Are you growing a crop for the next harvest or farming for the future?
Trend-setter advocates increasingly believe that a farming for the future philosophy is critical. Farmers who build a long-term base of soil health as the foundation for long-term profits will be miles ahead compared to simply growing next year's crop. Researchers, consultants and progressive farmers believe a more holistic, long-term approach is required to raise the bar on future productivity.
“In the past we talked more about the mechanical things – planting on time, adding the right nutrients and doing tillage and weed control correctly," says Bruce Erickson, agronomic education manager, American Society of Agronomy.” All those remain critical, but innovative farmers are increasingly concerned with the biological aspects of soils – areas we may not fully understand."
"The current approach is to apply control technologies to remove limitations – for example, fungicides and insecticides,” says Jerry Hatfield, plant physiologist and director, National Laboratory for Agriculture and the Environment, USDA-ARS, Ames, Iowa. “We have overlooked the role of a healthy soil on the biological components of the soil and how a healthy soil can offset the problems we think are occurring. “We have overlooked the value of soil biology in building a more robust soil-plant system."
NATURAL SOIL FERTILITY
Hatfield believes there is a need to look at the system and how it is fed from a more natural, biological fertility standpoint. "Let’s have the biological system do the work. We need to realize that soil biology requires feeding throughout the year and not just for short periods of time.”
Joe Nester works with innovative farmers in northwest Ohio, southern Michigan and northeastern Indiana who are doing just that. A former fertilizer plant manager, Nester has been working one-on-one with producers to improve management systems for nearly 20 years. Like Erickson, he sees a change in how they view these systems. “For years we said crop production had a chemical, physical and biological side, but we gave most of our attention to the chemical side,” he says. “That is changing, and the physical and biological sides are becoming more important. They take better management and outside-the-box thinking.”
Several factors are driving this new viewpoint. Hatfield cites the impact of yield monitors and precision agriculture that emphasize yield variations across a field and show how better soils offer more uniform yields from year to year. “We’ve been talking about the role of better soils on water availability and nutrient use efficiency for several years, and this is beginning to take hold,” he says.
Erickson warns that new challenges may emerge in the more automated system of crop production. “As we’ve reduced the production risks using seed treatments, better equipment, genetic engineering solutions for weeds and insects and more reliable genetics for emergence, and harvestability, our system has become more automated and prescriptive,” he says. “This has allowed farmers to manage other complexities such as farming more acres, or land spread over greater distances. But there is a danger when complex biological systems become simple in a manager's mind. Not all of our innovations will last forever, and new solutions may be needed to replace them.”
Sometimes those new solutions are old practices revisited, such as crop rotation. Others are newer practices revised, such as no-till and conservation tillage. Sometimes they are a combination of old and new, such as the rapid growth of between-season cover crops, especially in no-till cropping, and the resulting synergy. Although each of these practices initially appeared to resolve specific problems within the system, the confluence of them today points to a new understanding and appreciation for system-wide and long-term benefits.
The traditional benefits of crop rotation included market/product diversification, extended planting and harvesting windows and, in the case of legumes, added N. Commodity pricing has altered the market benefit in many areas, and bigger and more productive equipment has altered the importance of extended planting windows. Faster-emerging and more weather-tolerant seeds have further altered traditional planting cycles. In the case of weed and pest cycles, Erickson says the biotech solutions and other factors have altered the dynamics for many growers.
“The rotation question is influenced by many factors: input costs for each crop, such as seed, fertilizer, pesticides; what type of yields can be expected, influenced by soils, the farmer’s management, a crop’s position in the rotation; what prices one can expect for each crop, related to closeness to markets such as livestock, ethanol plants, rivers and railroads. These are different from region to region and from farmer to farmer.”
Fewer trips across the field combined with biotech-based weed control have made all levels of conservation tillage positive options. With increased attention to physical and biological aspects of the cropping system, new pieces join the calculation pie as soil health and structure are studied for incremental advantages in increased yields. However, it is that combination of no-till, crop rotation and cover crops that is really affecting soil health. In fact, Erickson compares adding a cover crop to adding a crop to the rotation.
