HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Joo, Y. K. Articles by Blackmer, A. M. Search for Related Content PubMed Articles by Joo, Y. K. Articles by Blackmer, A. M. Agricola Articles by Joo, Y. K. Articles by Blackmer, A. M.

Kentucky Bluegrass Recovery of Urea-Derived Nitrogen-15 Amended with Urease Inhibitor

Yonsei Univ., Inst. of Agricultural Development, Seoul 120-749, Korea

N. E. Christians^*

Dep. of Horticulture

A. M. Blackmer

Dep. of Agronomy, Iowa State Univ., Ames, IA 50011

*Corresponding author.

ABSTRACT

Urea is a commonly used N fertilizer on turfgrass areas. Urease inhibitors represent a possible method of reducing volatile loss of NH₃ from treated turf. In this study, the recovery of urea-N by a Kentucky bluegrass (Poa pratensis L.) turf was determined in the field by using a ¹⁵N tracer. The urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) also was evaluated as a fertilizer amendment to increase urea-N efficiency. The study was conducted on a Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll) soil. Treatments included urea labeled with 5% ¹⁵N applied at the rate of 49 kg ha^–1 with NBPT at 0 (urea alone), 0.25, and 0.5% of the weight of N. Grass clippings were collected weekly for 5 wk. Shoots, thatch, and rootzone samples were collected at termination. Total urea-derived N recovered from 5 wk of clippings ranged from 7.5% from the areas treated with urea alone to 8.1% in the urea + 0.5% NBPT treated areas. The 0.25% NBPT treatment increased N recovery in the 0 to 7.5 cm depth of soil from 13.6 (urea without NBPT) to 22.4%. This NBPT rate also increased N recovery from the whole soil-plant system from 28.8 (urea without NBPT) to 45.0%, whereas the 0.5% NBPT rate either had no effect or numerically decreased N recovery. The increased N recovery at the low rate of NBPT was probably due to a reduction in NH₃ volatilization. The reducing effect of the higher NBPT treatment may have been due to delayed urea hydrolysis and to subsequent increased free-urea loss below the rooting zone after an unusual 130 mm rain during the fifth and sixth days after treatment.

Published as Journal Paper no. J-13986 of the Iowa Agric. and Home Economics Exp. Stn, Ames. Project no. 2231.

Received for publication April 20, 1990.