Assessing soil quality changes in alternative and conventional cropping systems

Project Overview

LNC00-179
Project Type: Research and Education
Funds awarded in 2000: $93,300.00
Projected End Date: 12/31/2003
Matching Non-Federal Funds: $24,000.00
Region: North Central
State: Minnesota
Project Coordinator:
Deborah Allan
University of Minnesota

Annual Reports

Commodities

  • Agronomic: corn, oats, soybeans, hay

Practices

  • Animal Production: feed/forage
  • Crop Production: conservation tillage
  • Soil Management: organic matter, soil analysis, nutrient mineralization, soil quality/health

    Abstract:

    The effects of management on soil quality in a long-term field experiment were investigated. The trial compared two sites of differing initial fertility; management differences included rotation length, input level and type, and tillage intensity. Overall, LPI and ORG had the highest soil quality ratings. The two-year HPI, representing the vast majority of acreage in Southwest Minnesota, had the lowest soil quality. The four-year rotation was less variable and generally had higher soil quality than the two-year rotation, due to the soil-improving effects of oats and alfalfa.

    Introduction:

    Over the last 50 years, crop production in the Midwestern United States has become increasingly reliant on the corn and soybean rotation. Crop suitability, effective agro-chemicals, government policy, and economics have all aided in this shift (Porter et al., 2003). However producers have begun to recognize the need for alternative crops in response to increasing economic difficulty associated with the bi-culture rotation, rising environmental concerns, and the declining health of rural communities. Many traditional corn-soybean growers acknowledge the benefits of alternative managements and diversified rotations, but feel locked into the two-year rotation despite increased economic and biological sustainability in more diverse systems (Mahoney, 2001). While management decisions are normally based on marketing options and economics, soil quality is becoming a legitimate consideration in the decision making process. In a recent organic farming survey, three of the top five research priorities chosen by growers were topics related to soil management (Walz, 1999). A separate Wisconsin survey showed that farmers were interested in soil quality as a way to evaluate how well they are managing their land (Romig et al., 1995).

    Cultivation of native land results in the loss of organic matter because it changes soil drainage, disturbance patterns, and amounts and types of residues put into the soil (Balesdent et al., 2000). The magnitude of this change depends largely on the type of management system used. It is estimated that the current mix of tillages used in the cornbelt will lose 3.2 x 106 t-C yr-1 over the next 100 years; widespread adoption of no-tillage would reduce this loss by 70% (Lee & Phillips, 1993). Associated with cultivation is an increase in soil erosion that often surpasses sustainable rates (Wander & Drinkwater, 2000). Twenty percent of the difference between the two systems mentioned above is attributed to a reduction in erosion (Lee & Phillips, 1993). Erosion can account for a large amount of SOM loss.

    Alternative practices can have a beneficial effect on soil quality and organic matter loss. No-tillage management strategies have been shown to increase the labile organic matter fractions and percentage of stable macroaggregates in multiple studies (Wander & Bollero, 1999; Balesdent et al., 2000; Beare et al., 1994b; Wander & Yang, 2000). Organic matter content is also directly related to organic input levels (Gilley & Risse, 2000; Sommerfeldt, 1988). And crop rotation influences soil quality through both the residues the different crops return to the soil and the cultural practices associated with specific crops (Havlin et al., 1990; Grandy et al., 2002).

    The objectives of this study were to comprehensively examine the soil quality differences between management systems that integrate different crop rotation lengths, tillage intensities, and conventional and organic inputs.

    Project objectives:

    1) Characterize the effect of rotation and management systems on soil quality and biomass production in long-term experiments with previous high and low fertility management.
    2) Evaluate the same soil quality characteristics for similar soils using paired-field or paired-farm comparisons of long-term alternative production systems with those in conventional systems or systems recently converted to alternative management.
    3) Develop and implement an outreach component for dissemination of information concerning the impact of soil quality of alternative management systems.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.