This has not always been the case. Current fertilizer practices are relatively recent and date back to just the last half of the 20th century; however, traditional fertilizer practices are much older. Although it was previously thought that the concept of fertilizer use may have only dated back 2, to 3, years, it is now believed that early farmers were using manure to fertilize their crops as long as 8, years ago.
A team led by Amy Bogaard, an archaeobotanist at the University of Oxford, decided to look for evidence of earlier fertilizer use. In ancient times, manure would have been the most logical fertilizer to use and, due to the fact that manure has a higher than normal concentration of the rare nitrogen isotope N , the team noted that recent research showed that plants treated with manure have more N The researchers collected ancient samples of cereals such as wheat and barley, as well as pulses such as peas and lentils, from 13 early farming sites across Europe that dated from 4, years to 7, years ago.
But new research outlined in the SCOPE report indicates that, without a change of practice, meeting that goal could increase the nitrogen flux in the Mississippi by 37 percent. That pits ethanol production overwhelmingly against another national goal: reducing nitrogen flux in the same river by at least 40 percent to reduce the size of the dead zone in northern Gulf of Mexico.
Corn is a troublesome biofuel source , particularly from a nitrogen standpoint, Howarth says. Typical corn-growing practice is to apply high doses of fertilizer, with substantial losses to the surrounding environment. Corn has very shallow roots compared to most crops and so can use nitrogen only in the top one to two inches 0. Moreover, it only takes up nitrogen and other nutrients for 60 days out of the year. Other crops such as soybean and wheat have deeper roots that are active longer.
But the rising price of corn has encouraged farmers to grow more of this "nitrogen leaky" grain. Land set aside for conservation purposes as well as some active soybean and wheat fields are being converted back to active corn cultivation. Still, this growth in corn production cannot hope to enable the world to reach its ethanol production goals, the report says.
Based on this and other early findings, the SCOPE report projects that substituting 10 percent of the liquid fossil fuels used for transportation with biofuels could require a third of the world's arable land, causing trouble not only with nitrogen pollution but also food security. Current biofuel targets impart other major problems for global warming and human health that Howarth says scientists have "long underestimated. A analysis by Nobel laureate Paul Crutzen of the Max Planck Institute for Chemistry in Mainz, Germany, and his colleagues suggests that for most current biofuel crops, corn included, any CO2 savings will be wiped out by higher emissions of nitrous oxide and nitrogen oxide.
According to the U. Environmental Protection Agency, millions of Americans live in areas that exceed the national standards for ozone exposure. During the s, most of the ammonia was applied as solid ammonium nitrate pellets. But this form is highly explosive. In fact, ammonium nitrate mixed with fuel oil is a common explosive still used in mines. There were several disasters where the material exploded in ships or other transports. By the mid 40s, researchers were exploring ways to apply anhydrous ammonia directly into the soil.
It won't explode, but it has to be kept under pressure and usually refrigerated. It can "burn" skin by drying it severely, and it can crowd out oxygen in a closed area and even cause death by asphyxiation. But, anhydrous ammonia has the highest nutrient content of any fertilizer. It's So, in , researchers at the Mississippi Agricultural Experiment Station came up with a way of injecting anhydrous into the soil. They used a knife-like applicator with an iron pipe welded on the back of it to inject the material five or six inches below the soil.
Then adisc hiller followed immediately behind to cover the channel and trap the anhydrous in the soil. This method of ammonia application overtook the pellets by and still predominates in the Great Plains today. John Steingard left says that some farmers used too much fertilizer when anhydrous ammonia first came out.
Now, its more controlled. Holly Miller right saw the explosion of fertilizer use first hand. After the war, Holly opened a seed business in York, and he believed in educating farmers about the new technologies. For nitrogen-based fertilizers, the largest product group, the process starts by mixing nitrogen from the air with hydrogen from natural gas at high temperature and pressure to create ammonia.
The ammonia is used to make nitric acid, with which it is then mixed to produce nitrate fertilizers such as ammonium nitrate AN.
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