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Recovery of Point‐Injected Labeled Nitrogen by Corn as Affected by Timing, Rate, and Tillage
Author(s) -
Timmons D. R.,
Baker J. L.
Publication year - 1991
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/agronj1991.00021962008300050016x
Subject(s) - plough , tillage , dry matter , zoology , nitrogen , agronomy , chemistry , chisel , ammonium , fertilizer , mathematics , biology , materials science , organic chemistry , metallurgy
Point‐injection technology is being developed to improve fertilizer management, particularly N management. This study was conducted to evaluate the effects of the rate (number) and timing of point‐injections of an ammonium nitrate (NH 4 NO 3 ) solution on N uptake and corn growth and to measure any differences due to tillage. Nitrogen‐15 depleted NH 4 NO 3 (AN) was hand‐injected beside individual plants at the V1, V5, and/or V9 growth stages at rates of 50, 100, and/or 200 kg N ha −1 with fall moldboard plow (MP), fall chisel plow (CP), and ridge‐till (RT) systems. While MP had the highest grain and total dry matter production (but with the lowest N concentrations in those materials), tillage was not a significant factor in either the percentage of the total plant N derived from labeled AN (N F ) or its recovery (N R ) for any stage sampled. Generally the year (i.e. different environmental conditions) and application timing or a timing‐by‐year interaction had the greatest influence on N F and N R . Although plants sampled at the V9 stage on the average recovered more N from the V1 application (39%) vs the V5 application (27%), at maturity N R values for grain (35%) and total dry matter (47%) were the same for both V1 or V5 applications (when only two applications were made). However when three applications were made (at the V1, V5, and V9 stages), N R values decreased with time of application for both grain (38, 31, and 26%, respectively) and total dry matter (53, 43, and 33%, respectively). Across application timing, grain N R values were 34 and 31%, respectively, for MP and RT. Compared with preplant knifed‐in labeled N for MP and RT systems in an adjacent simultaneous study, grain N R values for point‐injected N in this study were 16 and 6% greater, respectively, indicating that multiple injections of fertilizer N improved N‐use efficiency.