Effect of Irrigation and Preplant Nitrogen Fertilizer Source on Maize in the Southern Great Plains

Table 1

Preplant surface (0–15 cm) chemical characteristics and soil classification of sites utilized in this study.

Location^a	Year	Soil mapping unit	Major component soil; taxonomic classification	pH^b	NH4-N^c	NO3-N^c	SO4-S^d	P^e	K^e	Total N^f	Organic C^f
					mg kg^−1					g kg^−1
STW	2012	Easpur loam, 0 to 1 percent slopes, occasionally flooded	Easpur: fine-loamy, mixed, superactive, and thermic Fluventic Haplustolls	6.2	11	4	13	30	119	0.8	9.4
LCB	2012	Port-Oscar complex, 0 to 1 percent slopes, occasionally flooded	Port: fine-silty, mixed, superactive, and thermic Cumulic Haplustolls; Oscar: fine-silty, mixed, superactive, and thermic Typic Nastrustalfs	5.6	8	3	8	22	111	0.6	7.8
STW	2013	Norge loam, 3 to 5 percent slopes	Norge: fine-silty, mixed, active, and thermic Udic Paleustolls	5.0	16	11	15	87	117	1.2	10.5
LCB	2013	Port-Oscar complex, 0 to 1 percent slopes, occasionally flooded	Port: fine-silty, mixed, superactive, and thermic Cumulic Haplustolls; Oscar: fine-silty, mixed, superactive, and thermic Typic Nastrustalfs	6.1	6	5	8	24	139	1.1	9.5

STW: Oklahoma State University Agriculture Experiment Station near Stillwater, OK; LCB: Oklahoma State University Agriculture Experiment Station near Lake Carl Blackwell, OK.
^b1 : 1 water.
^c2 M KCl extract [20].
^dCalcium monophosphate extract [21].
^eMehlich III extract [22].
^fDry combustion [23].