30-0-10 Fertilizer: What It Is Used For and How Much

A 30-0-10 fertilizer contains 30% nitrogen, no phosphate (P₂O₅) and 10% potash (K₂O) by weight. The three numbers are always N, P₂O₅ and K₂O, in that order (University of Maryland Extension). The nitrogen drives green leaf growth, potassium helps regulate the plant’s water use, and the zero means no phosphorus is added. That is why this grade is used on lawns and crops where a soil test already shows enough phosphorus.

This guide explains what this grade is used for, how it differs from 29-0-10 and 10-0-10, how much to spread, and what it costs per pound of nitrogen. It includes a calculator for your own lawn or field size, and a dated price chart. Always check the bag label, your soil test and local advice before you apply anything.

30-0-10 fertilizer meaning: what the three numbers say

Every fertilizer bag shows its grade, also called the nutrient analysis. The three numbers are the percentage by weight of nitrogen (N), phosphate (P₂O₅) and potash (K₂O). A 5 lb bag of 10-5-5 holds 0.5 lb of N, 0.25 lb of P₂O₅ and 0.25 lb of K₂O. The rest of the bag is filler that stops caking and makes the product easy to pour (University of Maryland Extension).

Apply the same reading to our three grades. In a 50 lb bag, the 30% grade holds 15 lb of nitrogen and 5 lb of potash. A 29-0-10 holds 14.5 lb and 5 lb. A 10-0-10 holds 5 lb of each. A fertilizer with only one or two of the three major nutrients is called an incomplete fertilizer. The University of Georgia gives 15-0-15 as an example, and all three grades here fit that description (University of Georgia Extension).

The last column is the grade math used by Virginia Tech: pounds of product equal the pounds of nitrogen you want divided by the nitrogen percentage, times 100. For example, 1.0 lb of N from a 28-0-4 fertilizer takes 3.6 lb of product (Virginia Tech, publication CSES-135).

Chart

Nitrogen share of the product, by weight

Percent nitrogen in two nitrogen sources and the three grades in this guide

What is 30-0-10 fertilizer used for?

It is used where plants need a lot of nitrogen and some potassium, and the soil already holds enough phosphorus. In practice that means three kinds of use.

• Lawns and turf. Virginia Tech notes that when soil tests show high phosphorus and potassium, fertilizers that supply only nitrogen are the right choice. A 30-0-10 fits when the test shows enough phosphorus but potassium is not high, because it adds some potash as well.
• Grass crops and pasture. Grasses respond to nitrogen, so a high-nitrogen grade can fit when a soil test shows phosphorus is adequate. Whether it suits a field crop, and at what rate, comes from your local extension service and the label, not from the grade alone.
• Vegetable and ornamental beds. Nitrogen needs depend on the crop and the soil test, so follow the label and your extension advice.

The potassium share also matters. The University of Georgia notes that potassium can leach through the soil, unlike phosphorus, which generally stays put, and that most Georgia lawns test lower in potassium than phosphorus. Georgia also reports that potassium does not contribute to water quality problems the way nitrogen and phosphorus can (University of Georgia Extension).

How 30-0-10 compares with 29-0-10 and 10-0-10

29-0-10 is the same type of product with one point less nitrogen. In practice you need about 3.4 lb of it for each pound of nitrogen, against 3.3 lb. The two supply almost the same nitrogen and potash per pound, but compare the label, because the nitrogen source, the share of slow-release nitrogen and the price can differ more than the grade does.

10-0-10 is a dilute 1:1 feed. You need 10 lb of product per pound of nitrogen, three times as much as with the 30% grade. It suits sites where both nitrogen and potassium are wanted in equal amounts and where you want a light, easy-to-spread rate. Because it is so dilute, bags cost more per pound of nutrient than a concentrated grade at the same shelf price. The calculator below shows this.

The grade numbers say nothing about how fast the nitrogen is released. Quick sources such as urea and ammonium sulfate act fast and can leach. Slow sources such as polymer-coated or methylene urea release over weeks. The label lists the slow-release share, often as water-insoluble nitrogen (Virginia Tech, publication CSES-135).

