Monday, 6 October 2008: 9:15 AM
George R. Brown Convention Center, 371D
Escalating energy and fertilizer N prices, and regulatory limits on ammonia emissions from livestock facilities require methods that reduce manure management costs, enhance the fertilizer value of manure and reduce ammonia volatilization. We compared two dairy herd management practices on manure N capture and recycling through crops: the conventional practice of barn manure collection and land application, and corralling dairy cattle directly on cropland. Cattle were kept in a barn for two (B2) or four (B4) days and manure was hauled to fields, or cattle were corralled directly on cropland for two (C2) or four (C4) days. Two manure application seasons, spring-summer (SS) and fall-winter (FW) were used each of two years. Each season was followed by three-year crop rotations: SS by wheat-sudangrass-winter rye-corn-winter rye-corn, and FW followed by corn-winter rye-corn-winter rye-corn. Corralling resulted in 50 to 65% greater N applications than barn manure. In-barn N losses (% of excreted N, ExN) were greater from B4 (30%) than B2 (20%). Apparent N recovery of applied N (ANR) by wheat ranged from 13% to 25% at the lower (B2 and C2) application rates and 8% to 14% at the higher (B4 and C4) rates. First-year corn following FW had ANR of 13 to 32% at the lower (B2 and C2) application rates and 9 to 20% of applied N at the higher (B4 and C4) rates. As a percent of ExN, ANR over the 3 yr rotation from C2 was 50%, B2 35%, C4 30% and B4 22%. Overall results demonstrated that corralling the dairy herd on cropland simplifies manure management, reduces ammonia loss, and improves urine N capture and recycling through crops.