December 2018 FINAL STUDY REPORT Bridger Plant Materials Center Bridger, MT

January Frost Seeding of Cover Crops Study Roger Hybner1, Joseph Scianna2, and Mark Majerus3

NRCS photo

Figure 1. Lacy phacelia, January frost seeding of cover crops study, Bridger, MT. 2015. ABSTRACT Although many agronomic crops are planted in the spring and early summer when soil temperatures are ideal for immediate and optimum plant growth (often ranging from 50 to 70°F), it may be possible to successfully establish stands of many species by planting early as a dormant seeding when soil temperatures are significantly lower. This practice may allow access to sub- irrigated sites that are difficult to plant in the spring or allow producers to accomplish field operations before the busy growing season. The purpose of this study was to determine if this technique held merit for implementation in Montana and Wyoming prior to developing a multi- year study. A frost seeding was planted on a fall-prepared site on January 26, 2015, at the USDA-NRCS Plant Materials Center in Bridger, Montana. Three plots each of 12 different single-species (‘Lavina’ barley, ‘Rockford’ oats, ‘Bayou’ rapeseed, VNS (variety not stated) lacy phacelia, ‘Dwarf Essex’ rapeseed, ‘Dwarf Siberian’ forage kale, ‘Selby’ flax, VNS yellow sweet clover, ‘Richlea’ lentil, ‘Whistler’ Austrian winter pea, ‘Biotill’ radish, and ‘Purple Top’ turnip) were planted in a completely randomized study. Additionally, three plots of eight different mixes were also seeded for a total of 60 test plots. Plots consisted of four rows, 20 feet long, with 14 inches between rows. Single-species and mix plots were evaluated for vigor, percent stand, plant height, and shoot biomass. Mean vigor of single species was high, rating above the median (4.5). 1 1 - Agronomist (retired), USDA-NRCS Plant Materials Center, Bridger, MT 2 - Manager, USDA-NRCS Plant Materials Center, Bridger, MT 3 – Manager/Botanist (retired), USDA-NRCS Plant Materials Center, Bridger, MT Mean vigor of mixes ranged from 2 (Mix 7) to 3 (Mix 5), and all ratings suggest high overall mix vigor. Mean percent stand among single species plots varied widely, with ‘Lavina’ barley (85%) the greatest and ‘Dwarf Essex’ rapeseed (0%) the lowest. VNS yellow sweet clover and ‘Biotill’ radish both established greater than 60%. All mixes established relatively well, ranging from 89.3% to 75.3%. With one exception, the cereal grain component of each mix represented the greatest percent stand establishment in each mix. Mean shoot biomass production of cereal crops (oats and barley) was greatest, followed by radish, turnip, lacy phacelia, and lentil. Mixes with ‘Cert 441’ triticale and ‘McNeal’ spring wheat had greater total mean biomass production than mixes with ‘Rockford’ oats and ‘Lavina’ barley. Although other environmental variables such as air temperature and amount and timing of precipitation are involved, preliminary results suggest January seeding of some cover crop species may result in successful stand establishment. Comparison of January versus conventional planting dates of the tested species and cultivars need to be evaluated. Dormant November seeding may prove more practical in Montana and Wyoming.

INTRODUCTION Cover crop mixes in Montana are increasingly utilized by producers as a tool to improve soil health. Producers plant cover crop mixes for a variety of reasons including but not limited to supplemental grazing, providing additional nitrogen (N), and reducing soil compaction. Depending on the goals of the producers, planting often occurs in April through June, or in July or August after an earlier grain or hay crop is harvested. Regardless of the month, producers are often short on time and labor, and weather can delay plantings. A January frost seeding would alleviate the time and la bor issue, as that is typically a slower time for producers. The purpose of this initial study was to determine if this technique was feasible in Montana and Wyoming climates prior to developing a formal study incorporating appropriate experimental design and data collection procedures.

