Broccoli residue-derived nitrogen immobilization following amendments of organic carbon: An incubation study

Date

2013

Authors

Congreves, K.A.
Voroney, R.P.
O'Halloran, I.P.
Van Eerd, L.L.

Journal Title

Journal ISSN

Volume Title

Publisher

Canadian Journal of Soil Science

Abstract

Cole crops, compared with many other crops, can pose a high risk of N losses after harvest due to substantial quantities of readily mineralizable N in crop residues. Organic C amendments (OCA) may reduce N losses via immobilization; however, the synchrony of OCA decomposition and cole crop residue N mineralization is crucial. A soil incubation study evaluated net N and C mineralization of broccoli residue-derived N or fertilizer-derived N with three OCAs: wheat straw, yard waste, or used cooking oil, to predict N immobilization and the potential to mitigate post-harvest N losses. By the 56th d of incubation, broccoli residue mineralized 67.0 mg N kg -1. In the broccoli residue-derived N treatments, wheat straw, yard waste, and used cooking oil significantly reduced the quantity of net N mineralization by 16.9, 12.3, and 86.0 mg N kg -1, respectively. The net N mineralization data were fitted to a first-order exponential model, and the overall trend of OCA was negative, indicating immobilization, whether N was derived from broccoli residue or fertilizer. The order of effect from OCAs on N immobilization corresponded to the order of effect on net C mineralization, where wheat straw and yard waste were lower than used cooking oil. In broccoli residue treatments, compared with fertilizer, higher N immobilization occurred for used cooking oil, and higher net C mineralization occurred for used cooking oil and yard waste. The higher N immobilization and net C mineralization suggest that broccoli residue produced a synergistic effect on the decomposition of used cooking oil. Additionally, both broccoli residue and used cooking oil treatments had synchronous peaks of net C mineralization at 4 d. This study provides evidence to warrant field studies to confirm that the application of organic C, especially used cooking oil, after cole crop harvest may be a beneficial management practice to minimize soil N losses.

Description

Keywords

Post-harvest, cole crops, wheat straw, yard waste, used cooking oil, nitrogen and carbon dynamics

Citation

Congreves, K.A., Voroney, R. P. , O'Halloran, I. P. , and Van Eerd, L. L. 2013. Broccoli residue-derived nitrogen immobilization following amendments of organic carbon: An incubation study. Canadian Journal of Soil Science. 93: 23-31

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