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Impact of manure injection on alfalfa and grass hay stands

Amir Sadeghpour1, Quirine Ketterings1, Gregory Godwin1, Karl Czymmek1,2
1Cornell University Nutrient Management Spear Program, 2PRODAIRY

Producers in New York have shown interest in injecting manure into grass fields and alfalfa fields but have concerns about the potential for mechanical damage when injecting manure. In 2014 and 2015, six field trials were conducted to answer two questions: (1) will application of manure increase alfalfa and grass yields?, and (2) does injection reduce yields due to mechanical damage of the root system? In 2014, trials were conducted using a 4th year, low producing, tall fescue site and a thin 4th year alfalfa stand at the Musgrave Research Farm, in Aurora, NY. These two trials were continued in 2015. In 2015, we also added two trials using two higher-producing 2nd year alfalfa fields at the Cornell University Ruminant Center (CURC), in Harford, NY. Treatments included: (1) “disk down no manure” (slicing the soil, no manure) (2) injection of liquid dairy manure (slicing the soil, with manure); (3) no manure addition (no slicing, no manure); and (4) surface application of manure (no slicing, with manure). In the alfalfa trial at Aurora, manure was applied after 1st cutting in both years (4000 gallons/acre in 2014 and 8000 gallons in 2015). In the tall fescue trial, manure was applied after 1st and 3rd cutting in 2014 (4000 gallons/acre) and in 2015 (8000 gallons/acre for each application). The 1st manure application to the CURC sites (4000 gallons/acre) took place in the fall of 2014, after 4th cutting. At CURC, a second manure application (8000 gallons/acre) took place after 1st cutting in the spring of 2015. Manure was injected using a Veenhuis shallow disk injector in 2014 and a modified, larger scale, unit in 2015 (Figure 1).

Figure 1. A shallow disk injector designed for small scale research used in 2014 (A) and a shallow disk injector designed for large scale operation used in 2015 (B).

Figure 1. A shallow disk injector designed for small scale research used in 2014 (A) and a shallow disk injector designed for large scale operation used in 2015 (B).

Does hay benefit from manure?
In Aurora, manure application to the older alfalfa stand resulted in a 0.40 (2-4th cutting, 2014) and 0.32 ton/acre (1-4th cutting, 2015) increase in yield, for both injected and surface-applied manure. The tall fescue stand at Aurora also responded with 0.39 (2nd+3rd cutting, 2014) and 1.49 ton/acre (1-4th cutting, 2015) higher yield with manure application (Table 1). In contrast to the findings for these old stands at Aurora, the 2nd year alfalfa at the CURC site did not respond to manure addition (Table 1). Alfalfa yields in 2015 were more than 2-fold higher at the Harford site compared to Aurora, most likely reflecting the age of the stand and manure history of the fields.

Does injecting manure decrease hay yield?
In Aurora, alfalfa and tall fescue yields were comparable between “disks down” (injected) and “disks up” (surface applied) treatments (Table 2) and also for the younger and higher producing alfalfa trials at CURC injection did not help or hurt yields.

Though more research (additional locations and year) is needed before drawing broad conclusions, in the test conditions here, manure application benefited old hay stands, both alfalfa and tall fescue, while neither benefiting nor harming higher producing 2nd year alfalfa. These results suggest that grass benefits most from manure addition but that yields of old alfalfa stands can be increased with manure as well. These results suggest as well that manure injection does not harm the stand. Further research is needed to better understand what drives the yield response.

NMSP ackThis material is based upon work that is supported in part by USDA-CIG (NFWF), Federal Formula Funds, Atkinson Center for Sustainable Future at Cornell, and the National Institute of Food and Agriculture, USDA, under Award no. 2013-68002-20525. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the USDA. We thank Aurora Ridge Dairy Farm for providing the liquid manure, Peter Kleinman of USDA-ARS for loaning us the Veenhuis unit in 2014, and Scott Potter for working with us on the applications in 2015. For questions about these results contact Quirine M. Ketterings at 607-255-3061 or qmk2@cornell.edu, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/.



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