Soil salinity is killing California crops

From 2011 to 2014, California experienced the worst drought in its recorded history. With that drought came a shortage of agricultural water supplies—in a state that produces nearly half of the fruits, nuts, and vegetables grown in the United States. Though the area has since seen a slight rebound, the central California region is still experiencing a significant loss of agricultural yield and revenue. The primary culprit? Soil salinity.

“Soil salinization is a global phenomenon that threatens the sustainability of agricultural production, at a time when food demand is increasing,” says EPP Assistant Professor Meagan Mauter.

While salts naturally occur in soil and water, they build up in the soil when irrigation water is saline and the rate of evaporation is high. Under Mauter’s advisement, Ph.D. student Paul Welle has been studying just how heavy the impact of soil salinization has been on California’s annual agricultural yield.

Taking advantage of high-resolution satellite data for crops grown in California and recently released information on soil salinity, Welle was able to estimate the effect of soil salinity on crop yield. What the data revealed was shocking.

“What we found is that the central California region is losing approximately $3.7 billion in annual agricultural revenue due to salinity levels in the soil,” Welle says. “This is about 10% of the region’s annual agricultural revenue. But current de-salinization technology, unfortunately, is very expensive. Even with this high $3.7 billion loss of revenue, the cost of current desalinization technology would be even more expensive. Barring substantial cost reduction, policymakers should not rely on current desalination tech to offset salinization.”

 

Batch of tomatoes

Source: CMU Engineering

A batch of tomatoes

Nanofarm: creating safer fertilizers and fungicides

NanoFARM, a research consortium formed between Carnegie Mellon University, the University of Kentucky, the University of Vienna, and Aveiro University in Prague, is studying the effects of nanoparticles on agriculture. The four universities received grants from their countries’ respective National Science Foundations to discover how these tiny particles—just four nanometers in diameter—can revolutionize how farmers grow food.

Applied pesticides and fertilizers are vulnerable to washing away—especially if there’s a rainstorm soon after application. But nanoparticles are not so easily washed off, making them extremely efficient for delivering micronutrients like zinc or copper to crops.

“If you put zinc salt in water it will dissolve rapidly,” says Ph.D. student Xiaoyu Gao, who has been with NanoFARM since its inception. “If you put in zinc oxide nanoparticles instead, it might take days or weeks to dissolve, providing a slow, long-term delivery system.”

Gao’s research is only one piece of the NanoFARM puzzle. The project’s principal investigator, CEE Professor Greg Lowry, traveled to Australia with Ph.D. student Eleanor Spielman-Sun to explore how differently charged nanoparticles were absorbed into wheat plants.

They learned that negatively charged particles were able to move into the veins of a plant—making them a good fit for a farmer who wanted to apply a fungicide. Neutrally charged particles went into the tissue of the leaves, which would be beneficial for growers who wanted to fortify a food with nutritional value.

“In developing countries like China and India, a huge number of people are starving,” says Gao. “This kind of technology can help provide food and save energy.”

 

Sprinkler system dispersing water over crops

Source: CMU Engineering

A sprinkler system dispersing water over crops.

Growing fresh food in your home

In many places in the world, fresh food is hard to come by. In certain areas within cities, called nutritional islands, residents often have to resort to feeding their families with pre-packaged foods. Not only are these expensive, but their lack of nutritional value is one of the primary causes of poor health outcomes for this population.

Led by EPP/ChemE undergraduate student Jack Ronayne, a group of Carnegie Mellon students is trying to solve this problem with a brand-new approach to indoor agriculture—and it all starts with LED lights.

“Something we identified was this idea of nutritional islands in urban communities: places with limited access to fresh food either by distance, freshness, or cost,” says Ronayne. “We asked ourselves: could you simply grow fresh fruits and vegetables in your house?”

The idea of vertical agriculture is nothing new. Where the team’s approach is novel, however, is in the type of light used to grow the food—and not only that, but the way the light is used. For their first trial, the team used tomato plants as a representational, nutritional food. They wanted to find out the optimal amount of light for a plant to grow, while using the least amount of energy possible.

“What we wanted to study was energy efficiency,” says Kelvin Gregory, CEE professor and faculty advisor on the project. “LEDs are already more energy efficient than old-school halogen bulbs, but they also have the added benefit of being able to be turned on and off very quickly. So by rapidly flickering these lights at different speeds, we have been able to measure how much light is necessary to grow the biggest plant, using the least amount of energy.”

Using this system, which looks like nothing more than a standard-sized bookshelf covered in a black tarp, a family could grow up to 40 tomato plants. For smaller plants, like lettuce, the system can fit at least 100. And this is only the household design. For larger, more community-focused models, the growth potential is exponentially greater.

Through this type of research, the team hopes to put access to fresh, healthy foods into the hands of everyone around the globe, no matter their socioeconomic status.