Impact of Accelerated Erosion on Soil Properties and Productivity of Grantsburg Soils in Southern Illinois Under Different Tillage Systems

by K. R. Olson and S. A. Ebelhar

• Introduction
• Procedures
• Results
• Summary
• Table 1
• Table 2
• Table 3
• Table 4

Introduction:

Tillage accelerates the erosion of sloping lands and decreases soil productivity. The conservation reserve program (CRP) was designed to reduce erosion and restore some productivity to previously eroded sites caused by tillage. This site was in a grass sod for greater than 10 years prior to the initiation of this study and would very closely mimic a CRP field in southern Illinois.

Objective:

To evaluate long-term tillage methods for the maintenance and/or restoration of soil productivity of previously eroded Grantsburg soil after greater than 10 years in a grass sod.

Procedures:

In 1989, a 10-year conservation tillage system project was initiated at the Dixon Springs Agricultural Center. A corn-soybean rotation with three tillage treatments (no-till, chisel plow (conservation tillage), and moldboard plow) was established on a backslope with an average slope of 6%. A randomized block design with six replications is being used to measure significant differences. A grid soil survey was made to determine the variability in soil properties and erosion phases. Representative pedons of the Grantsburg soils were described, sampled, and analyzed with depth.

Results:

Surface crop residue levels were significantly higher in the NT system compared to CP and MP systems, which provided better protection against water erosion. The annual estimated soil loss during the eight-year period from 1989-1996 was 3.9, 7.3, and 13.5 tons/acre in NT, CP and MP systems, respectively.

During the 1989 to 1997 growing seasons, the NT system had higher plant height, slightly more plant available water, and reduced soil temperature at 25 days after planting. Although plant population (Table 1) was higher in MP system during most years, crop yields (Table 2) were higher in NT system as compared to MP system due to more plant available water and less erosion. Plant population in the NT system was affected by the lower soil temperature and poor weed control during early growing seasons. In the first year, crop yield was higher in the MP system as compared to CP and NT systems; however, the NT system produced equal or higher crop yields during the last eight years. Tillage treatment did not affected 5-year average yield and plant population of corn. Five-year average soybean plant population (Table 3) was not affected by tillage; however, the 5-year average soybean yield (Table 4) was significantly (P = 0.05) higher in the NT system as compared to other tillage treatments. Corn yields in all tillage systems were equal as a result of the significantly higher MP system yield in the first year which offset higher CP and NT systems yields during the last three years. Soybean yield was 13 percent higher in the NT system in comparison with the CP and MP systems. Higher NT soybean yields could be due to a higher amount of residue from previous years corn, which improved the water conservation and reduces soil erosion. Crop yields were higher in NT system despite lower plant population, so greater water and nutrient availability per plant compensated for the effect of lower plant population.

Summary:

• The NT system performed better than CP and MP in dry years by conserving moisture and the NT yield improved over time.
• Based on 10-years of crop yield measurements (five years corn and five years soybean), the NT system appears to result in improved long-term productivity compared to MP and CP systems by reducing soil erosion.

Table 1. Corn population under different tillage systems at Dixon Springs, 1989-1997.

^† Values in the same year followed by the same letter are not significantly different at the 0.05 probability level.

Table 2. Corn yield under different tillage systems at Dixon Springs, 1989-1997.

^† Values in the same year followed by the same letter are not significantly different at the 0.05 probability level.

Table 3. Soybean population under different tillage systems at Dixon Springs, 1990-1998.

^† Values in the same year followed by the same letter are not significantly different at the 0.05 probability level.

Table 4. Soybean yield under different tillage systems at Dixon Springs, 1990-1998.

^† Values in the same year followed by the same letter are not significantly different at the 0.05 probability level.