Can mineralization of soil organic nitrogen meet maize nitrogen demand?
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High-yielding maize-based crop systems require maize to take up large quantities of nitrogen over short periods of time. Nitrogen management in conventional crop systems assumes that soil N mineralization alone cannot meet rapid rates of crop N uptake, and thus large pools of inorganic N, typically supplied as fertilizer, are required to meet crop N demand. Net soil N mineralization data support this assumption; net N mineralization rates are typically lower than maize N uptake rates. However, net N mineralization does not fully capture the flux of N from organic to inorganic forms. Gross ammonification may better represent the absolute flux of inorganic N produced by soil N mineralization.
Here we utilize a long-term cropping systems experiment in Iowa, USA to compare the peak rate of N accumulation in maize biomass to the rate of inorganic N production through gross ammonification of soil organic N.
Peak maize N uptake rates averaged 4.4 kg N ha−1 d−1, while gross ammonification rates over the 0–80 cm depth averaged 23 kg N ha−1 d−1. Gross ammonification was highly stratified, with 63% occurring in the 0–20 cm depth and 37% in the 20–80 cm depth. Neither peak maize N uptake rate nor gross ammonification rate differed significantly among three cropping systems with varied rotation lengths and fertilizer inputs.
Gross ammonification rate was 3.4 to 4.5 times greater than peak maize N uptake across the cropping systems, indicating that inorganic N mineralized from soil organic matter may be able to satisfy a large portion of crop N demand, and that explicit consideration of gross N mineralization may contribute to development of strategies that reduce crop reliance on large soil inorganic N pools that are easily lost to the environment.
KeywordsNitrogen mineralization Gross ammonification Maize Cropping systems Nitrogen uptake, nitrogen availability
This research was funded by the Iowa State University Department of Agronomy, the Frankenberger Professorship of Soil Science, and grants from the Leopold Center for Sustainable Agriculture (Projects # 2013-XP01 and 2014-XP01), the USDA Agriculture and Food Research Initiative (2014-67013-21712), and the Bi-national Agriculture Research and Development Fund (US-4550-12).
- Abendroth LJ, Elmore RW, Boyer MJ, Marlay SK (2011) Corn growth and development. PMR 1009, Iowa State University Extension, Ames IowaGoogle Scholar
- Blackmer A, Voss R, Mallarino A (1997) Nitrogen fertilizer recommendations for corn in Iowa. PM 1714, Iowa State University Extension, Ames IowaGoogle Scholar
- Brooks PD, Stark JM, McInteer BB, Preston T (1989) Diffusion method to prepare soil extracts for automated nitrogen-15 analysis. Soil Sci Soc Am J 53:1707–1711Google Scholar
- Drinkwater LE, Snapp SS (2007) Nutrients in agroecosystems: rethinking the management paradigm. Adv Agron 92:163–186Google Scholar
- Food and Agriculture Organization of the United Nations (2006) Fertilizer use by crop. FAO Fertilizer and Plant Nutrition Bulletin 17, RomeGoogle Scholar
- Hart SC, Stark JM, Davidson EA, Firestone MK (1994) Nitrogen mineralization, immobilization, and nitrification. In: Weaver RM, Angle S, Bottomley P, Bezdicek D, Smith S, Tabatabai A, Wollum A (eds) Methods of soil analysis: part 2 - microbiological and biochemical properties. Soil Science Society of America, Madison, pp. 985–1018Google Scholar
- Hodge A, Robinson D, Fitter A (2000) Are microorganisms more effective than plants at competing for nitrogen? Trends Plant Sci 5:304–308Google Scholar
- Hunt R (1982) Plant growth curves. Edward Arnold Limited, LondonGoogle Scholar
- Liebman M, Gibson LR, Sundberg DN, Heggenstaller AH, Westerman PR, Chase CA, Hartzler RG, Menalled FD, Davis AS, Dixon PM (2008) Agronomic and economic performance characteristics of conventional and low-external-input cropping systems in the central Corn Belt. Agron J 100:600–610CrossRefGoogle Scholar
- Lowrance R, Stiner BR, House GJ (1984) Agricultural ecosystems: unifying concepts. Wiley, New YorkGoogle Scholar
- Schomberg HH, Wietholter S, Griffin TS, Reeves DW, Cabrera ML, Fisher DS, Endale DM, Novak JM, Balkcom KS, Raper RL, Kitchen NR, Locke MA, Potter KN, Schwartz RC, Truman CC, Tyler DD (2009) Assessing indices for predicting potential nitrogen mineralization in soils under different management systems. Soil Sci Soc Am J 73:1575–1586CrossRefGoogle Scholar
- Weitzman JN, Kaye JP (2016) Variability in soil nitrogen retention across forest, urban, and agricultural land uses. Ecosystems 19:1345–1361Google Scholar
- Zaman M, Di HJ, Cameron KC, Frampton CM (1999) Gross nitrogen mineralization and nitrification rates and their relationships to enzyme activities and the soil microbial biomass in soils treated with dairy shed effluent and ammonium fertilizer at different water potentials. Biol Fertil Soils 29:178–186CrossRefGoogle Scholar