Nester says his clients are taking note of the benefits. “As we introduced cover crops into the system, the main thing we saw was a faster transition of soil quality that lends itself to more successful no-till,” he says. “Growers are getting better stands and sooner. With improved water infiltration, they are getting on fields sooner, and that really helps the no-tiller keep up in the early years of no-till.”
In the past, Nester says, he worried more about eliminating compaction and balancing calcium and magnesium before a grower converted to no-till. Cover crops are improving soil structure (particularly cereal rye and tillage radishes), earthworms are more prevalent and excess nutrients are being absorbed for later release. Nutrient absorption is especially important following a drought year that left many nutrients unused.
“Efficient recovery of nutrients and keeping them in the field is the No. 1 thing we need to raise better crops,” says Nester. “A healthy soil lets larger root systems proliferate, which captures a higher percent of the nutrients in the field. You need fewer applied nutrients. With poorer soil structure, you need to saturate the soil with nutrients, as the plant will find a smaller percentage of nutrients.”
As seen this past year, water is often the constraining nutrient. Here, too, cover crops take no-till to another level. While the increased biological activity, including earthworms, encourages heavy rains to move into the soil rather than off the surface, the increased organic matter from combined no-till and cover crops helps fight crop stress of all kinds.
“No-till has made good improvements in soil quality and soil health, but cover crops go beyond no-till alone, keeping something alive and growing throughout the year,” says Alan Sundermeier, Extension educator, Ohio State University. “We are seeing substantial bushel increases on healthier soils with cover crops and no-till.”
Just what are healthier soils? How do they impact crop growth? Nester points to more earthworms and better soil structure. Sundermeier points to water infiltration and increased organic matter. Hatfield points to biological components that can offset challenges to the plant.
“We are still working out how to bring together biological, chemical and physical measurements to evaluate both the soil and plant components,” says Hatfield. “For example, in cover crops, the growing roots supply fresh root material for the microbes to eat throughout a longer period of time.”
Senyu Chen, plant pathologist, Southern Research and Outreach Center, University of Minnesota, has taken that concept even further. He’s identified endoparasitic fungi that can biologically disrupt SCN. These friendly fungi seem to be more common in continuous-soybean than in corn-soybean rotations. He’s researching whether the endoparasite can be introduced into non-suppressive soils, whether in more common corn/soybean rotations, continuous corn or continuous soybean rotations.
Searching for a better understanding of SCN, Chen’s research team has identified SCN-suppressive soils. He defines them as soils that naturally contain physical, biochemical and biological factors that suppress SCN. These factors include fungal parasites of SCN, such as one that forms a special device that can catch nematodes in the soil, and extracellular enzyme activity related to suppression.
“We are mainly looking at SCN, but also at other nematodes, including those that act on corn,” Chen explains. “We are asking why one field is suppressive to SCN and others aren’t. What is the cooperating system of rotation and tillage that can influence suppression?
“There are many things we need to look at before we can use them,” says Chen. “One thought is to introduce a very small amount of inoculum into the field and let the agent build in population over time develop suppression in the soil. The benefit would be seen in future years.”
Improved soil structure due to cover crops and tillage or the lack thereof, higher organic matter and nutrient retention, and soil biota including disease and pest-suppressive organisms, are all pieces of the soil health and crop productivity puzzle. Hatfield suggests that, although more pieces are coming into view, there is still a long way to go before they all come together and farming systems are managed with this holistic approach.
“We really have not fully developed precision agriculture in a way in which we build a library of information about a field to help a producer evaluate the impact of his management system over a number of years,” says Hatfield. “We have lots of sources of data, but we still need to develop a methodology of making this data into information. Over the next few years, I envision an explosion in technology of how we can take this approach to the next level.”