Pea Seed Rate Calculator

Target Plant Density (plants/m²) Standard: 70-90 plants/m²

Thousand Seed Weight (g) Weight of 1000 seeds in grams

Germination Rate (%)

Expected Survival (%) Accounting for frost/pests

Calculation Results

Required Seeding Rate: 0 kg/ha

Equivalent to: 0 lbs/acre

function calculatePeaRate() { var target = parseFloat(document.getElementById('targetPlants').value); var tsw = parseFloat(document.getElementById('tsw').value); var germ = parseFloat(document.getElementById('germination').value); var surv = parseFloat(document.getElementById('survival').value); if (isNaN(target) || isNaN(tsw) || isNaN(germ) || isNaN(surv) || germ <= 0 || surv <= 0) { alert("Please enter valid positive numbers."); return; } // Formula: (Target plants/m2 * TSW) / (Expected emergence %) // Expected emergence = (Germination * Survival) / 100 var emergence = (germ * surv) / 100; var seedingRateKg = (target * tsw) / emergence; // Conversion to lbs/acre: 1 kg/ha = 0.892179 lbs/acre var seedingRateLb = seedingRateKg * 0.892179; document.getElementById('kgRate').innerText = seedingRateKg.toFixed(1); document.getElementById('lbRate').innerText = seedingRateLb.toFixed(1); document.getElementById('peaResult').style.display = 'block'; }

Optimal Seeding Rates for Field Peas

Calculating the correct seeding rate for field peas is critical for maximizing yield and managing weed competition. Unlike cereals, pea seed size can vary significantly between varieties and even between different lots of the same variety. This variation makes calculating rates based on "bushels per acre" highly inaccurate.

Key Variables Explained

Target Plant Density: Most agronomists recommend a target of 75 to 85 established plants per square meter (approx. 7-8 plants per square foot). Higher densities may be required in weed-heavy areas.
Thousand Seed Weight (TSW): This is the weight in grams of 1,000 seeds. Pea seeds vary from 150g to over 300g. A large-seeded variety requires a much higher weight of seed to achieve the same plant count as a small-seeded variety.
Germination vs. Survival: Germination is the percentage of seeds capable of sprouting in lab conditions. Survival (or emergence) accounts for field conditions, such as soil temperature, moisture, and seedling diseases. Usually, a 5-10% mortality rate is expected even in good conditions.

Field Pea Rate Calculation Formula

Seeding Rate (kg/ha) = [Target Density (plants/m²) × TSW (g)] ÷ [Survival %]

Practical Example

Suppose you are planting yellow peas with the following data:

Metric	Value
Target Population	80 plants/m²
Thousand Seed Weight	250 grams
Expected Survival	90%

Calculation: (80 × 250) / 90 = 222.2 kg/ha (approx. 198 lbs/acre or 3.3 bushels/acre).

Why Accuracy Matters

Over-seeding leads to unnecessary seed costs and increased risk of lodging and Sclerotinia. Under-seeding results in poor weed competition and reduced yield potential, as peas do not "tiller" or fill in gaps as effectively as wheat or barley.