Field Pea Production: Rotational Costs and Benefits

field pea comparison
Figure 1. Comparison of water use of two systems -- summer fallow and field peas -- between March 27 and July 20. (Photos by Stranhinja Stepanovic)

Field Pea Production: Rotational Costs and Benefits March 10, 2017

Grain-type field peas are a cool season grain crop (mid-March to late-July) typically grown as an alternative for no-till summer fallow in semiarid cereal-based cropping systems, such as wheat-corn-fallow or wheat-fallow. A two-year rotation study was conducted on a cooperator’s field in Chase County near Enders to compare the impact of field peas versus no-till summer fallow on the following parameters:

  1. Soil: nutrient cycling, microbial activity, and water infiltration
  2. Beneficial insects and microorganisms
  3. Water use (i.e., evapotranspiration)
  4. Yield of succeeding winter wheat crop
  5. Profitability

Soil Nutrient Cycling, Microbial Activity, and Water Infiltration

Table 1. Seasonal changes in soil nitrate (NO3), phosphorous (P), potassium (K), and microbial activity (Solvita test) for the field peas and fallow treatments in 2015 in Chase County.
Date*TreatmentDepthNO3-NPKSolvita
inchesppmlb/acppmppmCO2-C ppmlb of N/ac/year
Mar. 27, 2015 Baseline 0-8 8.5 20 23 389
0-8 8.1 19 26 365
Sep. 14, 2015 Field pea 0-4 16.5 20 69 515
5-8 11.1 13 33 451
Fallow 0-4 19.3 23 61 598
5-8 8.8 11 21 488
Oct. 16, 2015 Field pea 0-12 16.8 60 24 424 52.27 42
12-24 11.2 40 14 361
24-36 12.0 43 13 442
Fallow 0-12 26.4 95 90 431 27.72 22
12-24 9.7 35 9 340
24-36 13.0 47 9 519
Mar. 16, 2016 Field pea 0-12 2.6 9 37 514 71.63 57
12-24 1.5 5 9 344
24-36 2.9 10 2 452
Fallow 0-12 2.0 7 41 457 59.74 48
12-24 2.2 8 4 338
24-36 1.8 6 4 506
Aug. 30, 2016 Field pea 0-4 10.6 13 46 609 11.69 9
0-12 4.0 14 22 552 8.50 7
12-24 0.1 0 2 347
24-36 0.1 0 2 428
Fallow 0-4 7.4 9 70 623 14.00 11
0-12 4.0 14 37 479 14.00 11
12-24 1.3 5 11 323
24-36 1.1 4 2 449

Here are four key takeaways from our preliminary results on soil data:

  1. Concentrations of soil nutrients (N, P, and K) did not differ between areas growing field peas and fallow at any time during the two-year rotation study (Table 1).
  2. Solvita tests (soil microbial activity expressed as CO2-C release) conducted after wheat planting in the fall and in the spring had higher soil-microbial activity and annual nitrogen (N) release in areas of the field where field peas were grown. After wheat harvest, Solvita results did not differ between field peas and fallow treatment (Table 1).
  3. Rotational benefit from N fixed by field peas may already be scavenged by wheat or is likely to be seen in the next rotational crop (corn/sorghum); this is currently being investigated.  
  4. The initial soil water infiltration (Figure 1) was collected after wheat harvest by taking four subsamples in six replications. Time needed to infiltrate 0.4 inches (10 cm) of water until 50% of soil was exposed was 174 seconds for fallow treatment and 87 seconds for the field pea treatment, suggesting 50% faster soil infiltration rate with field peas in the rotation. 

Beneficial Microorganisms and Insects

Beneficial microbial analysis showed that more diverse species were recovered in the wheat plants following field peas as compared to following fallow (Table 2). Extraction of mycorrhiza spores showed an average count of 16.5 propagules in pea rhizosphere compared to average count of eight propagules from the fallow plots. There was no significant difference in terms of foliar disease levels between wheat samples following peas compared to wheat samples following fallow, although non-pathogenic Fusarium species were recovered from the root of samples from both treatments.

Planting field peas positively affected the diversity of microorganisms that could be beneficial for the subsequent wheat crop. The beneficial bacteria recovered from the wheat has the potential to stop or reduce the impact of field pea disease/pathogens.

In 2015, field peas supported greater numbers and diversity of insects than fallow (Table 3). In particular, there were a greater number of beneficial predators (wolf spiders, rove beetles, hoverflies), parasitoid wasps, and decomposers (dung beetles and carrion beetles), but also a greater number of potential pests (click beetles and leafhoppers). In 2016, aphids were lower and some natural enemies (crab spiders and parasitoid wasps) were higher in wheat following field peas (Table 3).

Table 2. Isolates recovered from wheat rhizosphere.
Wheat after fallowWheat after field pea
Bacillus megaterium Bacillus megaterium
(multiple strains) Bacillus pumilus
Lysinibacillus fusiformis
Table 3. Numbers of beneficial insects and potential pests in fallow and field pea treatments (letters signify significantly higher insect numbers at 0.05 significance level)
Insect GroupSpeciesFallowField Pea
— Pitfall Traps 2015 —
Predators Wolf Spiders 2.1a 4.8b
Flat Bark Beetles 1.7a 20.6b
Rove Beetles 6.3a 17.0b
Ants 1.1a 4.0b
Parasitoids Chalcid Wasps 0.7a 1.5b
Decomposers Dung Beetles 0.1a 2.6b
Carrion Beetles 1.9a 20.6b
Minute Brown Scavenger Beetles 53.2b 15.9a
Potential Pests Click Beetles (adult wireworms) 2.3a 8.6b
Sap Beetles 10.2a 110.2b
Leafhoppers 0.4a 10.4b
Bark Lice 31.7b 1.9a
— Sweep Nets 2015 —
Predators Crab Spiders 0.0a 1.4b
Long-jawed Orb Weaver Spiders 0.0a 0.8b
Hover Flies 0.0a 0.9b
Insect group Species Wheat after fallow Wheat after field pea
— Pitfall Traps 2016 —
Potential Pests Aphids 31.8b 1.6a
— Sweep Nets 2016 
Predators Crab Spiders 2.0a 3.1b
Parasitoid Wasps 1.3a 2.0b

