How existing cropland could feed billions more
Agriculture is responsible for 20 to 35 percent of global greenhouse gas emissions, largely in the form of carbon dioxide from tropical deforestation, methane from livestock and rice growing, and nitrous oxide from crop fertilization. The study found that the biggest opportunities for reducing greenhouse gas production are in Brazil and Indonesia for deforestation; China and India for rice production; and China, India, and the United States for crop fertilization.
With respect to nutrient use, the study found that worldwide, 60 percent of nitrogen and nearly 50 percent of phosphorus applications exceed what crops need to grow. China, India, and the United States — and three crops, rice, wheat, and corn — are the biggest sources of excess nutrient use worldwide, so offer the greatest opportunity for improvement.
With respect to water, rice and wheat are the crops that create the most demand for irrigation worldwide, and India, Pakistan, China, and the United States account for the bulk of irrigation water use in water-limited areas. Boosting crop water use efficiency, the researchers found, could reduce water demand 8 to 15 percent without compromising food production.
3. Use crops more efficiently. The third major category of opportunities characterized for boosting food production and environmental protection relate to making more crop calories available for human consumption by shifting crops from livestock to humans and reducing food waste.
The crop calories we currently feed to animals are sufficient to meet the calorie needs of four billion people. The study noted that the United States, China, and Western Europe account for the bulk of this “diet gap,” with corn the main crop being diverted to animal feed. Although cultural preferences and politics limit the ability to change this picture, the authors note that shifting crops from animal feed to human food could serve as a “safety net” when weather or pests create shortages.
In addition, some 30 to 50 percent of food is wasted worldwide. Particularly significant is the impact of animal products: The loss of one kilogram of boneless beef has the same effect as wasting twenty-four kilograms of wheat due to inefficiencies in converting grain to meat. The authors illustrate how food waste in the U.S., China and India affect available calories, noting that reducing waste in these three countries alone could yield food for more than 400 million people.
“Sustainably feeding people today and in the future is one of humanity’s grand challenges. Agriculture is the main source of water use, greenhouse gas emissions, and habitat loss, yet we need to grow more food,” West said. “Fortunately, the opportunities to have a global impact and move in the right direction are clustered. By focusing on areas, crops and practices with the most to be gained, companies, governments, NGOs, and others can ensure that their efforts are being targeted in a way that best accomplishes the common and critically important goal of feeding the world while protecting the environment. Of course, while calories are a key measure of improving food security, nutrition, access and cultural preferences must also be addressed. But the need to boost food security is high. So let’s do it.”
— Read more in Paul C. West1 et al., “Leverage points for improving global food security and the environment,” Science 345 no. 6194 (18 July 2014): 325-28 (DOI: 10.1126/science.1246067)
