Environmentally Smart Nitrogen Performance in Northern Great Plains’ Spring Wheat Production Systems

Table 3

(a) Simple effects of two-way interactions of source by at-seeding and topdress N rates for grain yield in selected site-years where interaction effect was significant at least at . (b) Simple effects of three-way interactions of source and at-seeding and topdress N rates on grain yield in selected site-years where interaction effect was significant at least at .

(a)

Site-year	At-seeding N rate, kg ha^−1	Blend	ESN	Urea
	kg ha^−1
Conrad-2013	56	4536	4578	4855
	112	4695	4570	4452
	168	4838	4200	4234
	Prob > (trend)	0.156	0.754	0.019^‡
Kalispell-2011	112	3656	4013	3785
	224	3878	3875	3603
	336	3749	3905	3342
	Prob > (trend)	0.745	0.689	0.05^‡
	Topdress N rate, kg ha^−1
Conrad-2011	0	2445	2255	2470
	45	2668	2943	2613
Conrad-2013	0	4648	4379	4743
	45	4732	4519	4284

Across rows for each site-year and at-seeding N rate, LS means followed by different letters are significant at .
^‡Significant linear trend for at-seeding N rate for each source.
Down a column for topdress N rates, LS means followed by different letters are significant at for each source.

(b)

At-seeding–topdress N rate, kg ha^−1	Blend	ESN	Urea	Blend	ESN	Urea
	Conrad-2011			Conrad-2013
56–0	2523	1812	2027	4385	4301	4755
56–45	2202	2268	2298	4688
112–0	2008	2480		4620	4486	4805
112–45	2454	2886	2885	4771	4654	4099
168/0	2804	2474	2450		4351	4670
168–45			2656	4738	4049	3797
	Kalispell-2011
112–0	3478	3808	3681
112–45	3833
224–0	3842	3755	3583
224–45		3994	3624
336–0	3625	3901	3431
336–45	3872	3910	3253

Down a column for each source, at-seeding–topdress N rate LS means followed by different lowercase letters are significant at .
^†Across rows for each site-year, at-seeding–topdress N rate combination, source LS means followed by different uppercase letters are significant at .