Beneficial Sequence of Perennial Forage Seed Crops and Annual Food Crops in Crop Rotations in Western Canada

Citation

Khanal, N., Lupwayi, N. Z., Azooz, R., & Rahman, N. (2022) Beneficial Sequence of Perennial Forage Seed Crops and Annual Food Crops in Crop Rotations in Western Canada [Abstract]. ASA, CSSA, SSSA International Annual Meeting, Baltimore, MD. Nov 6-9, 2022 https://scisoc.confex.com/scisoc/2022am/meetingapp.cgi/Paper/141405

Abstract

A cropping sequence study attempted to examine agroecological performance of cropping sequences integrating perennial forage seed crops in cropping systems. A replicated field experiment in split plot design comprised eight cropping sequences as main plot and three levels of N as sub-plot factors. The cropping sequences comprised four annual crops - barley (Hordeum vulgare L.), canola (Brassica napus L.), pea (Pisum sativum L.) and wheat (Triticum aestivum L.), and four perennial forage seed crops - alsike clover (Trifolium hybridum L.), creeping red fescue (Festuca rubra L. ssp. rubra), meadow bromegrass (Bromus riparius Rehmann) and red clover (Trifolium pratense L.). Crop yields expressed as canola equivalent yield (CEY), gross margins and various soil property parameters such as aggregates, permanganate oxidizable C, microbial biomass C, and enzymatic activities of β-glucosidase, β-N-acetyl-glucosaminidase, acid phosphomonoesterase and arylsulfatase were compared. Perennial legumes grown as biennial seed crops in the sequence replaced N fertilizer requirement for succeeding wheat and canola crops by up to 90 and 45 kg N ha-1. Crop rotations between annual and perennial crops showed promising effects on agronomic and soil health parameters. However, short intervals between perennial seed crops in the cropping sequences posed difficulty in termination of previous crops leading to impaired establishment, volunteer competition and poor performance of following crops. The perennial-intensive cropping sequences may be beneficial for transitioning from forage seed crop to feed crop phase. Among the test crops, wheat followed by canola may be suitable transition crops in the cropping sequence following perennial legume seed crops, while peas followed by canola may be suitable transition crops after perennial grass seed crops for enhancing agro-ecological performance of cropping systems. Further studies should assess the nutrients use efficiencies, greenhouse gas emissions and environmental health of different cropping sequences.