Maximum soil organic carbon storage in Midwest U.S. cropping systems when crops are optimally nitrogen-fertilized

• DOI: 10.1371/journal.pone.0172293
• Publication Date: 2017-03-01T13:33:45Z
• Authors: Hanna J. Poffenba...; Daniel W. Barker; Matthew J. Helmers; Fernando E. Miguez; Daniel C. Olk; John E. Sawyer; Johan Six; Michael J. Castel...
• Keywords: Monocropping; Cropping system; Soil carbon; Crop Residue

Nitrogen fertilization is critical to optimize short-term crop yield, but its long-term effect on soil organic C (SOC) uncertain. Here, we clarify the impact of N SOC in typical maize-based (Zea mays L.) Midwest U.S. cropping systems by accounting for site-to-site variability maize yield response fertilization. Within continuous and maize-soybean [Glycine max (L.) Merr.] at four Iowa locations, evaluated changes surface over 14 16 years across a range fertilizer rates empirically determined be insufficient, optimum, or excessive maximum yield. Soil balances were negative where no was applied neutral (maize-soybean) positive (continuous maize) agronomic optimum rate (AONR). For maize, storage increased with increasing rate, reaching AONR decreasing above AONR. Greater optimally fertilized system than attributed greater residue production efficiency system. Mean annual 22% per unit input 58% monocrop Our results demonstrate that maintain increase cropland.