Comparing Cropping Systems
Four crops received holistic scrutiny this year when systems such as "conventional," "organic IPM," and "future IPM" were compared in side-by-side plots.
Workers plant strawberries in rows separated by rye cover crop. Photo: J. Kovach
Specialization has been the favored path for medical professionals, lawyers, and business people for decades. In the realm of scientific research it is often considered a necessary path. The theory is, how do we find answers to the mysteries of our world unless we break them down into manageable components?
Three long-term IPM projects are taking the opposite approach as scientists study and demonstrate IPM practices for strawberries, sweet corn, field corn, and soybeans in a holistic fashion. These projects use the systems approach - an approach that involves the blending together of many components. Why? There is a great need to understand how all of the components of IPM technology interact and relate to one another. Farmers employ a systems approach to managing their pests; why not have IPM demonstrations that do the same? There are distinct advantages to such integration:
- Findings from finite projects can be validated by looking at them in combination with each other and over an extended period;
- Growers and Cooperative Extension IPM educators benefit from seeing all of the IPM strategies for one crop in one setting;
- The systems approach fosters teamwork at Cornell because it benefits both researchers and extension educators. Researchers are able to add knowledge from systems studies to their component studies. Extension educators can use this approach to gauge the likelihood of commercial success of various methods;
- Larger plots are used than the usual research plots, which means the results can be more readily transferred to commercial growers' fields.
How does a systems study work? Side-by-side plots are managed according to prescribed plans that cover all aspects of pest management. Both the strawberry and the sweet-corn projects use three treatments called "present IPM," "future lPM," and "organic IPM." The sweet-corn study also includes a "conventional" treatment. The field-corn/soybean project, the only one of the three that has been completed, examined the IPM benefits of crop rotation versus continuous corn under three weed and soil insect control regimes and two tillage systems (moldboard plow and chisel).
The strawberry systems
The strawberry cropping systems project was begun by a small-fruit team led by fruit IPM coordinator Joe Kovach in the spring of 1995. Cover crops were planted on approximately two acres at the New York State Agricultural Experiment Station in Geneva that year. In 1996, strawberries were planted. The first full fruiting year will be 1997, and it is anticipated that data will be collected through the year 2000.
No pesticides, either natural or synthetic, are being applied in the "organic IPM" system; only cultural and biological controls are being used. The "future IPM" system combines cultural and biological controls with minimal use of synthetic pesticides. IPM technology as published in Cornell's 1995 Pest Management Recommendations for Small Fruit Crops is applied to the "present IPM" system.
These treatments are being applied to four varieties of strawberries, two June-bearing and two ever-bearing (called "day-neutrals"). Varieties were selected for inclusion in the project either because of their tolerance to insects or because they are less susceptible to fruit rot than other varieties.
A wide spectrum of pest prevention methods has been or will be employed in this cropping comparison. A sampling of these follows.
Insect or nematode management
- marigolds, used as a cultural method for suppression of nematodes that feed on strawberry roots
- a one-meter strip of alfalfa planted around each plot as a trap crop for insects
- releases of parasitoids (biological control agents) in the alfalfa to manage tarnished plant bug
- vacuuming of strawberry plants to manage tarnished plant bug
- rye planted as a cover crop one spring and mowed the following spring before the strawberries are planted
- straw mulch applied between rows
- comparing banded applications of herbicides (in strips along the rows rather than broadcast over the fields) with no herbicides
- avoidance of spring nitrogen applications
- bee-delivered Trichoderma, a biological control agent that manages fruit rot
- comparing narrow rows of plants with wide rows
While the complexity of measuring so many factors in multiple treatments may seem daunting, many interesting results are expected that will raise the level of IPM knowledge.
The sweet-corn systems
The sweet-corn study, initiated by a team of vegetable scientists and led by vegetable IPM coordinator Curt Petzoldt, involves fine-tuning the use of a new type of cultivator for weed control so as to avoid damage to plants, and a seed treatment with a biological control agent, Trichoderma, to increase yield in the organic IPM plot. Researchers are also elucidating differences in soil structures and levels of biological activity in soils, the effects of rotating with cover crops, and the efficacy of banding of herbicides (application to narrow strips adjacent to plant rows) versus broadcasting of those materials (application to entire fields).
Results to date indicate that while there are certain tradeoffs between environmental impact and economic costs, all four systems (conventional, present IPM, future IPM, and organic IPM) have valuable components to contribute to a sustainable production system for fresh-market sweet corn. This project is scheduled to run for at least five years. Investigators have already tested the four management approaches during two very distinct growing seasons. The sweet-corn project is one of a series of vegetable systems comparisons. A cabbage comparison begun in 1992 with the same four systems ran for three years (1992-1994).
The field-corn/soybean systems
Various pest management systems for field corn have been demonstrated on Cornell research farms for several years. This work was begun by a team of scientists led by Bill Cox, of the Soil, Crop and Atmospheric Sciences Department at Cornell. Evaluations of economics and effectiveness have been made regarding tilling equipment, rotation, and three levels of pest management inputs.
Demonstrations of project results were conducted in four central and western New York locations in 1996. The demonstrations reinforced IPM principles and increased grower awareness by sharing these findings:
- growers can reduce weed problems in field corn by using a moldboard plow instead of a chisel plow
- the benefits of rotation over continuous corn are decreases in corn rootworm damage, yield increases of 10-30 bushels per acre, and greater net returns
- savings of $5-20 per acre can be realized and pesticide use can be reduced when growers replace broadcasting of herbicides with either of the following: 1) moldboard plow tillage followed by rotary hoeing and timely cultivation, or 2) banding of herbicides and timely cultivation
A systems approach provides a broader and more practical view than a traditional, single-component demonstration. One goal of this approach is to achieve a more biologically balanced system for raising a particular crop. "This can't be done in a year or two," asserts IPM Director Jim Tette. "As we rely more and more on biological plant protection mechanisms, we need more time to understand whether they will lead to systems that are as productive and economical as those we have now."