Evaluation of Sensor-Based Nitrogen Rates and Sources in Wheat

Table 7

Effect of preplant N rate and topdress N source on spring wheat grain yield (GY) and grain protein content (GP) for 6 site-years in Montana.

Effects	Growing season 2011				Growing season 2012				Growing season 2013
	Conrad		Corvallis		Conrad		Corvallis		Conrad		Corvallis
	GY,; kg ha^−1	GP,; %	GY,; kg ha^−1	GP,; %	GY,; kg ha^−1	GP,; %	GY,; kg ha^−1	GP,; %	GY,; kg ha^−1	GP,; %	GY,; kg ha^−1	GP,; %
Preplant N rate
0	942	9.5	2018	14.0	5851	9.6	3901	11.0	4304	12.4	3430	14.3
22	1480	9.5	3026	15.0	6658	10.5	6994	13.0	4304	14.0	3699	17.3
44	1614	9.6	3430	13.0	6860	11.1	7129	14.0	4371	14.6	3699	16.6
67	1950	9.5	3632	15.0	6994	11.8	7532	14.0	4708	15.2	3699	17.1
90	2152	9.6	3766	15.0	7196	14.3	7263	14.0	4640	15.7	3699	17.2
220	2690	9.7	3699	16.0	6187	15.4	6456	15.0	4102	17.2	3968	17.4
test		ns				ns			ns		ns
Topdress N source
Urea	1749	9.6	3497	14.5	5716	11.5	5985	14.1	4439	15.2	3968	17.2
UAN	1816	9.5	3430	14.4	5582	11.6	6456	13.6	4573	14.6	3430	16.9
test	ns	ns	ns	ns	ns	ns			ns			ns

and denote significant at 0.05 and 0.01 levels, respectively; ns denotes not significant.