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Microplot Size Reguirements for Measuring Balances of Fertilizer Nitrogen‐15 Applied to Maize
Author(s) -
Stumpe J. M.,
Vlek P. L. G.,
Mughogho S. K.,
Ganry F.
Publication year - 1989
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1989.03615995005300030028x
Subject(s) - fertilizer , agronomy , zea mays , dilution , poaceae , mathematics , biology , physics , thermodynamics
In order to reduce the amount of expensive labeled‐N fertilizer needed for field studies of 15 N balances in maize ( Zea mays L.), four experiments were conducted to determine the minimum microplot size requirement. The minimum microplot area required was ascertained by applying urea labeled with 15 N to 4.5‐ by 2.0‐m microplots inside larger plots treated with the same fertilizer and observing the dilution of 15 N in maize plants by N from outside the microplot with respect to proximity to microplot borders. Under the conditions of this study, interrow spacings of 75 cm resulted in dilution of 15 N in only the row located 37.5 cm from the microplot border. Intrarow plant spacings of 25 cm resulted in the dilution of 15 N in the plants located 12.5 and 37.5 cm from the microplot border. Microplots with 3.0‐ by 2.0‐m border dimensions, containing four rows and eight plants/row, resulted in the desired number of plants (eight) unaffected by proximity to the border from a minimum microplot area and thus minimized the requirement for 15 N. Complete recovery of 15 N in the plant‐soil system occurred when climatic conditions and fertilizer management practices favored N conservation, confirming that microplots were sufficiently large for an accurate determination of 15 N balance.