Illinois Fertilizer
Conference Proceedings
January 23-25, 1995
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Ted R. Peck1
This study is a three part program. We are in a transition of part two to part three. Part one was to map soil fertility conditions by intensive soil sampling and existing yield patterns. Part two was to spatially apply differential agricultural limestone or phosphorus and potassium rates to bring all areas of the field to non-limiting crop production levels. Part three will continue assessing crop yield while soil fertility levels are left residual.
Two fields are involved in the study. A 40-acre field in Piatt County near Mansfield has received differential agricultural limestone application in October of 1991. The phosphorus and potassium soil test levels are generally non-limiting to crop production and are residual of fertilization application since 1987. A 40-acre field in Champaign County near Thomasboro has received differential phosphorus and potassium application in October of 1992. It is believed this field has never received agricultural limestone. Soil pH ranges from small areas about 5.0 upwards to areas about 7.5. Due to weather and management problems, crop yields during the recent years were low and non-informative of soil fertility levels.
Corn yield for 1991 and soil pH, P and K results from samples collected in September, 1991 are shown in figures 1, 2, 3, and 4, respectively. Table 1 shows a data sort ranking the corn yield from low to high with corresponding location in field, soil pH, P and K test levels. Figures 5, 6, and 7 show a graphic plot of 1991 soil pH, P and K, with 1991 corn yield, respectively.
Soybean yield for 1992 and soil pH, P and K results from samples collected in September, 1992 are shown in figures 8, 9, 10, and 11, respectively. Table 2 shows a data sort ranking the soybean yield from low to high with corresponding location in field, soil pH, P and K test levels. Figures 12, 13, and 14 show a graphic plot of 1992 soil pH, P, and K, with 1992 soybean yield, respectively.
Corn yield for 1993 is shown in Figure 15. No field soil sampling as done in 1993. Table 3 shows a data sort ranking the 1993 corn yield from low to high with corresponding location in field, 1992 soil pH, P and K test levels. Figures 16, 17, 18 show a graphic plot of 1993 soil pH, P, and K with 1993 corn yield, respectively.
The statistics for yield and soil test (Figures
5, 6, 7,
12, 14,
16, 17,
and 18) do not show significant relationships.
Table 1: 1991 Corn Yield ranked from low to high
Table 2: 1992 Soybean Yield ranked from low to high
Table 3: 1993 Corn Yield ranked from low to high
Figure 1. 1991 Mansfield 40-acre Corn Yield
Figure 2. September 1991 Mansfield 40-acre soil pH Test Map
Figure 3. September 1991 Mansfield 40-acre soil P Map
Figure 4. September 1991 Mansfield 40-acre soil K Map
Figure 5. Relation of 1991 Corn Yield with pH
Figure 6. Relation of 1991 Corn Yield with P Test
Figure 7. Relation of 1991 Corn Yield with K Test
Figure 8. 1992 Mansfield 40-acre Soybean Yield Map
Figure 9. September 1992 Mansfield 40-acre soil pH Test Map
Figure 10. September 1992 Mansfield 40-acre soil P Map
Figure 11. September 1992 Mansfield 40-acre soil K Map
Figure 12. Relation of 1992 Soybean Yield with pH
Figure 13. Relation of 1992 Soybean Yield & P Test
Figure 14. Relation of 1992 Soybean Yield & K Test
Figure 15. 1993 Mansfield 40-acre Corn Yield
Figure 16. Relation of 1993 Corn Yield and 1992 pH
Figure 17. Relation of 1993 Corn Yield with P Test
Figure 18. Relation of 1993 Corn Yield with K Test
1Ted R. Peck is Professor of Soil Chemistry, Extension, University of Illinois, Department of Agronomy.
