Organic farms vary in agricultural ecological practices, with small farms incorporating a higher quantity of sustainable methods than larger ones, according to a recent US study.

Organic certification for U.S. farms requires abstinence from using harsh pesticides, synthetic fertilizers, and other banned substances. To enhance their crops and deter pests, organic farmers rely instead on practices that boost natural ecosystem functions, like pollination and pest control, but the organic standards are flexible and allow farmers to choose the practices that best suit their operations. Common practices include incorporating non-crop vegetation in and around fields, the application of compost, reducing tillage, and implementing diverse crop rotations. Although these practices are beneficial to the sustainability of all farms, their economic utility varies with farm size.

Large farms occupy the majority of U.S. farmland and their dominance continues to grow. In considering agricultural sustainability for the foreseeable future, it is important to understand how the most sizable farms bolster and utilize ecosystem services. This study seeks to examine the differences in agroecological practices between small, medium, and large U.S. farms. For this study, researchers designated small farms as those under 40 acres, medium farms as 40-404 acres, and large farms as 405 acres or more.

The data in this study was gathered from 594 survey respondents of organic farmers across 43 states. The researchers examined the application of eight agroecological practices:

• manure/compost application
• intercropping (planting different crops in the same field)

• insectary plantings

• reduced tillage

• diverse crop rotations

• cover cropping,

• border plantings, and

• riparian buffers.

Out of the eight examined agro-ecological practices, most small and medium sized farms utilized six or more, applying more of them on average than large farms.  All eight practices were utilized on over 50% of small and medium farms, and all but two–insectary planting and border planting– were incorporated on the majority of large farms. Diverse crop rotations, cover crops, and riparian buffers were incorporated on over 75% of farms in each size category.

Despite their potential benefits to ecosystem function, insectary and border plantings provide diminished returns on larger properties. Insectary planting provides a habitat for beneficial insects which prey on pests; however, these insects have limited range associated with these habitats. Sizable fields require several insectary plants to protect the entire range. Border plantings also provide key habitats to beneficial insects, while additionally protecting against erosion and runoff, but have a similarly dampened impact on large properties. As farm size increases, the proportion of the farm that is nearby to the border decreases, so border plantings ultimately benefit a relatively small portion of the farm.

This study demonstrates where opportunities are available to further incentivize conservation practices on larger farms, and to better reward smaller farms that are already using more sustainable practices. This research also demonstrates the wide variation that exists in what an organic farm can look like. Future studies should be careful to define the practices being used, not just categorize a farm as organic or non-organic, to better understand the sustainability of organic farming.

Photo by: Tomasz Bazylinski; https://unsplash.com/@bazylu