Disclaimer

Why a result will differ from what you actually need

• Soil settles. Fresh compost and bagged mixes lose volume as they settle and as organic matter breaks down. A bed filled exactly to the calculated volume will usually want topping up within a season.
• Bags vary. Bagged soil, compost and mulch are sold by volume that can be measured loose or compressed, and moisture content changes what is in the bag. Read the bag rather than assuming.
• Soil chemistry is local. Lime requirement in particular depends on buffering capacity, which no online form can measure. Two soils at the same pH can need substantially different amounts of limestone.
• Published rates are regional averages. Seeding rates, spacing, days to maturity and yields come from extension service and horticultural sources and reflect typical conditions, not your garden in a particular year.
• Frost dates are probabilities, not promises. An average last frost date is a statistical midpoint. Roughly half of years are later than it.

No professional advice

Nothing here is professional agronomic, horticultural, financial or legal advice. It is general information for home gardeners. Decisions with real cost or risk attached — amending soil chemistry, applying fertilizer near water, planting a commercial crop — should be made with a current soil test and advice from someone who can inspect the site. In the United States and Canada, a county or provincial extension service will usually do this cheaply or free; in the United Kingdom, the Royal Horticultural Society is a good starting point.

Chemicals and safety

Fertilizer, lime and other amendments are regulated products. Always follow the label on the product you actually bought: the label is the legal instruction and it overrides any figure this site gives you. Over-application can damage plants, and can run off into groundwater and watercourses. Keep products and treated areas away from children and pets as the label directs.

Accuracy and corrections

The formulas are unit-tested and the data files record the source of every published figure, but mistakes are still possible. If you find one, write to hello@soilsums.com and it will be fixed and noted. How the numbers are sourced and checked is described on the about page.

External links

Links to extension services, standards bodies and other sites are provided for reference. SoilSums does not control those sites and is not responsible for their content or their privacy practices.

Limitation of liability

The site is provided as-is, without warranty of any kind. To the fullest extent permitted by law, Muzamil Ali accepts no liability for loss or damage — including wasted material, crop loss or costs incurred — arising from use of this site or reliance on its results. The terms of use set this out in full.