A Systems Approach to Address The Practice of Continuous Cropping in International Fresh Produce Trade

Border towns like Nogales, Arizona are fascinating places full of people and goods passing from one side to the other, usually funneled through ports-of-entry (POE) where their flow is regulated by various government agencies. With inputs, outputs and regulation of flow, POEs offer a large-scale, physical example for describing Systems Thinking. Sankey Diagrams depict energy flows and work especially well within the context of POEs and Systems Thinking (see Figure 1).

Nogales Imports - 2017

Figure 1. Fresh Produce imports through the Nogales, AZ port-of-entry, 2017, organized by item type (i.e. grape tomatoes), general term (i.e. tomatoes), plant family (i.e. Solanaceae) and general terms used to describe rotational crops (i.e. fruits, roots, beans, leafy).

A watershed includes the tributaries that contribute to a river and in a similar way a foodshed includes the tributaries of a food system. The Sankey diagram above depicts fresh produce imports through Nogales, Arizona, one of the largest inland POEs for food in the world, in truckload equivalents­ of 40,000 lbs. The commodity types are organized by their plant families as well as more general terms used in describing rotational crops, before feeding into all fresh produce imports through the Nogales, AZ POE from 2017.

The practice of continuous cropping, planting the same crop from year after year, leads to a host of problematic issues including depletion of soil nutrients, declining yields over time, soil compaction, etc. Farmers that have made infrastructure investments such as drip irrigation or protected structure (greenhouse, shade house, etc.) or investments into their operation’s capabilities, for example, Food Safety or Organic certifications to enable market access, are incentivized to use their improved land or operations each year. Markets develop around their product but at the same time the practice of continuous cropping becomes reinforced from one season to the next.

Rotational crops are one effective way to address the practice of continuous cropping and may be described in general terms of “fruits,” “roots,” “beans” and “leafy.” In more technical terms, different plant families (i.e. Solanaceae, Apiaceae, Fabaceae, Brasicaceae) are generally suitable as rotational crops, though, resource availability, soil type, climate, pathogen pressure, markets, post-harvest requirements, etc. also need to be carefully considered.

While also enhancing biodiversity, planting different plant families from one season to the next helps to break the cycle of pathogen build-up and other problems related to continuous cropping. The annual rotation of crops also helps reduce costly external inputs such as fertilizers, herbicides, fungicides, pesticides, etc., all of which contribute to greenhouse gases including nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2).

Rotational crops can be non-commercial, such as Sunn Hemp, a legume that works well for building organic Nitrogen in the soil and Soil Organic Matter (SOM) to support microbial activity. Certain rotational crops can also be harvested for commercial use while achieving similar benefits for the soil as the non-commercial rotational crop options. Farms with limited land or improved infrastructure may be more interested commercial rotational crops as they may not be able to afford to leave fallow their improved infrastructure.

Farmers and their marketer counter-parts in a globalized world can use Sankey Diagrams of their international foodsheds to better understand their food systems and to make informed decisions for potential commercial rotational crop options that ultimately benefit the farmer, the environment and the bottom-line.

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Certified Organic in an Age of Synthetics

For many years my family practiced an intense form of conventional agriculture. At the beginning of each season we would cover the growing beds with plastic mulch and fumigate with methyl bromide to sterilize the soil. Young plants in trays of 200 cavities each would be taken from the nursery and transplanted into the sterile ground. The plants were then raised primarily on synthetic Nitrogen, Phosphorus and Potassium (NPK) through a drip irrigation system. Various pesticides, herbicides and fungicides were used to control the spread of pathogens. At the end of each season, there would typically be pest issues so plants would be removed and buried with a backhoe in another part of the farm.

After years of these highly extractive, conventional growing practices our soils were depleted and compacted. Lack of organic matter in the soil led to heavy mud after the summer monsoons, inhibiting the tractors and workers from entering the fields, prolonging transplant dates, shortening the growing season. The quality of our product, which had been renowned across North America with billboards announcing the arrival of our melons in San Francisco, for instance, was in steady decline. And things like soft-tip on the peppers, typically related to nutrient deficiency, kept appearing on the quality control (QC) reports. The same pest issues would return each season, growing in severity, requiring more external inputs and investment. Debts were owed and our entire approach to agriculture was in desperate need of revision.