MATERIALS AND METHODS On January 30, 2015, a dormant “frost seeding” study was installed at the Bridger Plant Materials Center (MTPMC). Soil at the site is a Haverson silty clay loam, 0 to 2% slope, moderately alkaline (Parker et al. 1975). The site had been mechanically prepared (clean till, no soil cover) the previous fall. Plots were installed using ar fou -row cone planter (Kincaid Equipment Manufacturing®, Haven, KS) equipped with double disk furrow openers, depth bands, and double packer wheels. Each non-replicated plot consisted of four rows of each variety measuring 20 feet long and 4.7 feet wide. All species were seeded to a 1-inch depth and 14-inch between-row spacing. Twelve cultivars were planted as solid stands (Table 1) and eight different mixes consisting of various combinations cover crop species and cultivars (Table 2). Seeds per pound and seeding rates, when available, based on Montana Specification Cover Crop 340 Job Sheet. It should be noted that two individual species plots (‘Dwarf Siberian’ forage kale and ‘Purple Top’ turnip) were seeded at less than the recommended full stand rate. Additionally, when the percent of full stand rates of the individual species were summed, Mix 5 was seeded at 117% and Mix 6 at 90%. Three replicate plots of each variety or mix were planted in a completely randomized design. Species and mixes were seeded at their recommended seeding rates. Although installed with the intent of maintaining the study as a dryland planting, a single irrigation of approximately 1.0 inch of supplemental water was applied on June 26, 2015, during

2 severely hot weather to prevent plant desiccation prior to sampling. No other supplemental irrigation was applied over the course of the study.

To prevent the potential spread of domesticated oats to adjacent foundation seed production fields, all single-species and mix plots containing ‘Rockford’ oats were biomass sampled, evaluated for vigor (single-species plots only), and then removed on June 25, 2015. All other plots were evaluated for vigor rating (1-best; 9-worst), percent stand, and height on July 15, 2015, and sampled for shoot biomass on July 21 and 22, 2015 (Appendix A). Data was collected from each of the three plots of each species or mix, and then averaged. Biomass collection in all cases involved sampling from random 24-inch sections of the center two rows of each plot. Biomass samples were dried in a forage drier at 60°C (140°F) for 48 hours. Rainfall and temperature data was collected in 2015 (Table 3).

Table 1. Individual species recommended seeding rates, January frost seeding of cover crops study, Bridger, M T . 2015. Recommended Individual Seeding Rate --PLS2/ Species Plots Cultivar Latin Name lb/acre Seeds/lb seeds/ft-- barley ‘Lavina’ Hordeum vulgare 55 11,223 16.5 oat ‘Rockford’ Avena sativa 60 15,000 24.1 rapeseed ‘Bayou’ Brassica sp. (hybrid) 5 152,600 20.4 lacy phacelia VNS1 Phacelia tanacetifolia 5 245,000 32.8 rapeseed ‘Dwarf Essex’ Brassica napus 5 152,600 20.4 forage kale ‘Dwarf Siberian’ Brassica oleracea 5 150,000 16.13 flax ‘Selby’ Linum usitatissimum 30 82,645 66.4 yellow sweet clover VNS Melilotus sp. 6 193,424 31.1 lentil ‘Richlea’ Lens culinaris 45 9,139 11.0 Austrian winter pea ‘Whistler’ Pisum sativum subsp. 100 2,000 5.4 arvense radish ‘Biotill’ Raphanus sativus 8 27,300 5.8 turnip ‘Purple Top’ Brassica rapa 8 259,740 27.84 1- variety not stated. 2- pure live seed. 3- 80% rate used. 4- 50% rate used.

