Understanding the Effects of Intercropping Peas, Oats and Canola On Grain and Forage Production

Research Conducted By: Alan Lee, MSc Student, Department of Sustainable Resources, University of Alberta

Funders: Canadian Agricultural Partnership, MD of Fairview

Collaborators: Akim Omokanye (PCBFA), Dr. Guillermo Hernandez (University of Alberta), Dr. Monika Gorzelak (Agriculture & Agri-Food Canada, Lethbridge)

Project Duration: 2019 – 2021

Article From: Peace Country Beef & Forage Association 2019 Annual Report

Introduction

The general goal for producers often is to produce the highest returns on their crops, either through increasing yield or decreasing inputs. Increasing yields through increasing fertilizer use has become a burden as of recent years due to unstable climate conditions and expensive input price, where the additional fertilizer was not effectively providing higher yield. Recently, producers in North America have been interested in using intercropping to mitigate and improve returns as research in European and Asian countries have concluded that it can help decrease inputs such as fertilizers, herbicides and pesticides. Here in the Peace Country region, we conducted an intercropping experiment to see the effects of intercropping using crops commonly grown in the Peace region: peas, oats, and canola. Research in intercropping systems can provide a better understanding of the roles of mycorrhizae fungi in cropping systems and the provision of ecosystem services.

We hypothesize that an intercrop could 1) provide yield stability, greater yield (grain & forage) and increased grain and forage protein content with land equivalent ratio >1; 2) reduce the risk of N leakage after harvest compared with monocropping; and 3) improve net returns (with a benefit:cost ratio >1), soil fertility and health, and water use efficiency.

Alan showcasing his trial at PCBFA's 2019 Field Day at the Research Farm, August 1st, 2019

Objectives

1. To assess the effectiveness of intercropping of oats, peas, and canola in increasing yield quantity and quality as both grain and forage.

2. To observe mycorrhizal abundance and colonization in the soil under different intercropping systems to determine if mycorrhizae is contributing to improved yields.

Methods

Experimental Site

The experiment was conducted at Fairview Research Farm (NW 5-82-3 W6M) on RR #35, MD of Fairview.

The previous crop at the site before seeding the crops for this experiment was an alfalfa hay crop for several years until the Fall of 2018. In the Fall of 2018, the site was sprayed with Roundup at 1.0 L/acre (to kill the existing alfalfa dominated vegetation) and plowed. The site was disced & harrowed in the Spring of 2019.

Soil analysis completed in the Fall of 2018 from 0-6” soil depth showed an organic matter content of 8.2%, pH of 6.2 and an electrical conductivity of 0.21 ds/m.

The soil test reports showed 10 lbs N/acre, 14 lbs P/acre and 485 lbs K/acre as well as 9 lb S/acre. Spring soil moisture at seeding was 12.0% (0-5 cm soil depth) and 11.4% from 0-20 cm soil depth. Spring soil temperature at seeding was 12.3°C (0-5 cm soil depth) and 10.3°C from 0-20 cm soil depth.

Experimental design: Factorial plot design (intercrops x N fertility rates) with 4 replications

Intercropping treatments

1. Monocrop canola (3.2 lbs/ac)

2. Monocrop oats (127.3 lbs/ac)

3. Monocrop peas (200.1 lbs/ac)

4. Canola/pea intercropping, each seeded @75% of its monocrop seeding rate

5. Canola/oat intercropping, each seeded @75% of its monocrop seeding rate

6. Oat/pea intercropping, each seeded @75% of its monocrop seeding rate

7. Canola/oat/pea intercropping, each seeded @75% of its monocrop seeding rate

N fertility rates (4)

1. 0 kg N ha-1

2. 50 kg N ha-1

3. 75 kg N ha-1

4. 100 kg N ha-1

Fertilizer blend (with P, K & S) was used in accordance with soil tests.

Plot size used was 16m (52.5 ft) x 1.7m (5.6 ft)

Seeding was completed on May 30, 2019.

Seeding method involved using a 6-row Fabro plot drill with 9” row spacing.

Varieties of crops used: Canola (Clearfield CS2500CL), Oats (Seabiscuit), Peas (CDC Meadow).

Some of the measurements taken in 2019:

1. Surface soil moisture and temperature with installed sensors and data loggers

2. Surface soil bulk density

3. Pea plant nodulation during flowering

4. Plant height at harvest

5. Forage and grain yield, and quality

6. Canopy normalized difference vegetation index (NDVI) with GreenseekerTM sensor

7. Mycorrhizal colonization (except from canola monocrop and intercropped plots)

8. Field notes will be taken on incidence of pests and diseases, and plant lodging

Preliminary Results

Forage Dry Matter (DM) Yield

The forage DM yield (Table 1) was significantly influenced by the treatments. With forage DM yield of 8,172- 8,708 lbs/ac, oats monocrop, oat/canola mixture and oat/pea mixture produced significantly higher forage DM yield than canola and pea monocrops. Monocropped canola and monocropped pea yielded lower forage DM than other monocrops and intercrops.

Forage Crude Protein (CP)

Both canola and peas monocrops had significantly higher forage CP than other treatments (Table 1).

In terms of protein requirements by beef cattle, monocrops and intercrops have been able to meet the 7, 9 and 11% CP needed by different categories of beef cows. Canola and pea monocrops, and oat/pea/canola intercrop exceeded the 11% CP needed by mature beef cattle.

Forage Energy

The energy or total digestible nutrients (TDN) on average was above 61% (Table 1). Monocropped oats produced the highest TDN (79%), and significantly higher than the second and third highest producing treatments (Oats/ canola intercropping: 74%, Monogropped peas: 67%). The rest of the treatments were similar with TDN values between 61 - 66%.

Forage Macro Minerals

The forage Ca ranged from 0.4-1.7%, while forage P ranged from 0.25-0.38% (Table 1). The Ca and P levels in the treatments have exceeded the Ca and P requirements by a dry gestating beef cow in all cases and that of a lactating beef cow in most cases.

The forage K was near the maximum tolerable level of 3%, ranging from 1.5-2.2%. Oat/pea intercropping, pea/canola intercropping, oat/pea/canola intercropping and monocropped pea exceeded the maximum tolerable level of Magnesium (0.4%).

The sodium values were up to 0.1% for canola and oat monocrops as well as canola/oat intercrop. Only canola monocrop was able to completely meet the Ca, P, K, Mg and Na requirements of mature beef cattle.

A microscopic view of Mycorrhizae. Pictured is the Hyphae, which is the thread-like structure of mycorrhizae. Picture by Alan Lee

Comments and Expectations for the Coming Season

The results above are the preliminary findings and demonstrate that there could be advantages to intercropping for livestock production. Apart from monocropped oats, the intercropped treatments outperformed the monocropped treatments, while also providing the necessary nutrients required for foraging.

Within the upcoming year, I hope to process the remainder of the data from the 2019 harvest and provide further insight to the relationship between intercropping and mycorrhizal colonization, as we are currently only aware of how intercropping can benefit producers and not yet how to adopt intercropping successfully into a producer’s practice.

In the upcoming season, we hope to replicate this year’s results again in a new field. Beyond what was taken in the previous season, I hope to include biweekly readings of NDVI and fluorometer readings to expand on the potential reasons for improved yield in intercropped systems. By the end of the upcoming season, we will have our first look into what role mycorrhizae plays in agricultural fields, as well as understanding the importance of reducing or eliminating tilling operations on agricultural lands.