2002 Agricultural Research Update

Table 2: Grain yields of non-wheat crops.
		2002		1996-2002 Avg
	Crop	Yield	Oil	Yield	Oil
		lb/a	%	lb/a	%

	Grain Lentil	911	--	984	--
	Field Pea	1243	--	1386	--
	Safflower	898	33.6	591	32.1

Applying insufficient N to continuous wheat reduced wheat yield this year and in four of the previous six years. Applying excessive N to wheat following green manure did not increase wheat yield this year or any of the eighteen cases (i.e., three legume species � six years) during the previous six years. The finding that insufficient N usually reduced yield and that excess N seldom increased yield supports the validity of fertilizer recommendations based on soil testing.

Table 3: HRSW performance in the WREC Annual Legume Study
	N	2002			1996-2002 Average
Previous Crop	Treatment	N	Yield	Protein	Yield	Protein
		lb/a	bu/a	%	bu/a	%

Wheat	Recommended	60	36.3	15.1	30.4	15.2
Wheat	Insufficient	0	19.1	11.9	21.6	12.3
Fallow	Recommended	60	37.2	17.0	36.9	15.7
Safflower	Recommended	30	32.6	16.1	27.4	16.1

Forage Lentil	Recommended	0	36.2	16.0	29.3	16.2
Green Manure [F.L.]	Recommended	0	34.9	17.1	36.7	15.7
Green Manure [F.L.]	Excessive	60	34.2	17.9	37.0	16.4

Grain Lentil	Recommended	0	32.3	16.1	29.1	16.4
Green Manure [G.L.]	Recommended	0	38.7	16.9	37.4	15.2
Green Manure [G.L.]	Excessive	60	37.9	17.8	37.1	16.4

Field Pea	Recommended	0	33.6	15.7	31.8	15.7
Green Manure [F.P.]	Recommended	0	33.7	16.8	36.6	15.6
Green Manure [F.P.]	Excessive	60	34.5	18.0	37.6	16.3

Average			33.9	16.3	33.0	15.6
LSD (5%)			6.6	0.6	--	--

Wheat protein content was generally greater (9 of 13 cases) this year than the corresponding 7-year average (Table 3). Protein content of the continuous wheat with insufficient N was lower than any other treatment.

Applying insufficient N to continuous wheat reduced wheat grain protein this year and in five of the six previous years. Applying excessive N to wheat following green manure increased wheat grain protein in all three cases (i.e., three legume species) this year as well as in nine of eighteen cases (i.e., three legume species � six years) during the previous six years. This suggests that although protein content is maximized at a greater N rate than is yield, applying more N than recommended inconsistently increases protein content and may not be economically beneficial.

This study is being continued to determine if the observed trends continue and if long-term benefits such as improvement in soil quality are obtained.