| Total | Conservation tillage | ||||||
| area | Intensive | Reduced | No- | Ridge- | Mulch- | ||
| Year | planted | tillage | tillage | till | till | till | Total |
| million acres | |||||||
| 1989 | 279.6 | 137.3 | 70.7 | 14.1 | 2.7 | 54.7 | 71.7 |
| 1990 | 280.9 | 136.7 | 71.0 | 16.9 | 3.0 | 53.3 | 73.2 |
| 1991 | 281.2 | 129.8 | 72.3 | 20.6 | 3.2 | 55.3 | 79.1 |
| 1992 | 282.9 | 120.8 | 73.4 | 28.1 | 3.4 | 57.3 | 88.7 |
| 1993 | 278.1 | 107.9 | 73.2 | 34.8 | 3.5 | 58.9 | 97.1 |
| 1994 | 283.9 | 111.4 | 73.2 | 39.0 | 3.6 | 56.8 | 99.3 |
| 1995 | 278.7 | 109.7 | 70.1 | 40.9 | 3.4 | 54.6 | 98.9 |
| 1996 | 290.2 | 111.6 | 74.8 | 42.9 | 3.4 | 57.5 | 103.8 |
| 1997 | 294.6 | 107.6 | 77.3 | 46.0 | 3.7 | 60.0 | 109.8 |
| 1998 | 293.4 | 106.1 | 78.1 | 47.8 | 3.5 | 57.9 | 109.2 |
| 1999 | nd | nd | nd | nd | nd | nd | nd |
| 2000 | 297.5 | 127.1 | 61.3 | 52.2 | 3.3 | 53.6 | 109.1 |
| percent of planted acres | |||||||
| 1989 | 100 | 49.1 | 25.3 | 5.1 | 1.0 | 19.6 | 25.6 |
| 1990 | 100 | 48.7 | 25.3 | 6.0 | 1.1 | 19.0 | 26.1 |
| 1991 | 100 | 46.1 | 25.7 | 7.3 | 1.1 | 19.7 | 28.1 |
| 1992 | 100 | 42.7 | 25.9 | 9.9 | 1.2 | 20.2 | 31.4 |
| 1993 | 100 | 38.8 | 26.3 | 12.5 | 1.2 | 21.2 | 34.9 |
| 1994 | 100 | 39.3 | 25.8 | 13.7 | 1.3 | 20.0 | 35.0 |
| 1995 | 100 | 39.3 | 25.2 | 14.7 | 1.2 | 19.6 | 35.5 |
| 1996 | 100 | 38.4 | 25.8 | 14.8 | 1.2 | 19.8 | 35.8 |
| 1997 | 100 | 36.5 | 26.2 | 15.6 | 1.3 | 20.4 | 37.3 |
| 1998 | 100 | 36.2 | 26.2 | 16.3 | 1.2 | 19.7 | 37.2 |
| 1999 | na | na | na | na | na | na | na |
| 2000 | 100 | 42.7 | 20.6 | 17.6 | 1.1 | 18.0 | 36.7 |
Source: Conservation Technology Information Center, National Crop Residue Management Survey Annual Report (CTIC, West Lafayette, IN, annual through 1998 and biennial thereafter).
Notes: nd = no data. No survey was conducted in 1999. na = not applicable. Intensive (or conventional) tillage leaves less than 15 percent residue after planting. Reduced tillage leaves 15-30 percent residue after planting. Conservation tillage leaves over 30 percent residue after planting. Conservation tillage includes no till (the soil is left undisturbed prior to planting, except for nutrient injection, and planting or drilling is accomplished in a narrow seedbed or slot created by coulters, row openers, disk openers, inrow chisels, or rototillers), ridge till (the soil is left undisturbed prior to planting, except for nutrient injection, and planting is completed in a seedbed prepared on ridges with sweeps, disk openers, coulters, or row cleaners; residue is left on the surface between ridges), and mulch till (the surface is disturbed before planting but 30 percent or more residue remains after planting).
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