Conserving Nitrogen from Fall Dairy Manure Applications when Coupled with Winter Annuals Before Corn Silage PDF Download

Author: Rachel Milliron
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Languages : en
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Book Description
In Pennsylvania, dairy farming is the largest agricultural industry in the state. On these farms as well as others in the Northeast, manure storage capabilities are limited, requiring farmers to empty storage multiple times throughout the year. Although manure is a valuable source of nutrients, it can lead to water quality impairment. Applying manure in the fall is inherently more risky due to a lack of vegetative growth and a long time delay before primary crop uptake. This thesis research focused on different management strategies that would protect water quality and conserve nitrogen for crop use when manure is applied in the fall. In a two-year field study conducted at the Russell E. Larson Agricultural Research Farm, winter rye (Secale cereal L.) was planted before corn (Zea mays L.) in fields managed as a no-till system. Three different management strategies were evaluated: i) winter rye management (rye grown as a cover crop or harvested as silage); ii) method of manure application (broadcasted or injected); and iii) timing of manure application (applied early or late in the fall, in September or November respectively. In the first half of the study, effects of manure application strategies on nitrogen conservation for winter rye were evaluated by measuring ammonia volatilization, rye biomass, nitrogen content in aboveground rye, and soil-N to a depth of 90cm. Consistently in both years, ammonia volatilization was lower after early-injected manure than early-broadcasted. More nitrogen was conserved in the soil, and ryelage biomass was 48 and 38% higher after early-injected manure than after early-broadcasted manure in 2014 and 2015, respectively. After late-broadcasted and late-injected manure, there were no differences in ryelage biomass. However, late-injected manure resulted in 3.8 and 10.6% rye damage in 2014 and 2015, respectively. There were no differences in rye cover crop biomass due the method or time of manure application. Following rye, soil NO3-N tended to be higher after each of the following management practices: i) a rye cover crop compared to ryelage; ii) injected manure compared to broadcast manure; iii) a late manure application compared to early application; but differences were not always significant. In the second half of the study, previous management of manure and rye effects on manure-N availability from fall-applied manure for corn were assessed by: i) measuring pre-sidedress soil nitrate, corn yields, and total harvested corn and rye forage; ii) estimating adjusted N-recommendations and cost; and iii. calculating manure-N equivalency. In 2014 and 2015, pre-sidedress soil nitrate test (PSNT) results were below 25mg kg-1 for all treatments, and N-recommendations tended to be lower after each of the following: i) a cover crop compared to ryelage, ii) injected manure compared to broadcast manure and iii) late applied manure compared to early applied manure. Manure N-equivalencies were highest after a rye cover crop with late-injected manure (57.4%) and lowest after ryelage with early-broadcasted manure (4.3%). Averaged over the two years, total harvested forage, (either corn silage only after a cover crop, or ryelage and corn silage dry matter), was 19% higher after ryelage than after a rye cover crop and 22% higher after injected manure than after broadcasted manure. Winter rye coupled with nitrogen conserving manure application strategies can provide Northeast dairy producers flexible field management strategies that can increase fall manure-N utilization for crop production, and reduce nitrogen loss to the environment.