Yellow field peas (Pisum sativum L.) recently gained popularity across Nebraska due to their rotational benefits and increase in consumers' demand for plant-based alternatives to meat and dairy products. Protein isolate manufacturers have a special interest in grain with high protein content as it reduces the amount of raw material being processed and increases the efficiency of the protein isolation process (Figure 1).
The objective of this project was to identify the impact that location, variety selection, irrigation, tillage and fertility programs have on yellow field pea protein content in Nebraska (Figure 2).
Figure 1. 2017 USA Pulse Growing Regions by County (left); Field peas grain processing chart from plant to grain to protein, starch and fiber isolates (right).
Figure 2. Field experiments including irrigated field pea variety evaluation (left), tillage (center) and fertility programs (right) were conducted during 2019 growing season at Grant, NE
2019 grain protein studies
Four field experiments were conducted at Henry J. Stumpf International Wheat Center near Grant, NE to evaluate yellow field pea grain yield (t/ha) and protein content (%; Near-Infrared (NIR) Spectroscopy - method):
Variety evaluation of 20 yellow field pea varieties at 3 sites:
Grant, NE dryland – non-replicated strips
Grant, NE irrigated – 4 reps
Mead, NE dryland – 4 reps
Irrigated study at Grant, NE had 3 treatments using field pea variety Durwood (Pulse USA):
Dryland (11.9 inch of rainfall)
Deficit Irrigation (11.9 inch of rainfall + 2.2 inch irrigation)
Full Irrigation (11.9 inch of rainfall + 4.4 inch irrigation)
Tillage study at Grant, NE had 2 treatments using field pea variety Durwood (Pulse USA):
Tillage (conventional - disk)
No-till
Fertility study at Grant, NE had 10 treatments including combinations of seed and in-furrow applied rhizobia inoculants and foliar products (Table 2). Salamanca (Valesco Genetics) field pea variety was used in the study.
Key findings from each study
AAC Profit had the highest grain protein content (28.1%) across three sites (Table 1). AAC Profit was also the highest yielding variety among 20 other yellow field pea varieties evaluated.
Tillage had no impact on yellow field pea protein or yield (Figure 3).
Irrigation had no impact on yellow field pea protein. Deficit irrigation increased field pea yield by 4.5 bu/ac compared to dryland treatment, while no yield increase was observed with full irrigation (Figure 3).
Fertility treatments caused no significant change in grain protein content (P-value 0.098). Grain yield ranged from 25 to 48 bu/ac depending on the treatment (Table 2). Rhizobia inoculant product selection and mixing were critical in achieving high nodulation scores and high yields (Table 2). Foliar products had a positive impact on yield when applied at reproductive stages (R1-R4).
Figure 3. Effect of tillage and irrigation on field pea (cv. ‘Durwood’) yield (bu/ac) and grain protein (%) during 2019 growing season at Grant, NE
Table 1 - Grant, NE - Dryland
Variety
Company
Grant, NE - Dryland
Yield (bu/ha)
Protein (%)
Protein rank
AAC Profit
Valesco Genetics
52.1
28.9
1
LG Amigo
Pulse USA
40.6
28.1
2
CDC Spectrum
Meridian Seed
41.6
26.9
4
Salamanca
Valesco Genetics
42.2
26.4
7
CDC Inca
Meridian Seed
53.2
26.6
5
Spider
Valesco Genetics
40.5
26.4
8
Durwood
Pulse USA
35
26.3
9
CDC Saffron
Meridian Seed
48.5
25.2
14
AC Agassiz
Meridian Seed
39.1
27.6
3
Jetset
Meridian Seed
37.8
25.8
11
CDC Amarilo
Meridian Seed
33.1
25.3
13
Polancos
Montana Integrity
36.9
26
10
SW Midas
Pulse USA
38.6
24.6
20
Bridger
Valesco Genetics
39.9
25.2
15
Montech 4152
Arrow Seed
35.4
26.5
6
AC Earlystar
Valesco Genetics
43.2
24.7
18
Montech 4195
Arrow Seed
34.2
25.3
12
Nette 2010
Pulse USA
