Greg Godwina, Quirine M. Ketteringsa, Karl J. Czymmeka,b, Todd Dumondc, and Doug Youngd
a Nutrient Management Spear Program, Dept. of Animal Science, Cornell University, Ithaca, NY, b PRODAIRY, Dept. of Animal Science, Cornell University, Ithaca, NY, cDumond Farms, Union Spring, NY, and dSpruce Haven Farm and Research Center, Union Springs, NY
The application of manure to an actively growing crop can improve the uptake of nutrients, with benefits to both the crop and the environment. The “Nutrient Boom” (Figure 1) is a new tool developed by Doug Young of Spruce Haven Farm and Research Center (Union Springs, NY) and partners that allows for the application of liquid manure to corn as tall as 7 ft. It applies manure through flexible hoses in a 120 foot swath with little damage to the standing corn. Mid-season manure application allows for greater flexibility in the spring for planting and can reduce runoff by delaying spreading to a drier part of the growing season. Two years of field trials were conducted to compare corn yield with mid-season manure application with yields obtained with inorganic nitrogen (N) application.
A trial was conducted in Union Springs, NY, in 2016 and 2017. There were two 120 foot wide manure treatments, each replicated three times: (1) No manure (control treatment); and (2) Manure (targeted rate of ~12000 gallons/acre). Within each manure treatment, six 300-foot long subplots were established that received the following sidedress N treatments after the manure was applied: (1) No sidedress N; (2) 35 lbs N/acre; (3) 70 lbs N/acre; (4) 105 lbs N/acre; (5) 140 lbs N/acre; and (6) 175 lbs N/acre. In 2016, one corn variety was used (PO157AMX). In 2017, each strip was split through the middle and planted to two corn varieties (DKC54-36AR and P0506). Corn stalk nitrate test (CSNT) samples were taken when the corn had a moisture content of about 35% dry matter (typical silage harvest time). The field was harvested for grain in both years. Yields were obtained from yield monitor maps calculated from 200-ft lengths in the middle 80 ft (40 ft per variety in 2017) of the plots to minimize the influence of adjacent treatments.
Plots receiving manure mid-season averaged 181 bu/acre (2016) and 159 bu/acre (2017). The corn grown in these plots did not respond to extra N fertilizer regardless of rate. The corn in plots that did not receive manure responded to N fertilizer (Figure 2). Pre-sidedress nitrate tests taken prior to manure and inorganic N application indicated a response to N was likely in both years.
Because corn grown in plots that received manure was not responsive to extra fertilizer N, the most economic rate of fertilizer N (MERN) where manure was applied was 0 lbs N/acre. The MERN for the non-manured plots was 121 lbs N/acre in 2016, and 133 lbs N/acre (DKC54-36AR) and 143 lbs N /acre (P0506) in 2017, using $4.35/bu of grain and $0.32/lb of N fertilizer. Yield at the MERN averaged 157 bu/acre in 2016, and 122 bu/acre (DKC54-36AR) and 145 bu/acre (P0506) in 2017. Manure addition increased yield to 16-35 bu/acre above yields obtained at the MERNs with fertilizer N only.
Results were similar both years despite large differences in precipitation between the two growing seasons. Of the two varieties planted in 2017, both performed similarly in the manured plots but P0506 responded more to the N in non-manured plots and used N more efficiently (MERN was 10 lbs/acre higher while yield at MERN was 23 bu/acre higher for P0506).
The CSNT results (Figure 3) showed an increase in CSNT when N fertilizer was added beyond the MERN in plots that had not received manure, resulting in peak in grain yield to CSNT ratio just prior to the MERN. For plots that had received manure, this relationship was different, reflecting that additional N fertilizer could not increase yield but did increase CSNT values.
These results show two things: (1) the benefit of the manure application mid-season for overall yield of the field; and (2) the potential for both gains in yield and savings in N fertilizer costs with application of manure to fields that are N deficient.
Conclusions and Implications
Manure application mid-season with the Nutrient Boom at rates applied in the study benefitted corn grain yield beyond what could be obtained with fertilizer in 2016 (dry year) and 2017 (wet year). Corn that was grown on plots that received the manure did not respond to sidedress N application in 2016 or 2017, independent of variety. Thus, manure applications were high enough to meet the crops’ N needs but N supply was not solely responsible for the higher yield. The higher yield and lack of response to fertilizer N in the manured plots suggest great potential for lowering of whole farm nutrient mass balances with manure application mid-season, especially for fields that are N deficient and would otherwise have needed a fertilizer N application. Future work should focus on rate calibration and control of the applicator and comparisons of impact of rates and timing of application on yield and N use efficiency. The current model was susceptible to clogging, but this is being addressed in the next version of the Nutrient Boom.
This work was supported by the New York Farm Viability Institute and Federal Formula Funding. We would like to thank the staff at Dumond Farms and Spruce Haven Farm and Research Center and NMSP team members who helped out with the trials. For questions about these results, contact Quirine M. Ketterings at 607-255-3061 or firstname.lastname@example.org, and/or visit the Cornell Nutrient Management Spear Program website at: http://nmsp.cals.cornell.edu/