The use of conservation tillage has been increasing in the United States in response to growing concerns about the impact of agricultural production on the environment. There is an identifiable upward trend until the last few years, which shows no discernible change. A longer term perspective can be obtained from Fig. 1. The use of conservation tillage increased from 1% of planted acreage in 1963 to 37% of planted acreage in 1997.

Use of conservation tillage practices frequently reduces the negative impacts associated conventional tillage systems which include energy use, soil erosion, leaching and run-off of agricultural chemicals, and carbon emissions. The relationship between energy and the use of conservation tillage is of special importance and is the subject of what follows. Before exploring this, however, some background is needed.

Farmers in general tend to make production-practice changes slowly. The adoption process generally can be viewed as having five stages. Initially, farmers are unaware of a new practice (stage 1). They become aware of new practices through various sources, including neighbors, farm publications, mass media, extension agents, chemical dealers and crop consultants (stage 2). Farmers then evaluate the practice in terms of their own operations through educational sources such as demonstration projects, talking with agents, and talking with neighbors who have tried the practice (stage 3). Farmers may then test the practice on part of their farm (stage 4). The ability of a practice to be tested on part of the farm enhances its potential for adoption [42]. Finally, full adoption occurs if the practice is found to be better that what they are currently doing (stage 5).

A variety of economic, demographic, geographic, and policy variables have been identified that affect the adoption and use of conservation tillage in the US. The rate of adoption (diffusion) of a new technology – e.g., conservation tillage – determines the rate of technological change. The first empirical assessment of the diffusion of a new technology was applied to hybrid corn. The diffusion follows an innovation cycle. The cycle starts with efficient producers first introducing the new technology that requires a threshold level of technical skill for profitable use. As skill levels of other farmers increase through experience, the new technology is more widely adopted. The time path of adoption of the new technology can be derived analytically as a function of the distribution of technical ability among producers and the rate of change in technical skill.

Adoption is also a function of exogenous factors, and these will retard or accelerate the rate of adoption. Investment costs associated with the adoption of the new technology will have an important influence on a farmer’s choice. Government policy in the form of conservation compliance is an example of an exogenous factor that would be expected to accelerate the rate of adoption of conservation tillage. Yet another exogenous consideration is what is nominally referred to as learning by doing. When specialized management skills are required for production, owner/operators will gain proficiency with experience; that is, they learn by doing.

In the context of the diffusion of conservation tillage as a new technology (production practice), a sizeable number of studies are available that provide some insights into the important factors that affect the adoption of conservation tillage. Because there is considerable redundancy in the results of the studies, an exhaustive survey will not be provided. Pagoulatos et al. using an erosion-damage function analysis for corn grown in Kentucky found that the decision to convert to conservation tillage from conventional tillage is dependent on the price of output, the discount rate (with a higher discount rate leading to a slower adoption of conservation tillage), and the capital cost of conversion. Large capital costs for new machinery serve as a deterrent to the adoption of conservation tillage.

Uri used a two-stage decision model econometrically estimated for corn produced in the US in 1987. The data came from the Farm Costs and Returns Survey (FCRS) conducted by the US Department of Agriculture. He found that cash grain enterprises were more likely to adopt conservation tillage than other farm types. The slope of the cropland was an important factor (the greater the slope, the greater the likelihood of conservation tillage adoption), and average rainfall (but not average temperature) was associated with a greater likelihood that conservation tillage was adopted. Finally, conservation tillage adopters spent more on fertilizer and pesticides. Several factors including expenditures on some inputs and farm and farm owner/operator characteristics were found not to be associated with the adoption or non-adoption of the conservation tillage production practice. For example, the age and education level of the farmer/operator was not associated with the adoption of conservation tillage. The productivity of the soil, as measured by average yield across farms in a county, had no identifiable impact on the decision to adopt conservation tillage. The texture of the soil, the total acres planted, the number of acres in the acreage reduction program, the extent of irrigation, and the proportion of acres not receiving any pesticide treatment likewise were not associated with the adoption of conservation tillage on corn acreage.

Gray et al. used a simulation model to compare the adoption of conservation tillage systems to conventional tillage systems for wheat production in western Canada. Crop yield and the price of the burndown herbicide (the herbicide used to eliminate vegetation prior to planting) were key determinants to the shortrun profitability of adopting conservation tillage.

Carter and Kunelius analyzing data from Atlantic Canada found that some soil types are simply not suitable for conservation tillage. The soils require a high degree of cultivation to maintain their structure and regular tillage to ensure adequate crop productivity. Moreover, climatic constraints such as a short growing season, cold temperatures and excessive precipitation can influence the choice of a conservation tillage system.

Batte et al. found that commercial farms in Ohio in 1992 tended to operate with a single system. Thus, farms classified as no tillage used no tillage on 85% of planted acreage while conventional tillage farms used moldboard plowing on 80% of their acreage. Also, farms using conservation tillage tended to be substantially larger than farms using conventional tillage.

The greater risk associated with the use of conservation tillage has been shown to be a deterrent to the adoption of conservation tillage in a number of studies. Risk in these studies is typically defined as variability in yields or variability in net returns. Thus, Miskesell et al. using a simulation model evaluated the expected net returns and risk of alternative tillage systems for a 640-acre grain farm in northeastern Kansas. Conservation tillage systems had slightly higher expected incomes but were more risky. A risk-averse farmer would prefer conventional tillage to conservation tillage. Williams et al. using a simulation model found that conservation tillage used in grain sorghum production had higher expected net revenues but greater risk than conventional tillage.

Westra and Olson estimated a structural model based on survey responses for farmers in two counties in Minnesota. Their results suggest that larger farms are more likely to use conservation tillage. Also, if the owner/operator is relatively more concerned about erosion, the probability of adopting conservation tillage is greater. The greater complexity associated with the use of conservation tillage requiring greater management skill is identified as a deterrent to the adoption of conservation tillage.