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

Table 5

Simple effects of two-way interactions of source by at-seeding and topdress N rates for wheat grin protein from selected site-years where interaction effect was significant at least at .

Site-year	⁢At-seeding N rate, kg ha^−1	Source
		Blend	ESN	Urea
	%
Conrad-2012	56	11.1	11.1	11.2
	112	12.1	12.6	13.3
	168	12.9	13.7	14.3
	Prob > (trend)	0.012^‡	0.021^‡	0.011^‡
Kalispell-2012	112	14.4	14.3	13.0
	224	13.7	14.2	13.9
	336	14.5	14.8	14.5
	Prob > (trend)	0.023	0.047	0.009^‡
	Topdress N, kg ha^−1
Conrad-2012	0	11.6	12.2	12.4
	45	12.4	12.8	13.5
Corvallis-2011	0	14.7	14.6	14.8
	45	15.9	15.8	15.4
Corvallis-2012	0	13.2	12.6	13.2
	45	12.5	12.8	13.7
Corvallis-2013	0	17.2	17.1	16.4
	45	16.4	17.1	17
Kalispell-2012	0	14.6	14.8	13.8
	45	13.8	14.1	13.8

Across rows for each site-year, at-seeding N rate, or topdress N rate, LS means followed by different uppercase letters are significant at .
  &   represent significant linear and quadratic trends, for at-seeding N rate for each source.
Down a column for topdress N rates, LS means followed by different lowercase letters are significant at for each source.