Effects of 3-nitrooxypropanol manure fertilizer on soil health and hydraulic properties.

Supplementing beef cattle with 3-nitrooxypropanol (3-NOP) decreases enteric methane production, but it is unknown if fertilizing soil with 3-NOP manure influences soil health. We measured soil health indicators 2 yr after manure application to a bromegrass (Bromus L.) and alfalfa (Medicago sativa L.) mixed crop. Treatments were: composted conventional manure (without supplements); stockpiled conventional manure; composted manure from cattle supplemented with 3-NOP; stockpiled 3-NOP manure; composted manure from cattle supplemented with 3-NOP and monensin (3-NOP+Mon), a supplement that improves digestion; stockpiled 3-NOP+Mon manure; inorganic fertilizer (150 kg N ha-1 and 50 kg P ha-1 ); and an unamended control. Select chemical (K+ , Mg2+ , Mn+ , Zn+ , pH, and Olsen-P), biological (soil organic matter, active C, respiration, and extractable protein), physical (wet aggregate stability, bulk density, total porosity, and macro-, meso-, and micro-porosity), and hydraulic (saturation, field capacity, wilting point, water holding capacity, and hydraulic conductivity) variables were measured. The inclusion of monensin decreased soil Zn+ concentrations by 70% in stockpiled 3-NOP+Mon compared with stockpiled conventional manure. Active C and protein in composted conventional manure were 37 and 92% higher compared with stockpiled manure, respectively, but did not vary between 3-NOP treatments. 3-Nitrooxypropanol did not significantly alter other soil health indicators. Our results suggest that composted and stockpiled 3-NOP manure can be used as a nutrient source for forage crops without requiring changes to current manure management because it has minimal influence on soil health.

Greenhouse gas and ammonia emissions from stored manure from beef cattle supplemented 3-nitrooxypropanol and monensin to reduce enteric methane emissions.

The investigative material 3-nitrooxypropanol (3-NOP) can reduce enteric methane emissions from beef cattle. North American beef cattle are often supplemented the drug monensin to improve feed digestibility. Residual and confounding effects of these additives on manure greenhouse gas (GHG) emissions are unknown. This research tested whether manure carbon and nitrogen, and GHG and ammonia emissions, differed from cattle fed a typical finishing diet and 3-NOP [125-200 mg kg-1 dry matter (DM) feed], or both 3-NOP (125-200 mg kg-1 DM) and monensin (33 mg kg-1 DM) together, compared to a control (no supplements) when manure was stockpiled or composted for 202 days. Consistent with other studies, cumulative GHGs (except nitrous oxide) and ammonia emissions were higher from composted compared to stockpiled manure (all P < 0.01). Dry matter, total carbon and total nitrogen mass balance estimates, and cumulative GHG and ammonia emissions, from stored manure were not affected by 3-NOP or monensin. During the current experiment, supplementing beef cattle with 3-NOP did not significantly affect manure GHG or NH3 emissions during storage under the tested management conditions, suggesting supplementing cattle with 3-NOP does not have residual effects on manure decomposition as estimated using total carbon and nitrogen losses and GHG emissions.