Relationship between organic fertility management, plant nutrition, and insect response

Project Overview

Project Type: Graduate Student
Funds awarded in 2009: $9,842.00
Projected End Date: 12/31/2010
Grant Recipient: UW-Madison
Region: North Central
State: Wisconsin
Graduate Student:
Faculty Advisor:
Dr. Eileen Cullen
UW-Madison Dept. of Entomology

Annual Reports

Information Products


  • Agronomic: corn, oats, soybeans, wheat, grass (misc. perennial), hay


  • Animal Production: feed/forage, pasture fertility
  • Crop Production: crop rotation, organic fertilizers, tissue analysis
  • Education and Training: demonstration, extension
  • Pest Management: biological control, economic threshold, integrated pest management, physical control, prevention
  • Production Systems: agroecosystems, holistic management, organic agriculture, transitioning to organic
  • Soil Management: organic matter, soil analysis, soil chemistry, soil quality/health

    Proposal abstract:

    Both organic and conventional growers in the North Central region follow one of two approaches to crop plant mineral fertilization. Those using the “soil balance” or “basic cation saturation ratio” (BCSR) approach seek to maintain high levels of exchangeable calcium relative to magnesium and potassium, maintaining that this enhances crop plant nutrient uptake and improves aspects of plant health such as resistance to insect pests. By contrast, for growers relying on the “sufficient levels of available nutrients” (SLAN) concept, cation ratios are less important than identifiable levels of each nutrient in the soil above which crops are presumed not to respond to additional fertilization. This proposal seeks funds to support new aspects of an ongoing study comparing the BCSR and SLAN approaches and their effects on pest and beneficial insects in organic cropping systems. Initiated at the request of an advisory board of organic farmers and consultants, this study is being conducted in three progressively more controlled settings: working organic farms in southern Wisconsin, experimental plots (in transition to organic certification since fall 2006), and greenhouse trials. Previous research has supported the SLAN approach on the basis of fertilizer cost, but new data including measures of insect populations, mineral content of plant tissues, and physical and chemical properties of soils may inform growers trying to choose between the BCSR and SLAN approaches. Records of field operations and data on weed pressure in the experimental plots could also assist growers transitioning to organic certification. Participating growers are receiving updates periodically, and field days, extension publications, and peer-reviewed research papers have been and will be used to share results with others.

    Project objectives from proposal:

    In the short term, this project will provide participating growers and attendees at field days with a summary of the field operations, yields, weed pressure, and other agronomic considerations involved in transitioning one of the region’s most common cropping systems (small grain/alfalfa-alfalfa-corn-soybeans) to organic certification.

    Other short-term and intermediate-term outcomes represent exploratory research needed to affect organic growers’ choices between two approaches to crop plant fertility management. Each season of field work in experimental plots will provide additional information about the relative impact of these practices on soil, plants, and insects. Greenhouse studies will demonstrate the feasibility of creating soils with particular cation ratios and their effects (if any) on insect feeding and population growth under controlled conditions. Project coordinators and stakeholders will use field and greenhouse results to implement experiments on working farms with growers that will provide additional useful information.

    In the intermediate to long term, growers in the North Central region may change their fertilization practices as a result of benefits (soil quality, pest control, yield, or otherwise) associated with one or the other of the approaches studied. Extension personnel and soil testing labs might also alter their recommendations and/or information available to growers.

    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.