Robert L. Blevins

No-Tillage Agriculture

The no-tillage cropping system, a combination of ancient and modern agricultural practices, has been rapidly increasing in use. By the year 2000, as much as 65 percent of the acreage of crops grown in the United States may be grown by the no-tillage practice. Soil erosion, the major source of pollutants in rural streams, is virtually eliminated when no-tillage agriculture is practiced. The no-tillage system reduces the energy input into corn and soybean production by 7 and 18 percent, respectively, when compared to the conventional tillage system of moldboard plowing followed by disking. In addition, crop yields are as high as or higher than those obtained with traditional tillage practices on large areas of agricultural land.

Changes in soil properties after 10 years continuous non-tilled and conventionally tilled corn

Soil properties were evaluated after 10 years of continuous non-tilled and conventionally tilled corn (Zea mays L.) production on a Maury silt loam (Typic Paleudalfs) soil, which had been in bluegrass (Poa pratensis L.) for 50 years. On limed and nonlimed plots soil samples from 0, 84, 168 and 336 kg/ha N treatments were taken in the 0–5, 5–15 and 15–30 cm layers for determination of organic C and N, soil pH, and exchangeable Al, Mn, Ca, Mg, K. Tillage treatments had no effect on soil bulk density in the 0–15 cm layer. In the 0–5 cm surface layer, organic C and N were approximately twice as high with no-tillage as with conventional tillage; N fertilizer induced a high level of both organic C and organic N. No-tillage decreased soil pH for unlimed plots as compared to conventional tillage, especially at high N-rates, which produced an increase in exchangeable Al and Mn and a decrease in exchangeable Ca down to the 30 cm depth. When lime was applied, the pH of the surface soil was slightly higher under no-tillage. On treatments receiving lime, exchangeable Al and Mn levels were very low with no significant difference in tillage systems. At low rates of N fertilization the 10-year average corn yield was higher for conventional tillage than for no-tillage, but at high rates of N fertilization it was equal or higher for no-tillage treatments receiving lime. Unlimed no-tillage treatments produced lower yields at all N levels during 1975–1979. Deterioration of soil physical properties was not observed.

Impacts of agricultural management practices on C sequestration in forest-derived soils of the eastern Corn Belt

Soil organic matter has recently been implicated as an important sink for atmospheric carbon dioxide (CO 2 ). However, the relative impacts of various agricultural management practices on soil organic matter dynamics and, therefore, C sequestration at spatial scales larger than a single plot or times longer than the typical three year experiment have rarely been reported. Results of maintaining agricultural management practices in the forest-derived soils of the eastern Corn (Zea mays L.) Belt states of Kentucky, Michigan, Ohio and Pennsylvania (USA) were studied. We found annual organic C input and tillage intensity were the most important factors in affecting C sequestration. The impact of rotation on C sequestration was primarily related to the way it altered annual total C inputs. The removal of above-ground plant biomass and use of cover crops were of lesser importance. The most rapid changes in soil organic matter content occurred during the first five years after a management practice was imposed with slower changes occurring thereafter. Certain management practices, e.g. no-tillage (NT), increased the soils ability to sequester atmospheric CO 2 . The impact of this sequestration will be significant only when these practices are used extensively on a large percentage of cropland and when the C-building practices are maintained. Any soil C sequestered will be rapidly mineralized to CO 2 if the soil organic matter building practices are not maintained.

Changes in Soil Properties Under No-Tillage

When farmers shift from a system of agricultural production that includes numerous tillage operations to a reduced or no-tillage system it is reasonable to show concern about how this change in soil management may affect soil properties. For any crop production system to be widely accepted and used it must maintain the physical properties of the soil, and allow for replacement of nutrient removal and other losses. It must also maintain a soil environment favorable for the numerous necessary biological reactions. The microbial activity of the soil is largely determined by the chemical and physical properties of the soil. For example, the placement and amount of organic material directly influences biological activity, as it also does the chemical and physical properties.

Soil Adaptability for No-Tillage

The unique properties of individual soils determine their limitations and suitability for land use. Because of these wide ranges of differences among soils of the world it is understandable that no one tillage system would be best suited for all soils. Soil properties and climatic conditions should be carefully evaluated before selecting a tillage system. Soil conditions that favor no-tillage farming or modifications of these systems will be discussed in this chapter as well as conditions that are less favorable for the adoption of no-tillage farming techniques.

Sustaining Soil Quality with Legumes in No-Tillage Systems

Abstract Tillage, cropping system, and cover crops have seasonal and long‐term effects on the nitrogen (N) cycle and total soil organic carbon (C), which in turn affects soil quality. This study evaluated the effects of crop, cover crop, and tillage practices on inorganic N levels and total soil N, the timing of inorganic N release from hairy vetch and soybean, and the capacity for C sequestration. Cropping systems included continuous corn (Zea mays L.) and stalk residue, continuous corn and hairy vetch (Vicia villosa Roth), continuous soybeans (Glycine max L.) plus residue, and two corn/soybean rotations in corn alternate years with hairy vetch and ammonium nitrate (0, 85, and 170 kg N ha−1). Subplot treatments were moldboard plow and no tillage. Legumes coupled with no tillage reduced the N fertilizer requirement of corn, increased plant‐available N, and augmented total soil C and N stores.

No-Tillage in the Tropics

In the tropical regions of the world there exists a wide range of differences in climate, vegetation and soil resources. The so-called tropical zone comprises about one-third of the land surface of the earth. It is difficult to clearly define the tropics, and for convenience is often given a latitudinal definition, which includes the zone between Tropic of Capricorn and Tropic of Cancer or latitudes of 23.5° N and S (Kalpage, 1974). Another definition of the tropics (Sanchez, 1976) is that part of the world where the mean monthly temperature variation is 5°C or less between the average of the three warmest and three coldest months. Located within this tropical zone are many of the developing nations that face food supply problems (U.S. President’s Science Advisory Council, 1967) because food production technology has lagged behind population growth.