Extension Ag Update
January/February 2002
Articles Research Resources Internet Links Ag Facts Education

Research Results

C-FAR Project: Processed & Unprocessed Manures Effect on Crop Yield, Soil & Ground

Paul M. Walker, College of Applied Sci. and Tech., Illinois State University and Walton Kelly, Ground-Water Geochemist, Illinois State Water Survey

Regulations regarding field application of liquid swine manure are becoming more stringent. EPA proposed total maximum daily loads (TMDL) in surface water (rivers, etc.) could limit the application of swine manure. Procedures which decrease manures nutrient (element) content must be identified and evaluated. The effect of applying manure and inorganic fertilizer on subsurface water must be qualified and quantified. This multi-year project is designed to compare the use of raw, unprocessed liquid swine manure, effluent collected from a solid-liquid separator and traditional inorganic fertilizer as soil amendments for corn and soybean production, and to evaluate their effects on subsurface water quality. The objectives are to: 1) compare plant growth and grain production, 2) evaluate potential for pathogen transfer from manure to grain, and 3) monitor subsurface chemical and bacterial water quality beneath treated plot replicates.

Outcomes and Impact

The agronomic results are based on data collected from three growing seasons. Compared to ground water, the unprocessed swine slurry and separated effluent had elevated levels of many constituents, especially NH4-N, phosphate, BOD, Al and Zn. The concentrations of potentially harmful constituents were clearly lower in the effluent than in the slurry. In addition, the concentrations of key fractionates were substantially reduced in the effluent for year four compared to years 1, 2 and 3.

The effluent applied during year four was separated using a continuous gravity belt thickener in combination with a polyacrylamide polymer derived flocculant compared to a static gravity screen-rolled press separator without polymer in years 1, 2 and 3. Mean concentrations of coliform were higher in slurry than in separated-aerated effluent. Microbial concentrations of total and fecal coliforms, and E. coli were not detected in soybean and corn grain samples. Nitrate concentrations were significantly elevated in the soil water beneath the inorganic fertilizer plot and slightly elevated beneath the effluent and slurry plots. It also appears that C1- concentrations were elevated in groundwater beneath the effluent and manure plots. Other constituents that were elevated in the slurry and effluent (NH4-N, HCO3-, PO43-, B, F-, K, Na, Al, Cr, Cu, Fe, Zn, NVOC, BOD) were not found in anomalous concentrations in the subsurface water beneath these plots.

Previous manure applications on the control plot made comparisons difficult. It appears that the soil water and groundwater were impacted by these applications, with very high concentrations of NO3-N and C1-, although not the other constituents listed above. During this four-year project when no treatment was performed on this plot, the concentrations of NO3-N and C1- tended to decrease with time. Although groundwater quality was not significantly impacted by the slurry and effluent amendments in this study, the fact that NO3-N and C1- concentrations were elevated in the wells impacted by previous long-term manure applications indicates the potential for groundwater quality degradation. However, NO3-N and C1- were the only two contaminants found in the groundwater; the metals and other elevated constituents found in the slurry (and effluent) did not appreciably migrate through the soil and were thus not good indicators of manure contamination of groundwater at this site.

For soybean, seed yield was similar for the four treatments. Since soybean can acquire nitrogen from the atmosphere, this result was expected. For corn, grain yield of plants supplied with effluent, inorganic nitrogen fertilizer, or unprocessed slurry tended to be greater than the control. For corn plants that received an application of nitrogen (effluent, inorganic nitrogen fertilizer, or unprocessed slurry), no significant differences in grain yield were observed. Data needs to be collected over a number of years to assess seasonal variation and long-term effects of application to agricultural soils. Data collected thus far suggest that effluent and slurry can serve as satisfactory nitrogen replacements for inorganic nitrogen fertilizer.

C-FAR Project: Corn Hybrid & Drying Temperature Effects on End Use Quality

Kevin Baker, College of Applied Sci. and Tech., Illinois State University
S.R. Eckhoff and M.R. Paulsen; Agricultural Engineering Dept., University of Illinois

The objectives of this project were: to use a laboratory-scale dryer to dry corn samples at four drying temperatures and evaluate hybrids by drying temperature differences in wet milling yield; and to improve estimates of added value for processing of specialty corn hybrids, including waxy, high-starch, and hard endosperm hybrids.

Outcomes and Impact

Fifteen commercial hybrids including three waxy varieties were used in this study. They were grown on the Agricultural Engineering Farm at the University of Illinois. They were harvested at three harvest moistures of about 30, 25, and 14 percent wet basis. The two higher moisture samples were dried at temperatures of 50, 70, 85 and 100°C, using a convection drier at ISU Bloomington to a target moisture of about 14 percent wet basis.

Samples harvested at 14 percent were not dried further. Stress cracks in the samples were measured as an index of the effect of drying severity. The dried samples were scanned with an Infratec 1229, that uses near infrared transmittance. Extractable starch yields were predicted using an equation with an R2 of 0.81, and SECV of 1.33. The starch was studied for the effects of high drying temperature on elatinization using a differential scanning calorimeter (DSC 2920), an electron microscope, and with water activity measurements.

