Oxbow Farm & Conservation Center

The long road to good broccoli

broccoli in tank

It has been a pretty good year for broccoli at Oxbow Farm. Aside from some early-season heat sensitivity, our plants have done well. Bright green heads—most around a pound—have made it into all of our CSA boxes at least once so far this season and we have had additional broccoli to offer to our restaurant and wholesale partners.

But the road leading to this year’s broccoli crop was rocky and longer than you might expect. In fact, it starts years ago with a bumper season that we took a gamble on recreating, and for which we ended up paying a hefty price. This is the behind-the-scenes of eco-agricultural farming – an unsuccessful effort to strategically increase revenue ultimately taught us more about the health of our soil and acted as a catalyst to dig deeper into the cause and effects of soil fertility.

In 2012, our farmers were trialing a few new varieties of broccoli that were performing especially well under the season’s cool conditions. We not only had plenty of broccoli for our CSA members, but a consistent supply for wholesale, restaurants and farmers market customers, too. Our single planted acre was stocking the shelves at PCC Redmond week-in, week-out for much of the growing season.

Broccoli crown

A beautiful head of Oxbow broccoli

As you might imagine, we came off the 2012 season with a lot of enthusiasm for broccoli. We planned to double our production to two acres that spring and summer, based in large part on a contract with PCC Redmond.  They agreed to purchase 900 pounds of broccoli each week from July through October, and we would still have enough broccoli for our other outlets. While we comfortably aim to gross around $15,000 per acre, we were optimistic that 2013’s broccoli crop would gross more than $20,000 per acre thanks to the promising performance of our trail varieties.

Plan in place, we planted out the agreed-upon two acres. Little by little as the season wore on, it became apparent that the bumper crop was not coming back. A hot and humid summer (in contrast to the previous one) gave rise to disease and to flea beetles, aphids, and other brassica-loving insects. The broccoli heads turned out stunted, yellowed, and spotted by alternaria fungus, some edible but almost none wholesale quality. We ended up grossing less than a quarter of the projected revenue per acre.

broccoli alternaria rot credit unacr

Broccoli exhibiting alternaria rot (photo via UCANR)

The weather and its resultant pest problems take a lot of credit for the broccoli’s underperformance, but these factors would not have spelled total failure were it not for a major underlying factor. Nutrient deficiencies in the fields the broccoli occupied led to a crop that was particularly susceptible to lasting damage from pests and disease. Just like humans, crops weakened by malnutrition are less resilient than healthy plants. To prevent malnutrition, we must monitor and attend to various nutrient levels present in the soil—in other words, the soil’s fertility.

Adam McCurdy is Oxbow’s Production and Research Manager and has been focusing on soil fertility for years. By his judgment, 2013’s weak broccoli crop was mainly a result of deficient boron, a micronutrient that plays a big role in the production of strong cell walls in vascular plants. Our fields have always been low on boron, but Adam suspects that increasing levels of calcium in our soil (a byproduct of the lime we apply seasonally to bring our soil pH, or acidity, levels into acceptable range) rendered the already minimal amount of boron even harder for the broccoli to access.

Adam on the G

Adam working the Oxbow production fields

Compared to large single-crop farms, managing the nutrient needs of our many different crops is a particular challenge we share with other diversified farms. Thoughtful fertilization can offer yields equal to or surpassing those of conventional farming while eliminating chemical runoff and fostering a healthy community of microorganisms. Because of the particularities of each individual crop, however, it does require a much more involved and nimble resource management strategy than a blanket approach with a single crop. At Oxbow, we don’t only have broccoli’s nutritional needs to manage, but also carrots’, potatoes’, cucumbers’, lettuce’s, and those of many dozens of other crops we cultivate each season.

Every year we get better at managing the diversity. This season, Adam ordered a series of custom fertilizer blends specific to Oxbow’s soil structure and tailored to the needs of different crop families. The goal is to ensure that plants in the brassica family, like broccoli and kale, get what they need to thrive, as do the cucumbers and squashes, carrots and cilantro, and the list goes on. Our broccoli beds got an extra dose of boron this year and we’ve been seeing healthy heads throughout the summer (so have our CSA members!) While it’s still too early to be certain, it looks like Adam’s fertility plan is working.

Adam has also been fortunate to work with Dr. Doug Collins, a soil scientist at Washington State University, to understand how best to manage different soil types in an organic system. Doug’s recent research on nitrogen uptake in broccoli is directly applicable to our practices. With his help we have devised a fertility management strategy based on field maps and systematic soil testing so Adam can monitor and respond to soil needs more consistently.  We are looking forward to collaborating with Doug on another broccoli study in 2016, this one broadening the scope to examine mineralization of several other elements critical to broccoli’s growth.

There is a staggering amount to be learned, yet limited resources to devote to the learning. At Oxbow, all of our research takes place within the context of REAL farming, where the economic bottom line must be a top priority. As we experiment with different measures to protect the soil’s fertility, factors beyond our control—fluctuating temperatures or microorganism activity—interfere with our game plan. In these instances, Adam responds in the moment with foliar (spray) applications of certain nutrients to give crops direct boosts.

Fertility is truly at the heart of eco-agriculture’s double bottom line – responsible ecosystem management combined with economic viability.  Adam’s dedicated understanding of our broccoli’s fertility needs has helped us turn around our yields. For a small farm business like ours, this effort can indeed translate into a make-or-break impact.

Soil systems are so complex that we cannot hope to understand them but bit by bit. We hope we are helping to build that collective understanding. At the very least, we are doing our best to grow good broccoli in the Pacific Northwest. If you’re eating Oxbow broccoli this season, we hope you enjoy it! But remember that it wasn’t just sunlight and water that made it grow.

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