Illinois
Fertilizer Conference Proceedings
January 26-28, 1998
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W. L. Pedersen, S. A. Ebelhar, and K. L. Barber 1
Soil-borne diseases are responsible for yield losses in soybeans and wheat in Illinois every year. Previous research has demonstrated that the disease severity of take-all of wheat, common root rot of barley, and stalk rot of corn were reduced with the application of chloride fertilizers. In addition, several foliar diseases, e.g. powdery mildew and leaf rust of wheat have been shown to be suppressed by the application of chloride fertilizers. The objective of this study were to determine if chloride fertilizer affects plant disease, plant growth, and yield of soybeans and wheat at three locations in Illinois.
Three commercial soybean cultivars (Pioneer Brand 9392, 9394, and 9451) were planted at Urbana, Brownstown, and Dixon Springs on May 29th, May 15th, and June 12th respectively. Plots were 6-rows-wide, 7.5 inch spacing, and 28 feet long. The seeding rate was 200,000 seeds/acre and treatments were replicated 5 times. The experiment was arranged in a split plot, with the main plots as the fertilizer rates and the subplots the varieties. KCl, K2SO4, CaSO4 for the different salt comparisons, as well as, KCl for the rate study, were applied at planting (pre-emerge) or at growth stage (V2) by hand. Soil samples were obtained from each plot and analyzed for chloride (Cl), sulfur (S), and potassium (K). In addition, leaf petioles from each plot were also analyzed for the three nutrients. Severity of root diseases were visually rated and plant pathogens were isolated from representative soybean roots. Plots were mechanically harvested and grain weights were converted to yield (bu/a).
No significant differences were observed for either K, S, or Cl for the different fertilizers nor the different times of application (Figure 1). The level of all three nutrients was higher at Urbana than Dixon Springs, except Cl at Dixon Springs in the check treatment. The highest yield at Dixon Springs was obtained from the plots receiving KCl at V2 and the check plots receiving no additional fertilizer (Figure 2). However, there was no significant difference among the treatments and times of application for yield. There was a significant increase in infection by Rhizoctonia solani with the application of K2SO4 at Urbana (Figure 3), but disease severity at Brownstown and Dixon Springs were very low and not presented in this report. SDS was not observed in any plots in 1997.
There was a significant increase in potassium levels with all fertilizer applications at Dixon Springs, but not at Urbana (Figure 4). However, there was not a linear response of K to increasing rates of KCl. Levels of Cl were the highest from the check plots at Urbana and the check plots were significantly different from any of the treated plots No significant differences were observed among the check and the rates and times of application of KCl at Dixon Springs. Grain yields were significantly higher from all pre-emerge applications of KCl than the applications at V2 (Figure 5). However, the pre-emerge application was not significantly higher than the nontreated check plots. No differences in yields were observed at Urbana or Brownstown. There was a significant increase in Rhizoctonia solani with the application of KCl at the highest rate on Pioneer 9451 at Urbana (Figure 6). The lowest disease level for Pioneer 9451 was observed with the lowest rate of KCl applied pre-emerge.
The application of chloride fertilizers to soybeans in 1997 had little effect on disease or yield. However, at the three locations, little disease was observed. There was a significant increase in Rhizoctonia root rot with Pioneer 9451 with the application of KCL at growth stage V2, but not at any other variety, rate, or timing.
Wheat plots were planted at Urbana, Brownstown, and Dixon Springs in October and pre-emerge fertilizers and rates were applied. The second application will be done in March. Stands at all three locations are excellent.
Greenhouse studies on soybeans and wheat, as described in the proposal, are being conducted this winter.
Figure 2. Effect of form and application time of fertilizer on yield of soybeans.
Figure 5. Effect of rate and application time of chloride fertilizer on yield of soybeans
1W.L. Pedersen is an Associate Professor, Dept. of Crop Sciences, University of Illinois; S.A. Ebelhar is an Agronomist, Dixon Springs Agricultural Center, University of Illinois; K.L. Barber is a Senior Research Specialist, Brownstown Agronomy Research Center, University of Illinois.
