Finding a solution for Southeast growers

Furrow diking is nothing new. It was practiced by growers as early as 1915, when the first patent was issued for furrow diking equipment.

PHOTOS BY TOMMY BENNETT (USDA-ARS).
A furrow-diked field of corn holding water.

However, this tillage system of creating little basins and dams to hold rain or irrigation water throughout a crop field has been the subject of intense research in the past decade for two important reasons: increased irrigation costs and the competition for dwindling water resources between agriculture and populated urban areas.

While the practice of creating ridge-like barriers to hold water and allow it to soak into nearby crop rows makes perfect sense for arid areas of the country (such as in the western United States), what about other areas that get plenty of rainfall, but experience dry spells or have sloped fields prone to water runoff or pooling?

Two scientists with the USDA ARS—Russell Nuti, research agronomist, and Clint Truman, soil scientist—aimed to find that out in their research at the ARS National Peanut Research Laboratory in Dawson, Ga. The goal was to find out if furrow diking would work in the Southeast, where water runoff for peanut, cotton and corn crops is an ongoing issue.

“In the Southeast, we do get plenty of rain to produce plenty of crops, but there are sporadic periods [of rain and drought],” said Nuti. “We wanted to see if we could capture that water and get more use out of it.”

What they found is that furrow diking is well worth the effort and produces a return on investment in the form of reduced irrigation costs.

The benefits of furrow diking

During a moderate drought, the practice saved growers an inch of irrigation water per acre. It also significantly reduced runoff and helped stop soil erosion. In the next year the study was done—a year with more severe drought conditions—the practice saved 5 inches of irrigation water.

The study was done on peanut, cotton and cornfields that were furrow diked and compared to the same crops that were grown in traditionally tilled soil.

Similar studies have been, and are still being, conducted in areas throughout the Southeast, including fields in Georgia, Mississippi, North Carolina, Alabama and Louisiana, with comparable results.

A comparison of furrow diking next to conventional tillage.

“In areas that get plenty of rainfall, furrow diking helps take better advantage [of the water] and reduces soil erosion,” says Nuti.

While Nuti would not speculate on how furrow diking would work on other crops and in other areas of the country because the research has not yet been done in those areas, he did say that growers with sloped fields would most likely get the most benefit.

“Any field that has any slope at all will have runoff in any rainfall event, or any place that has any drought period will see a benefit,” says Nuti.

Even growers who use irrigation to supplement rainfall will see a benefit, he says. “If you get enough rainfall, but not at the right time optimal for crop growth, furrow diking will help,” he says.

Of the two soil types—clay and sandy—the most runoff happens in clay soil. “So we speculate that [growers] with clay soils would get better benefits of the dikes than those in sandy soils,” says Nuti.

In drought-ridden areas, Nuti says, growers can irrigate directly into the dikes and reduce potential evaporation.

A good return on investment

The money you save on irrigation will pay for the money spent on labor and equipment costs of furrow diking, says Nuti.

Just one significant rainfall of 1 inch will give the grower an ROI. “A series of rainfalls, particularly if it causes a grower to irrigate just one less time, will pay for the [entire diking equipment and labor],” says Nuti.

According to the study, based on a rate of $12 per acre-inch to pump irrigation water and $7.50 per acre for furrow diking, “ … producers would recover 60 percent of their diking cost by saving the first acre-inch of water and 100 percent of their diking cost by saving 1.25 acre-inches of water. Water and financial savings do not include the environmental benefits of reduced natural resource consumption, runoff, soil erosion and associated contaminates,” the researchers write.

How furrow diking works

Furrow diking is a simple tillage technique used between crop rows using paddles that can be attached to existing cultivating equipment. The furrow diking paddles make a series of ridges, or little dams, that hold water in the depression. The little pools of water slow the runoff to allow it greater time to infiltrate.

Growers know that in uneven, sloped areas, the high spots will show drought first. So with these small dikes in place, a grower will not only see an even water distribution in high areas, but less ponding at the bottom of a field.

The furrow diking paddles cost about $300 each. The type of cultivator a grower owns will determine how many paddles would be necessary to dike a field. For example, if cultivator equipment is for four rows, a grower will need three paddles.

Furrow-diked seedling corn the morning after rainfall.

The researchers used two-row equipment, with one furrow diking paddle in the middle. “You just don’t want to dike in rows where you’ll be running vehicles [such as harvesting or spraying equipment] through,” says Nuti, which will make it difficult for vehicles to maneuver because of the depressions created by the furrow diking equipment.

The furrow dikes will last one season; growers practicing no-till can also use furrow diking since the paddles will not disturb the area where the crops are planted. “You’ll get the most benefit out of freshly diked [fields] each year,” says Nuti.

Tips for successful furrow diking

Furrow diking is a simple process once the paddles are installed behind the cultivating equipment, but Nuti has some tips for successfully creating these little pools of irrigation water on your fields:

  1. Move faster for harder soils, slower for loose soils.
  2. Nuti suggests experimenting with tractor speed to get a large depression. “Sometimes going faster does a better job than going too slow,” he says. Moving too slowly in fields where soil is heavily compacted, the paddles won’t dig into the ground as well as when the tractor is moving faster. For loose soil, try going slightly slower in order to create high piles to make an effective dam. The size and appearance of the dikes will depend on soil type, condition and moisture at the time you dike.

  3. Furrow dike as soon as you can after planting or before planting so you don’t disturb the crop.
  4. Apply soil-applied herbicides after furrow diking so herbicides are not disturbed.

Effective technique, but not widely used—yet

While furrow diking is a simple technique that gives a good return on investment after just one significant rainfall, it is not widely used by growers, but that may change.

Freshly furrow-diked peanuts.

“Furrow diking has caught on, but not as much as we’d like to see at this point,” says Nuti. “If you look at the population increase and the increased demand of fresh water supplies, it only makes sense that you make every bit of water use as efficient as possible.”

The technique has become accepted by the NRCS (Natural Resource Conservation Service) as an accepted practice for water use reduction. In Mississippi, it has become approved for cost share in the state’s EQIP (Environmental Quality Incentives Program), a federal program administered at the state level by the USDA (www.nrcs.usda.gov/PROGRAMS/EQIP/).

The furrow diking EQIP, currently only available in Mississippi, gives incentives to growers on a per acre basis to furrow dike. For example, if it cost $8 per acre (for labor and fuel costs) to furrow dike, the program reimburses growers for half that.

“If Mississippi is successful with this program and it gets good results [to reduce water consumption], it will give a head start to other states,” says Nuti.

For more information:

American Farmland Trust: www.farmland.org

U.S. Department of Agriculture, Natural Resources Conservation Service: www.nrcs.usda.gov

U.S. Department of Agriculture, Economic Research Service: www.ers.usda.gov

The author is a freelance writer from Keene, N.H.