Which Soil Is Ideal for Growing Cotton? pH, Texture, Salt

Cotton grows best in deep, fertile, well-drained soil such as a sandy loam or silt loam, with a pH of about 5.8 to 7.0. That is the answer to which soil is ideal for growing cotton. The pH range comes from Mississippi State University Extension, and the depth and drainage advice from Cotton SA. Sandy loams, silt loams, clay loams and cracking clays all produce cotton when they drain well and the pH is right. This guide gives the target numbers for texture, pH, depth, salt and warmth, shows how cotton soils differ in the US and Australia, and ends with a nitrogen cost calculator for your own acres.

Which soil is ideal for growing cotton: the target numbers

No single soil name fits every farm. What matters is a short list of soil traits. The table shows the targets that university and industry sources give, with the place each one applies to.

Cotton SA adds that cotton will do well on most soil types, preferably deep, fertile and well drained, and that it reacts poorly to acid soil. The rest of this page explains each target and how to check it on your own field.

Soil texture and water holding

Texture is the mix of sand, silt and clay. It decides how much water the soil stores and how fast it drains. The University of California chart below shows the plant-available water held in each foot of soil. Loamy sands hold 0.75 to 1.25 inches per foot, while clay loams hold 1.75 to 2.5. Sandy soils therefore need smaller irrigations at shorter intervals, which is also the advice Cotton SA gives for sandy and heavier soils.

Chart

Plant-available water by soil texture

inches of water per foot of soil; range for each texture group

A simple sum shows why this matters. Over a 3-foot root zone, a sandy loam holds about 3.75 to 5.25 inches of plant-available water (1.25 to 1.75 times 3), and a clay loam holds about 5.25 to 7.5 inches. The clay loam therefore holds about 1.5 to 2.25 inches more water in that root zone.

Loams and sandy loams sit in the middle. They store a useful amount of water and still drain after rain. The Mississippi Delta bulletin says the well-drained Delta soils are mostly sandy loam, silt loam or loamy soils, and that they can be planted soon after a rain. Heavy clays hold about as much water as clay loams in the chart above (1.6 to 2.5 inches per foot) but drain slowly, so they need bedding and good surface drainage.

Cotton soil types around the world

Cotton is grown on very different soils in different countries. The USDA Economic Research Service says US cotton grows mainly in 17 southern states and that Texas gave about 40% of US production in recent years, mostly from the High Plains. Other top producers include Georgia, Mississippi and Arkansas.

Alluvial soils

Alluvial soils are laid down by rivers. The Mississippi Delta is a large US example. Mississippi researchers describe the higher, well-drained ridges as sandy loam, silt loam or loamy soils. They compact easily under equipment and usually respond to subsoiling. Many of these soils are low in organic matter, from 0.5% to 2%, and 0.9% to 1.5% is most typical. Heavier Delta clays such as Sharkey have poor internal drainage and need special treatment, while Forestdale silty clay loam can grow cotton because it drains a little better. Fall plowing, subsoiling and bedding are often needed on it.

Cracking clays (Vertosols)

Cotton Australia says its crop is mostly grown on cracking, self-mulching clay soils called Vertosols, which give about 60% of Australian cotton. A further 30% grows on red-brown soils and the rest on river alluvial soils. Vertosols are called Vertisols in the US system. They swell when wet and shrink when dry, so water management and drainage matter more than texture alone.

Sandy loams and light soils

Sandy loams drain freely and warm early in spring. LSU AgCenter notes that soils holding less moisture warm faster than clay soils. The downside is leaching. NC State says nitrogen, sulfur and boron can be washed out of sandy soils by heavy rain, and Mississippi State sees sulfur shortages on sandy soils low in organic matter.

Red and yellow acid soils

Many red and yellow soils are acid. They can grow cotton if lime lifts the pH into range, which the next section explains. Without liming, aluminum can damage the roots.

