In-Crop Nitrogen Management Effects on Protein Content in Wheat | ARDI | Agri-Food Research & Development Initiative | Manitoba Agriculture, Food and Rural Initiatives

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PROJECT RESULTS

In-Crop Nitrogen Management Effects on Protein Content in Wheat

Applicant:

Dr. Cynthia A. Grant

Brandon Research Centre
Agriculture and Agri-Food Canada
Brandon, Manitoba R7A 5Y3 Canada

Table of Contents:

Background and Objectives
Procedure and Project Activities
Results and Discussion
Conclusions

ARDI Project:

#98-080

Total Approved:

$8,000

Date Approved:

May 27, 1998

Project Status:

Completed June, 2000

Background and Objectives:

High protein content is a desirable factor for bread wheat and customers are willing to pay a higher price for enhanced protein content, which is passed on to producers in the form of protein premiums. Over the last several years, premiums for high protein content in wheat have been considerable, while the base price for wheat has been relatively low. This has rekindled interest in using late applications of nitrogen fertilizer to increase the protein content of the wheat. Application of N fertilizer near the time of seeding tends to be more effective in increasing yield than later applications, while N applied from tillering to after anthesis will have a lesser effect on yield and a greater effect on grain protein content. Combining solution N in with a herbicide application could reduce the number of applications required, and so lower operation costs. However, little information was available on the effectiveness of available foliar N sources either blended with herbicides or applied as separate applications. This study was conducted to evaluate foliar applications of urea, urea ammonium nitrate and "Foliar Pride", a multinutrient blend, for their effects on leaf burn, crop yield, protein concentration, and weed control from herbicide applications, when applied as a tank-mix with a Horizon/broadleaf herbicide tank mix or applied in separate applications.

Procedure and Project Activities:

Field experiments were conducted in 1998 and 1999 to evaluate foliar applications of urea, urea ammonium nitrate and "Foliar Pride", for their effects on leaf burn, crop yield, protein concentration, and weed control from herbicide applications, when applied as a tank-mix with a Horizon/broadleaf herbicide tank mix or applied in separate applications. Studies were conducted under no-till on AC Barrie hard red spring wheat at two locations each year in western Manitoba, on a silty clay and fine sandy loam in 1998, and a fine sandy loam and clay loam soil in 1999. Soil samples were taken prior to seeding to determine background soil nutrient level. Phosphorus and potassium were applied as a side-band application to eliminate deficiencies and to ensure that amounts of P and K applied to each treatment were the same. Seeding rate was 100 kg ha-1. Seeding depth was 2.5 to 4.0 cm depending on soil moisture conditions. Plots were direct-seeded with a Seed-Hawk style plot seeder, equipped with hoe openers. Horizon tank-mixed with a broadleaf herbicide was applied at recommended rates for control of the weed spectrum present. The foliar nutrient applications were tank-mixed with the herbicide, except in treatments 6, 7 and 8 where they were applied separately. Applications were made at the 4-6 leaf stage. There were 8 treatments with 4 replications on 2 sites for a total of 64 plots. Design was a randomized complete plot. Data were collected on air and soil temperature, soil moisture, rainfall, leaf burn, herbicide efficacy, tissue N concentration at heading, crop yield, protein content and nitrogen accumulation in the grain.

Results and Discussion:

Application of N fertilizer generally increased both yield and protein content of AC Barrie wheat. However, the increase was as great when all N was applied at the time of seeding as when a 15 kg N ha^-1 portion was delayed and applied as a foliar application at the 4-6 leaf stage (Tables 1 and 2). Source of N did not affect the protein content of AC Barrie wheat, with UAN, urea and Foliar Pride performing equally well. Blending the fertilizer with an application of Horizon/broadleaf tank-mix did not generally influence protein response or decrease herbicide efficacy.

Table 1. Effect of fertility management on dry matter yield at heading, straw yield and grain yield on two soil types (1998).

	Silty clay					Fine Sandy Loam
Treatment	Dry Weight	Straw	Grain	Protein	Dockage	Dry Weight	Straw	Grain	Protein	Dockage
Control	6626	3500	2400	15.7	185	6263	5670	2929	15.5	74
65 kg N at seeding	7642	4870	2547	16.0	207	6665	6940	3142	15.8	89
Foliar UAN	6883	4275	2367	16.1	183	6498	6295	2776	16.2	93
Foliar urea	7995	4745	2751	15.8	209	5774	6775	2725	16.2	87
Foliar Pride	7791	5000	2715	16.1	210	6249	6265	2549	16.3	95
Foliar UAN (Separate)	8119	4715	2486	16.1	206	6801	6640	2853	15.8	102
Foliar urea (Separate)	7772	4805	2845	16.2	215	7194	6625	2749	16.0	104
Foliar Pride(Separate)	8477	4025	2467	15.9	200	7140	7260	3038	15.9	111
Contrast
Control vs rest	ns	0.0103	ns	0.0268	ns	ns	0.0044	ns	0.0647	0.0330
N at seeding vs rest	ns	ns	ns	ns	ns	ns	ns	0.0892	ns	ns
UAN vs Foliar Pride	ns	ns	ns	ns	ns	ns	ns	ns	ns	ns
Urea vs Foliar Pride	ns	ns	ns	ns	ns	ns	ns	ns	ns	ns
UAN vs Urea	ns	ns	0.0271	ns	ns	ns	ns	ns	ns	ns
Blended vs separate	ns	ns	ns	ns	ns	0.0321	ns	ns	ns	0.0843
Blended vs separate UAN	ns	ns	ns	ns	ns	ns	ns	ns	ns	ns
Blended vs separate urea	ns	ns	ns	0.0989	ns	0.0425	ns	ns	ns	ns
Blended vs separate FP	ns	ns	ns	ns	ns	ns	0.0278	0.0787	ns	ns
SE	712.0	371.5	156.2	0.147	15.6	464.6	297.5	187.4	0.230	9.451

