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By Megan Wittmeyer
  • Environment
  • Water
  • Dairy
  • Soil

For over 20 years, Cornell CALS’ Nutrient Management Spear Program has helped dairy farms responsibly manage manure to meet crop nutrient needs while improving farm profitability and sustainability. Key to this success is the whole-farm nutrient mass balance tool, which offers indicators to reduce nutrient imports, saving farms money while limiting nutrient losses that can pollute water. A recent NMSP study reaffirms the tool’s value for sustainable nutrient management and suggests additional indicators to improve the tool. 

New York state is a major dairy-producing state with over 3,600 dairy farms collectively producing around 15 billion pounds of milk per year. Dairy farms face the challenge of recycling manure while avoiding excess loss of the nutrients nitrogen and phosphorus, which can degrade water quality. 

The nutrient mass balance tool assesses whole-farm nutrient imports and exports. A high balance indicates significantly more nutrients are imported than exported, increasing the risk of nutrient loss to the environment. The tool offers indicators to reduce the balance, helping farmers keep valuable nutrients on their farms and out of water sources.

The findings

Farm nutrient mass balances are mainly driven by feed and fertilizer imports. A farm can reduce its balance by reducing these imports, which not only lessens the risk of nutrient loss and water pollution but also saves the farm money.

Other key balance drivers include how efficiently the farm uses its nutrients, the amount of homegrown feed and the number of animals per acre of farmland. New indicators such as the ratio of heifers (female cattle that have not had their first calf) to cows, and the ratio of farmland used to grow forage versus grain could offer further insight on decisions affecting the balance. 

The study also found that farms can attain previously established balance benchmarks that provide an optimal range to target economic and environmental sustainability. 

Why it matters

Dairy farming is an important industry for New York state, with over 1.5 million acres used for dairy feed production. New York’s water quality largely depends on dairy’s ability to recycle nitrogen and phosphorus in manure while limiting losses. Farm viability depends on recycling these nutrients in a profitable manner. The nutrient mass balance tool provides an accessible and reliable method to monitor and improve environmental and economic sustainability of dairy farms while maximizing the nutritional value and soil health benefits of manure.

What the experts say

“The nutrient mass balance tool is a straightforward way for farmers to evaluate nutrient management practices with readily-available data. As consumers become increasingly interested in their food’s footprint, this tool helps farmers demonstrate responsible environmental stewardship," said Mart Ros, postdoctoral research associate with the Nutrient Management Spear Program.

"Farmers who use the nutrient mass balance tool appreciate its simple approach and recognize the importance of monitoring their nutrient imports and exports to not only improve farm efficiency and profitability but to also benefit the environment and meet consumer expectations," said Olivia Godber, research associate with the Nutrient Management Spear Program.

“The nutrient mass balance tool helps farms understand opportunities to reduce nutrient imports for improved profit and reduced environmental impact. This research reinforces the importance of whole-farm assessments and shows both progress made and future opportunities," said Quirine Ketterings, director of the Nutrient Management Spear Program and professor of nutrient management in the Department of Animal Science in Cornell CALS.

Study Authors

Mart Ros, Olivia Godber, Agustin Olivo, Kristan Reed, Quirine Ketterings


Department of Animal Science in Cornell’s College of Agriculture and Life Sciences

Read the full study

"Key nitrogen and phosphorus performance indicators derived from farm-gate mass balances on dairies"


Megan Wittmeyer is a writer for the Cornell Nutrient Management Spear Program. 


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