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    Flint on Crops: Cotton Conserves Soil Fertility

    There are several reasons why cotton became established as the crop of choice in the Old South. These included the fact that it was in high demand for export to England and Europe in support of their textile industries. The market is always the most important issue for any crop, but this was not the only thing cotton had going for it.

    The first cotton varieties that were brought to this part of the world came from climates that were different from this region with most of them being long season varieties. The extra long staple (ELS) cottons like pima (Gossypium barbadense) were actually grown here even though the yields were usually poor.

    This cotton is a different species from the ones we grow today which we refer to as “upland” cotton which is Gossypium hirsutum. The very early cotton farmers such as Dr. Rush Nutt of Rodney discovered that cotton could be grown on “good land” for several years before any yield decline was noticed.

    Dr. Nutt, a medical doctor, was actually the first cotton breeder that is widely recognized even though there were likely others during that period. When he crossed a Mexican strain with a locally grown variety to produce the variety he called Petit Gulf cotton spread rapidly across the South because this variety yielded well and matured within the normal growing season of this region.

    Cotton has always been recognized as a “good fit” for this region since it can withstand the high temperatures, droughts, and even excessive rains we have to some degree. This year has proven again in most cases that this plant is suited to the South. It grows well in a wide range of soil types from coarse sands to heavy clays.

    One old farmer told me many years ago that “anywhere you see hardwoods growing cotton will do well there”. He was correct in that belief, but with some lime to correct the acid soil pH normally associated with sites that prefer pine cotton will grow well there too.

    With good management cotton will grow on almost any soil unless the topsoil has been eroded away, which is the case in some parts of our area. Even in these situations a concerted effort to replace nutrients and organic matter can make most of these soils produce good cotton yields.

    The fundamental reason cotton “fits” our land is that it does not require large amounts of nutrients as would be needed for other crops.

    We can maximize profits in most cases with 80 pounds of nitrogen per acre for cotton while corn needs at least double that amount. This lower N rate does not drive down soil pH as fast so liming may not be required as frequently for cotton.

    A two bale cotton crop will remove around 28 pounds of phosphate while a 150 bushel corn crop will haul away almost 70 pounds. As for potash cotton needs a good supply for reproduction, but only removes about 40 pounds for a two bale crop while a 150 bushel corn crop will remove at least 50 pounds per acre.

    Soybeans require very little applied N, but remove the most phosphate and potash of all the crops we grow as they remove around 50 pounds of phosphate and 80 pounds of potash. They also drive soil pH down fast because they exude acidic hydrogen ions directly into the soil as the nodules fix atmospheric nitrogen at the rate of over 250 pounds per acre.

    Cotton loves good soil pH and will punish you if you fail to supply it, but it does not make the problem worse as rapidly as other crops like corn or soybeans.




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