Why the middle number is zero

Phosphorus is a needed nutrient, but extra phosphorus can wash off land into streams and lakes. The US Environmental Protection Agency says excess nitrogen and phosphorus can wash from fields into waterways and cause eutrophication, which can lead to oxygen-poor dead zones and fish kills (US EPA). Its nutrient pollution page counts more than 165 documented dead zones across the US.

That is why several US states and counties limit phosphorus fertilizer on lawns. Minnesota was the first state to do so. Its law bars phosphorus lawn fertilizer unless a soil or plant tissue test shows a need, the lawn is new, or the site is a golf course or sod farm. A grade counts as zero in Minnesota if it holds less than 0.67% phosphate (Minnesota Department of Agriculture). Maryland also has a lawn fertilizer law, and University of Maryland Extension tells residents to follow its guidelines. In Florida, five Central Florida counties bar fertilizer containing nitrogen or phosphorus from June 1 to September 30 (Central Florida Public Media), and Miami-Dade bars both from May 15 to October 31 (UF/IFAS Extension).

Rules vary by state, county and city, and they change. Before you buy any fertilizer, check your local ordinance and your extension office. A zero-phosphorus grade is not a permit to apply nitrogen in a restricted season.

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How much 30-0-10 to spread: a worked example

Start from the nitrogen your soil test or extension guide recommends, not from the bag. Recommendations for lawns are given in pounds of nitrogen per 1,000 square feet. Then convert to product with the grade.

Virginia Tech’s 2015 guide cites the state’s nutrient management standards (revised 2014), which allow no more than 0.7 lb of available nitrogen per active growing month for cool-season turf, with seasonal totals up to 3.5 lb of N per 1,000 square feet for cool-season lawns and 4 lb for some warm-season lawns, and not every lawn needs the full amount. Those are Virginia’s limits, so use your own state’s guide.

A worked example: a 5,000 square foot lawn, a target of 1 lb of nitrogen per 1,000 square feet, and a 30% nitrogen product. That is 5 x 1 / 0.30 = 16.7 lb of product, which also supplies 1.7 lb of K₂O across the lawn. With 10-0-10 the same job takes 50 lb of product. Check the bag for the maximum rate per application, and do not exceed it.

Chart

Product needed for 1 lb of nitrogen per 1,000 sq ft

Pounds of fertilizer, from grade math (100 divided by the N percentage)

Try the numbers for your own farm below.

What nitrogen costs per pound

Compare fertilizers by the price of the nutrient, not the bag. The cost per pound of N is the bag price divided by the pounds of nitrogen in it. At the retail urea price of $858 per ton for the week of April 13, 2026, one pound of nitrogen in urea (46% N) cost about $0.93 (farmdoc daily, University of Illinois, using DTN weekly retail prices; 2,000 lb per ton). That urea price was up 41.1% from the week of February 16 and 48.7% from a year earlier. Potash averaged $491 per ton, up 0.8% from the week before the conflict and 5.1% from a year earlier.

The World Bank reports a different basis: a price for urea above $850 per metric ton in April 2026, up 80% since February, with its fertilizer price index at its highest since October 2022 (World Bank, Commodity Markets Outlook, April 2026). It expects prices to ease in 2027 if exports recover. Bag prices for lawn products vary by store and by the nitrogen source, and these are list and retail averages, not what you will pay today.

Chart

US retail fertilizer price rise, April 2026

Percent change in weekly average retail price, week of 13 April 2026. Urea: vs week of 16 Feb; potash: vs week before the conflict

When a different grade is the better choice

Use a grade with phosphorus when a soil test says phosphorus is low, when you seed or sod a new lawn, or when a crop is known to respond to it. Virginia Tech advises choosing the product closest to the N:P₂O₅:K₂O ratio your soil test gives, and lists the fertilizers normally used to correct severe phosphorus or potassium shortages: 0-20-20, 0-28-0, 0-0-50 and 0-0-60. A grade like 13-13-13 gives equal parts of all three; see our guide to 13-13-13 fertilizer if the test shows a need for all three.

Nitrogen-only or potassium-only products can be better when the test shows only one gap. A fertilizer such as 30-10-10 holds 10% phosphate, so it is not phosphorus-free and may not be allowed on lawns in states with phosphorus rules.

