Marijuana Business Magazine July 2018

“By looking at tissue analysis data, we can see what a plant is metabolizing and using,” Vaos said. But tissue analysis requires gas chromatography, which can be expensive, Vaos cautioned. Another way to gauge what nutri- ents – and how much – your plants are consuming is to run a sap analysis that looks at the composition of soluble ions in the juice of the plant, Vaos explained. The difference between the two, he noted, is that a plant tissue analysis examines the nutrients that have built up over time, while a sap analysis tells you what nutrients are being consumed at that moment. 2 Whip Up Your Own Mix Making your own nutrient mixes can lower your costs and environmental impact. But it requires some expertise and lots of experimentation. San Diego County, California-based grower OutCo was using a commercial brand fertilizer in 2016, when Allison Jus- tice joined the company with a Ph.D. in plant and environmental science. Justice, the company’s cultivation director, said the fertilizer did a great job, but it was pricey. She estimated OutCo spent $200,000 annually on one room of 500 plants while going through five crop cycles. Justice didn’t dispute the results. She came from the vegetable-growing world, where a good profit margin is just 1.5%, and wanted to dwell less on bolstering the bottom line. She spent a year looking at nutrient mix formula- tions for poinsettias, tomatoes and other plants. She also combed through the scant amount of literature on cannabis and nutrients, explored the ingredients of the commercial brands and then developed her own formulation. That brew is now being tested in a room of 500 plants that at press time were a week from being harvested.Their overall appearance was as good or better than plants grown on commercially available bottled solution. The big difference: The homemade nutrient mix cost only about $8,000, or a fraction of the cost of the com- mercial product. “It’s exactly the same ingredients,” Justice said. “And they’re all sustainable.” Like Vaos, she stressed the impor- tance of not overfeeding. Many of those solutions also load up on ingredients that can be harm- ful when used in excess, Justice said. For example, most plants need 50-70 parts per million of phosphorous, a major plant growth booster. But some commercial brands have as much as 250 parts per million of phosphorous. “Phosphorous runoff in agriculture is a huge problem for aquatic life,” she said. “Giving the plant just what it needs, making sure it can take up most of what it’s fed, making sure there’s minimal runoff, that’s how we go about being sustainable in our approach.” 3 Go Organic Growers who use soil have a wide variety of organic nutrient options to choose from. Some organic soil and nutrient sources are: Kelp: Also known as seaweed, kelp is not a primary source of the three macronutrients: nitrogen, phosphorus and potassium. But it has more than 60 trace minerals, plus amino acids, enzymes and alginates. Kelp also contains mannitol, a natural sugar that breaks down micronutrients and makes them available to plant cells. Kelp improves soil health, seed germination, plant vigor and sugar content. And it stimulates more lateral root growth and larger root mass. Guano: A combination of seabird and bat droppings, guano is loaded with beneficial bacteria and – depending on the type of bats – essential macronutri- ents. For example, Mexican bats have a bug diet, and their guano is high in nitrogen, while Jamaican bats eat fruits and therefore produce high-phos- phorous excrement, which aids in the flowering stage. Lobster and Crab Shells: Lobster and crab shells, typically harvested from seafood processors, are excellent sources of nitrogen, phosphorous and calcium that are best applied in the flower stages of the plant cycle.They also contain a carbohydrate called chitin that helps retain moisture and deter insects. Worm Castings: The manure cre- ated by worms is packed with bacteria, fungi, protozoa and nematodes, which revitalize the soil’s food web, or com- munity of organisms, which help keep soil rich. Worm castings also help break down organic matter such as decompos- ing food waste. Super Soils: Super soils are aug- mented with nutrients, microbes and other materials that are beneficial to both marijuana and hemp plants. Some growers favor putting plants in super soils rather than adding nutrients to plants. Making your own nutrient mixes can lower your costs and environmental impact. SUSTAINABLE CULTIVATION 68 • Marijuana Business Magazine • July 2018