Soil pH and liming

Soil pH controls how much of each nutrient the roots can take up. MSU Extension says cotton grows best between pH 5.8 and 7.0, and that yield losses are not usually severe until pH falls below 5.5 on sandy loam and silt loam, or below 5.2 on clay loam. NC State sets a tolerable range of 5.8 to 6.5 on mineral soils and uses a target of 6.2.

Chart

Cotton soil tests by pH and lime need, North Carolina

share of mineral-soil samples submitted for cotton, fiscal year 2020

The cost of ignoring pH is real. NC State calls cotton one of the crops most sensitive to acidity in that state. Below pH 5.5, aluminum and manganese dissolve from the clay and slow root growth, so roots reach less water and fewer nutrients. The chart above shows what North Carolina cotton soil tests found in the 2020 fiscal year.

When the test says lime, apply it early. MSU Extension advises incorporating lime several months before planting and notes that it works best 5 to 6 months after it goes on. Lime rate depends on texture, organic matter and past lime use, so use a lab recommendation and follow local rules and the product label. High-pH soils are less of a problem. Cotton SA describes cotton as resistant to soils with a fairly high pH, with an ideal range of 5.5 to 7.5.

Salty soils

FAO’s irrigation paper lists cotton among the salt-tolerant field crops. It gives a threshold of 7.7 dS/m soil salinity (ECe) for full yield potential, with about 5.2% yield lost for each unit above that. Emergence falls by half only at about 15.5 dS/m.

Chart

Soil salinity at which yield loss starts

ECe in dS/m for 100% yield potential, selected field crops

The threshold is a guide for the root zone, not the seedbed surface. Salts can build up in irrigated land with poor drainage. If your test shows high salinity, ask a local adviser about leaching and drainage before planting.

Drainage, depth and compaction

Cotton roots go deep. Cotton SA quotes an ideal soil depth of 800 to 900 mm or more, with the taproot reaching about 1 to 1.2 m. Cotton also suffers when it is over-irrigated, says the same source.

The Mississippi Delta bulletin warns that its well-drained silt and sandy loams compact easily under equipment and respond to subsoiling. Dig a few pits after harvest to look for a hard layer, and treat compaction only where you find it.

Soil temperature at planting

A good soil can still fail if it is too cold at planting. LSU AgCenter advises waiting for a mean daily soil temperature of 65°F or more at 4 inches, measured at 8 a.m. for at least three days in a row. It also reports that yield may drop if fewer than 10 degree days (above 60°F) build up in the five days after planting. Dark soils and soils with less moisture warm faster; heavy residue cover slows warming. Thresholds differ by state, so check your own extension office.

Common cotton soil problems and fixes

Most poor cotton fields trace back to one of a few soil problems. The table pairs each with what the sources say to do.

Nutrients and organic matter

NC State lists nitrogen, potassium, sulfur and boron as the nutrients cotton is most sensitive to, and says potassium is the least likely of them to leach. Cotton also needs a large supply late in the season. Soil tests are the cheapest way to find out where you stand.

Nitrogen needs depend on texture. Mississippi State Extension gives a guide of 50 to 60 pounds of nitrogen per bale on light soils, 60 to 70 on medium soils and 70 to 80 on clay and clay loam soils. For a medium soil with a two-bale yield goal that works out to 120 to 140 pounds of nitrogen per acre. Rates above 100 pounds per acre should be split to reduce salt injury. The calculator below turns that guide into a cost for your farm.

Organic matter helps soil hold water and nutrients, but no source we reviewed sets a single ideal percentage for cotton. Many well-drained Delta soils that grow cotton hold only 0.9% to 1.5% organic matter, as noted above. Build it up over years with residue, cover crops and rotation, and track it with repeat soil tests.

Try the numbers for your own farm below.

