Calculate optimal pounds per acre based on target plant population and seed size.
Recommended: 22-25 for yield, higher for silage.
Weight of 1,000 seeds in grams. Usually 40-50g.
Found on your seed tag analysis.
Accounts for field loss. Typically 80-90%.
6 inches
7.5 inches
10 inches
12 inches
15 inches
Used to calculate seeds per linear foot.
Price per bushel (48 lbs/bu for barley).
Required Seeding Rate:0 lbs/acre
Bushels per Acre:0 bu/ac
Seeds per Linear Foot:0 seeds/ft
Total Survival Rate:0%
Estimated Seed Cost:$0.00 / acre
Understanding Barley Seeding Rates
Calculating the correct seeding rate is one of the most cost-effective management decisions a barley grower can make. Relying on the old "bushels per acre" rule of thumb often leads to under-seeding when kernels are heavy (high TKW) or over-seeding when kernels are small, directly impacting your stand establishment and yield potential.
The Formula Explained
This calculator uses the industry-standard agronomic formula to determine exactly how much seed weight is required to achieve your target plant population. The math considers the weight of the individual seeds and the expected mortality rate in the field.
Target Plant Density: For general malt or feed barley, a target of 22 to 25 plants per square foot is typically recommended to maximize yield while minimizing lodging risk. Silage barley may benefit from higher densities.
Thousand Kernel Weight (TKW): This is the weight in grams of 1,000 seeds. Barley TKW can range significantly from 35g to 55g depending on the variety and growing conditions of the seed lot. Heavier seeds require a higher seeding rate (in lbs) to achieve the same number of plants.
Germination Rate: This comes from your seed lab analysis. It represents the percentage of seeds capable of sprouting under ideal conditions.
Emergence/Survival: This factors in field mortality due to insects, disease, depth of seeding, and environmental stress. A typical value is 80-90%. If seeding into cold, wet, or heavy trash conditions, consider lowering this percentage (which will increase your seeding rate).
Why Calibrate by Seeds per Foot?
Once you have your target pounds per acre, it is crucial to verify your drill's output. The "Seeds per Linear Foot" metric provided in the results helps you ground-truth your calibration. By digging up a few feet of row after a pass, you can count the seeds and ensure your drill is delivering the calculated population effectively.
function calculateBarleyRate() {
// 1. Get input values
var targetDensity = parseFloat(document.getElementById('targetDensity').value);
var tkw = parseFloat(document.getElementById('tkw').value);
var germination = parseFloat(document.getElementById('germination').value);
var emergence = parseFloat(document.getElementById('emergence').value);
var rowSpacing = parseFloat(document.getElementById('rowSpacing').value);
var seedCost = parseFloat(document.getElementById('seedCost').value);
// 2. Validate inputs
if (isNaN(targetDensity) || targetDensity <= 0) {
alert("Please enter a valid target plant density.");
return;
}
if (isNaN(tkw) || tkw <= 0) {
alert("Please enter a valid TKW (Thousand Kernel Weight).");
return;
}
if (isNaN(germination) || isNaN(emergence)) {
alert("Please enter valid percentages for germination and emergence.");
return;
}
// 3. Calculation Logic
// Calculate Total Survival Factor (Decimal)
// Example: 95% Germ * 85% Emergence = 0.95 * 0.85 = 0.8075
var totalSurvivalDecimal = (germination / 100) * (emergence / 100);
var totalSurvivalPercent = (totalSurvivalDecimal * 100).toFixed(1);
// Constant conversion factor for Imperial units
// Based on: (Plants/sq ft * 43560 sq ft/ac * TKW g / 1000 seeds) / 453.6 g/lb
// 43.56 / 453.6 * 1000 is approx 96, but simplified formula usually uses 10.
// Precise factor is 9.604. Let's use 9.6.
var conversionFactor = 9.6;
// Formula: Rate (lb/ac) = (Target Plants/ft² * TKW * 9.6) / Total Survival Decimal * 100?
// Actually the formula is usually: (Target * TKW * 10) / Survival% (where survival is an integer like 85)
// Let's stick to the precise math:
// Numerator: Target seeds per acre in grams / 1000 * 9.6 ??
// Let's do it raw:
// Plants per acre needed = (Target Density * 43560) / Total Survival Decimal
var plantsPerAcreNeeded = (targetDensity * 43560) / totalSurvivalDecimal;
// Total weight in grams
var weightInGrams = plantsPerAcreNeeded * (tkw / 1000);
// Total weight in lbs (1 lb = 453.59237 g)
var lbsPerAcre = weightInGrams / 453.59237;
// Bushels (Barley = 48 lbs/bu)
var buPerAcre = lbsPerAcre / 48;
// Linear Seeds per foot
// Formula: Target Plants/ft² * (Row Spacing in inches / 12) / Total Survival Decimal
// We want SEEDS dropped, not plants surviving.
// Seeds per sq ft = Target Density / Total Survival Decimal
var seedsPerSqFt = targetDensity / totalSurvivalDecimal;
var seedsPerLinearFoot = seedsPerSqFt * (rowSpacing / 12);
// Cost per acre
var costPerAcre = buPerAcre * seedCost;
// 4. Update UI
document.getElementById('resLbsAcre').innerText = lbsPerAcre.toFixed(1);
document.getElementById('resBuAcre').innerText = buPerAcre.toFixed(2);
document.getElementById('resSeedsFoot').innerText = seedsPerLinearFoot.toFixed(1);
document.getElementById('resTotalSurvival').innerText = totalSurvivalPercent;
if (!isNaN(costPerAcre)) {
document.getElementById('resCostAcre').innerText = costPerAcre.toFixed(2);
} else {
document.getElementById('resCostAcre').innerText = "0.00";
}
// Show results
document.getElementById('resultArea').style.display = 'block';
}