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

*For each crop means in a same year followed by the same letter is not significantly different at the 𝑃=0.05 probability level.