The results indicated that the two harvest moistures were significantly different, with the 25 percent harvest moisture having higher starch yields, than the 30 percent corn. Corn dried at temperatures of 50 and 70 o C had significantly higher starch yields than those dried at 85 and 100°C.

Sprays, Trap Promise to Slash Insecticide Use in America's Corn Belt

Don Comis, (301) 504-1625, comis@ars.usda.gov, Source: ARS News Service, USDA

While Agricultural Research Service scientists are not about to satisfy a plant pest's craving for pumpkin by serving pie, they are only too happy to serve a family recipe to die for. The ingredients of that recipe, including cucurbitacins and other chemicals from the pumpkin and gourd or cucurbit family, attract corn rootworm beetles. One of these ingredients is in three new, low-insecticide bait sprays and a monitoring trap for the beetles.

These commercial products have emerged from a 6-year joint ARS- university research and demonstration program in the Corn Belt. The bait sprays are CideTrak, made by Trece, Inc. Salinas, Calif.; Invite, made by FFP Agriscience, Inc., of Eustis, Fla.; and SLAM, made by MicroFlo, of Memphis, Tenn. The trap is the Pherocon Corn Rootworm Trap, made by Trece.

The trap lures beetles with volatile plant chemicals. It enables farmers or consultants to make sample counts of the beetles to decide when the numbers are high enough to warrant spraying with CideTrak, Invite, or SLAM. The baits are sprayed aerially on corn leaves where the beetles eat. The sprays form drops containing cucurbitacins and insecticide. The cucurbitacins cause the beetles to feed almost exclusively on the drops, so they ingest a lethal dose of insecticide. CideTrak and SLAM get their cucurbitacins from wild buffalo gourd root powder, while Invite relies on a Hawkesbury watermelon juice ingredient.

The actual active insecticidal ingredient in the three sprays is an ounce or less per acre, which is 95 to 98 percent less than in conventional sprays. The bitter cucurbitacin doesn't appeal to other insects, so it is safe for bees and other beneficial insects. The musky smell released when a cantaloupe is sliced comes primarily from cucurbitacin.

Relay Intercropping of Soybeans and Wheat

Jim Beuerlein, Agronomist, Ohio State University, (614) 292-9080, beuerlein.1@osu.edu and Tony Vyn, Agronomist, Ohio State University, (765) 496-3757, tvyn@purdue.edu

Ohio and Indiana farmers who practice relay intercropping of soybeans and wheat can choose from an array of wheat varieties that perform well in wider-row spacing, saving on equipment and seed costs. Wheat row spacing normally is 7.5 inches wide, said Jim Beuerlein, Ohio State University agronomist. But in studies conducted by Beuerlein and Purdue University agronomist Tony Vyn, certain wheat varieties performed just as well when row spacing was widened to 15 inches.

About two dozen wheat varieties were analyzed for their performance in Ohio and Indiana. The purpose of making the rows wider than normal is for the machinery to get through, so you can get more light coming down into the canopy to help the soybeans grow," Beuerlein said. Beuerlein and Vyn grew wheat varieties in both 7.5- and 15-inch row spacings, and compared yield, test weight and a variety of agronomic characteristics such as height and heading date. Beuerlein found that varieties that perform well in wide rows tend to be either tall by nature or grow tall because of favorable weather; and exhibit a nonerect growth habit that compensates for skips in the row or low population.

The research showed that wheat normally grown in 15-inch rows produces 5 percent to 15 percent less yield than wheat grown in 7.5-inch rows, but the lower yield from wide rows is partially offset by reduced seed costs, Beuerlein said. "When growing wheat in 15-inch rows, a farmer only has to use half as much seed per acre," Beuerlein said. "So, for example, if a 7.5-inch row has a two-bushel seeding rate, the farmer has saved one bushel at $12 a bushel for seed. He may lose four bushels of grain in yield, but at a grain cost of $3 per bushel he can still make the same profit. One bushel of seed has the same value as four bushels of grain."Seeding rates are significantly lower in 15-inch rows, Vyn said. He added that plants in the wider rows appear to be somewhat shorter than wheat in narrower rows.

"We observed that it is important to keep seeding rates at 850,000 seeds per acre in 15-inch rows," Vyn said. "That's much less than the traditional seeding rate in 7.5-inch rows of 1.3 million to 1.5 million seeds an acre. "We also found that wide-row wheat is less likely to lodge even with high nitrogen fertilizer rates." Wider-row spacing saves on equipment costs, because fewer seed meter units are necessary on the drill, Beuerlein said. "Farmers are looking for anything that will reduce production costs," Beuerlein said.

The relay intercropping process usually involves planting wheat in October, then interplanting soybeans the following year in late May or early June. Even earlier soybean planting dates are possible with polymer-coated seeds that delay soybean emergence. The OSU-Purdue data indicates both crops in an intercropping system perform well. "In many ways we are not sacrificing wheat yields in order to gain the potential of 30-bushel-an-acre relay soybean yields in areas that are traditionally not suited for double-crop beans," Vyn said.

Source: Candace Pollock, Associate Editor, OARDC Research Services, Ohio Agricultural Research, and Development Center, The Ohio State University, 1680 Madison Ave., Wooster, OH 44691, (330) 202-3550, pollock.58@osu.edu