Winter Annual Weed Response to Nitrogen Sources and Application Timings prior to a Burndown Corn Herbicide

Table 4

Winter annual weed number in the spring following N application timings. Data were averaged over application timings.

Nitrogen sources	2006	2007	2008	2009	2010	Average
	Weed number m^−2
32% urea ammonium nitrate	153	7	28	161	208	106
Ammonium nitrate	284	28	60	184	182	147
Anhydrous ammonia	123	1	95	89	171	95
Polymer-coated urea	204	14	74	142	201	125
Nontreated control	212	28	101	52	215	123
Urea + NBPT (N-(n-butyl) thiophosphoric triamide)	215	3	79	222	183	137
Urea	218	6	93	130	165	122
LSD ()	77	15	46	NS	NS	26