Effects of 24 Years of Conservation Tillage Systems on Soil Organic Carbon and Soil Productivity

Table 4

Effect of different tillage treatments on corn and soybean yields during 1989–2012 at Dixon Springs.

Tillage	Crop yield (Mg ha^−1)
Corn year	1989	1991	1993	1995	1997	1999	2001
NT	8.99b*	6.57a	11.79a	11.60a	9.87a	8.12a	9.73b
CP	9.99b	6.10a	11.61a	11.55a	9.32a	6.78b	9.60b
MP	11.26a	6.60a	10.98a	10.37a	9.59a	6.98b	10.34a
Year	2003	2005	2007	2009	2011	12-yr ave.	% of MP yield
NT	6.67a	11.40a	6.46a	13.10a	6.13a	9.18a	96
CP	7.33a	11.82a	6.80a	13.60a	6.85b	9.24a	97
MP	7.82a	11.41a	7.33a	14.03b	7.68ab	9.53a	100
Soybean year	1990	1992	1994	1996	1998	2000	2002
NT	2.37a	3.74a	2.87a	2.63a	2.63a	2.32a	2.37a
CP	2.62a	3.46a	1.81b	2.27a	2.63a	2.38a	2.07a
MP	2.62a	3.65a	1.49b	2.43a	2.75a	2.32a	1.98b
Year	2004	2006	2008	2010	2012	12-yr ave.	% of NT yield
NT	0a	3.17ab	2.84a	2.94a	2.65a	2.54a	100
CP	0a	3.37a	2.84a	2.79a	1.96b	2.35a	93
MP	0a	3.10b	3.04a	2.88a	1.82b	2.34a	92

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