If we built a Green Friendship Bridge composed of 8,600 algae microfarms given to Mexican and Central American farmers in lieu of 1%, (13 miles) of additional border wall, what environmental benefits would accrue? NAFTA and U.S. farm subsidies artificially reduced crop prices lower than Mexican farmers could produce, forcing thousands of families into bankruptcy. Many other farmers were forced off their land when their irrigation water that they had depended on for generations ran out when flows from U.S. rivers dropped to a trickle. Others were forced to abandon their farms because the scarce water was too salty or polluted to grow food crops.

Why did Mexican farmers immigrate north?

The Colorado River is one of the principal rivers of the Southwestern U.S. and northern Mexico. The 1,450-mile Colorado River drains an expansive, arid watershed that encompasses parts of seven U.S. and two Mexican states before reaching the Gulf of California. Unfortunately, the extended Rocky Mountain drought and expanded demand from seven U.S. states’ cities and farmers consume nearly all the river water before it gets to Mexico.

The “doctrine of prior appropriation” governs water law in most western states. The first person to make “beneficial use” of water gains the right to use that quantity for that purpose forever, and that the claim takes precedence over every claim made later. Large tracks of U.S. farmland have claims that pre-date cities. Those farmlands take their full allotment every year, leaving Mexican farms parched.

The Colorado River provided irrigation water for Northern Mexican farmers for decades. In recent years, the stream into Mexico has slowed to a trickle. Water has flowed to its natural outlet at the upper end of the Gulf of California only once since the 1990’s. Each time irrigation water evaporates, additional salt is left to invade downstream farms. People who drive into or out of the town of San Luis Río Colorado, in the Mexican state of Sonora, complain about having to pay a six-peso toll to cross a bridge that spans only sand.

(L) San Luis Río Colorado Bridge, Sonora, (R) Abandoned farmland in Mexico

(L) San Luis Río Colorado Bridge, Sonora, (R) Abandoned farmland in Mexico

The minimal Colorado River water flowing into Mexico, when it flows, is extremely salty. Salt and other minerals left from irrigation evaporation migrate to the river and amplify salts. Runoff from farms and treated waste from cities are channeled back into the river adding more salt, industrial chemicals and discarded pharmaceuticals. Heavy use of agricultural chemicals and pesticides along the Colorado River further pollute downstream water and degrade soils, springs, creeks and aquifers.

The other major river Mexican farmers have depended on for irrigation is tapped by U.S. farmers before its water gets to Mexico. The Rio Grande, or Rio Bravo del Norte in Spanish, serves as part of the natural border between the U.S. state of Texas and the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas. Since the mid–20th century, heavy water consumption of farms and cities along with many large diversion dams on the river has left less than 20% of its natural discharge to flow to the Gulf.

Many springs and creeks in northern Mexico have gone dry, as well as many aquifers. When water for crops become either too degraded to use for crops or totally unavailable, farmers are forced to move off their land. Some rural communities have had to move when household water became unavailable.

Food without fresh water

Algae microfarms can produce excellent edible protein using some forms of waste, brackish or brine water. Algae recycle and reuse the nutrients in the water and transform them to green biomass. Algae grown in waste or other water containing heavy metals cannot be eaten but may provide valuable biofertilizer.

These production systems are insufficient to provide food by themselves but can supplement other scarce food supplies. Of critical importance, microfarms can provide the essential nutrition necessary to assure the avoidance of malnutrition for pregnant mothers and infants. Several microfarm applications designed for environmental benefits require production of algae species other than spirulina.

Technology will be available in the near future to use microfarms to clean some types of waste or brine water. Half the water stored on the planet is brine water and many algae species thrive in saline or brackish water. Numerous brine water aquifers are distributed throughout Mexico and Central America. Algae have been used in the U.S. for wastewater treatment for over 50 years. In some communities, algae’s ability to clean water may be more valuable than the production of food, feed, biofertilizer or nutraceuticals.

Algae biofertilizer

Decades of crop production, cultivation, irrigation and erosion from wind and water have degraded and worn out substantial regions of cropland. Many farmers do not have sufficient money to buy agricultural fertilizer and degraded soils require increasing amounts of fertilizer to produce acceptable yields.

