It was a corporate initiative supporters claimed could mainstream sustainable agriculture.

Now critics are wondering how much impact it’s really having.

When Land O’ Lakes, the dairy giant, announced SUSTAIN, an ambitious program designed to reduce nitrogen-based fertilizers, both business giants like Walmart and environmental groups hailed the measure as a significant step forward.

To appreciate the buzz SUSTAIN created, it’s important to understand the role nitrogen-based fertilizers play in foodways and their ecological consequences.

Nitrogen is essential to crop growth. Although the air we breathe is mostly nitrogen, most of it isn’t available in a form plants can use. For centuries, traditional manure-based fertilizers supplemented naturally-occurring nitrogen deposits in the soil. This helped, but farmers struggled to produce yields sufficient to feed growing populations.

Then two German scientists, Fritz Haber and Carl Bosch, developed a means for synthesizing nitrogen in ammonia form, fueling the industrialization of agricultural production. The Haber-Bosch Process supercharged crop productivity, feeding billions and making ag producers rich.

If the industrial use of nitrogen-based fertilizers helped feed a growing global population, however, it also degraded the environment. The process of manufacturing fertilizer consumes energy and emits carbon. Excess nitrogen seeps into waterways, polluting streams and creating oceanic dead zones. Bacteria reacts with nitrogen particulate in the soil, releasing greenhouse gases.

Farmers may regret these ecological consequences, but reducing fertilizer use cuts into thinning profit margins. In these tough economic times, they’re loathe to do that.

That’s why SUSTAIN seemed so promising to boosters. Here was a program backed by an industry leader that aimed to reduce nitrogen’s impact on the environment without sacrificing profitability. If the initiative met with success, it could become an important model for the future.

The program depends on high-tech sensors to monitor nitrogen application and the use of stabilizers to help prevent fertilizer runoff. By using these tools, farmers can use nitrogen more efficiently, and grow more with less.

Those are good things, and response to SUSTAIN has been positive. Farmers like to feel like they’re helping the environment as they make a living. Stores carrying products raised under the program are touting it as the latest in sustainable agriculture.

Critics are less enthusiastic about the program. They allege it’s failing in the only metric that matters: how much nitrogen is being introduced into the environment. While farmers are doing a better job of rationing out their nitrogen use, the program doesn’t actually reduce the total amount of fertilizer used. SUSTAIN only seeks more efficient use.

But the best existing measure of how much greenhouse gas ends up in ecosystems isn’t how much is wasted, it’s how much is used in the aggregate. If that’s the case, SUSTAIN may be overselling its environmental impact.

To make a real difference, environmentalists say, farmers should seek to reduce dependence on nitrogen-based fertilizers. Growing less intensive crops, like oats, could do much more than tracking devices and chemical stabilizers.

It’s not surprising to many observers that SUSTAIN maximizes efficiency without fostering huge environmental improvements. Still, it’s good to see corporate leaders trying to reconcile sustainability with productivity. If farming is going to get more sustainable, it’s going to need to keep refining initiatives like SUSTAIN.