Seed Rate Calculation

by
Seed Rate Calculator .src-container { font-family: 'Segoe UI', Roboto, Helvetica, Arial, sans-serif; max-width: 800px; margin: 0 auto; padding: 20px; background-color: #f9fbf9; border: 1px solid #e0e0e0; border-radius: 8px; } .src-header { text-align: center; margin-bottom: 30px; } .src-header h1 { color: #2e7d32; margin: 0; font-size: 28px; } .src-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 20px; } @media (max-width: 600px) { .src-grid { grid-template-columns: 1fr; } } .src-input-group { margin-bottom: 15px; } .src-input-group label { display: block; margin-bottom: 5px; font-weight: 600; color: #333; } .src-input-group input { width: 100%; padding: 10px; border: 1px solid #ccc; border-radius: 4px; font-size: 16px; box-sizing: border-box; } .src-input-group small { color: #666; font-size: 12px; } .src-btn { grid-column: 1 / -1; background-color: #2e7d32; color: white; padding: 15px; border: none; border-radius: 4px; font-size: 18px; cursor: pointer; width: 100%; margin-top: 10px; transition: background-color 0.3s; } .src-btn:hover { background-color: #1b5e20; } .src-results { margin-top: 30px; padding: 20px; background-color: #e8f5e9; border-radius: 8px; border-left: 5px solid #2e7d32; display: none; } .src-results h3 { margin-top: 0; color: #1b5e20; } .src-result-row { display: flex; justify-content: space-between; margin-bottom: 10px; padding-bottom: 10px; border-bottom: 1px solid #c8e6c9; } .src-result-row:last-child { border-bottom: none; } .src-value { font-weight: bold; font-size: 18px; color: #2e7d32; } .src-content { margin-top: 40px; line-height: 1.6; color: #333; } .src-content h2 { color: #2e7d32; margin-top: 30px; } .src-content ul { padding-left: 20px; } .src-highlight { background-color: #fff3cd; padding: 2px 5px; border-radius: 3px; }

Precision Seed Rate Calculator

Calculate optimal seeding rates based on TGW, germination, and emergence.

Plants per acre
Weight in grams per 1,000 seeds
Value from seed tag
Field survival estimate (mortality)
Total area to be seeded
Optional: Cost calculation

Calculation Results

Required Seed Rate: 0 lbs/acre
Actual Pure Live Seed (PLS) %: 0%
Seeds per Pound: 0
Total Seed Needed for Field: 0 lbs
Estimated Total Cost: $0.00

Why Use a Seed Rate Calculator?

Calculating the correct seed rate is one of the most critical steps in agronomy to ensure maximum yield potential. Using a flat rate (e.g., "100 lbs per acre" or "2 bushels per acre") is often inaccurate because seed size varies significantly between varieties and even between seed lots of the same variety.

This calculator determines the exact weight of seed required to achieve your target plant population by accounting for three critical variables: Thousand Grain Weight (TGW), Germination Rate, and Field Emergence.

Understanding the Inputs

  • Target Plant Population: The number of live plants you want established per acre. This varies by crop (e.g., Wheat might be 1.2 million, Corn might be 32,000).
  • Thousand Grain Weight (TGW): The weight in grams of 1,000 seeds. This measures seed density. Larger seeds require a higher seeding rate by weight to achieve the same plant count.
  • Germination Rate: Found on the certified seed tag, this is the percentage of seeds expected to germinate under ideal lab conditions.
  • Expected Emergence: The percentage of germinated seeds that actually survive field conditions (soil temperature, depth, pests). Typical values range from 85% to 95%.

The Seed Rate Formula

The calculation performed by this tool uses the following logic to convert target population into pounds per acre:

Seed Rate (lbs/acre) = (Target Pop × TGW (g)) ÷ (Germination % × Emergence % × 453.6) × 100

Example Calculation

Let's say you are planting spring wheat:

  • Target: 1,200,000 plants/acre
  • TGW: 35 grams
  • Germination: 98%
  • Emergence: 90%

First, calculate the survival factor: 0.98 × 0.90 = 0.882 (88.2% survival).

Then, determine total seeds needed: 1,200,000 ÷ 0.882 ≈ 1,360,544 seeds.

Finally, convert to weight: (1,360,544 seeds ÷ 1000) × 35g = 47,619 grams.

Convert grams to pounds: 47,619 ÷ 453.6 = 105 lbs/acre.

function calculateSeedRate() { // Get Input Values var targetPop = document.getElementById('targetPop').value; var tgw = document.getElementById('tgw').value; var germination = document.getElementById('germination').value; var emergence = document.getElementById('emergence').value; var fieldSize = document.getElementById('fieldSize').value; var seedCost = document.getElementById('seedCost').value; // Basic Validation if (targetPop === "" || tgw === "" || germination === "" || emergence === "") { alert("Please fill in Target Population, TGW, Germination, and Emergence fields."); return; } // Parse Floats var target = parseFloat(targetPop); var weightTGW = parseFloat(tgw); var germPercent = parseFloat(germination); var emergPercent = parseFloat(emergence); var acres = fieldSize ? parseFloat(fieldSize) : 0; var cost = seedCost ? parseFloat(seedCost) : 0; // Prevent division by zero if (germPercent === 0 || emergPercent === 0) { alert("Germination and Emergence cannot be zero."); return; } // 1. Calculate Pure Live Seed (PLS) decimal // Example: 95% germ * 90% emergence = 0.855 var survivalFactor = (germPercent / 100) * (emergPercent / 100); // 2. Calculate actual seeds needed per acre to hit target var seedsNeededPerAcre = target / survivalFactor; // 3. Calculate weight in Grams per acre // (Seeds needed / 1000) * TGW var gramsPerAcre = (seedsNeededPerAcre / 1000) * weightTGW; // 4. Convert Grams to Pounds (1 lb = 453.59237 g) var lbsPerAcre = gramsPerAcre / 453.59237; // 5. Calculate Seeds per Pound (Inverse of TGW logic) // 1 lb = 453.59g. (453.59 / TGW) * 1000 var seedsPerLb = (453.59237 / weightTGW) * 1000; // 6. Totals var totalLbsNeeded = lbsPerAcre * (acres > 0 ? acres : 1); var totalCostVal = totalLbsNeeded * cost; // Display Results document.getElementById('resultOutput').style.display = "block"; // Update HTML Elements document.getElementById('resRate').innerHTML = lbsPerAcre.toFixed(1) + " lbs/acre"; document.getElementById('resPLS').innerHTML = (survivalFactor * 100).toFixed(1) + "%"; document.getElementById('resSeedsPerLb').innerHTML = Math.round(seedsPerLb).toLocaleString(); if (acres > 0) { document.getElementById('resTotalWeight').innerHTML = Math.ceil(totalLbsNeeded).toLocaleString() + " lbs"; } else { document.getElementById('resTotalWeight').innerHTML = "Enter Field Size"; } if (acres > 0 && cost > 0) { document.getElementById('resTotalCost').innerHTML = "$" + totalCostVal.toFixed(2).replace(/\d(?=(\d{3})+\.)/g, '$&,'); } else { document.getElementById('resTotalCost').innerHTML = "Enter Size & Cost"; } }

Leave a Comment