42.9
24.9
17
LG Sunrice
Pulse USA
36.1
24.7
19
AAC Carver
Meridian Seed
34
25
16
Average of all Varieties
40.8
26.1
P-value
Difference required at 5% level
Table 1 - Grant, NE - Irrigated
Variety
Company
Grant, NE - Irrigated
Yield (bu/ha)
Protein (%)
Protein rank
AAC Profit
Valesco Genetics
72.5
26.8
1
LG Amigo
Pulse USA
69.3
26.4
2
CDC Spectrum
Meridian Seed
70.9
26
8
Salamanca
Valesco Genetics
65.4
26
9
CDC Inca
Meridian Seed
70
25.4
12
Spider
Valesco Genetics
68.2
26.1
4
Durwood
Pulse USA
71.7
26.4
3
CDC Saffron
Meridian Seed
75.4
26
7
AC Agassiz
Meridian Seed
64.3
25.4
11
Jetset
Meridian Seed
78.5
26.1
6
CDC Amarilo
Meridian Seed
68.7
25.3
13
Polancos
Montana Integrity
71.1
25.5
10
SW Midas
Pulse USA
65.5
26.1
5
Bridger
Valesco Genetics
70
25.3
14
Montech 4152
Arrow Seed
68
24.8
15
AC Earlystar
Valesco Genetics
65.8
24.4
18
Montech 4195
Arrow Seed
70.3
24.4
17
Nette 2010
Pulse USA
84.2
24.8
16
LG Sunrice
Pulse USA
70.5
24.4
19
AAC Carver
Meridian Seed
73.5
24.1
20
Average of all Varieties
70.5
25.6
P-value
0.005
<.0001
Difference required at 5% level
8
0.7
Table 1 - Mead, NE - Dryland
Variety
Company
Mead, NE - Dryland
Yield (bu/ha)
Protein (%)
Protein rank
AAC Profit
Valesco Genetics
80.3
28.5
1
LG Amigo
Pulse USA
72.4
26.7
7
CDC Spectrum
Meridian Seed
68.5
27.7
3
Salamanca
Valesco Genetics
76.4
27.8
2
CDC Inca
Meridian Seed
68.5
27.2
4
Spider
Valesco Genetics
69.5
26.6
8
Durwood
Pulse USA
71.5
25.9
12
CDC Saffron
Meridian Seed
71.5
26.9
5
AC Agassiz
Meridian Seed
73.4
24.6
16
Jetset
Meridian Seed
74.4
25.2
14
CDC Amarilo
Meridian Seed
72.4
26.2
9
Polancos
Montana Integrity
76.4
25.2
13
SW Midas
Pulse USA
75.4
25.9
11
Bridger
Valesco Genetics
68.5
26.1
10
Montech 4152
Arrow Seed
65.6
25.1
15
AC Earlystar
Valesco Genetics
76.4
26.8
6
Montech 4195
Arrow Seed
76.4
24.3
18
Nette 2010
Pulse USA
76.4
24
20
LG Sunrice
Pulse USA
63.6
24.5
17
AAC Carver
Meridian Seed
75.4
24.1
19
Average of all Varieties
73
26.2
P-value
0.0024
<.0001
Difference required at 5% level
8
0.8
Table 1 - Average across sites
Variety
Company
Average across sites
Yield (bu/ha)
Yield rank
Protein (%)
Protein rank
AAC Profit
Valesco Genetics
68.3
1
28.1
1
LG Amigo
Pulse USA
60.8
10
27.1
2
CDC Spectrum
Meridian Seed
60.3
11
26.9
3
Salamanca
Valesco Genetics
61.3
8
26.7
4
CDC Inca
Meridian Seed
63.9
4
26.4
5
Spider
Valesco Genetics
59.4
15
26.4
6
Durwood
Pulse USA
59.4
16
26.2
7
CDC Saffron
Meridian Seed
65.1
3
26
8
AC Agassiz
Meridian Seed
58.9
17
25.9
9
Jetset
Meridian Seed
63.6
5
25.7
10
CDC Amarilo
Meridian Seed
58.1
18
25.6
11
Polancos
Montana Integrity
61.5
7
25.6
12
SW Midas
Pulse USA
59.8
13
25.5
13
Bridger
Valesco Genetics
59.5
14
25.5
14
Montech 4152
Arrow Seed
56.4
20
25.5
15
AC Earlystar
Valesco Genetics
61.8
6
25.3
16
Montech 4195
Arrow Seed
60.3
12
24.7
17
Nette 2010
Pulse USA
67.8
2
24.5
18
LG Sunrice
Pulse USA
56.7
19
24.5
19
AAC Carver
Meridian Seed
61
9
24.4
20
Average of all Varieties
61.4
26
P-value
Difference required at 5% level
Conclusions
There was no evidence that a higher grain yield of yellow field peas causes a reduction in grain protein content (Figure 4).
Variety selection is the most important factor influencing grain protein content of yellow field peas; AAC Profit consistently provided high protein content and high yields.
Farmers should make every effort to follow the best irrigation, tillage, and fertility practices to increase grain yield and profitability.
Figure 4. Yellow peas yield (bu/ac) vs grain protein (%) relationship in 2019 yellow field pea experiments.
Table 2
Table 2. Effect of 10 different fertility treatments field pea (cv. ‘Salamanca’) yield (bu/ac), grain protein (%) and nodulation score as affected by different fertility treatments during 2019 growing season at Grant, NE.