2021 Winter Wheat Nitrogen Management -NWARC

Objective

Objective: To evaluate the performance of the split-application of nitrogen in a rainfed winter wheat production environment in northwestern Montana

Personnel

Summary

The off-station winter wheat nitrogen (N) trial was planted under no-till rainfed ground with row-spacing 12-in apart on Sept. 22, 2020. See Table 1 for detailed management information.

The nitrogen rates applied were: 1) 0 as control, 2) 40, 3) 80, 4) 80 but were split-applied, 5) 120, and 6) 120 but were split-applied lbs N/A. Urea was used as an N fertilizer source. The soil had a 52 lbs/A residual nitrate and 10 lbs N drilled with the seeds at planting.

Grain yield linearly increased from no N application until 80 lbs/A, then plateaued afterward. No significant yield differences were recorded between 80 lbs/A and 120 lbs/A N applications in either N-applied in early spring or split (early spring + heading) treatments. The grain protein increased up to the split 80 lbs/A N application (Figure 2). The spring-applied 80 lbs/A N had an inferior grain protein in relation with the split 80 lbs/A N application (40 lbs in spring & 40 lbs at heading). Increasing N application to 120 lbs/A (split or not) did not show a significant protein increase compared to the split 80 lbs/A N application. The plant height, test weights, and the falling number increased at 80 lbs/N and plateaued after that (data not presented).

In the spring, this nursery received 9.7 inches of rain.

Table 1. Field Management Information
Seeding date: 9/22/2020 Field Location: R13
Julian date: 266 Harvest date: 8/12/2021
Seeding rate: 130 lbs/A Julian date: 224
Previous crop: Barley Soil type: Creston Silt Loam
Herbicide: 5/6: CleansweepM Tillage: No-till
Variety FourZeroSix
Insecticide: None Soil residual nutrient
(NO3-, P, K lb/A): 52-28-604
Fungicide: 6/11: Headline Nutrient fertilizer applied 10-50-10 (&5 S) - drilled
( N, P2O5, K20 lb/A): N applied varied, see N treatment
grain yield response to added nitrogen
Figure 1. Yield response to nitrogen (N) application rates and timing (split-applied at heading). The first application was in early spring. The split (second) application is indicated by a ‘+’ sign and H (at Heading). The application rate treatments specified did not include the residual N (52 lbs/A) and the amount drilled with the seeds (10 lbs/A). The same letter assignment indicates nonsignificance at α= 0.05.
grain protein response to added nitrogen
Figure 2. Grain protein response to nitrogen (N) application rates and timing (split-applied at heading). The first application was in early spring. The split (second) application is indicated by a ‘+’ sign and H (at Heading). The application rate treatments specified did not include the residual N (52 lbs/A) and the amount drilled with the seeds (10 lbs/A). The same letter assignment indicates nonsignificance at α= 0.05.