Foliar applications of N tended to produce some leaf damage, but crop tolerance was generally good and there was little evidence of damage by 21 days after application. Foliar Pride tended to be more damaging than urea or UAN in 1998, but in 1999, urea was more damaging than the other two sources. Where differences occurred between tank-mixed and separate application, damage was lower when N solution was applied separately from the herbicide. By 21 days after treatment, there was generally little evidence of damage remaining. Use of N tended to improve weed control, although it sometimes increased dockage, possibly due to an increase in small kernels.

Table 2. Effect of fertility management on dry matter yield at heading (kg/ha), straw yield (lg/ha) and grain yield (kg/ha) on two soil types (1999).

	Clay Loam					Fine Sandy Loam
Treatment	Dry Weight	Straw	Grain	Protein	Dockage	Dry Weight	Straw	Grain	Protein	Dockage
Control	1712	3073	1230	13.4	302	1540	915	828	13.4	142
65 kg N at seeding	4062	5090	2522	13.8	350	2322	2760	1406	15.6	460
Foliar UAN	3651	4845	2539	13.6	337	.	.	.	.	.
Foliar urea	3368	4915	2199	13.5	338	2525	2115	1907	15.5	232
Foliar Pride	3436	4580	2390	13.5	311	2343	2275	1688	15.0	342
Foliar UAN (Separate)	3432	4895	2063	13.4	379	.	.	.	.	.
Foliar urea (Separate)	3401	5110	2053	13.4	407	2632	1925	1630	15.5	232
Foliar Pride(Separate)	3584	4960	2136	13.4	409	2862	2235	2073	15.3	178
Contrast
Control vs rest	0.0001	0.0001	0.0001	ns	ns	0.0001	0.0001	0.0001	0.0001	0.0100
N at seeding vs rest	0.0155	ns	0.0705	ns	ns	ns	0.0156	0.0073	0.0494	0.0007
UAN vs Foliar Pride	ns	ns	ns	ns	ns	.	.	.	.	.
Urea vs Foliar Pride	ns	ns	ns	ns	ns	ns	ns	ns	0.0056	ns
UAN vs Urea	ns	ns	ns	ns	ns	.	.	.	.	.
Blended vs separate	ns	ns	0.0203	ns	0.0060	0.0775	ns	ns	ns	0.0909
Blended vs separate UAN	ns	ns	0.0278	ns	ns		ns	.	.	.
Blended vs separate urea	ns	ns	ns	ns	0.0938	ns	ns	ns	ns	ns
Blended vs separate FP	ns	ns	ns	ns	0.0218	0.0420	ns	0.0394	ns	0.0215
CV	204.0	215.0	141.8	0.200	27.9	164.0	204.2	120.5	0.097	45.4

Conclusions:

High protein content is a desirable factor for bread wheat and customers are willing to pay a higher price for enhanced protein content, which is passed on to producers in the form of protein premiums. Application of N fertilizer is used to increase both grain yield and protein content. Nitrogen may be applied prior to seeding, at seeding or as in-crop applications. Foliar applications are often proposed as a way of increasing protein more effectively than application of N prior to or at the time of seeding. This study provides information on the relative benefit of using three sources of solution N, either alone or tank-mixed with a herbicide, for a portion of the N application as compared to applying all of the N at the time of seeding.

Grain yield was higher with N fertilization than in its absence. While yield was not generally increased with foliar N, there appeared to be no serious negative impact of foliar N applications on crop yield parameters, leaf damage or herbicide efficacy.

Protein content was increased by N application, even when protein content was over 15.0%, but there was generally no additional benefit from applying a portion of the N in-crop as compared to at time of seeding. The exception was on the clay loam soil in 1999 when weather conditions were extremely wet, seeding was late and conversion of biomass to grain was restricted. There was little difference among the various sources of N in their effects on protein content. Foliar damage occurred about ½ of the time and was greater in 1999 with urea solution tank-mixed with the herbicide than the other sources, although in 1998 damage was greatest with Foliar Pride. Where differences occurred between tank-mixed and separate application, damage was lower when N solution was applied separately from the herbicide. By 21 days after treatment, there was generally little evidence of damage remaining. Use of N tended to improve weed control, although it sometimes increased dockage, possibly due to an increase in small kernels.

Based on the results of this study, producers have several effective options for increasing protein content of the grain. Application of extra N at time of seeding is likely the simplest approach, as there is no requirement for a later in-crop operation. Under some conditions, this may lead to increased dockage and reduction in grain yield as compared to later applications, but the frequency of occurrence of these negative effects is likely to be low. Where early application of extra N is not desirable, or when changes in growing season conditions increase yield potential and risk of N deficiency, in-crop applications of any of the N sources evaluated can be effective. All three of the N sources studied could be applied with a Horizon/broadleaf tank-mix without reducing herbicide efficacy, however, leaf damage was increased when the N and herbicide were blended in some cases.

Acknowledgements:

This project was made possible through funding from the governments of Manitoba and Canada through the Canada-Manitoba Agri-Food Research and Development Initiative (ARDI) and by a contribution from Agrium US, Inc.

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