Cropping Systems 282 Agronomy Journal  Volume 102, Issue 1  2010 Published in Agron. J. 102:282–288 (2010) Published online 11 Dec. 2009 doi:10.2134/agronj2009.0263 Copyright © 2010 by the American Society of Agronomy, 677 South Segoe Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. M ultifunctional cropping systems provide food, feed, fber, and other primary inputs for society and are based on ecological principles to maximize ecosystem func- tion. Cropping systems dominated by crops with the same life cycle generally do not match ecosystem processes with internal ecosystem functions. Annual crops only use a fraction of the available incident solar energy and expose soil to erosion and nutrient losses during periods without adequate residue cover and crop nutrient uptake. Singer et al. (2007) reported that interseeded red clover ( Trifolium pratense L.) in winter wheat ( Triticum aestivum L.) intercepted on average 50% of incident photosynthetically active radiation during the remainder of the growing season afer wheat harvest. Kaspar et al. (2007) reported that a cereal rye (Secale cereale L.) cover crop reduced 4-yr average fow-weighted nitrate concentrations by 59% and load by 61% compared with a no cover crop control in a corn–soybean rotation in Iowa, USA. Goolsby et al. (1999) estimated that mineralized soil N contributed 29% of the total N delivered to the Gulf of Mexico. Data quantifying annual soil loss between row crops and sod from a wide range of soil types indicate that soil loss in sod is 1% or less of the soil losses that occur in row crops (Karlen et al., 2007). Tese are all compelling reasons to develop multifunctional cropping systems that enhance ecosystem function. Combining annual and perennial plant species in a cropping system is one approach to achieving enhanced ecosystem func- tion. Concurrent management of multiple plant species, includ- ing one with an immediate cash value (commodity or staple) and typically a perennial(s), is ofen termed a living mulch cropping system. Perennial cover crops and perennial groundcovers are ofen used synonymously. Living mulches extend the functions of winter annual cover crops that are usually planted afer har- vesting the cash grain or oilseed crop in the fall and killed before planting the following cash crop. Interest in using living mulches evolved as a management practice to protect soil from erosion on highly erodible land and provide forage for fall and winter animal grazing. Most of the living mulch research has focused on comparisons between living mulch treatments and a control to quantify crop yield response. Few studies have presented data on the nutritive value of living mulches. Zemenchik et al. (2000) used Kura clover as a living mulch in corn and managed the Kura using various herbicide treatments. Corn grain yields were highest when Kura was killed with a herbi- cide and fertilized with N, although corn grain yields were similar when Kura was killed in a 61-cm band centered on the corn row compared with killing the entire stand without supplemental N. Kura in the killed band treatment fully recovered and had similar seasonal forage yields during the subsequent growing season when it was managed as a forage crop. Kura nutritive value during the forage year was afected by the herbicide treatment during the previous corn phase of the rotation. Average seasonal acid deter- gent fber (ADF) concentrations were higher in the band-killed treatment compared with the untreated Kura in 1 of 2 yr following ABSTRACT Living mulches can function to supply forage in multifunctional cropping systems. Information quantifying nutritive value of for- age plants in living mulch cropping systems is limited. Te objective of this research was to quantify the nutritive value of forages from diferent plant functional groups managed as living mulches in 2 of 3 yr and as a forage crop in the third year of this 3-yr corn (Zea mays L.)-soybean [ Glycine max (L.) Merr.]-forage rotation. Alfalfa (Medicago sativa L.), Kura clover ( Trifolium ambiguum M. Bieb.), and birdsfoot trefoil (Lotus corniculatus L.) were evaluated in sole seedings and binary mixtures, reed canarygrass (Phalaris arundinacea L.) and orchardgrass (Dactylis glomerata L.) were included in three-way mixtures, and a nondormant alfalfa was seeded each spring for comparison as a control. Average crude protein (CP) and neutral detergent fber (NDF) during 2005, 2006, and 2007 was 190 and 449 g kg –1 for Kura + alfalfa + reed canarygrass compared with 182 and 458 g kg –1 averaged across birdsfoot trefoil + alfalfa + orchardgrass and Kura + alfalfa + orchardgrass mixtures, 195 and 397 g kg –1 averaged across alfalfa, Kura + alfalfa, and alfalfa + birdsfoot trefoil, and 193 and 404 g kg –1 for the nondormant alfalfa treatment. Weed densities averaged 104, 178, and 116 weeds m –2 in 2005, 2006, and 2007 among living mulch treatments compared with 14, 84, and 67 weeds m –2 in the nondormant alfalfa. Despite high weed densities in the living mulch treatments, no specifc treatment efect was detected for nutritive value. All of these living mulch treatments produced high nutritive value forage. J.W. Singer, USDA-ARS National Soil Tilth Lab., 2110 University Blvd., Ames, IA 50011; K.J. Moore, Dep. of Agronomy, Iowa State Univ., 1571 Agronomy Hall, Ames, IA 50011 Received 2 July 2009. *Corresponding author (jeremy.singer@ars.usda.gov). Abbreviations: CP, crude protein; IVDDM, in vitro digestible dry matter; IVDMD, in vitro dry matter digestibility; NDF, neutral detergent fber. Living Mulch Nutritive Value in a Corn-Soybean-Forage Rotation Jeremy W. Singer* and Kenneth J. Moore