Testing Locally: Site-Specific Testing Is Key to Success

eKonomics News Team

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A fertilizer strategy is only as good as the data used to guide it — which is why recent site-specific testing should take priority for growers. This was the main message at this year’s 4R Summit.

It is pretty clear that no two farms are the same, and no one management strategy is a “one-size-fits-all.” Therefore, farmers are being challenged to determine the Best Management Practices (BMPs) for their specific farms. To achieve this, The Fertilizer Institute (TFI) has developed a program in which nutrient stewardship is defined using the 4R approach.

4R Summit and the 4R Principles

People from all levels of the agriculture industry are invited to attend the yearly 4R Summit, which TFI held June 12-13 last year. Conservation organizations, such as The Nature Conservancy, the Conservation Technology Information Center and the National Association of Conservation Districts, also participated.

The 4R Nutrient Stewardship concept provides the framework to achieve cropping system goals, whether they are to increase production, increase profitability or enhance environmental protection and improve sustainability.

To achieve these goals, the 4R concept incorporates the Right Fertilizer Source at the Right Rate, at the Right Time and in the Right Place.

The 4R Nutrient Stewardship program encourages farmers to implement the BMPs that optimize the efficiency of fertilizer use on their farm. This concept of BMP is what makes the 4Rs site-specific because no one farm is exactly the same.

According to TFI, while the 4Rs are the same globally, how they are used depends on local characteristics, such as climate, cropping systems, management techniques and soil conditions.

The science-based principles are explained as:

  • Right Source: Ensure a balanced supply of essential nutrients, considering both naturally available sources and the characteristics of specific products, in plant-available forms.
  • Right Rate: Assess and make decisions based on soil nutrient supply and plant demand.
  • Right Time: Assess and make decisions based on the dynamics of crop uptake, soil supply, nutrient loss risks and field operation logistics.
  • Right Place: Address root-soil dynamics and nutrient movement, and manage spatial variability within the field to meet site-specific crop needs and to limit potential losses from the field.

Benefits, Implementation and Sustainability

The 4R practices are based on measurements of nutrient inputs against outputs, collecting the data and analyzing it on more farms throughout North America. Best practices include GPS mapping of fields, grid or zone soil sampling, yield monitors, variable rate applications and split nutrient applications.

Steps to implement the 4Rs include preparing growers and local crop consultants in several ways:

  • Monitor field conditions.
  • Select the best source of fertilizer to use in each field.
  • Vary application by placing fertilizer close to the roots, injecting it into the soil or placing it with seed.
  • Note how many times the rate of fertilization can be split and how many times farmers fertilize during the growing season.

Farmers and crop consultants need up-to-date data to correlate 4R practices with harvest results. A range of tests and technologies are available:

  • Nutrient sources
  • Enhanced efficiency product selections
  • Soil tests and yield monitors
  • Tissue and stalk samples
  • Electrical conductivity probes
  • Soil penetrometer readings
  • Tile-line monitors

Additionally, multi-year research is underway with in-field studies in five states; and another study is being conducted at eight locations in six states to update and localize information upon which nutrient management practices are based. The need for long-term research was highlighted during the 4R Summit. The fertilizer industry provided $7 million in funding (in which TFI coordinates the research efforts), and a number of government and nonprofit agencies contributed another $4 million to initiate or continue the studies over three or five years.

“This research will identify gaps and figure out what else we should be doing to provide good science to policymakers and decision-makers on the farm,” says Dr. Sally Flis (Director of Agronomy with TFI).

Farmers can implement 4R practices on their own, but they should consult extension agents, state specialists, conservationists and retail agronomists about their practices and the results. Additionally, these people should also be consulted to plant nutrient management strategies.

Don’t rely on a consultant who offers only one recommendation, Flis says. Instead, expect the expert to offer multiple nutrient management options. Nutrient management recommendations should consider the farm’s technical capabilities and business goals.

“It can be really hard for a producer to adopt a 4R practice across their entire farm. Taking the time to try one, so the farmer can see how it performs before recommending it across a large landscape, can be an effective way to get new practices incorporated,” Flis says.

A Shift in Nutrient Management Decisions

“We need to shift people from passively making nutrient decisions to very actively making nutrient decisions,” says Flis.

As part of that shift, it is recommended that every three to four years, growers begin or expand monitoring of nutrient levels in both the soil and the crops. This will allow them to make informed decisions about not only how much fertilizer to invest in, but also when and how to apply nutrients to maximize yields and profitability in sustainable ways.

Flis says, the “right” thing is going to be different depending on each farm’s unique in-field conditions, the crop, and crop management system. “The 4Rs are really a site-specific suite of management practices that can be tailored by a grower and a consultant to meet their production goals,” she says.

This “test locally” methodology can also help growers avoid the pitfalls of using existing federal and state data out of context.

“A challenge for the industry is that many nutrient management practices are based on research historically conducted on row crops in the Midwest,” Flis says. “What’s known about nutrient management for corn and soybeans in Iowa, for example, should not be applied to farms in southern Florida growing fruits and vegetables. There are too many local variables to be considered.”