Roller-Crimping Cover Crops on Irrigated Organic Cropland

Objective 1 - Determine best performing species and varieties of winter cereal grain to use as a rolled-down mat in the Western Slope region of Colorado.

Several varieties of winter rye, winter triticale, winter wheat and winter barley have been used in organic no-till pulse studies. However, as suggested by a review published by Vincent-Caboud et al, in 2019, “future research should focus on (i) screening species and cultivars to identify cover crop and crop combinations that optimize cropping system performance [...].”. A research paper published by the same authors in 2019 showed differences in soybean yield and weed emergence with various winter rye and winter triticale varieties, which had produced comparable biomass amounts.

At David Harold’s farm, in addition to a tilled plot for control, we will plant multiple varieties of cereal rye, winter barley and triticale.

Protocol, Year 1, 2024

1/ Fall cover crop assessment, October 13, 2023

One rep per plot:

• Total Stems (Culms+Tillers) / 3' Drill Row
• Stems as Tillers / 3' Drill Row
• Stems as Culms / 3' Drill Row
• Stage of Growth Tillers (excluding Culm)
• Stage of Growth Culm
• Plants / 3' Drill Row
• Rooting Extent (in)

2/ Spring Cover Crop Assessment

2.1/ February 18, 2024

One rep per plot:

• Total Plants per 6.75" Drill Row
• Total Stems (culm + tillers) Emerged per 6.75" Drill Row
• Mass of Leaves + Roots (g) per 6.75" drill row
• Stage of growth

2.2/ April 2024

• Stand evenness, assessed with computing the greenness from UAV imagery

2.3/ April 10, 2024

3 reps per plot, 5 plants per rep:

• Stage of growth
• Height
• Number of erect or elongating tillers
• Overall weed pressure of the plot, very low, low, medium, high, very high.

2/ Biomass at termination, according to a review by Silva and Delate, 2017 a good stand will exceed 8,000 kg of dry matter of winter cereal per hectare. 

May 2024 - Clipped above ground winter cereal biomass, air dried it, and weighed samples

3/ Weed control will be assessed in August of each growing season. PI, TA, Educator and Intern will clip above ground weed biomass in random plot places (including tiller control), air dry it on farm and weigh samples.

Weed control was not systematically assessed in 2024.

Objective 2 - Determine best planting date of winter cereal grain

A determining factor in obtaining 8,000 kg per ha of winter cereal, or more, at the time of planting is the cereal planting date. A study by Mirsky et al showed that winter cereal cover-crop biomass increased approximately 2,000 kg of dry matter per ha from latest to earliest fall planting dates (August 25-October 15).

Olathe CO, is qualified as a USDA hardiness zone 6b, same as Kutztown PA, where Rodale Institute’s main farm is located. There, for a successful organic no-till soybean crop, winter cereal should be planted before October 10 (verbal communication with Dr. Andrew Smith, COO, Rodale Institute). While a later planting date is desirable to allow more flexibility in the choice of the preceding crop, planting too late will result in poor cereal stand and biomass production. At Tuxedo farm, we will plant winter cereals at a minimum of two different dates between September 15 and October 15.

To assess the performance of different seeding dates, we will use the same protocol described in Objective 1.

Objective 3 - Assess quality of cover crop termination using a roller crimper

Adequate timing of the roller-crimping has been documented as late anthesis into early milk stage: “Cereal rye biomass peaked at the late dough stage but optimal mechanical control was obtained between 50% anthesis and early milk stages.” (Keene et al, 2017). Adequate termination is critical to improve water use efficiency of the whole system. A poorly terminated cover crop will continue evapotranspiration at the crop’s detriment. 

Protocol:

1/ Computing the greenness of the mat from UAV imagery taken 5,10 and 15 days after termination. Hired drone photographer will take UAV photos and TA will analyze them.

2/ Measure water use efficiency. In August, PI, TA, Educator and Intern will collect crop above ground biomass at random locations of each treatment (including the tilled control). TA will pair the crop biomass data with the water input date collected using the flow meter to calculate water use efficiency of each winter cereal.

Objective 4 - Measure water use efficiency/infiltration as influenced by rolled-down cereal

See “Relevance to sustainable agriculture” section for references on relationship between no-till into rolled-down cereal mat and water use efficiency.

Protocol:

1/ On-farm visual observation of soil surface condition: establish a rating system of surface soil moisture and assess it monthly  (PI, TA and/or Educators and/or Intern)

2/ Infiltration rate using infiltration rings, monthly, PI, TA and/or Educators and/or Intern will insert infiltration rings into the soil to a depth of two inches and fill them with water to measure the rate of infiltration in the rolled-down mat and the bare soil.

3/ Protocol 2/ of Objective 3

No water measurements were made in 2024.

Objective 6 - Compare weed control under tilled and no-till organic pinto bean production

Protocol:

see Objective 1, 3/

Weed control was not systematically assessed in 2024.