Many farms that have found themselves in a similar situation have given up on the soil. They sheet the ground with plastic, house their fields under insect netting, plastic or glass. Plastic sacks of sterile substrates, typically derived of coconut fiber, are used to support the roots of the plants as they are fed a liquid diet of synthetic NPK. But there is a growing amount of evidence connecting the health of the soil to human nutrition, most famously beginning with the work of William Albrecht in the 1930s. And there has been more evidence showing a decline, since around the 1950s, in the nutrients of the food we eat.

We didn’t immediately set out to be USDA certified Organic farmers. With our soil in such a poor state, we needed a broad range of tools to address the recurring pest issues, we had a business to run, employees that depended on us, and a single application of a prohibited substance would set the required three-year transition period back to zero. Slowly, however, after seven years, our soils have improved and we are now in our third and final year of the transition to Certified Organic.

The transition period has been especially difficult. On the production side, yields are typically 20-30% less than under conventional growing practices. And on the market side, without the Organic certification, there’s no premium on the sale. As of this year, there is now a certification for farms in transition, Certified Transitional. Unfortunately, Certified Transitional has not really caught on yet despite the support of powerful companies like Kashi and Patagonia Provisions. However, certified Organic has continued to grow in market share year-after-year and there is pressure to fill market demand.

The soil vs. –ponic debate

For nearly 20 years there has been debate in the US over what growing methods should be included in organic certification of the food we eat. One side of the debate includes those in favor of foods grown in soil. The other side of the debate includes those in favor of -ponic (i.e. hydroponic, aquaponic, aeroponic) and containerized systems. There are merits to both approaches to food production and they each play a critical role in addressing needs related to hunger and nutrition in a world with an estimated population of 9 billion by 2050.

Just last week, the National Organic Standards Board (NOSB) voted 8-7 in favor of including hydroponic systems in the National Organic Plan (NOP). The recommendation of the Board will now go to the U.S. Department of Agriculture (USDA) for a formal ruling-making process and will most likely go into effect.

To be clear, this debate primarily addresses specialty crops (i.e. fruits and vegetables), not row crops (i.e. grains, corn, soy, etc.). Furthermore, the debate currently pertains to certain high-value specialty crops such as tomatoes, peppers, cucumbers, berries, but a lesser extent to lower-value crops such as squash, eggplant, melons, etc., which are not typically grown commercially in -ponic systems.

As a fourth-generation farmer of soil-based specialty crops that has spent the last seven years focused on transitioning all production to certified organic, when I heard the news that the NOSB voted in favor of including hydroponics, I felt like a part of me died.

Most, I think, use the terms “soil” and “dirt” interchangeably. To me, the distinguishing factor between “soil” and “dirt” is the presence or absence of organic matter, respectively. In reflecting on the debate, I find it interesting that the highly organized and well-funded –ponics & containerized side of the debate began to refer to the opposing side as, not soil-based farmers but rather those in favor of growing methods using only the “outer crust of the earth” or “outer-crustacean farmers.” This terminology seemed to shift the conversation away from “soil,” beyond “dirt” and in the direction of sterile, synthetic substrates of which coco peat would be included. In hindsight, I think the soil side of the debate should have made more effort to shift the conversation in the opposite direction toward soil “tilth,” related to the quality of the soil, or perhaps “humus,” related to the organic matter decomposed by soil microorganisms. After all, there is no tilth, humus or three-year transition period for hydroponic systems.

I have read about the importance of ecosystem services, but what about the value of micro-ecosystem services? In the past, I used to cringe at the thought of nematodes in the soil, as I think many farmers do. Little did I know at the time that nematodes are everywhere, and there are many different types of them—including some that feed on other nematodes! There are endo-mycorrhizae fungi that penetrate the plant roots, acting as an extension of the root system while protecting it from certain pathogens at the same time. Bacteria play an equal if not more important role in all of this. How do we support these micro-ecosystems and their services? I don’t think hydroponic organic systems have that answer, but as an Organic soil-farmer I can assure you that we’re working on it.