Pecans, Pongamia, and Water

Near Austin, Lake Travis sat at 54 feet below its full level as of January, 2012.

Near Austin, Lake Travis sat at 54 feet below its full level as of January, 2012.

If you live in Texas, water has been the biggest agricultural issue for the last several years. The coastal bend of Texas – where we are growing about 150 acres of pongamia – has historically been a big region for rice production. But that’s been on the decline, due (among other reasons) to less available water. As cities like Austin continue to grow, and rainfall remains erratic, it’s becoming increasing difficult to grow crops that are dependent on irrigation.

Water in TX -- not a good situation

Water in TX — not a good situation

Further up North, near Lubbock, the situation has gotten so bad that some pecan farmers are losing their trees. In this article – http://bit.ly/Y3Ff1w – we read about a family that’s selling its land because of lack of water for its pecan trees. Pecans need lots of water. Anecodtally, we heard from one farmer that it takes 40 gallons of water to make one pecan. More concretely, one of our colleagues at TerViva took a course on pecan horticulture and learned that, during a 6-month period, one acre of pecan trees requires 1 inch of irrigation per week (about 27,150 gallons). Over those six months, that’s over 706,000 gallons per acre, or 14,700 gallons per tree.

As a comparison, we have planted pongamia near the Phoenix area in Arizona – where it’s often very hot and always extremely dry. Our project is with a water treatment facility. Although the facility ends up producing very clean water, that water cannot be used for consumption or agriculture. So we partnered with this facility to try out some pongamia trees. Using drip irrigation, we’re applying about 5 gallons of water per tree per day. Over the course of a year, that equals 260,000 gallons per acre, or about a third of the water required by one acre of pecan trees over 6 months.

Pongamia in AZ -- waste water, drip irrigation, and some good looking saplings.

Pongamia in AZ — waste water, drip irrigation, and some good looking saplings.

Pongamia seeds are not pecans. For one, pongamia seeds don’t taste as good. But oil from pongamia seeds can be extremely useful for making bio-pesticides, lubricants and working fluids. And because pongamia is a legume, the seed cake left over from expelling the oil is also usable as an animal feed.

We’re not making the case that pongamia trees should replace pecan trees. But we do believe that new crops being used in non-food applications, like pongamia, should exhibit water footprints that improve upon water usage by existing crops.

That can be hard to prove concretely. Pongamia is known to grow well in dry areas of the world, producing bountiful harvests under rain-fed conditions 25 inches annually. But even we haven’t done the work to precisely measure optimal pongamia production under irrigation. We’re committed to obtaining the answers, in support of a common agricultural goal – the optimal use of water.

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