Cotton is a natural fiber with seemingly supernatural qualities. Its long history is marked by its dependence on specific growing conditions. But today, it is an abundant crop—thanks to boron.
The Industrial Revolution of 18th
century England was sparked by the need to build efficient cotton processing machinery, and the inventor of the cotton gin (which brought automation to the laborious extraction of fiber from the cotton boll) was later responsible for the invention of a variety of new machines and tools that made industrial mass production possible.
The Industrial Revolution in turn ushered in chemical, biochemical, and biological revolutions. These breakthroughs helped cotton growers increase cotton yields. Growers started using fertilizers and insect-control treatments (new bio- and genetic engineering measures have added to this armory). Selective breeding has produced new plant strains—some even enable naturally-colored cottons to be grown to order. And a major advance, some 70 years ago, was the recognition of the importance of boron in cotton. Boron is an essential micronutrient, without which the crop cannot prosper.
Cotton industry challenges, met with innovation
Cotton is the most-used vegetable fiber for making textiles and is grown in 70 countries. It is big business; the largest producers are the U.S.
and the People's Republic of China
. As the world demand for cotton has increased, many major cotton-producing countries face production problems caused mainly by insects. The shortfall has been mitigated largely by increases in American production, aided by new insect control measures, better cotton yields per hectare, and newcomers to cotton-growing, encouraged by governments to exploit this ready market.
To the north of Florida, the 14 states of the southern U.S. make up the Cotton Belt. Here, for the last two centuries, cotton has been cultivated on a vast scale. During the Industrial Revolution, invention after invention to aid planting, harvesting, and processing helped production of U.S. cotton yields increase from a tiny 680 tonnes in 1790 to around 350,000 tonnes 50 years later. Modern developments in agriculture, harvesting, and processing took the U.S. yield to more than 9,000,000 tonnes of seed cotton with more than four million hectares under cultivation at the end of the 20th
But at the root of this increase is a combination of climatic and geologic factors without which the plant just will not grow and prosper on an economic scale. Cotton is a very particular plant when it comes to the weather. It likes the sun and can't stand frosts; summer temperatures need to be higher than the mid-70s, with plenty of rain (or irrigation) in the germination and growing seasons.
Cotton's history as an economic force, of course, goes back much further than its cultivation in the U.S. Prehistoric remnants of cotton yarn and fabric have been found in Pakistan, New Mexico, and Arizona, and there is evidence that the dyeing of cotton fabric was practiced even then.
When Christopher Columbus landed in the New World, he found the West Indian natives wearing cotton clothes, and it is known that it was also indigenous in the southwestern U.S., Mexico, and Peru. Even in Columbus’s day, it was an important trade commodity. Cotton cultivation in the Cotton Belt began with plantings in Florida by the Spanish in the mid-1500s. These were not very successful, probably because of poorly-drained land and torrential autumn rains, but further north and west the conditions were much better. Cotton cultivation was to start, in earnest, two centuries later.
Battling boron deficient soils with the right micronutrients for cotton
However, where the U.S. climate is right for cotton, the element boron is generally in short supply. Lack of this essential plant micronutrient is felt keenly by cotton, but it is rare for a cotton crop to show any visible symptoms—unusual for a crop that is critically boron-dependent. Plantations can look perfectly healthy, but the yield of fiber (lint) is severely depressed. And with every season that goes by, the boron available from the soil depletes as it is used up by the crop.
Planters can detect boron deficiency by an analysis of plant or soil boron content and avoid the risk of low cotton yield with a replenishment regimen. For example, growers can provide tailored boron supplements through regular applications of the fertilizer borate Granubor®
to the soil. Alternatively, Solubor®
—which is highly effective in liquid formulation—can be applied directly to the plants. Granubor
granules can be applied alone or mixed by the planter or fertilizer makers with other nutrients. Solubor
can conveniently be combined with pesticide sprays.
The best amount to apply depends upon local conditions, but typically about 1 to 3 kg boron equivalent per hectare is sufficient. (U.S. Borax is always happy to give advice.) With a few kilos of Borax product, seed cotton yields can increase 25% or more—perhaps yielding an extra 500 kg a hectare.
For cotton, boron availability is now acknowledged to be the crop's principal limiting nutrient factor. No amount of any other fertilizer can produce so significant an increase in productivity. When the plants are growing and fruiting vigorously, they are also better able to naturally resist the attentions of voracious boll weevils and pink boll worms.
New strains of cotton plant—for example, the genetically-engineered 'Bt' strain, named for the inclusion of Bacillus thuringensis genes that make the plant unattractive to weevils—are, with other eradication programs, helping to combat insect-depleted yields.
As the insect menace is pushed back, low yields due to boron deficiency are coming into more prominence. Growers who are new to the crop can take a tip from the “old hands:” By supplementing each hectare with a few kilos of borate, their seed cotton yields can increase massively.