title: Economic and phosphorus-related effects of precision feeding and forage management at a farm scale.
abstract: Structural best management practices were implemented throughout the Cannonsville Reservoir Watershed (CRW) in an effort to reduce P losses to the reservoir. Yet long-term water quality control efforts within CRW are hindered by continuous P build-up in the soils resulting from dairy farm P imports exceeding exports. Addressing the P imbalance problems and maintaining economic viability of the farms requires a system-level redesign of farm management. One possible innovative strategy, precision feed management (PFM), reduces soil-P build-up by limiting feed and fertilizer purchases, and increasing high-quality homegrown forage production. This study applied the integrated farm system model (IFSM) to 2 CRW dairy farms to quantify the benefits of a PFM farm planning strategy in controlling P imbalance problems, and maintaining farm profit-ability and reducing off-farm P losses. The IFSM accurately simulated the 2 farms based on farm data supplied by farm planners; these scenarios were used as the baseline conditions. The IFSM simulations of more accurate feeding of P (based on P required in animal diets) integrated with increased productivity of grass-forage and increased proportion of forage in the diet reduced the P imbalance of 1 farm from 5.3 to 0.5 kg/ ha and from 9.6 to 0.0 kg/ha for the second farm. For both farms, soluble P lost to the environment was reduced by 18%. Feed supplement purchases declined by 7.5 kg/cow per year for dietary mineral P, and by 1.04 and 1.29 t/cow per year for protein concentrates through adoption of the PFM system. Moreover, when a land management practice of converting corn to grass was coupled with the precision feeding of P and improved forage management, IFSM predicted reductions of 5.8 and 9.3 kg/ha of converted land sediment-bound P in erosion loss each year. The model predicted slight purchase increases in corn grain to offset reductions in corn silage production and feeding rates, but no appreciable change in the farm P balance due to land conversion. The model-based studies conducted on a farm-by-farm basis complement farm planning efforts in exploring innovative farming systems. Moreover, the results set a benchmark for potential benefits of PFM strategies, economically and environmentally.
authors.affiliation: Agricultural and Biological Engineering, Pennsylvania State University, University Park 16802, USA. ltg106@psu.edu
authors.forename: L T
authors.initials: LT
authors.lastname: Ghebremichael
authors.forename: P E
authors.initials: PE
authors.lastname: Cerosaletti
authors.forename: T L
authors.initials: TL
authors.lastname: Veith
authors.forename: C A
authors.initials: CA
authors.lastname: Rotz
authors.forename: J M
authors.initials: JM
authors.lastname: Hamlett
authors.forename: W J
authors.initials: WJ
authors.lastname: Gburek
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000502:physiology*; D003198:Computer Simulation; D003612:Dairying / Q000191:economics / Q000379:methods*; D004032:Diet / Q000662:veterinary; D004787:Environmental Pollution / Q000517:prevention & control; D005248:Feeding Methods / Q000191:economics / Q000662:veterinary*; D008954:Models, Biological; D009518:New York; D016226:Phosphorus, Dietary / Q000008:administration & dosage / Q000032:analysis; D006109:Poaceae; D003313:Zea mays
chemical_list: D016226:Phosphorus, Dietary