Minimizing Soil Disturbance: A New Perspective on Tillage

While tillage is a practice rooted in antiquity, determining the most suitable tillage system for a specific field or farm remains a complex task. Before delving into the various tillage systems, let’s explore why humans began tilling the earth. The inception of tillage can be traced back to farmers who cultivated small-grain crops like wheat, rye, and barley, predominantly in western Asia (the Fertile Crescent), Europe, and northern Africa. The primary reason for practicing tillage was to create a fine seedbed, which significantly enhanced germination. It also provided the crop with an early advantage before a new wave of weeds emerged and stimulated the mineralization of organic nitrogen into forms that plants could utilize. The soil was presumably loosened by a simple ard (scratch plow) in multiple directions to form fine aggregates and a smooth seedbed. The loosened soil also tended to offer a more conducive rooting environment, aiding seedling survival and plant growth. Animal traction was utilized to carry out this 

labor-intensive task. As the growing season concluded

The entire crop was gathered because the straw held significant economic value for uses such as animal bedding, roofing thatch, brick production, and fuel. Occasionally, fields were set ablaze post-harvest to eliminate remaining crop residues and manage pests. This farming system persisted for centuries, but it led to severe erosion, particularly in the Mediterranean region, causing widespread soil degradation. Over time, as the climate grew drier, deserts expanded.

In contrast, ancient farming systems in the Americas did not employ intensive full-field tillage for grain cultivation, as they lacked oxen or horses to carry out the strenuous tillage work. Instead, early Americans primarily used direct seeding with planting sticks or manual hoes to create small mounds (hilling). These practices were well-suited to the staple crops of corn and beans, which have large seeds and necessitate lower plant densities than the cereal crops of the Old World. Multiple seeds were sown in each small mound, which was spaced several feet apart.

The hills were spaced several feet apart from each other. In regions with temperate or wet climates, the hills were raised to offer a temperature and moisture benefit to the crop. Unlike the cereal-based systems (wheat, rye, barley, rice) that cultivated only one crop in a monoculture, these fields frequently incorporated the simultaneous intercropping of two or three plant species, such as the corn, bean, and squash of the Three Sisters system in North America. This method of hilling was employed

In general, hilling systems were less susceptible to erosion than full-field tillage, but the climate and soil conditions on steep slopes often led to significant soil degradation.

A third ancient tillage method was employed as part of the rice-growing cultures in southern and eastern Asia. Here, paddies are tilled to manage weeds and puddle the soil to form a dense layer that restricts downward water loss through the soil. The puddling process takes place when the soil is worked while wet—in a plastic or liquid consistency state—and is specifically aimed at breaking down soil aggregates. This system was designed to benefit rice plants, which flourish under flooded conditions, especially compared to competing weeds. There is minimal soil erosion because paddy rice must be grown either on flat or terraced lands, and runoff is managed as part of the crop cultivation process. Recent research efforts have focused on reducing puddling and ponding to preserve soil health and water.

Reducing Tillage

Full-field tillage systems became more prevalent because they are better suited to mechanized agriculture, and over time, some of the traditional hill crops like corn transitioned into row crops. The moldboard plow was invented by the Chinese 2,500 years ago but was reengineered into a more efficient tool in England in the 1700s. It provided weed control by fully turning under crop residues, growing weeds, and weed seeds. Its benefits were initially compelling; it facilitated a more stable food supply and also aided in the breaking of new lands in the Americas. The development of increasingly powerful tractors made tillage a less strenuous task (some say a recreational activity) and resulted in more intensive soil disturbance, ultimately leading to the degradation of soils.

New technologies have reduced the need for tillage. The development of herbicides diminished the need for soil plowing as a method of weed control. New planters achieve better seed placement, even without preparing a seed-bed beforehand. Amendments, such as fertilizers and liquid manures, can be directly injected or band-applied. Now there are even vegetable transplanters that provide good soil-root contact in no-till systems. Although herbicides are often used to kill cover crops before planting the main crop, farmers and researchers have discovered that they can achieve good cover crop control through well-timed mowing or rolling—significantly reducing the amount of herbicide needed. If there is sufficient cover crop biomass, the mat acts as an effective barrier to weeds and provides nearly complete control. Reducing Tillage

Increased mechanization, intensive tillage, and erosion have degraded many agricultural soils to such an extent that people believe tillage is necessary to provide temporary relief from compaction. As aggregates are destroyed, crusting and compaction create a soil “addicted” to tillage. Except perhaps for organic production systems, in which tillage is often needed because herbicides aren’t used, a crop produced with limited or no-tillage can yield better economic returns than one produced with conventional tillage systems. However, managing soil in the right way to make reduced tillage systems successful remains a challeng