Improving dairy farm sustainability I: An approach to animal and crop nutrient management planning

This two-part article reports on a process for integrating knowledge to develop and evaluate nutrient management plans for dairy farms. The focus is on accounting for and managing N, P, and K on a commercial farm. The case study farm was a well managed, progressive dairy farm located in central New York with 320 lactating cows (Bos taurus), 290 heifers, and 600 acres of crop land. This farm had the resources and management skills that are a model for dairy farming in the future. However, mass nutrient balances indicated that 60 to 72% of imported N, P, and K were in excess of nutrient exports from the farm; 60 to 80% of the imported nutrients were from purchased feeds. Evaluation and refinement of animal diets resulted in a reduction in crude protein content of the rations by 2 percentage points while supporting a 13% increase in milk production and a 34% decrease in total N excretion. Partial budgets projected that ration reformulation increased net farm income by $40200. Implementation of a crop nutrient management plan was expected to decrease fertilizer purchases and application expenses by about $1350, but construction of a remote manure storage pond and custom spreading of manure resulted in a decrease of net farm income of $4000. The vast quantity of data required and the complexity of the analysis indicate that developing computerized decision aid tools will be necessary to apply the process to a large number of farms.