How we checked the numbers

Every figure above comes from a university extension service, an experiment station, FAO, USDA or an industry body, and each is dated or named where it is given. Pages differ by region: Mississippi and North Carolina give different pH ranges, and Australia’s cracking clays differ from the Mississippi Delta’s loams. We show the range each source gives rather than one blended number. Ask your local extension office which figure applies to your state.

How to test and fix your cotton soil

1. Sample in fall. Both MSU Extension and NC State suggest fall sampling so there is time to get results and lime before planting. NC State suggests sampling every two to three years in its coastal plain.
2. Test pH, lime need, P, K and S. Add boron and nematodes if your lab and local advisers recommend them.
3. Check depth and compaction. Dig a pit or use a probe in several spots.
4. Lime first, early. Apply lime months ahead of planting.
5. Plan nitrogen by texture. Split large rates and subtract any credits your adviser allows.
6. Check soil temperature before planting. Use the 8 a.m. rule from above.

Fertilizer, lime and chemical rules differ by place. Follow the product label, your local rules and the advice of a certified crop adviser.

Soil management practices for cotton

Good soil management keeps a suitable soil suitable. Four practices protect soil structure and organic matter:

• Crop rotation. Rotating cotton with another crop changes the pest, disease and nutrient pattern in the field; see our notes on crop rotation. Read our guide to sustainable cotton production for more.
• Conservation tillage. Fewer passes leave residue on the surface and protect soil from erosion.
• Cover crops. Roots and residue protect bare ground between seasons and add organic matter over time.
• Precision nutrients. Apply where a soil test or field map shows a need, not the same rate everywhere.

Our page on soil management for lime-rich ground goes further, and our overview of regenerative agriculture covers soil health over the long term.

▶ Seven simple ways to protect soil and water, explained in plain English · 4:34

Using satellites to see soil differences in a cotton field

A satellite cannot measure pH or nitrogen. What it can show is how the crop grows on each part of a field. If one zone is always weaker, that zone is the place to take a soil sample. Sentinel-2, a public satellite pair run under the EU Copernicus programme, passes over the same place about every 5 days at the Equator, according to the Copernicus SentiWiki. Clouds can block some passes.

Farmonaut Satellite + AI Farm Monitoring System maps crop health from satellite images, so you can see which parts of a field lag. Satellite maps cover whole fields at once, soil sensors measure one spot continuously and drones give close-up views on demand. Each tool measures something different. Our guide to cotton farming with sensors explains where each tool fits.

▶ A walkthrough of satellite crop monitoring: reading NDVI maps and running an advisory report on your own field · 19:36

Other limits on cotton yield

Soil is one of several limits. Pests, water and weather also set yield. This video from our channel covers pest control, water management and other hurdles cotton growers face.

▶ Challenges in cotton cultivation, from pest control to water management · 7:38

FAQ

What is the best soil type for cotton?

Deep, fertile, well-drained soil is the safest choice. Sandy loam, silt loam and clay loam all work when pH is 5.8 to 7.0 (MSU Extension). Cracking clays carry most of Australia’s crop.

Can cotton grow in sandy soil?

Yes. Sandy soils warm early and drain well, but hold less water and lose nitrogen, sulfur and boron to leaching (NC State). Irrigate in smaller amounts, more often.

Can cotton grow in black clay or Vertosol soil?

Yes. About 60% of Australian cotton grows on Vertosols (Cotton Australia). Drainage and water control matter most on these soils.

What pH does cotton need?

Aim for 5.8 to 7.0 (MSU Extension). Check your state’s own figure, because NC State uses 5.8 to 6.5 on mineral soils.

Can cotton tolerate salty soil?

Fairly well. FAO lists cotton as tolerant, with yield loss starting above 7.7 dS/m ECe.

How can I tell if my soil is too acid?

Send a sample to a lab. NC State also suggests looking for J-shaped taproots, a sign of root damage from acid subsoil.

Related pages on our site: agribusiness partnerships, crop monitoring system, AI crop monitoring, climate change, the Farmonaut Web App and the API Documentation.