Using satellite maps to check results

After you apply nitrogen, a lawn or field should green up evenly. Satellite vegetation maps such as NDVI show where plant vigour differs inside a field. Farmonaut Satellite + AI Farm Monitoring System can draw these maps for your fields through the season. A map shows that an area is weaker, not why. Confirm the cause with a soil test, a tissue test or a look in the field before adding more fertilizer.

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Reading a soil test before you buy

A soil test report gives two things: how much of each nutrient is in the soil, and what to add. For lawns, the advice is usually in pounds of nitrogen, phosphate and potash per 1,000 square feet. A report that says “apply nitrogen, no phosphate, a little potash” points to a grade of this type. A report that asks for phosphate points elsewhere. The nitrogen advice is often given for the kind of grass, because Virginia Tech notes that a lawn soil test report holds a nitrogen recommendation for the grass, not a nitrogen test level.

Take the sample the way your lab asks, and use a certified lab. Each lab has its own sampling method, so follow your lab’s instructions.

When to apply

Timing depends on the grass and the region. In Virginia, the best window for cool-season grasses is mid-August to early November, and warm-season grasses do best when fertilized between April 1 and August 15 (Virginia Tech). In Florida, local rules can bar nitrogen and phosphorus for months in the rainy season. For field crops, ask your extension service for the stage and split of nitrogen for your crop. A high-nitrogen grade is a poor fit when the plant is no longer growing, because unused nitrogen can be lost from the soil (US EPA).

Common mistakes with high-nitrogen blends

• Using the product rate in pounds per bag as if it were the nitrogen rate. Compare nitrogen, not bags.
• Applying more than the label allows in one pass. Virginia’s nutrient management standards (quoted by Virginia Tech in 2015), for example, cap available nitrogen at 0.7 lb per 1,000 square feet per growing month for cool-season turf; slow-release products are allowed more.
• Spreading on hard surfaces or before a storm.
• Assuming zero phosphorus means zero risk. Nitrogen also reaches waterways (US EPA).

Best practices for any zero-phosphorus blend

• Take a soil test first, and re-test every few years. University of Maryland Extension notes that labs usually give phosphorus and potassium advice as pounds of phosphate and potash, matching the bag. If you need to convert, P x 2.3 gives P₂O₅ and K x 1.2 gives K₂O.
• Pick the product by the pounds of nitrogen you need, then check the slow-release share on the label.
• Spread evenly, at or below the label rate, and sweep granules off paved surfaces. Minnesota requires spills on sidewalks and streets to be cleaned up at once.
• Do not fertilize before heavy rain, on frozen ground or in a restricted season.
• Keep compost or organic matter in the plan; the University of Maryland notes that need falls as soil organic matter rises.
• Keep notes of date, product and rate for each area, so next year’s test and plan build on what you did.

This page is general information, not advice for your site. Follow the product label and local rules, and ask your extension office or a certified crop adviser for rates that fit your soil and crop.

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FAQ

What is 30-0-10 fertilizer used for?

It feeds plants that need plenty of nitrogen and some potassium where the soil already has enough phosphorus. Typical uses are lawns, turf and grass crops. Check the label rate and your soil test first.

What does 29-0-10 fertilizer mean?

It means 29% nitrogen, 0% phosphate and 10% potash by weight. It works like 30-0-10 with one point less nitrogen, so you need about 3.4 lb of product per pound of nitrogen instead of 3.3 lb.

What is 10-0-10 fertilizer good for?

It gives equal parts nitrogen and potassium in a dilute form. It is used where a light feed of both is wanted and soil tests show enough phosphorus. It takes 10 lb of product per pound of nitrogen, so compare cost per pound of nutrient before you buy.

What is 30-10-10 fertilizer?

It is 30% nitrogen, 10% phosphate and 10% potash. Unlike the zero-phosphorus grades it contains phosphorus, so lawn phosphorus rules may apply.

How do I know if my soil needs phosphorus?

Use a soil test from a certified lab. The Minnesota Department of Agriculture ties phosphorus use on lawns to a soil or plant tissue test, and Virginia Tech advises nitrogen-only fertilizer when tests show high phosphorus and potassium.

Can I use zero-phosphorus fertilizer on every crop?

Only where the soil test shows enough phosphorus. Crops grown in low-phosphorus soil need a grade or a separate product that supplies it. Ask your local extension service for crop rates.