Pedosphere 28(2): 332--340, 2018
ISSN 1002-0160/CN 32-1315/P
©2018 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Nitrogen Release from Slow-Release Fertilizers in Soils with Different Microbial Activities
Pierfrancesco NARDI1, Ulderico NERI1, Giovanni DI MATTEO1, Alessandra TRINCHERA1, Rosario NAPOLI1, Roberta FARINA1, Guntur V. SUBBARAO2, Anna BENEDETTI1
1CREA-Council for Agricultural Research and Economics, Research Center for Agriculture and Environment, Via della Navicella 2, Rome 00184 (Italy)
2Japan International Research Center for Agricultural Sciences (JIRCAS), Tsukuba 305-8686 (Japan)
Corresponding Author:Pierfrancesco NARDI
      Soil microbial activity is recognized as an important factor affecting nitrogen (N) release from slow-release fertilizers. However, studies on the effect of size and activity of soil microflora on fertilizer degradation have provided contrasting results. To date, no clear relationships exist between soil microbial activity and the release of N from slow-release fertilizers. Hence, the aim of this study was to better understand such relationships by determining the release of N from three slow-release fertilizers in soils with different microbial activities. Soils were amended with urea-formaldehyde (UF), isobutylidene diurea (IBDU), and crotonylidene diurea (CDU). Urea, a soluble fertilizer, was used as the control. Fertilized soil samples were placed in a leaching system, and the release of N was determined by measuring ammonium-N and nitrate-N concentrations in leachates during 90 d of incubation. Non-linear regression was used to fit N leaching rate to a first-order model. In all the treated soils, N was released in the order:urea (89%-100%) > IBDU (59%-94%) > UF (46%-73%) > CDU (44%-56%). At the end of incubation, N released from CDU did not differ (P > 0.05) among soils. On the contrary, UF and IBDU released significantly lower (P < 0.05) amounts of N in the soil with higher microbial activity and lower pH. The rate constant (K0) for UF was lower (P < 0.05) in the soil with lower pH. Taken together, our results indicated that soil microbial size and microbial activity had a marginal effect on fertilizer mineralization.
Key Words:  ammonium-N,crotonylidene diurea,isobutylidene diurea,nitrate-N,non-linear regression,urea-formaldehyde
Citation: Nardi P, Neri U, Di Matteo G, Trinchera A, Napoli R, Farina R, Subbarao G V, Benedetti A. 2018. Nitrogen release from slow-release fertilizers in soils with different microbial activities. Pedosphere. 28(2):332-340.
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