Few farmers have access to the 10 tons of organic material needed for composting one ton of fertilizer recommended by the USDA. Even if massive amounts of organic wastes were available, most farmers have neither the heavy equipment nor the diesel available to cultivate organic material into the soil. Organics spread on top of the ground do not deliver enough fertilizer to crops because most of the nitrogen volatizes into the air. Organic material such as animal or human manure typically has too many pharmaceuticals to use as crop fertilizer because those pharmaceutical molecules are likely to be absorbed into the food crop.

Algae are tiny cells, often about 5 microns in diameter. These small cells cannot absorb a huge pharmaceutical molecule. Instead, the tiny cells strip the molecule of individual elements, especially carbon, which detoxifies the pharmaceutical. Therefore, when the algae biofertilizer enters a food crop, there is no pharmaceutical molecule left to enter the crop, only the bionutrients needed by the plant.

Algae can recover and recycle the nutrients in wastewater very efficiently and deliver the nutrients in a form immediately bioavailable to field crops. Field studies have shown farmers can cut chemical fertilizer costs 50 to 80% with algae biofertilizer.

A two-year field study with Del Monte Fresh Produce demonstrated the value proposition for algae biofertilizers. We extracted two algae species from an abandoned 200-acre field near Yuma bounded on three sides by Arizona’s raw desert. The field was worn out from years of crop production, cultivation, compaction and salt invasion.

The desert soil was extremely compacted with a pH of 9.4. We cultivated an indigenous terrestrial cyanobacteria ­– blue-green algae – to fix nitrogen from the air, along with green algae to deliver nutrients to the cantaloupe crop. We selected algae in situ because those algae have adapted over eons for survival in the extreme heat, sometimes 125o F. The algae were grown together in a mixatrophic system near the field. A simple ¼ inch hose fed the algae culture to a small canal that fed the field’s drip system.

(L) Terrestrial algae, (R) Algae crust on desert land

(L) Terrestrial algae, (R) Algae crust on desert land

The microfarm provided substantial value by minimizing fossil inputs, increasing productivity, and reducing costs. The Del Monte field study exceeded the metrics reported in the table below. The comparisons are to a nearby control field and Del Monte’s field norms.

Microfarmers can use algae biofertilizers to improve soils and reduce water, energy and fertilizer waste while decreasing soil erosion and air, water, and soil pollution.

Algae Microfarm Benefits for Farmers

Algae Microfarm Benefits for Farmers

Possibly the strongest attribute of algae biofertilizers may be the ability to repair degraded and even abandoned soils. More research is needed to quantify the microfarm size required to support specific acreage. A 50 m2 (544 ft2) surface area microfarm should produce enough biofertilizer to support about 200 hectares, (500 acres) of crop production. This repair function provides a critical need in nearly every food growing region globally.

(L) Higher germination with algae biofertilizer; (R) larger melons with algae biofertilizer

(L) Higher germination with algae biofertilizer; (R) larger melons with algae biofertilizer

Farming is hard on soils, as each crop extracts about half the applied fertilizer while the other half percolates below the root zone or erodes on the wind. Algae biofertilizer replaces nutrients and rebuilds humus, thus upgrading degraded soil with every crop. Increasing soil porosity enables substantially better root structure and depth, which improves water and nutrient uptake. Porosity also allows an influx of helpful symbiotic microflora communities.

Environmental summary

Algae microfarms distributed throughout Central America and Mexico can make a huge environmental difference for farmers and for the local ecology. Farmers and their families could make a living while providing healthy, nutritious food for their community.

Each microfarm can grow enough algae biomass to support about 200-hectares of field crops. Algae biofertilizers can improve crop yields 20 to 40% while improving size, color, taste and texture. Microfarms can cut fertilizer costs by >50%, water by >25%, fuel, (due to less need for cultivation) by 25% and pesticides by 80%. Biofertilizers have demonstrated 40% higher germination rates, 30% better survival rates and 10% faster growth to maturity.

Algae biofertilizers can repair and restore fertility to degraded cropland. Instead of continually subtracting and degrading soil, farmers can improve soil structure and fertility with every crop.