The WPVGA-World Wildlife Fund potato project has two major goals that will directly benefit farmers in the state. First, our efforts must earn and sustain tangible economic rewards from the market, as we document progress along the IPM continuum that makes it possible for growers to reduce reliance on high-risk pesticides. Second, we must find ways to advance the science and art of biointensive IPM within the state's potato production systems.
Given how the real world works, our challenge is to make progress toward both goals simultaneously. Recognition and rewards in the market are needed and will help underwrite evolving efforts to refine and apply biointensive IPM systems. New IPM methods, tools and knowledge – the science and art of IPM -- will be essential in facilitating progress along the IPM continuum and in reducing use of high-risk pesticides – the steps that will earn the attention of, and hopefully rewards from the market.
In my visits with Wisconsin potato growers, discussion seems to very quickly center around one promising way to move toward biologically-based pest management systems – the enhancement of soil quality. The interest, indeed passion, felt by WPVGA members about soil quality is music to my ears, because I believe the structured enhancement, and then management of soil quality is going to be the foundation of the next quantum leap in agricultural productivity and profitability worldwide.
The soil is the well of agriculture. In many places, the soil is crying out for a lighter touch and a little help from its friends. But too often the response by farmers to productivity problems linked to the soil is to do more, or apply more of the very things that systematically destroys soil quality. I am delighted that many Wisconsin farmers realized this a long-time ago, and are in the active phase of exploring how to manage their soils to enhance soil quality. Their efforts will lead, over time to a re-capitalization of value back into the Wisconsin landscape, reversing the slow degradation of intensively cultivated soils underway for over 70 years.
The retiring farmer that passes along to the next generation cleaner water and fields with higher organic matter content than when he or she started farming should feel great pride in their accomplishment. Our job is to make such accomplishments routine across the vegetable growing regions of Wisconsin. If successful, we can say with confidence that potato production in the region is sustainable, and indeed poised to keep up with growing demand for high quality, safe food.
A few decades will be needed to fully launch the "soil quality" revolution. Steady, patient effort will be necessary to learn enough about the intricate secrets of natural systems and cycles, particularly the interactions among organisms, to reliably manage soil quality across the diversity of landscapes, climates, and farming systems in America. But my guess, and a personal goal, is that when the history of this next agricultural revolution is written, key steps forward, both in science and field applications, will be traced to potato fields in Central Wisconsin, circa the years 1997-2000.
While there are a million ways to combine words in defining "soil quality," any good farmer knows what "soil quality" is – the capacity of a soil to take in, hold, and cycle nutrients and water, while also providing a healthy environment for root systems to develop fully within, in part by warding off or otherwise overcoming the attacks of damaging pathogens.
Quality soils till easier than degraded soils, they smell alive and feel crumbly. They take in water faster and hold it longer. Plants take off faster and grow more vigorously, often providing a key leg up on weeds and other pests. Organic materials and crop residues break down through more complex, multifaceted food chains in high quality soils, through processes that end up helping the farmer in many ways.
The capacity of soil to support microbial communities sufficient to bring about a substantial degree of microbial biocontrol of soil borne pathogens, insects and even weeds is an extremely important dimension of soil quality that has, until recently, received little serious attention from researchers. Microbial communities are, after all, the "inputs" that make microbial biocontrol possible.
The lack of attention to soil microbial biocontrol reflects the fact that for decades, most farmers have had fumigants and other pesticides like ethylene dibromide, methyl bromide, metam-sodium, DBCP, Telone II and a host of hot OPs and carbamates like aldicarb to draw upon in dealing with soil borne pests. But as these tools fall by the way-side, for one reason or another, everyone is scrambling to find biological alternatives. While no one has found the key to the city, building up soil quality is almost certainly a strategy that will help get most farmers, and the potato industry as a whole, closer to the day when such materials will no longer be routinely necessary.
Proven Steps to Enhance Soil Quality
Potato farmers are experimenting with a number of well-known approaches to build soil quality. Anything that increases soil organic matter content, or the quantity of organic matter cycling through the soil is a step in the right direction. The planting of cover crops can be helpful, as is reducing tillage. Almost universally, tillage is the enemy of soil microorganisms, and hence also of biological efforts to enhance soil structure and quality.
All steps that lessen compaction will contribute to steady progress in building soil quality. Compaction drives out spaces in the soil where air and moisture linger. Both are essential in sustaining high levels of microorganisms in the soil. Compaction leads to fewer organisms, which then can cause reductions in the amount of nitrogen flowing through the soil, hence increasing farmers' reliance on applied N, and the risk of groundwater problems.
Recent, exciting scientific breakthroughs are beginning to unravel why some soils have the capacity to suppress certain pests. An article published in the journal Science in January, 1997 shows that the biosynthesis of ethylene in the soil can help root systems ward off pathogens. Other research in potato producing states has shown that rapeseed cover crops produce isothiocyanate gas as they break down, a precursor of metam-sodium.
These and other findings suggest the possibility that we might be able to develop biologically-based soil fumigation techniques that will compete well with metam-sodium, both in terms of efficacy and cost, but require no application of harsh chemicals. Such systems will have many components, and it will take years to fully understand how and why they work in different settings, but the mysteries that stand in the way of successful biological fumigation are no greater than those overcome many times in the past, once a decision was made that it is important to do so.
Success will lead to many rewards. The ability to pull out of potato production systems most uses of fumigants and broadly toxic soil insecticides will make it possible to gradually enhance the diversity and populations of organisms living in the soil, and for parts of their life-cycle, above the soil. New above- and below-ground biological control options may well emerge. As the diversity of soil food webs grows, so too will the nitrogen flowing through it. Under skillful management, a good portion of the N cycling in the soil can be made accessible to potato plants at key points of the year, allowing farmers to back-off N rates at times of the year when the risk of leaching is greatest.
Soil quality is an enormously complex topic, but given the talent of the U.W. team, recent breakthroughs in S+T, and the willingness of growers to experiment, our ability to make progress might surprise everyone, including ourselves. Most of what we learn will simply lead to more questions, but in time, insights will emerge leading to the roots of soil quality. As Wisconsin farmers learn how to deepen and nurture these roots, growers will produce better crops at lower cost, while also enhancing the quality of the State's environment and providing consumers safe and nutritious products.
Lofty goals? Yes indeed, but more than worth the effort.
