Spring Crop Choice Influence on Winter Wheat

Ray Olson
with Paul Peterson and Lawrence Brown, Spokane Co. Extension;
Baird Miller and Ron McClellan, WSU

Objective

Compare yields, N carryover, and economics of canola, lentil and barley, and determine their influence on winter wheat yields and profitability of the rotation.

• Location: Mt. Hope (Rockford), WA
• Annual precipitation: 17 inches
• Soil series: Larkin silt loam
• Rotation:
  • 95 - spring rotation crops
  • 94 - winter wheat
  • 93 - spring rotation crops
  • 92 - winter wheat
  • 91 - lentil

Treatments

Spring rotation crops: canola, lentil, spring wheat, barley, oats; all except lentil received 250 lb/ac 25-10-0-7 fertilizer broadcast and incorporated prior to seeding.

Comments

This is the third year of the study and the first year of the second crop rotation, so we are reporting current year yields (Tables 1 and 2) and economic return for all crops (Table 3) along with a comparison of residue production for the three cereals (Table 4); canola and lentil residue were not measured. Yield results are reported separately for canola/lentil/barley from spring wheat/oats for statistical purposes - although the various plots were located in the same area, they were not intermingled and randomized. An auxiliary experiment was conducted on oats that received no fertilizer application for 1 and 2 years respectively. Soil samples were taken (Table 5) to 15 inches to help determine N requirements for the winter wheat rotation.

Yield data was taken from a 12 ft. by 650 ft. swath for canola and lentil and 18 ft. by 650 ft. swath for cereals. Soil samples were taken for purposes of N application to the following winter wheat plots. Although erosion data would be valuable, the plot layout was not deemed suitable for meaningful measurement.

Insights that the cooperator is particularly interested in gaining from this trial include economics, visible erosion, residues and humus, weed control, fertilizer requirement, and volunteer carryover.

Data

 

Yield of canola, lentil and barley, (lb/ac)

Treatment	Rep 1	Rep 2	Rep 3	Rep 4	Average
Canola	1151	1273	1196	950	1143a
Lentil	782	815	1263	1117	994a
Sp. barley	3194	3425	3299	2970	3222b
LSD (5%)					331 lb
CV					10.7%

Yield of spring wheat vs. oats, (lb/ac)

Treatment	Rep 1	Rep 2	Rep 3	Average
Sp. wheat	3843	2799	2970	2870a
Oats	2993	3134	3336	354b
LSD (10%)				154#
CV				2.74%

Gross return of spring rotation crops, $/ac

Crop	Ave. Yield	Price	Gross return
Sp. wheat	47.5 bu/ac	$4.47	$212.25
Lentil	994 lb/ac	$.18	$178.92
Barley	1.61 T/ac	$109	$174.29
Oats	1.53 T/ac	$95	$145.31
Canola	1143 lb/ac	$.12	$137.16

Residue production of spring cereals, (lb/ac)

Treatment	Rep 1	Rep 2	Rep 3	Average
Barley	3043	2801	2379	2741a
Sp. wheat	3422	2862	3499	3261ab
Oats	3895	3182	4020	3699b
LSD (10%)				600#
CV				10.7%

Soil N to approximately 15 inches deep following spring crops, (lb/ac)

Crop	Nitrate N	Amm. N	Org. N Release	Total N
Canola	32	15	60	107
Lentil	42	9	51	102
Barley	42	20	57	119
Oats (0 fert 1yr)	16	11	48	75
Oats (0 fert 2yr)	16	10	45	71

Conclusions

Order of yield (highest to lowest) of the cereals was barley (3222 lb/ac), oats (3154 lb/ac) and spring wheat (2870 lb/ac). In the auxiliary test, oats, unfertilized for one year yielded 3022 lb/ac and unfertilized for 2 years yielded 2925 lb/ac. All told, oat yields were a pleasant surprise. However, the order of gross return of the cereals was wheat, barley, oats, because of the respective market prices. Canola, while outyielding lentils, was at a similar disadvantage, price-wise, although weed control and residue production are concerns in lentils. Oat residue was higher than spring wheat and significantly higher than barley. The trial site was seeded to winter wheat and will be harvested in 1996 for an additional year of data.