3 Table 2. Mix seeding rates, January frost seeding of cover crops study, Bridger, MT. 2015. Percent Recommended of a Total Mix Species Seeding Rate PLS2/ Full PLS PLS Composition Cultivar lb/acre Seeds/lb Stand Seeds/ft Seeds/ft Mix 1 barley ‘Lavina’ 55 11,223 0.20 3.3 - lacy phacelia VNS1/ 11 245,000 0.10 7.2 - radish ‘Defender’ 8 27,300 0.25 1.5 - rapeseed ‘Dwarf Essex’ 5 152,600 0.10 2.0 - yellow sweet clover VNS 6 193,424 0.10 3.1 - Austrian winter pea ‘Whistler’ 100 2,000 0.25 1.4 - 18.5 Mix 2 oat ‘Rockford’ 60 15,000 0.15 3.6 - rapeseed ‘Buckbuster’ 5 152,600 0.15 3.1 - turnip ‘Purple Top’ 8 259,470 0.10 5.6 - flax ‘Selby’ 30 82,645 0.25 16.6 - lentil ‘Richlea’ 45 9,139 0.20 2.2 - Austrian winter pea ‘Whistler’ 100 2,000 0.15 5.4 - 36.5 Mix 3 barley ‘Lavina’ 55 11,223 0.20 3.3 lacy phacelia VNS 5 245,000 0.15 4.9 radish ‘Defender’ 8 27,300 0.20 1.2 rapeseed ‘Dwarf Essex’ 5 152,600 0.15 3.1 yellow sweet clover VNS 6 193,424 0.05 1.5 spring pea ‘4010’ 140 3,113 0.25 2.9 16.9 Mix 4 oat ‘Rockford’ 60 15,000 0.20 4.8 - rapeseed ‘Buckbuster’ 5 152,600 0.10 2.0 - turnip ‘Seven Top’ 8 259,470 0.10 5.6 - flax ‘Selby’ 30 82,645 0.20 13.3 - lentil ‘Richlea’ 45 9,139 0.20 2.2 - spring pea ‘4010’ 140 3,113 0.20 2.3 - 1- variety not stated. 2- pure live seed. 30.2

4 Table 2. Mix seeding rates, January frost seeding of cover crops study, Bridger, MT. 2015 (continued). Percent Recommended of a Total Mix Species Seeding Rate PLS2 Full PLS PLS Composition Cultivar lb/acre Seeds/lb Stand Seeds/ft Seeds/ft

Mix 5 triticale ‘Cert 441’ 55 13,080 0.15 2.9 - forage kale ‘Dwarf Siberian’ 5 150,000 0.15 3.0 - radish ‘Grazor’ 8 27,300 0.37 2.2 - Brassica hybrid ‘Hunter’ 5 175,000 0.15 3.5 - lentil ‘Indianhead’ 45 21,142 0.15 3.8 - field pea ‘Flex’ 140 1,800 0.20 1.3 - 16.7 Mix 6 triticale ‘Cert 441’ 55 13,080 0.15 2.9 - rapeseed ‘Bayou’ 5 152,600 0.15 3.1 - turnip ‘Purple Top’ 8 259,740 0.10 5.6 - forage kale ‘Forage Premier’ 5 150,000 0.15 3.0 - yellow sweet clover VNS1 6 193,424 0.10 3.1 - field pea ‘Flex’ 140 1,800 0.25 1.7 - 19.3 Mix 7 spring wheat ‘McNeal’ 50 11,400 0.15 2.3 - forage kale ‘Dwarf Siberian’ 5 150,000 0.10 2.0 - radish ‘Grazor’ 8 27,300 0.20 1.2 - Brassica hybrid ‘Hunter’ 5 175,000 0.15 3.5 - lentil ‘Indianhead’ 45 21,142 0.20 5.1 - Austrian winter pea ‘Whistler’ 100 2,000 0.20 1.1 - 15.1 Mix 8 spring wheat ‘McNeal’ 50 11,400 0.20 3.0 - rapeseed ‘Bayou’ 5 152,600 0.15 3.1 - radish ‘Seven Top’ 8 27,300 0.20 1.2 - forage kale ‘Forage Premier’ 5 150,000 0.15 3.0 - yellow sweet clover VNS 6 193,424 0.10 3.1 - field pea ‘4010’ 140 1,800 0.20 1.3 - 1- variety not stated. 2- pure live seed. 14.8

