Research Article
Effects of 24 Years of Conservation Tillage Systems on Soil Organic Carbon and Soil Productivity
Table 3
Effect of different tillage treatments on the corn and soybean populations during 1989–2012 at Dixon Springs.
| Plant population (1000 plants ha−1) |
| Corn year | 1989 | 1991 | 1993 | 1995 | 1997 | 1999 | | NT | 55.3b* | 57.9a | 51.4a | 58.8ab | 46.9a | 69.2a | | CP | 59.2ab | 47.4b | 54.1a | 55.7b | 51.9a | 64.2ab | | MP | 62.9a | 52.2ab | 52.6a | 62.2a | 51.9a | 62.7b | |
| Year | 2001 | 2003 | 2005 | 2007 | 2009 | 2011 | 12-year average | NT | 64.5a | 59.5a | 70.5b | 68.8a | 65.0a | 75.7a | 59.4a | CP | 56.5b | 61.3a | 76.0a | 68.5a | 65.5a | 67.7ab | 58.6a | MP | 65.9a | 60.0a | 69.5b | 68.3a | 64.0a | 61.3b | 60.2a |
| Soybean year | 1990 | 1992 | 1994 | 1996 | 1998 | 2000 | | NT | 191.0b* | 344.0a | 303.0a | 263.0b | 271.0b | 422.0a | | CP | 247.0a | 335.0a | 229.0b | 277.0b | 273.0b | 398.0a | | MP | 249.0a | 343.0a | 181.0c | 309.0a | 294.0a | 405.0a | |
| Year | 2002 | 2004 | 2006 | 2008 | 2010 | 2012 | 12-year average | NT | 293.0b | 240.0a | 320.0a | 310.0b | 294.0a | 168.5a | 284.4a | CP | 393.0a | 228.0a | 363.0b | 390.0a | 279.0a | 125.6b | 296.5a | MP | 420.0a | 255.0a | 388.0c | 360.0ab | 288.0a | 176.0a | 297.8a |
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*For each crop means in a same year followed by the same letter is not significantly different at the probability level.
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