Extending Irrigated Alfalfa Stand Life and Long-Term Profitability by Alteration of Late-Season Harvest Schedules

Extending Irrigated Alfalfa Stand Life and Long-Term Profitability by Alteration of Late-Season Harvest Schedules

Summary

There was a 30% first cutting yield increase when the final 2003 cutting was skipped in strip plot comparisons. A harvest date study was conducted with 5 final cutting dates. There was a 0.8% increase in subsequent first cutting yield for every day delay in the final cutting. In a 4-cutting system, first 2004 cutting yield was increased by 18% when the final 2003 cutting was delayed. Overall yield was increased if the final cutting was delayed but utilized, but decreased if the final cutting was not utilized. Harvest schedule did not affect yield in a 3-cutting system.

Objectives/Performance Targets

• Determine if modification of present late-season alfalfa harvest practices will affect stand persistence.

  Determine relationships and interactions between late-season harvest management practices and alfalfa varieties on non-structural carbohydrates, alfalfa stem nematodes, and root and crown rot diseases of alfalfa.

  Conduct an economic analysis of traditional and modified late-season harvest practices to determine how long-term profitability is affected by management changes.

  Demonstrate to growers the effectiveness and economics of modification of late-season harvest management practices in maintaining alfalfa stands.

Accomplishments/Milestones

• Three harvest timing demonstration strips were conducted in 2003/04, bringing the number of demonstrations to 13 and cooperating growers to seven during the two years of the project. There has been a subsequent first-cutting yield increase of 30% following delayed fall harvest in four cutting systems. There has been no impact of fall harvest date on subsequent yield in three cutting systems.

  Two years of data have been collected from long-term fall harvest management/variety studies at two locations. Significant yield differences exist between late season harvest schedules, variety dormancy and pest resistance in 4-cutting systems. There have been no significant differences between treatments in the 3-cutting system.

  An experiment designed to evaluate the impact of fall harvest date on subsequent first cutting yield demonstrated a strong relationship in 2003-04. First cutting yield increased by 0.8% for each day the previous fall harvest was delayed after September 29. This experiment has been repeated during the fall of 2004.

  Demonstration strips have been visited or discussed at three field tours with local growers, three winter grower workshops, in radio interviews, and in two magazine articles. More than 100 growers have seen or discussed the demonstration strips and research plots first hand, and many time that amount have heard of the research through other media.

  The final year of the project will see continued data collection in the long-term management plots at Fruita and Yellow Jacket, and in the late season harvest date experiment at Orchard Mesa. Root and crown rot diseases and alfalfa stem nematode evaluations will be made on all plots during their third production year. The data collected will be used in extension efforts to publicize the impacts of late-season harvest management on alfalfa yield, persistence, and economics. Grower acceptance of the research will be evaluated with a questionnaire during the fall of 2005.

Impacts and Contributions/Outcomes

Discussion of the late-season cutting schedule modifications has been vigorous at grower gatherings, and many growers have expressed interest in experimenting with harvest schedule changes. Several western Colorado growers have changed to a 3-cutting schedule, followed by grazing of the regrowth. The fall 2004 weather was not conducive to hay making, and a significant acreage was not cut. The spring growth on much of this unharvested acreage may be enough to convince some growers that changes in harvest schedules may be beneficial in the long-term health of alfalfa fields.

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