Location: Soil and Water Management Research
Title: On-farm environmental assessment of corn silage production systems receiving liquid dairy manure Authors
Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 25, 2013
Publication Date: December 2, 2013
Citation: Krueger, E., Baker, J.M., Ochsner, T.E., Wente, C.D., Feyereisen, G.W., Reicosky, D.C. 2013. On-farm environmental assessment of corn silage production systems receiving liquid dairy manure. Journal of Soil and Water Conservation. 68(6):438-449. Interpretive Summary: The possible environmental impact of large dairies is a serious concern, because of the large amount of manure produced and the limited land area on which it is applied. This study was conducted to measure the offsite transport of of nutrients from a silage corn field receiving dairy manure at permitted application rates, and to see if nutrient losses might be reduced through the use of a winter rye cover crop. The research was conducted in two adjacent tile-drained fields near a large dairy in west central MN. Manure was applied each fall following silage harvest at rates at average total N and P rates of 410 and 98 kg ha-1, respectively. We monitored tile drainage outflows for NO3-N and dissolved reactive phosphorus (DRP). NO3-N concentrations in the field that had a winter rye cover crop were lower (38 versus 53 mg/L), but there was no difference in DRP or total drainage flow. The cover crop also had no discernible effect on soil carbon levels. The rye did reduce spring soil N levels, but it also reduced the yield of the following corn silage crop by 16%. We conclude that a winter rye cover crop can reduce NO3-N losses, but the possible impact on subsequent silage yields makes it a risky option, at least in this region. These results will be useful in developing agronomic practices that reduce the environmental footprint of large dairies.
Technical Abstract: Increased corn silage and manure production accompanying the proliferation of large dairies has prompted concern regarding their environmental impacts. Our objectives were (1) to quantify soil chemical properties and offsite nutrient transport under field-scale corn (Zea mays L.) silage production and high-rate manure application on artificially drained soils and (2) to assess the environmental and agronomic impacts of a winter rye (Secale cereal L.) cover crop within this cropping system near Morris, MN. From 2007-2009, corn for silage was grown on two adjacent 65 ha fields with rye planted after corn on one field in 2007. Manure was fall applied annually at average total N and P rates of 410 and 98 kg ha-1, respectively. Drainage NO3-N concentration was reduced from 53 mg L-1 before rye to 38 mg L-1 after rye, but rye had no apparent effect on DRP concentration or drainage volume. Annual NO3-N and dissolved reactive phosphorus (DRP) loads averaged 52 and 0.8 kg ha-1 yr-1, respectively. Soil nutrient accumulation did not occur, and soil organic carbon (SOC) and total nitrogen (TN) were maintained or increased with or without rye. Rye reduced spring soil NO3-N by 46% compared with winter fallow but did not impact Olsen P. Rye increased ground cover, but corn dry matter (DM) yield was 16% lower after rye than after winter fallow. Offsite nutrient transport and limited ground cover with corn silage production suggest alternative management strategies are needed, but possible corn DM yield reduction after winter rye makes it a risky option.