Monday, November 13, 2006

Evaluation of Forage-based Cropping Systems: Data from WICST.

Janet Hedtcke1, Joshua Posner1, and Jon Baldock2. (1) University of Wisconsin-Madison, Agronomy Dept., 1575 Linden Drive, Madison, WI 53706, (2) AGSTAT, 6394 Grandview Rd, Verona, WI 53593, United States of America

In Wisconsin, there are over 3 million acres of forage production including alfalfa, grass-legume hay and pasture that support the livestock industry. Some research has suggested however, that intensive alfalfa management is the most productive way to feed dairy cows. Included in the Wisconsin Integrated Cropping Systems Trial (WICST), are three forage-based cropping systems that range from an intensive alfalfa system (CS4, a-a-a-c) to an organic forage rotation including a companion seeding of alfalfa (CS5, o/p/a-a-c) to a cool-season grass-legume pasture rotationally grazed by dairy heifers (CS6). During the cool wet 2004 and the hot dry 2005 seasons, an exclusion strip in CS6 allowed for haying all three systems. First-year established forage production of CS4 and CS5 and continuous production of CS6 are evaluated here. Yields across systems averaged 5.14 and 3.70 tons DM/a in 2004 and 2005, respectively (p<0.0001); the grass-based pasture was most affected during the dry 2005 season, and was only about half as productive as in the wetter, cooler season of 2004. Winterkill (~ 10% of area) on the alfalfa during January 2005 also impacted the established stands during the following summer. Yields were similar among systems during the productive 2004 season, but there were significant differences in 2005 (CS4>CS5>CS6) RFQ was inversely related to yield, all systems being higher in 2005 (p<0.0001). All systems produced acceptable quality for dairy animals (RFQ>140) with the exception of CS5 in 2004. Protein levels were different across systems but all systems were above the minimum of 16.5% recommended for lactating dairy cows. It appears from this data that the intensive alfalfa management plots (CS4) were equally productive as the lower input forage systems in 2004 but better in 2005.

Handout (.ppt format, 873.0 kb)