I am looking for alfalfa growers who are interested in plowing down a portion of a small field (or small section of the field, shooting for an acre total) in the fall and another portion in the spring. Below is a brief summary of the CIG proposal that I am working on, which is dependent on cooperators for alfalfa tissue and soil samples. If you know of anyone who would be willing to work with us on this project, please let me or your local extension educator know asap. Thanks!
Amber Moore
Assistant Professor - Extension Soil Specialist
University of Idaho - Twin Falls Research and Extension Center
315 Falls Avenue, Evergreen Bldg
P.O. Box 1827
Twin Falls, ID 83303-1827
Office - 208 736-3629
Cell - 208 404-8547
Fax - 208 736-0843
amberm@uidaho.edu
PROJECT DESCRIPTION
Idaho growers are interested in accounting for nitrogen in alfalfa after plowdown into their nutrient management plans. While there are calculators from other regions that estimate N availability based on the nitrogen content and total mass over the cover crop, a calculator has not been developed under Idaho conditions. The objective of this research proposal are to 1) test Oregon State University Cover Crop Calculator under Idaho conditions, 2) account for the effect of season incorporation timing on N availability, 3) adapt the calculator based on nitrogen (N) mineralization studies, and 4) create a new version of the calculator for Idaho.
We will select 10 alfalfa growers in Southern Idaho for this study. We will request that each grower select a portion of an existing field that can be plowed down in the spring, and another that can be plowed down in the fall. Tissue samples will be collected from small quadrants of predetermined dimensions prior to plowdown and analyzed for nitrogen content, total mass weight, and dry matter content, as described at http://smallfarms.oregonstate.edu/sites/default/files/Cover_Crop_Sampling_Instructions.pdf. Additional information on growing degree days, precipitation, soil texture, previous cropping systems, and other factors that may impact nitrogen mineralizaton of the alfalfa residue will also be collected.
Soil samples from both the fall and spring plowed portions of these fields will be collected in early April, prior to planting of the next crop. The soils will be incubated and analyzed for ammonium and nitrate concentrations regularly over a 5 month period to estimate the availability of nitrogen from the alfalfa plant tissue. This study will be repeated in 2012 and 2013 to improve the accuracy of the nitrogen mineralization data, as yearly changes in climate can significantly affect nitrogen mineralization rates over the winter.
Collected data on plant available nitrogen will be tested for correlation to tissue data in the OSU calculator. Statistics will be used to determine if there are additional factors, such as plowdown timing, that significantly impact N availability. Adjustments will be made in a new Idaho based calculator will be made to account for these other factors. A simple calculator will be created using Excel spreadsheet software, as has been done for the OSU calculator. This calculator will be posted on the UI Nutrient Management website, and will be available to post on the Idaho NRCS website.
Thursday, May 27, 2010
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This looks like a good project. Would the age of the stand at the inception of the study also be a variable that needs to be considered?
ReplyDeleteI cannot be sure, without talking to Dr. Moore, however, I believe that she is looking for a "mature" stand, so it would have accumulated some N over its lifetime. However, alfalfa fixes 50-150 lbs of N per year, and we remove much of it when we cut the alfalfa, so what will mostly be residual in the root system and nodules.
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