Maintaining or increasing agricultural productivity in the face of climate change, global hunger, and environmental damage will require innovation and creativity. Scientists and farmers in the US and elsewhere are working to develop nitrogen-fixing solutions that conserve nitrogen in the soil while minimizing use of commercial fertilizer.
China’s solutions so far have consisted mainly of attempting to convince farmers to reduce their use of nitrogen fertilizer. Because so many farmers use so much more fertilizer than they need, simply reducing use would conserve resources and mitigate ecological damage. But so far, these efforts have met with little success. As populations expand and demand for meat increases, China’s fertilizer use is increasing as well.
One place to find nitrogen-fixing solutions is in traditional agricultural practices – that is, how people farmed before the existence of chemical fertilizer. Many organic farmers in the United States operate their farms as closed systems with no external inputs. They use nitrogen-containing manure from animals such as cows, pigs, and chickens to fertilize their fields. In addition, they plant nitrogen-fixing crops – soybeans, alfalfa, and clover – in the fall, which are tilled into the soil before planting corn in the spring. Bacteria on the roots of alfalfa and clover fix nitrogen in the soil, which is then absorbed by the corn. Corn is fed to the animals and its nitrogen ends up in their manure, which then goes back onto the fields.
Organic farming’s nitrogen-fixing effects are valuable. But this method of farming takes more time, patience, and dedication than many of the world’s farmers are able to commit to growing food. An official of China’s Institute of Soil Science stated, “Organic farming is not a solution for China.” Lower yields with higher inputs of time and money are simply not feasible for most of the world.
Fortunately, there is a middle ground between self-contained organic systems and nitrogen fertilizer use, and it has been implemented with success in the United States and in Africa. At Michigan State University, agricultural scientists have been growing wheat, corn, and soybeans using both conventional and organic methods, and meticulously recording the data associated with each plot.
Their findings are intriguing: the conventional fields lost about half the commercial nitrogen fertilizer that was applied – less than what is typically lost in China, but enough to cause serious environmental harm on a large scale. The organic fields used no commercial fertilizer, but had about a 20 percent lower crop yield. However, when the scientists combined nitrogen-fixing winter cover crops (clover, alfalfa) with small amounts of fertilizer, yields matched those of the conventional fields, and nitrogen loss was nearly as low as the organic fields.
This technique has been implemented in the African country of Malawi over the last decade. There, the government was providing subsidized fertilizer to about half the country’s farmers. But money is running out to fund the program. So local hospitals, farmers, and agricultural scientists have begun incorporating nitrogen-fixing crop rotations into farming practices. Replacing some corn with nitrogen-fixing legumes has multiple benefits: nitrogen in the soil is replenished, and the legumes provide an additional source of dietary protein. Best of all, because the soil’s fertility was maintained or improved, corn yields increased.
Of course, these changes did not happen overnight. Farmers had to learn how to plant, grow, harvest, and process the legumes. Local people had to adapt to the addition of legumes in their diet, and learn how to prepare meals with them. But the inputs are worthwhile. Using nitrogen-fixing crops in addition to commercial fertilizer results in higher grain yields, greater variety in diet, and increased soil fertility – all while minimizing environmental damage.
Making changes to the status quo is effective, but difficult and time consuming. Those of us lucky enough to live in the United States, the most agriculturally productive country in the world, need to adapt our eating habits to meet the world’s needs. The clearest solution to global agriculture’s biggest problems is a worldwide reduction of meat consumption. It requires far more grain to produce meat than it does to feed people directly with grain. Reducing meat consumption makes the same amount of grain, and thus the same amount of nitrogen, go much further. As one Chinese climate change and agricultural scientist stated, “If Chinese people change their diet to be like yours [in the West], the environmental pressure will be very high. We have to tend to this problem. Otherwise it will be very big.”