Green Fertilizers From Garbage
Fertilizer has historically been one of clean water‘s top enemies. That’s because crops – especially irrigated crops – don’t absorb all of it. That excess fertilizer – as much as 25% of nitrogen applied, according to the EPA – makes its way to groundwater, rivers and oceans. There, it causes algae blooms and kills aquatic life. And in well water used for drinking, excess nitrogen can harm human health, especially babies. Due to an exemption in the US Clean Water Act, this pollution goes largely unregulated.
But a California startup called California Safe Soil has created a fertilizer that contains far less of these pollutants, potentially reducing the quantities entering the water supply. Founder Dan Morash also claims his product, Harvest-to-Harvest, makes plants more efficient at sucking up fertilizer, which could further reduce pollution.
Standard fertilizers are mined from the ground, but Morash is turning to an urban source for his feedstock: the 43bn pounds of food that grocery stories throw away each year, according to a report by the Natural Resources Defense Council.
Most of this waste goes to landfills, where it rots and generates methane, a potent greenhouse gas that traps 34 times more heat in the atmosphere per century than carbon-dioxide. Landfills account for 16% of US methane emissions, and the vast majority of that comes from rotting food. It’s also an expense for grocery stores, which pay disposal fees to landfills.
California Safe Soil hopes to cut both the water and air pollution while reducing the amount of food waste grocers send to landfills. The company takes disposed produce, seafood, meat, cakes and bread and turns them into rich fertilizer through a process that uses aerobic digestion and is somewhat similar to traditional composting – but accelerated.
“Think of the human digestive system,” Morash said. “We use mechanical action to reduce the size of the particles, like chewing. We heat the material and add enzymes, like in your stomach. The proteins become amino acids. The fats become fatty acids. And the carbs become simple sugars. Those are the nutrients that circulate in your blood stream and nourish your body.”
Those nutrients are also beneficial to plants. The digester produces the liquid fertilizer Harvest-to-Harvest, which California Safe Soil plans to sell to farmers.
“We get a 90% yield inverting food to liquid fertilizer,” Morash said. “The 10% solids we’re selling as pig food.” There is no effluent, he said, referring to leftover waste.
The process takes just three hours, as opposed to months for composting. And the heating step pasteurizes the product, killing pathogens, according to Morash.
The company is a finalist in this year’s Imagine H2O global competition for water technology startups. California Safe Soil addresses the wasted water consumption and climate impacts inherent in wasted food, said Scott Bryan, chief operating officer at Imagine H20, referring to the amount of water and greenhouse gas emissions expended to grow food. When the food is wasted, the water consumed and greenhouse gases emitted are all for nothing. But California Safe Soil’s supply chain innovations are turning “waste into a profitable resource with financial and ecological benefits,” Bryan said.
Harvest-to-Harvest also helps farmers lighten their environmental footprint by tending to soil health, Morash said. Micronutrients such as sugars and amino acids in Harvest-to-Harvest benefit soil microorganisms, including bacteria, fungi and worms, which, in turn, benefit crops, he said.
By increasing soil organism activity, Harvest-to-Harvest fertilizer stimulates plants to grow additional roots, allowing them to better absorb nutrients, thereby reducing the amount that could pollute water, Morash said. “The organisms have a symbiotic relationship with plants,” he said.
Ed Lewis, a University of California-Davis entomologist who studies soil ecology at the University of California at Davis, is studying the impact of Harvest-to-Harvest on crop yields, soil health and water quality. Lewis is currently analyzing data on soil characteristics to see whether Morash’s claims about his product improving soil health bear out. His initial impression is that it makes sense. The nitrogen, phosphorus and potassium (NPK) fertilizers farmers typically use don’t benefit the soil. “NPK are just chemicals,” he said. “It’s put on soil to nourish plants. Period. Nothing else can use it.”
Last year, Lewis conducted field trials on various crops. While the results have not yet been peer-reviewed, Lewis said Harvest-to-Harvest does appear to improve crop yield.
“We did about 40 trials,” he said. “In most of them there was some improvement.”
One crop, strawberries, showed a 40% increase in crop yield. “That’s a big number and it’s very hard for farmers to believe it,” Morash said. “We need more of them to do field trials and find out for themselves.”
As for Morash’s claim that his product will reduce water pollution from nutrient runoff, Lewis has not yet studied this issue, but he said the runoff should be reduced if farmers using Harvest-to-Harvest apply less NPK. That’s because farmers often apply a mixture of 10% nitrogen, 10% phosphorus and 10% potassium, known as 10-10-10. Harvest-to-Harvest contains small amounts of these ingredients, but it’s more like 1-1-0, Lewis said. So if farmers replace, say, half of their NPK applications with Harvest-to-Harvest, they’d be using significantly less NPK.
Cary Oshins, director of education for the US Composting Council, is interested in California Safe Soil’s technology, but is cautious about some of the claims. Killing pathogens is key, he said. “And the relationship between their material and soil organisms needs to be [proven] as well.”
Oshins also questioned the energy footprint and cost of production.
Morash claims that the process is “cheaper than most compost applications and a little more expensive than nitrate”.
But will that be cheap enough?
“The challenge is that landfills in our state are charging $30 to $50 a ton,” Oshins said. “So he’s not going to get many food waste generators to pay him for disposal service.”
California Safe Soil is currently in pilot phase, taking food for free from 10 stores. In its commercial phase, it plans to bill supermarkets at a rate competitive with landfills. “Selling fertilizer to farmers is our main source of revenue,” Morash said.
The United States is a bit late to the food-rescuing party.
The EU issued a Landfill Directive in 1999 that phased in the reduction of biodegradable waste going to landfill and promoted recycling and recovery of that waste. “They’re way ahead of us,” said Nick Lapis, the legislative coordinator for Californians Against Waste. “We’re still putting all this valuable stuff in a hole in the ground.”
But that may be changing. California state assembly member Wesley Chesbro plans to introduce a bill this month that would require restaurants and supermarkets to separate their food for digestion or composting, Lapis said.
Vermont and Connecticut enacted laws in 2012 and 2013, respectively, that will direct food away from landfills, and Massachusetts has proposed a ban on food waste in landfills and incinerators that would go into effect this year. New York City, San Francisco, Portland, and Seattle have also banned landfill disposal of food waste.
Through the entire food cycle from field to fridge to landfill, 40% of all food grown in the United States is wasted. The US Environmental Protection Agency has created a hierarchy of options to address this dross. First choice is to eliminate waste on the production side by producing less food. Next is feeding hungry people, then animals, followed by industrial uses such as biofuels production. Composting and digestion, including California Safe Soil’s technology, are just one step above the bottom rung: incineration or landfill.
Morash is in talks with a supermarket company to set up a long-term supply agreement that would support construction of a commercial plant. “We’re hoping to go commercial later this year,” he said.
“I would be thrilled if this technology can be scaled to produce a fertilizer that’s commercially acceptable at a reasonable price,” Oshins said. “But this is still a pilot project. We’ll be interested to see how it performs.”
Erica Gies is an independent reporter who covers water and energy for The New York Times, The Economist, Scientific American and other publications.