Chris Lawrence, Virginia Cooperative Extension Agent-King & Queen/King William Counties
Greg Evanylo, Virginia Tech Associate Professor and Extension Specialist-Waste Management
Evaporated Vegetable Solubles (EVS), a by-product of soybean processing generated by Divers Processing Co., Inc. of Portsmouth, Virginia, has been registered as a beneficial soil amendment with the Virginia Department of Agriculture and Consumer Services following positive results in laboratory and greenhouse tests conducted by Virginia Tech researchers. The EVS is a viscous liquid largely promoted as a phosphorus nutrient source. The material used in the study described below had a guaranteed analysis shown in Table 1.
Table 1: Guaranteed Analysis of EVS (wet or as-delivered basis)
|N||P2O5||K2O||Sodium (Na)||Sulfur (S)||Moisture|
The application rate of the material is limited by its sodium (Na) content. High concentrations of sodium restrict water flow in soils in the arid western U.S. These problems are almost never seen in Virginia because rain leaches sodium through our soils before it can build up to problem levels. Due to the high sodium content of the EVS product, the label carries the following two restrictions:
The goal for this study was to demonstrate the effects of increasing application rates (up to the label limit of one dry ton per acre) of EVS on crop performance and soil properties. The objectives were to determine the effects of EVS rates on:
Table 2: Material and Nutrients Applied in EVS Treatments
|gallons||dry tons||-------------------- pounds --------------------|
The study was conducted on the farm of John R. and David Carlton. The EVS treatments were applied shortly before corn planting (between March 29 and April 4, 200). Soil was sampled from each treated strip to a depth of 2" and 6" on May 2 (1 month after application). Another set of soil samples were taken on October 9 (6 months after application). We did not independently analyze the actual EVS material applied to the soil. All information on nutrient and Na content was provided by the manufacturer.
Hybrid: Longest L15.
Planting date: April 5, 2000.
Tillage: No till except for subsoiling (3rd year no till).
Population: 22,000/A in 30" rows.
Herbicides: 1.8 qt. Bicep, 1 pt. Atrazine, 1 pt. Simazine.
Insecticides:Kernal Guard seed treatment at planting.
Previous crop: Small grain/doublecrop soybeans.
Broadcast: 0 - 0 - 120 EVS treatments
Starter: 10 gal/A of 15 - 15 - 0
In herbicide: 75N
Harvest date: September 9, 2000
Table 3: Grain Corn Yields
|Treatment||Replication||Moisture at harvest (%)||Yield
(bu/acre at 15.5%)
Figure 1: Soil Sodium (Na) Saturation Percentage, Soil Samples Taken in May and October to 6"
Figure 2: Soil Test Phosphorus (P) Levels, Soil Samples Taken in May and October to 6" Depth (Analyzed by VA Tech Soil Testing Lab).
Increasing the rate of the EVS produced no significant differences in corn yield (Table 3). Corn yields were apparently not limited by the combination of background soil test phosphorus (P) concentrations, which were M+ or less prior to application of the EVS, plus the starter P fertilizer.
Figure 1 demonstrates that increasing the amount of EVS applied increased soil Na saturation percentage. One month after spreading EVS, Na saturation percentage was above the label limit of 5% on the 3X strips. Sodium saturation declined to equal (and low) levels in all treatments five months later. These results confirm that the buildup of Na in our soils is unlikely, even when EVS is applied at maximum rates. Six months of summer rains were sufficient to wash the excess Na through the soil profile. Note that the summer of 2000 was usually wet. Prolonged drought might have produced different effects.
Figure 2 demonstrates that increasing EVS rates increased soil test P levels. Soil test P levels were slightly lower in October than in May. This decrease in soil test P with time was probably a result of the combined effects of plant uptake and soil P immobilzation that often occurs following the application of fertilizer phosphorus. Nevertheless, increasing EVS rates resulted in increasing long-term buildup of soil test P to a depth of 6 inches.
Other soil test results:
Although EVS does contain some K2O, increasing EVS rates did not produce an increase in soil potassium (K) levels (soil test K values not shown here). The higher rates of Na may have prevented significant binding of the supplied K by the cation exchange sites in the soil. The concentration of K may possibly have been significantly increased in the clayey subsoil horizon of this soil, where it may be available for deep rooting crops such as soybean, corn, and small grains.
The EVS did not affect soil pH, whose values were equal in all treatment strips both one and six months after EVS application.
There may be significant potential for farmers to save money on P fertilizer by using this EVS material; however the manufacturer reports that supplies limited at this time.
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