 

Water Use and Crop Yield

Water use data indicated that field peas used 10.9 inches of water in 2015 to produce 36 bu/ac yield, which resulted in crop water productivity of 3.3 bushel per acre-inch (Table 4). Fallow used 6.0 inches of water without producing any grain (Table 4). Available soil water at wheat planting (top 4 ft) was 3.2 inches less after field peas as compared to fallow treatment, which resulted in a 18 bu/ac yield peanalty in wheat at the end of the season (Table 4). Seasonal soil water dynamics are summarized in Figure 2.  Note that the soil water level for wheat after field peas (green line) was below the 50% field capacity line for most of the growing season which likely led to the lower yield of 18 bu/ac as compared to the wheat after fallow treatment (Figure 2b).

 

Table 4. Grain yield, seasonal evapotranspiration (ET), and soil water status at the beginning and ending of the growing season for the field pea (3-foot soil profile) and wheat (4-foot soil profile) treatments; yields with different letters indicate significantly higher wheat yield.
PeriodTreatmentbeginning soil waterending soil waterETYield (bu/ac)
3-27-15 to 7-20-15 Field peas 6.0 6.0 10.9 36
Fallow 6.0 3.0 6.0  0
9-14-15 to 07-15-16 Wheat after field peas 5.8 3.5 TBD 74a
Wheat after fallow 8.0 4.3 TBD 92b
3-27-2015 field peas planted, 7-20-2015 field peas harvested, 9-14-2015 wheat planted, 7-15-16 wheat harvested
Chart of seasonal soil water
Figure 2a (left) and 2b. Seasonal dynamics in soil water availability for field peas in the top 3 feet of the soil profile and wheat in the top 4 feet of the soil profile. An estimate of field capacity (FC; blue line) and 50% of FC (red line; level of soil water at which most crops exhibit drought stress) are shown for the Blackwood loam soil.
pans measuring soil water infiltration
Figure 4. Measuring soil water infiltration in the field.

Profitability

 Table 5 shows a simplified simulation of the input costs for the field pea-wheat and fallow-wheat rotations. In this example with wheat at $3/bu and field peas at $7/bu, field pea-wheat had a $98/acre profitability advantage over fallow-wheat rotation (Table 6). Assuming no changes in the costs estimated in Table 5 or the price of peas at $7/bu, wheat prices would have to be a little greater than $8/bu to provide a profitability advantage of fallow over field pea (Table 6).

Conclusions

Field peas have potential to be used as an alternative to no-till summer fallow in wheat-fallow and wheat-corn-fallow rotations to increase sustainability of crop production systems in western Nebraska. Preliminary results of our rotation study show that replacing fallow with field peas can

  • increase soil microbial activity and soil water infiltration,
  • provide habitat for a greater number of beneficial microorganisms and insects,
  • provide more efficient cropping system water use, and
  • be more profitable than no-till summer fallow.

Weather conditions throughout the first year of the experiment favored growth and production of field peas. Therefore, more research is needed to evaluate rotational effects of field peas during dry years.

Table 5. Input costs ($/ac) for field pea-wheat and fallow-wheat rotations
InputProductRateField pea ($/ac)Fallow ($/ac)
Insurance Crop insurance $69.41/ac 7.22  —
Planting 11.23
Spraying 4.23
Seed Salmanca 3.3 bu/ac 45.00
Inoculant Cell-tech dry and liquid Labeled 12.00
Herbicide Sharpen 1.5  oz/ac 28.20
Pendimethalin 1.5  oz/ac
RT3 (Round-up) 22 oz/ac
Harvest 24.10
Spraying 4.23
Herbicide Honcho (Round-up) Labeled 14.92
Latigo (generic 2,4-D) Labeled
Spraying 4.23
Herbicide Honcho (Round-up) Labeled 14.92
Latigo (generic 2,4-D) Labeled
Spraying 4.23
Herbicide Honcho (Round-up) Labeled 14.92
Latigo (generic 2,4-D) Labeled
Spraying 4.23
Herbicide Honcho (Round-up) Labeled 14.92
Latigo (generic 2,4-D) Labeled
Insurance After fallow $138.31/ac 7.45
After field pea $89.71/ac 10.54
Fertilizer dry mix + application 30.50 30.50
Planting 11.23 11.23
Starter Fertilizer Fertilizer 10-34-0 + mix 3 gal/ac 23.00 23.00
Seed Winterhawk cert/treat 65 bu/ac 15.20 15.20
Fertilizer 10-20-0-0.5 10 gal/ac 35.91 35.91
Herbicide Affinity + Barrage 36.4 + 3.55 oz/ac
Harvest 24.10 24.10
Total costs  —  — 301.61 204.84

 

Table 6. Field pea-wheat profitability advantage over fallow-wheat rotation (shaded) for a given range of wheat and field pea market prices.
Field pea
($/bu)
45678910
Wheat
($/bu)
3 -10 26 62 98 134 170 206
4 -29 7 43 79 115 151 187
5 -48 -12 24 60 96 132 168
6 -67 -31 5 41 77 113 149
7 -86 -50 -14 22 58 94 130
8 -105 -69 -33 3 39 75 111
9 -124 -88 -52 -16 20 56 92
10 -143 -107 -71 -35 1 37 73