Legume versus fertilizer sources of nitrogen: ecological tradeoffs and human needs

• Published in: Agriculture, ecosystems & environment Vol. 102; no. 3; pp. 279 - 297
• Main Authors: Crews, T.E, Peoples, M.B
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-05-2004; Elsevier Science
• Subjects: Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Conservation, protection and management of environment and wildlife; cropping systems; Energy; Environmental degradation: ecosystems survey and restoration; environmental factors; Fertilizer; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Legume; legumes; Nitrogen; Nitrogen fertilization; nitrogen fertilizers; nitrogen fixation; Nitrogen, phosphorus, potassium fertilizations; Security; soil pollution; Soil-plant relationships. Soil fertility. Fertilization. Amendments; sustainable agriculture; Energy; Nitrogen; Security; Legume; Fertilizer; Nitrogen fertilization; Traditional farming; Cropping system; Pollution; Sustainable agriculture; Leguminosae; Dicotyledones; Crop rotation; Food security; Angiospermae; Dependence; Spermatophyta; Nitrogen fertilizer
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2003.09.018

During the 20th century, farmers around the world replaced legume rotations and other traditional sources of nitrogen (N) fertility with synthetic N fertilizers. A sizable percentage of the human population now depends on synthetic N fertilizers for survival. In recent decades, N fertilizers have been linked to numerous environmental hazards including marine eutrophication, global warming, groundwater contamination, and stratospheric ozone destruction. Some researchers suggest that legumes, which can support biological N
2 fixation, offer a more environmentally sound and sustainable source of N to cropping systems. This perspective is countered by researchers who argue that, (1) legume-derived N has equally negative environmental impacts as the N derived from synthetic fertilizers, and (2) the human population now exceeds the carrying capacity of agricultural systems that depend on legumes for N inputs. In this review, we compare the sustainability of obtaining N from legume versus industrial sources in terms of ecological integrity, energetics and food security. We conclude that obtaining N from legumes is potentially more sustainable than from industrial sources. We further suggest that while some countries are fundamentally dependent on synthetic N for food production, many countries have the capacity to greatly reduce or eliminate dependence on synthetic N through adoption of less meat-intensive diets, and reduction of food waste.