Agriculture Uncovered: Soil Health Practices on Cropland

Agriculture is a major part of life in the Chesapeake Bay watershed. Farms can help support clean water and healthy communities, but they can also be a source of pollution if soils and nutrients wash into rivers and streams. Soil health practices on cropland are an important way to protect both our land and water. Across the United States, farms cover about 880 million acres, almost 40% of all land. About 382 million of those acres are cropland. How cropland is managed affects not only the food supply, but also the environment.

Traditional farming practices have often led to the loss of topsoil, organic matter, and helpful soil organisms. Soil health practices help address these challenges and build more resilient farms. These practices are based on the four core principles of managing soil for health: maximizing living roots, soil cover, and biodiversity and minimizing disturbance. Soil health practices on croplands can help reduce the runoff coming from farms by reducing the loss of topsoil, increasing water infiltration, and reducing the need for fertilizers.

Conservation tillage

Crop field on the Eastern Shore of Maryland

Conservation tillage means disturbing the soil as little as possible and leaving crop residue on the surface. Benefits of this practice include reduced soil erosion, better water infiltration, improved soil organic matter, and increased carbon storage. There are several types of conservation tillage, from reduced tillage to complete no-till. One common reduced-tillage method is strip tillage, where only a narrow strip of soil is tilled before planting. There are some obstacles when transitioning from conventional tillage; such as increased weed pressure which may lead to higher herbicide use and specialized equipment needed for planting and cover crop termination. Even with these challenges, conservation tillage continues to grow. The U.S. Census of Agriculture found that from 2012 to 2022, acres under no-till increased from 35 to 38% and under reduced tillage increased from 28 to 35%.

Cover crops

Cereal rye is a very popular cover crop species with an extensive root system that provides many soil health benefits. Photo credit: PennState Extension

Cover crops are planted during times when a cash crop, the crop grown for income, is not in the field. They keep the soil covered for more of the year, which helps prevent erosion and supports the microbes and insects that live in the soil. Adding a cover crop involves several decisions, including which species to plant, and how and when to plant and terminate it. Cover crop use has grown as well. The U.S. Census of Agriculture shows a 50% increase in acres with cover crops from 2012 to 2017 and another 17% increase from 2017 to 2022. In addition to environmental benefits, cover crops may help reduce weeds, lower fertilizer needs for the cash crop, and improve water infiltration and retention. Livestock farms may also use cover crops as forage, either by grazing animals on the fields or harvesting the crops for feed.

Crop rotations

A corn field in Lancaster County, PA. A two-year corn-soybean rotation is one of the most popular forms of crop rotation.

Crop rotation is the practice of growing different crops on the same field over time. Changing the type of crop helps reduce pest buildup and supports soil heath, especially when the crops have different root systems and nutrient needs. Crop rotation is one of the most common soil health practices in the United States. Continuous monocropping, growing the same crop every year, is much less common than using rotations. The most common rotation is a two-year corn-soybean cycle, as soybeans help make nitrogen more available in the soil for the corn grown the following year. Adding even more crop diversity provides additional soil health benefits. Crop rotations also help diversify farm income by providing products for different markets. This reduces financial risk if prices drop for any single crop.

intercropping

A field with row intercropping showing alternate rows of onion and hairy vetch. Credit: Heather Karsten

Intercropping is the practice of growing two or more crops in the same field at the same time. Like crop rotation, it increases plant diversity, but instead of spreading diversity over time, intercropping increases it across the field. There are several types of intercropping. Strip cropping plants different crops in wide strips across multiple rows, row intercropping plants different crops in adjacent rows, and relay intercropping adds a second crop before the first is harvested. Intercropping can also include companion plants, which benefit each other when grown together. A well-known example is the “ Three Sisters” from Native American agriculture, corn, squash, and beans, where each plant provides support, nutrients, or pest protection for the others.

Nutrient management

Manure management on dairy farms is essential to promote soil health and protect water quality.

Nutrients are essential for plant growth, but if they are not managed well, they can become a source of pollution. When applying fertilizers, compost, or manure, it is important to follow the “4Rs” of nutrient management: right source, right rate, right time, and right place. The right source means choosing the correct amendment for the crop and soil. The right rate means applying only the amount the crop needs, based on soil tests. The right time means applying nutrients when the crop can use them. The right place means keeping nutrients close to the crop and soil. Using the 4Rs helps ensure nutrients are taken up by the plants, reduces runoff into nearby waterways, and prevents farmers from spending money on fertilizer that crops cannot use.

Soil profile along a streambank in Lancaster, PA.

Building healthy soil on cropland is vital to the longevity of our farms and the protection of the Chesapeake Bay watershed. Supporting soil health practices is important, but change is difficult. Transitioning from a conventional to conservation practice requires significant planning, time, labor and often new equipment. The Alliance prioritizes meeting farmers where they are and focusing on continuous improvement, acknowledging that not all of these practices are suitable for every farm. By providing farmers with the information and resources they need, they can make choices that benefit their soil, water, and climate while maintaining efficiency and productivity.

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