PRODUCTION AND DEPLOYMENT OFPHOTOSYNTHETIC NITROGEN-FIXINGBIOFERTILIZERS

摘要

The task of revegetating the delicate arid landscapes is a challenging proposition.The major limiting factors are water, nitrogen fertility and easily eroded sandy soils. Thecurrent art often includes the application of seeds, chemical fertilizers, tackifiers, and mulch.If inadequate precipitation or poor nutrient status prevents the establishment of vascularplants, these soil amendments are often reapplied, creating additional expense.In contrast, Primordial Solutions, Inc., has developed a technology that is designedto restore soil fertility, water retention, and reduce erosion without relying on the presence ofvascular plants. Instead, we exploit photosynthetic microorganisms, called cyanobacteria or“blue-green algae,” which convert solar energy to stored chemical energy, and fixatmospheric nitrogen (N2) into usable ammonia (NH3). The fixed nitrogen is ultimatelyincorporated into proteins and nucleic acids, biopolymers essential to life.Throughout the world, cyanobacteria, lichens, bacteria, and fungi, establish selfsufficientmicrobial communities called “Biological Soil Crusts” (BSC). In the Americansouthwest, BSC are responsible for 99% of the nitrogen input, represent up to 70% of theliving ground cover, improve the nutritional value of forage plants, improve water retention,and control erosion. However, following a disturbance, the BSC are slow to recover.Recovery estimates range from 4 to 4000 years depending on the climate, inoculum proximityand the definition of recovery.Primordial Solutions’ approach for restoring soil fertility involves isolatingcyanobacteria that are native to the disturbed area, mass-producing the microorganisms andapplying the mixed culture to the disturbed soil. This process establishes a self-perpetuating,living, green-manure that becomes active when hydrated. Once established, the restoredBSC creates a substrate suitable for the survival of vascular plants.A preliminary experiment was done to compare inoculated soil with an uninoculatedcontrol. Following 18 months of incubation under ambient climate, the inoculated soil had atwelve-fold increase in nitrogen content compared to the control treatment. Additionally, thecyanobacterial biomass increased almost ten-fold from the initial 500 mg·m-2 to 4788 mg·m-2 (dry weight biomass). These results show that the cyanobacteria are alive and retainthe ability to fix and secrete nitrogen into the soil. We plan to describe the 2005 fieldexperiments that are being conducted in the desert west of Grand Junction, Colorado. Thiswork was supported by the Small Business Innovation Research program of the U.S.Department of Agriculture, grant #2003-33610-13086.