Phosphate rock: Correlation
Prices it moves with, and why
Phosphate rock is mined mainly in Morocco, China, the US and Russia and mostly turned into phosphoric acid and fertilisers. Prices follow fertiliser demand, Chinese export curbs and the cost of the sulphur and ammonia used to process it.
Market price World Bank Pink Sheet: Phosphate rock $/mt · monthly, Jan 2006 to Sep 2026What its price moves with
Selected linkPhosphate rock and Phosphoric acid
Monthly changes 0.07 little or none correlation 12-month changes 0.54 moderate correlation Last 5 years -0.04 monthly changes Lead or lag +5 mo Phosphoric acid tends to lead by 5 months (r 0.40) Price function, Dec 2009 to Sep 2026 Phosphate rock ≈ 0.309 × (Phosphoric acid)1.20 R² 0.61 On this fit, a 10% higher phosphoric acid price goes with a 12.2% higher phosphate rock price over the long run. Units: $/mt and index (BLS base period).Chart: Phosphate rock and Phosphoric acid prices rebased to 100 at Dec 2009, log scale
Both prices rebased to 100 at Dec 2009, on a log scale so equal percentage moves look the same size.Chart: Phosphate rock price against Phosphoric acid price, monthly, log scales, with fitted line
Each dot is one month; paler dots are older (2009), darker dots recent (2026); the ringed dot is the latest month. The dashed line is the fitted price function. Both axes are logarithmic.Rock is dissolved in sulphuric acid to make phosphoric acid, the base of nearly all phosphate fertilisers. Rock is often sold on quarterly or annual contracts, so the proxy index leads by about 5 months; yearly moves correlate at 0.54 while monthly moves barely do (0.08).
little or none co-movement month to month · 202 months Show chartsDAP is made by reacting phosphoric acid with ammonia, and its price is the clearest signal of phosphate demand. Rock prices respond slowly: DAP leads by about 6 months, yearly changes correlate at 0.36 and monthly ones at only 0.05.
little or none co-movement month to month · 249 months Show chartsSulphuric acid, made mostly from refinery and gas plant sulphur, is needed in large amounts to break down rock, so acid costs squeeze or widen processors' margins. Monthly moves correlate at 0.16 and yearly moves at 0.57 with the US acid index.
little or none co-movement month to month · 225 months Show chartsAmmonia is the other input to DAP and MAP, so gas-driven ammonia spikes raise finished phosphate fertiliser prices and feed back slowly into rock contracts. With the US nitrogen fertiliser index as proxy, yearly changes correlate at 0.59 and ammonia tends to lead by about 6 months.
little or none co-movement month to month · 249 months Show chartsFarmers buy phosphate and potash together, so both follow crop prices and fertiliser affordability, even though their mines, producers and export politics are quite different. Monthly changes correlate at 0.25 and yearly changes at 0.60.
weak co-movement month to month · 249 months Show chartsLithium iron phosphate batteries use purified phosphoric acid, a small but fast-growing call on phosphate rock that competes with fertiliser for high-grade supply. The battery proxy is a US battery price index and shows almost no monthly link (0.06).
little or none co-movement month to month · 243 months Show chartsHow to read these numbers
Correlation of monthly changes (the number in the coloured pill) compares how much each price moved, month by month, since 2006 or the first month both series exist. It runs from −1 to +1: near +1 the two usually rise and fall in the same months, near 0 there is no link, and a negative number means they tend to move in opposite directions. Above 0.7 is strong, 0.4 to 0.7 moderate, 0.2 to 0.4 weak.
12-month changes compare year-on-year moves, which shows whether two prices share the same cycles even when the month-to-month noise differs.
Price function is a straight-line fit of the two prices on logarithmic scales: price ≈ k × (partner price)β. β is how much this price moves, in per cent, for a 1% move in the partner over the whole period, and R² is the share of the variation the fit explains. Two prices that both drift up with inflation can fit well without any real link, so read it together with the monthly correlation.
Lead or lag checks whether the monthly correlation is clearly higher when one price is shifted by 1 to 6 months.
Correlation is not cause. The reasons on each card explain the economic link; the numbers show how strongly it has shown up in prices. Proxy series are US producer price indexes or related prices and can blur the real link.
Data: World Bank Commodity Price Data (Pink Sheet), October 2026; US Bureau of Labor Statistics producer price indexes, IMF primary commodity prices and US EIA prices via FRED, Federal Reserve Bank of St. Louis, retrieved November 2026. Calculations by this site.