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Progress Report: Strategies to Reduce Fertility Inputs and Improve Soil Health and Carbon Stocks

Written by: Akim Omokanye,

Location: Fairview Research Farm

With Collaboration from:Chinook Applied Research Association (CARA)

From: Peace Country Beef & Forage Association 2019 Annual Report


Nitrogen is the most common limiting nutrient for crop production systems. In Alberta, the direct input expense reports by Alberta Agriculture & Forestry showed that fertilizer costs constitute up to 25% of the total variable costs in cereal production, and up to about 30% for canola. The high cost of fertilizer is compelling producers to seek options for efficient management of production systems that will improve soil nutrients and overall soil health, while reducing fertilizer input expenses, but not sacrificing the yield obtained. Options to cut production costs include: cover crop cocktails (CCC), grazing (swath and annual pasture crop) in cropping systems, and the use of manure & foliar fertilizer to nurture the soil food web, stimulate the activity of soil micro-organisms and improve nutrient cycling. CCC mixtures can cut fertilizer costs by contributing N to the next crop, and by scavenging and mining soil nutrients. Inorganic fertilizer use contributes to a rise in atmospheric nitrous oxide (N2O), a major greenhouse gas contributing to global climate change. Soil C-sequestration through changes in land use and management is an important strategy to mitigate greenhouse gas (GHG) emissions at the farm level. This project will investigate the effects of different cropping/rotation systems, including CCCs and the use of manure & foliar fertilizer, on soil health improvement, fertility savings and potential C-sequestration rates over a 3-year study period on two soil types using a systems analysis.

Objectives

1. To examine the effects of incorporating CCCs swath grazing in crop rotations/cropping systems, and the use of manure and foliar fertilizer on soil health improvement, fertility savings, C storage & potential carbon sequestration rates.

2. To compare the cost-benefit analysis of the different systems on two soil types in Alberta.

Methods

Fairview site: Fairview research farm (NW 5-82-3-W6M) on RR 35.

The initial baseline soil characteristics at the site in May 2018 at seeding are shown in Table 1 below.

The project was set up in 2018 using a randomized complete block design (RCBD) with three (3) replications with the following treatments (see Table 2).

In 2019, Pioneer canola 45CM39 (glyphosate resistant) was seeded on May 22, at 4.1 lbs/acre using a 6-row Fabro plot drill at a row spacing of 9”. The seeding depth was 0.5”.

Glyphosate (StartUp) was used as a pre-seed burn off and in-crop herbicide.

A small area was manually cut on September 20 in each plot and threshed with a stationary thresher to extract the canola seed.


A systems approach will be used to analyze the data emanating from this project over a 3-year period. This will involve looking at different components of agricultural production.

Field Measurements (data being collected from 2018-2020) include the following:

1. Soil (physical, biology & physics) and environmental components (soil organic C sequestration)

Surface soil water infiltration, bulk density, soil moisture

Soil nutrients (N, P, K, S) from different depths

2. Crop Component

Plant growth, plant vigour, grain yield & quality, Straw yield and quality

GreenSeeker readings for soil cover and plant health

3. Livestock component (Forage yield and quality in year 1 only (2018))

4. Economic component (economic analysis) - A simple economic analysis of the input costs and output revenue will be an important aspect of the project.

Preliminary Results

Soil Characteristics

The soil characteristics in the spring of 2019 at seeding are shown in Table 3.

At seeding in the spring of 2019, the soil pH in the 0-6” soil depth varied from 5.00 to 5.37 (Table 3).

Percent organic matter is a measurement of the amount of plant and animal residue in the soil. The soil organic matter (OM) in the 0-6” soil depth at seeding in 2019 was also similar for all treatments and this varied from 6.15-6.90% (Table 3).

Cation Exchange Capacity (CEC) - Cation exchange capacity measures the soil's ability to hold nutrients such as calcium, magnesium, and potassium, as well as other positively charged ions such as sodium and hydrogen. In the spring of 2019, the soil CEC varied from 22.6 meq/100g for CCC Grazed to 26.1 meq/100g for treatment which had manure applied to barley the year before (Barley – manured).

Overall, in the spring of 2019 (at seeding), the treatment which had manure applied to barley the year before (2018) consistently showed higher soil N, P and K as well as the tendency to improve soil S.

Also, Barley – manured treatment (2018) showed potential for higher soil ENR than most treatments. The ENR is an estimate of the amount of nitrogen that will be released over the season. In addition to organic matter level, ENR may be influenced by seasonal variations in weather conditions as well as physical soil conditions.

Seed Yield

The seed yield for canola that was seeded in 2019 differed significantly between treatments with Barley-manured treatment producing the highest seed yield of 44 bushels/acre, followed by Barley-Penergetic (40 bushels/acre), CCC Grazed treatment and Peas (each with 36 bushels/acre) (Table 4).

The lowest seed yield came from CCC Rolled (10 bushels/acre). The CCC swath grazed was thought to have lower seed yield than other CCC (particularly CCC Grazed) because of uneven spread of cattle manure across the field and urine across the field during grazing.

HL-CCC Greenfeed produced lower seed yield than most treatments probably because of the lower spring soil moisture (data not shown here) and depleted soil nutrients (see Table 3) at seeding. The CCC Rolled had the highest soil moisture than other treatments at seeding, but the lowest seed yield from this particular treatment was thought to have come from poor seed to soil contact during seeding. We seeded at 0.5”. Perhaps, we should have seeded a little bit deeper to about 1” so as to have a good seed to soil contact. Increasing seeding depth to 1” will attempt to have seeds ‘cut’ through the rolled CCCm plant material, which would have been ideal under these conditions.

Seed Quality

All seed quality parameters measured here had similar values for all treatments (Table 4).

The seed protein varied from 22.8 to 24.8% CP.

The seed energy (total digestible nutrients, %TDN) varied from 67-71%.

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