In the year 2000, over 80 million metric tons of nitrogen fertilizers were used in producing food for the world’s 6 billion people. Food production, use of nitrogen fertilizers, and world population all had grown over the preceding 40 years, but at somewhat different rates. During this time, food production grew slightly faster than population while relatively little additional land was converted to agricultural use. Fertilizer use grew most rapidly. Demographers predict that global population will continue to increase. As population increases, which of the following statements represents future agricultural changes for maintaining an adequate food supply? Question 6 options: Lower use of N fertilizer per unit of land Higher agricultural land-to-population ratio Higher food production per unit of agricultural land Higher food production due to greater use of N fertilizer

With respect to the rate of fertilizer usage in relation to food production over the past 40 years, we can assume that we are almost getting to the limit to which Nitrogen fertilizer input can further increase food production using the same area of land. Further higher input of nitrogen fertilizer might be counter productive, and neither do lower use of Nitrogen fertilizer per unit area solve the predicted increase in demand of food in the future. The most plausible statement that represents future agricultural changes for maintaining an adequate food supply in response to growing population is “Higher food production per unit of agricultural land”. This can be achieved through other technological innovations compared to nitrogen use.