DR. Don Research Update
Whole-farm nutrient budgets to assess pollution

By Don Lotter

August 17, 2004: One of the top priority environmental impacts of agriculture, perhaps the top priority, is nutrient pollution – led by the big two: nitrogen and phosphorus. U.S. policymakers are just beginning to get a handle on the issue, but their hand-on-the-handle keeps getting slapped or pulled off by the powerful and almost completely profit-oriented big-agriculture and agricultural chemical lobby.

The governments of the European Union have managed to get a pretty good grip on issues relating to agricultural pollution and other “externalized” costs – and the Dutch are the ones who have done the most rigorous job on this. Their land base is extremely sensitive to water pollution – sandy soils, shallow water tables, dense population, high input capital-intensive agriculture, etc.

An entire issue of the European Journal of Agronomy (Number 20, 2003) is devoted to research on balancing farm nutrient budgets. Balancing the farm nutrient budget essentially means that what comes off the farm (nutrients in grain, milk, manure, etc.) should be balanced by what goes in.

Balancing the farm nutrient budget, however, turns out to be much more complex and challenging to carry out than it sounds, mainly because the soil-crop-animal system on a farm is a huge buffer that can soak up and hold nutrients for years and even decades before releasing them, as pollution, to the environment at differing rates for different farms.

One research group out of Wageningen, where most Dutch agricultural research is carried out, has studied whole-farm nitrogen balances to determine the optimum amount of data collection needed to enable farmers to fully visualize their nitrogen budget. Farm data can then be integrated into regional-scale views of nitrogen pollution.

The authors explain the Dutch mineral accounting system (MINAS), which is used to assess farm performance in nutrient balancing. Fines of 2.5 Euros per kg of nitrogen (a Euro is approximately a dollar) are levied on farms that exceed limits.

There are problems of accuracy with the MINAS system when applied at the farm level. To give an example of the complexity of the issue: two dairy farms have the same nitrogen inputs, number of cows, and soil type, but one farmer skillfully rotates his herd so that pastures accumulate their manure in some kind of balance with plant needs, while the other farmer keeps his herd on one pasture without rotation. This pasture accumulates excessive nutrients and pollutes the waterways via runoff and leaching.

The researchers found that to effectively balance the farm nutrient budget and determine if pollution is occurring, a certain amount of testing of deep groundwater, shallow groundwater, and soils needs to be done on farms, and even on different fields within farms.

In the end, in my opinion, in order to minimize agricultural pollution, it is probably going to be easier and cheaper to simply reward farmers to convert to certified organic farming. Research has shown over and over (and over again – check my paper “Organic Agriculture” downloadable from my resume on my website www.donlotter.com) that organic farms pollute far less than comparable conventional farms.

Another paper in the same European Journal of Agronomy issue gives an overview of the different types of agricultural pollution accounting systems used in Europe – including those that include pesticide and micro-nutrient pollution.

Sources:
Schroder, J.J. et al. 2003. An evaluation of whole-farm nitrogen balances and related indices for efficient nitrogen use. European Journal of Agronomy (20) 33-44.

Goodlass, G. et al. 2003. Input output accounting systems in the European community – an appraisal of their usefulness in raising awareness of environmental problems. European Journal of Agronomy (20) 17-24.


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