5 Table 3. Monthly precipitation and minimum and maximum air and soil temperature. Bridger, Montana. 2015. Total Air Air Air Soil Soil Soil Monthly Temperature Temperature Temperature Temperature Temperature Temperature Month Precipitation Maximum Minimum Average Maximum Minimum Average ---inches------F° ------January 0.2 37.9 16.7 26.7 32.4 32.1 32.2 February 0.3 45.8 21.7 33.8 36.4 34.2 35.2 March 0.2 57.5 28.7 43.3 41.5 37.8 39.6 April 1.2 61.1 32.4 47.1 52.2 45.1 48.3 May 1.8 62.8 41.9 52.0 58.5 52.5 55.3 June 1.0 83.1 53.7 68.3 76.5 67.3 71.6 July 0.2 86.6 54.6 70.8 81.0 72.0 76.3 August 0.0 86.2 52.9 70.2 76.3 67.2 71.5 September 0.0 81.2 46.6 64.1 72.9 63.9 68.2 October 1.2 66.3 39.0 52.4 56.7 51.0 53.8 November 0.2 44.8 23.1 34.6 39.4 36.8 38.1 December 0.4 37.5 15.8 27.6 32.3 31.7 31.9 Total 6.7 62.7 35.7 49.3 54.8 49.4 51.9

RESULTS AND DISCUSSION

Evaluation results appear in Appendix A. Statistical differences determined by analysis of variance and Tukey HSD (∞=0.05) (Statistix10, Tallahassee, FL). Single species vigor (1-best, 9-worst) ranged from 2.0 (‘Lavina’ barley, ‘Rockford’ oats, VNS lacy phacelia) to 4.0 (‘Purple Top’ turnip), representing limited variation and excellent to good vigor for all species. Vigor data was not collected on ‘Dwarf Essex’ rapeseed because random sampling on July 15 did not capture any of the few established plants. There was a significant difference (p=0.0002) in vigor between ‘Purple Top’ turnip and ‘Biotill’ radish, ‘Lavina’ barley, ‘Rockford’ oats, VNS lacy phacelia, Mix 8, and Mix 7, but no significant differences among the other species, cultivars, or mixes. Mean vigor of mixes ranged from 2 (Mix 7) to 3 (Mix 5), indicating high vigor in all cases. Mean vigor data was not collected on mixes containing oats (Mixes 2 and 4) since these plots were harvested early.

Mean percent stand among single species varied widely, ranging from 85% (‘Lavina’ barley) to 0% (‘Dwarf Essex’ rapeseed) (Figure 2). Lacy phacelia and oats established very well as single species but were harvested prematurely and stand data was not collected. Among single species there was a significant difference (p<0.0001) between Lavina barley (85.0%) and all other treatments except VNS yellow sweet clover (68.3%) and Biotill radish (63.3%). There was no significant difference among mixes for percent stand establishment which ranged from 89.3% (Mix 8) to 75.3% (Mix 6) (Figure 3). Mean percent stand establishment by individual species in each mix are presented in Table 4. With one exception (Mix 1), the cereal grain component of each mix represented the greatest percentage of stand establishment in the mix. Other relatively well establishing mix species included VNS lacy phacelia (Mixes 1 and 3), ‘Indianhead’ lentil (Mixes 5 and 7), VNS yellow sweet clover (Mix 6), and ‘Grazor’ radish (Mix 7). ‘Forage

6 Premier’ kale, ‘Flex’ pea, ‘Dwarf Essex’ rapeseed, and ‘Dwarf Siberian’ forage kale established poorly in mixes.

Significant differences (p<0.0001) among plots for shoot biomass were observed. Among single- species plots, mean shoot biomass production of cereal crops (oats and barley) was greatest, followed by radish, turnip, lacy phacelia, and lentil (Figure 3). Biomass production in ‘Rockford’ oats was significantly greater than ‘Whistler’ winter pea, ‘Dwarf Siberian’ forage kale, ‘Bayou’ rapeseed, and VNS yellow sweet clover, ‘Dwarf Essex’ rapeseed. ‘Lavina’ barley biomass was significantly greater than ‘Dwarf Siberian’ forage kale, ‘Bayou’ rapeseed, VNS yellow sweet clover, and ‘Dwarf Essex’ rapeseed. There was a significant difference between Mix 6 (triticale) and Mix 1(barley), as w ell as between Mix 6 and the six lowest biomass producing individual species/cultivars. There was no significant difference between individual non-cereal crops. Mean shoot biomass production of mixes containing ‘Cert 441’ triticale (Mixes 5 and 6) and ‘McNeal’ spring wheat (Mixes 7 and 8) was greater than mixes containing ‘Rockford’ oats (Mixes 2 and 4) or ‘Lavina’ barley (Mixes 1 and 3) (Figure 5).

