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Confined Microplot Size for Nitrogen‐15 Uptake by Corn Plants in a Corn Intercrop System
Author(s) -
Zhou Xiaomin,
Leibovitch Stewart,
MacKenzie Angus F.,
Madramootoo Chandra A.,
Dutilleul Pierre,
Smith Donald L.
Publication year - 1998
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1998.00021962009000020006x
Subject(s) - monocropping , intercropping , agronomy , lolium multiflorum , fertilizer , cropping system , poaceae , zea mays , biology , cropping , crop , agriculture , ecology
The high cost of labeled N fertilizer places practical limitations on measuring the fate of applied N. Applying of the labeled 15 N to a microplot within a larger plot can reduce the cost. The objective of this study was to assess microplot dimensions required to produce reliable 15 N data and cropping system effects on corn 15 N uptake under a regime of monocropped corn ( Zea mays L.) and corn intercropped with annual Italian ryegrass ( Lolium multiflorum Lam.). Nitrogen was applied to large plots (15 by 75 m) at 270 kg N ha −1 on a fine, silty, mixed, nonacid, frigid Typic Humaquept soil during the 1993 and 1994 growing seasons. Enriched N fertilizer was applied to 1.15 by 1‐m 2 confined microplots located in opposite halves of the large plot in each year of the study. Corn plants inside the confined microplots were sampled at 0.1, 0.3, and 0.5 m from the end borders of each microplot. In 1993, monocropping resulted in increases in leaf, stalk, and total dry matter production of 22, 41, and 30%, respectively, within microplots and relative to intercropped corn. There were no cropping system effects for these parameters in 1994. Monocropping increased atom % 15 N enrichment in corn grain and stalks and increased fertilizer N recovery in all plant tissue compared with intercropping in both years. There were no differences in atom % 15 N enrichment and fertilizer N recovery for plants harvested at the three sampling positions. These results suggest that a confined microplot with an area as small as 0.4 by 1.15 m can provide a reliable measure of fertilizer N recovery for corn plants in monocrop or intercrop systems. Any or all of the five plants within the microplot could be used to supply a reliable estimation of 15 N recovery by corn plants.