                b_lu_harvest_date: new Date(),
+                harvestable: {
+                    b_id_harvestable: "harvestable1",
+                    harvestable_analyses: [
+                        {
+                            b_lu_yield: 1000,
+                            b_lu_n_harvestable: 20,
+                        },
+                    ],
+                },
+            },
+        ]
+        const cultivationDetailsMap = new Map<string, CultivationDetail>([
+            [
+                "catalogue1",
+                {
+                    b_lu_catalogue: "catalogue1",
+                    b_lu_croprotation: "cereal",
+                    b_lu_yield: 1000,
+                    b_lu_n_harvestable: 20,
+                    b_lu_hi: 0,
+                    b_lu_n_residue: 14,
+                    b_n_fixation: 0,
+                },
+            ],
+        ])
+
+        const result = calculateNitrogenEmissionViaAmmoniaByResidues(
+            cultivations,
+            harvests,
+            cultivationDetailsMap,
+        )
+
+        //Check for approximation due to floating point
+        expect(result.total.equals(new Decimal(0))).toBe(true)
+        expect(result.cultivations).toEqual([
+            { id: "cultivation1", value: new Decimal(0) },
+        ])
+    })
 })

fdm-calculator/src/balance/nitrogen/emission/ammonia/residues.ts

@@ -97,6 +97,14 @@ export function calculateNitrogenEmissionViaAmmoniaByResidues(
         const b_lu_hi = new Decimal(cultivationDetail.b_lu_hi ?? 0)
         const b_lu_hi_res = new Decimal(1).minus(b_lu_hi)
 
+        // If cultivation has no residues possible return 0
+        if (b_lu_hi.isZero()) {
+            return {
+                id: cultivation.b_lu,
+                value: new Decimal(0),
+            }
+        }
+
         // Get the Nitrogen content of the crop residues
         const b_lu_n_residue = new Decimal(
             cultivationDetail.b_lu_n_residue ?? 0,

fdm-calculator/src/balance/nitrogen/removal/residue.test.ts

@@ -17,6 +17,18 @@ describe("calculateNitrogenRemovalByResidue", () => {
                 b_n_fixation: 0,
             },
         ],
+        [
+            "catalogue2",
+            {
+                b_lu_catalogue: "catalogue2",
+                b_lu_croprotation: "quinoa",
+                b_lu_yield: 1000,
+                b_lu_n_harvestable: 20,
+                b_lu_hi: 0,
+                b_lu_n_residue: 2,
+                b_n_fixation: 0,
+            },
+        ],
     ])
 
     it("should return 0 if no crop residues are left", () => {
@@ -216,4 +228,28 @@ describe("calculateNitrogenRemovalByResidue", () => {
         expect(result.total.toNumber()).toBeCloseTo(-3) //Approximation due to floating point
         expect(result.cultivations[0].value.toNumber()).toBeCloseTo(-3) //Approximation due to floating point
     })
+
+    it("should return 0 if b_lu_hi is 0", () => {
+        const cultivations: FieldInput["cultivations"] = [
+            {
+                b_lu: "cultivation1",
+                b_lu_catalogue: "catalogue2",
+                b_lu_start: new Date("2022-01-01"),
+                b_lu_end: new Date("2022-12-31"),
+                m_cropresidue: true,
+            },
+        ]
+        const harvests: FieldInput["harvests"] = []
+
+        const result = calculateNitrogenRemovalByResidue(
+            cultivations,
+            harvests,
+            cultivationDetailsMap,
+        )
+
+        expect(result).toEqual({
+            total: new Decimal(0),
+            cultivations: [{ id: "cultivation1", value: new Decimal(0) }],
+        })
+    })
 })

fdm-calculator/src/balance/nitrogen/removal/residue.ts

@@ -75,7 +75,9 @@ export function calculateNitrogenRemovalByResidue(
 
             // Fallback to default yield from cultivation_catalogue
             if (yieldForThisHarvest === null) {
-                yieldForThisHarvest = cultivationDetail.b_lu_yield
+                yieldForThisHarvest = new Decimal(
+                    cultivationDetail.b_lu_yield ?? 0,
+                )
             }
 
             if (yieldForThisHarvest !== null) {
@@ -101,6 +103,14 @@ export function calculateNitrogenRemovalByResidue(
             cultivationDetail.b_lu_n_residue ?? 0,
         )
 
+        // If cultivation has no residues possible return 0
+        if (b_lu_hi.isZero()) {
+            return {
+                id: cultivation.b_lu,
+                value: new Decimal(0),
+            }
+        }
+
         // Calculate the amount of Nitrogen removed by crop residues of this cultivation
         const removal = b_lu_yield
             .dividedBy(b_lu_hi)
@@ -115,7 +125,7 @@ export function calculateNitrogenRemovalByResidue(
         }
     })
 
-    // Aggregate the total maount of Nitrogen removed by crop residues
+    // Aggregate the total amount of Nitrogen removed by crop residues
     const totalValue = removalsResidue.reduce((acc, residue) => {
         return acc.add(residue.value)
     }, new Decimal(0))