Weather data at Bridger, Montana, in 2015, appears in Table 4. Monthly precipitation in 2015 was less than the long-term average in each month from March through July, and annual precipitation (6.7 inches) was less than the long-term average (11.9 inches). Mean monthly air temperature in 2015 was greater than the long-term average for each month. Based on long-term weather data, dormant planting in November or later should ensure soil temperatures under 40°F and low air temperatures with no likelihood of early germination.

Lavina barley

VNS yellow sweet clover

Biotill radish

Richlea spring lentils

Selby flax Species Whistler winter pea

Bayou rapeseed

Dwarf Siberian forage kale

Purple Top turnip

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 Percent Stand Establishment

Figure 2. Percent stand of single-species plots, January frost seeding of cover crops study, Bridger, MT. 2015.

7 MIX 8

MIX 5

MIX 3

MIX 7 Mix

MIX 1

MIX 6

65.0 70.0 75.0 80.0 85.0 90.0 95.0

Percent Stand Establishment

Figure 3. Percent stand of mix plots, January frost seeding of cover crops study, Bridger, MT. 2015.

8 Table 4. Mean percent stand of mixes by species and total, January frost seeding of cover crops study, Bridger, MT. 2015. Mean Total Mix Mix Species Percent Stand Percent By Species Stand --%-- --%-- Mix 1 ‘Lavina’ barley 23.3 79.7 VNS lacy phacelia 38.3 ‘Defender’ radish 3.3 ‘Dwarf Essex’ rapeseed 1.3 VNS yellow sweet clover 5.0 ‘Whistler’ Austrian winter pea 8.3 no establishment 20.3 Mix 3 ‘Lavina’ barley 53.3 85.3 VNS lacy phacelia 14.0 ‘Defender’ radish 3.3 ‘Dwarf Essex’ rapeseed 1.3 VNS yellow sweet clover 6.7 ‘4010’ spring pea 6.7 no establishment 14.7 Mix 5 ‘Cert 441’ triticale 63.3 88.7 ‘Dwarf Siberian’ forage kale 1.0 ‘Grazor’ radish 6.7 ‘Hunter Hybrid’ brassica 1.0 ‘Indianhead’ lentil 16.7 ‘Flex’ pea 0.0 no establishment 11.3 Mix 6 ‘Cert 441’ triticale 60.0 75.3 ‘Bayou’ rapeseed 4.3 ‘Purple Top’ turnip 0.3 ‘Forage Premier’ kale 0.0 VNS yellow sweet clover 10.0 ‘Flex’ pea 0.7 no establishment 24.7 Mix 7 ‘McNeal’ spring wheat 55.0 83.7 ‘Dwarf Siberian’ forage kale 0.3 ‘Grazor’ radish 10.0 ‘Hunter Hybrid’ brassica 2.7 ‘Indianhead’ lentil 13.3 ‘4010’ spring pea 2.3 no establishment 16.3 Mix 8 ‘McNeal’ spring wheat 75.0 89.3 ‘Bayou’ rapeseed 2.0 ‘Seven Top’ radish 1.7 ‘Forage Premier’ kale 0.0 VNS yellow sweet clover 6.7 ‘4010’ spring pea 4.0 no establishment 10.7

9 Rockford oats Lavina barley Defender radish Purple Top turnip VNS lacy phacelia Richlea spring lentil Whistler winter pea

Species Selby flax Dwarf Siberian forage kale Bayou rapeseed VNS yellow sweet clover Dwarf Essex rapeseed

0 500 1000 1500 2000 2500 3000 3500 4000 Mean Shoot Biomass Production lb/acre

Figure 4. Mean shoot biomass of single-species plots, January frost seeding of cover crops study, Bridger, MT. 2015.

