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

This Article Figures Only Full Text Free Full Text (PDF) Free 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 Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Zemenchik, R. A. Articles by Albrecht, K. A. Search for Related Content PubMed PubMed Citation Articles by Zemenchik, R. A. Articles by Albrecht, K. A. Agricola Articles by Zemenchik, R. A. Articles by Albrecht, K. A. Related Collections Soil Fertility and Productivity Forage Management Nutrient Management Water Pollution Soil Analysis

TECHNICAL REPORT
Surface Water Quality

Bioavailable Phosphorus in Runoff from Alfalfa, Smooth Bromegrass, and Alfalfa–Smooth Bromegrass

^a CNH Soil Management Division, Rt. 150 E., P.O. Box 65, Goodfield, IL 61742
^b Soil Tech Inc., 5720 Smetana Dr., Minnetonka, MN 55343
^c Dep. of Agronomy, 1575 Linden Dr., Univ. of Wisconsin-Madison, Madison, WI 53706

* Corresponding author (rob.zemenchik{at}cnh.com)

Received for publication December 4, 2000. Runoff from sloping landscapes cropped with established alfalfa (Medicago sativa L.) may contain bioavailable P (BAP) which accelerates eutrophication of surface water bodies. Such BAP exists as either dissolved reactive P (DRP) or bioavailable reactive particulate P (BPP). We hypothesized that before and after harvest, sod-forming smooth bromegrass (Bromus inermis Leyss.) or alfalfa–smooth bromegrass mixtures would have less BAP, DRP, and BPP runoff losses than taprooted alfalfa. Swards established in 1992 near Lancaster, WI were subjected to a 72 mm simulated rainfall applied for 1 h in 1993 and 1994 to forage regrowth at 4 and 6 wk after first harvest and immediately (0 wk) after second harvest. Hourly BAP losses for all sward types were 82% less when 1.5 Mg ha^-1 of forage dry matter was present. High DRP losses (>0.050 kg ha^-1) were associated with high DRP concentrations (>7.1 µmol L^-1) and high surface soil P concentrations (>59 mg kg^-1) resulting from broadcast maintenance P fertilizer. High BPP losses (>0.035 kg ha^-1) were associated with high runoff volumes (>24 mm) and sediment concentrations (>2 g L^-1). Summed over all 6 rainfall simulations, total BAP loss was only 0.07 kg ha^-1 at the 6 wk stage of regrowth compared with 0.35 at 4 wk, and 0.41 at 0 wk. Moreover, there was no significant difference between sward types for DRP concentration, DRP loss, or BAP loss. We conclude that avoiding excessive defoliation was more effective at reducing BAP losses than specific forage species selection.

Abbreviations: BAP, bioavailable phosphorus • BPP, bioavailable reactive particulate phosphorus • DRP, dissolved reactive phosphorus • EDI, effective depth of interaction

This article has been cited by other articles:

				C. A. Rotz, F. Taube, M. P. Russelle, J. Oenema, M. A. Sanderson, and M. Wachendorf Whole-Farm Perspectives of Nutrient Flows in Grassland Agriculture Crop Sci., September 23, 2005; 45(6): 2139 - 2159. [Abstract] [Full Text] [PDF]