Mix 6 Triticale

Mix 8 Spring wheat

Mix 5 Triticale

Mix 7 Spring wheat

Mix 4 Oats Cereal Component Cereal - Mix 2 Oats Mix Mix 3 Barley

Mix 1 Barley

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Mean Shoot Biomass Production lb/acre

Figure 5. Mean shoot biomass of mix plots, January frost seeding of cover crops study, Bridger, MT. 2015.

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CONCLUSIONS In general, the vigor of established plants was good, even when stand establishment of a species was poor. Stand establishment results varied widely and suggest several test species do not grow well when planted early, including ‘Dwarf Essex’ rapeseed, ‘Purple Top’ turnip, ‘Dwarf Siberian’ forage kale, ‘Bayou’ rapeseed, and ‘Whistler’ winter pea (< 25%). Conversely, ‘Lavina’ barley, VNS yellow sweet clover, and ‘Defender’ radish, all established relatively well. Shoot biomass production of several species was also negatively impacted by early planting, including ‘Dwarf Essex’ rapeseed, VNS yellow sweet clover, ‘Bayou’ rapeseed, ‘Dwarf Siberian’ forage kale, ‘Selby’ flax, and ‘Whistler’ winter pea. In contrast, ‘Rockford’ oats, ‘Lavina’ barley, ‘Defender’ radish, ‘Purple Top’ turnip, and VNS lacy phacelia all produced relatively well. Mixes with triticale and spring wheat produced more shoot biomass than mixes with oats and barley, and these cereals may prove a better choice for early seeding. January seeding of several cover crops species in Montana and Wyoming climates may provide adequate establishment and growth during the growing season as soil temperatures increase, but before recommending this practice, a multiple year study is needed to verify if frost planting of cover crop is a viable practice in the northern plains. Comparison of stand establishment and biomass production between a January seeding and later conventional planting dates are needed before technical recommendations can be made. Future work should focus on dormant cover crop seeding in November at locations like Bridger, Montana where soil temperatures are 40°F or less at that time of year and there is less risk of snow cover or frozen soil, which are major drawbacks of seeding cover crops in January.

LITERATURE CITED Parker, J., G. Decker, L. Gray, and O. Muller. 1975. Soil Survey of Carbon County Area, Montana, USDA, in cooperation with the Montana Agricultural Experiment Station. 137 p.

11 Appendix A. Evaluation results, January frost seeding of cover crops study, Bridger, MT. 2015.

Mean Mean Mean Vigor Percent Mean Shoot Species Rating1/ Stand Height Biomass

--#-- --%-- --cm-- --lb/acre--

‘Purple Top’ turnip 4.0 5.0 35.0 1,845 ‘Bayou’ rapeseed 3.0 15.0 60.0 384 ‘Defender’ radish 2.3 63.3 91.7 1,945 ‘Dwarf Essex’ rapeseed NA NA NA 187 ‘Dwarf Siberian’ forage kale 2.7 13.3 45.0 508 ‘Lavina’ barley 2.0 85.0 65.0 3,543 ‘Richlea’ spring lentil 3.3 45.0 23.3 1,262 ‘Rockford’ oats 2.0 NA NA 3,718 ‘Selby’ flax 3.0 37.5 55.0 694 VNS lacy phacelia 2.0 NA NA 1,650

VNS yellow sweet clover 3.3 68.3 43.3 322

‘Whistler’ winter pea 3.3 23.3 40.0 628 Mix 1 2.7 79.7 56.7 1,317 Mix 3 2.7 85.3 66.7 1,862 Mix 4 NA NA NA 3,550 Mix 5 3.0 88.7 105.0 3,927 Mix 6 2.7 75.3 106.7 4,455 Mix 7 2.0 83.7 76.7 3,577 Mix 8 2.3 89.3 73.3 3,927 1- vigor rating scale of 1 = best 9 = worst.

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