Seed‐Drill Opener Type and Crop Residue Load Affect Canola Establishment, but Only Residue Load Affects Yield

Abstract

Core Ideas Canola establishment can be affected by the residues of the previous crop.Different planting tools may handle crop residue differently.Tine and disc furrow openers at different residue loads were tested.Canola performed best when established with tine openers and when residue load is low. Handling crop residue during planting operations is a challenge to conservation agriculture (CA) farmers worldwide. It remains unclear which tools are most effective in which conditions. Canola (Brassica napus L.), an oilseed crop widely used in rotation with cereals, is particularly sensitive to seedbed conditions, and thus may be influenced by residue loads and the choice of seed‐drill openers. To identify optimal planting practices, this study compared the performance of disc and tine openers on canola establishment, growth, and yield under differing residue loads in a Mediterranean‐type climate region. First, soil disturbance caused by disc and tine openers was evaluated to assess their effect on seedbed conditions; and second, the interacting effects of the openers with different residue loads was investigated. Tine openers and low crop residue loads resulted in the best (P < 0.05) canola establishment. However, canola at reduced plant populations compensated in both biomass and grain yield, so that no yield differences resulted from different opener types, and only small yield differences occurred between residue loads (P > 0.05).

Canola is injured by in‐row nitrogen placement associated with disc openers, but not by tine openers

“…Plot dimensions were 1.5 × 20 m. Replication across various soil forms was done to ensure representativeness in true situations on farms, as the soils are highly variable within short distances in the region. However, previous research has shown that a combination of various soil physical, chemical, and biological indicators of soil quality did not influence performance of openers in the region (Swanepoel et al., ).…”

“…It is clear that tine openers with the ability to separate fertilizer from seed in the row had the lowest risk of seedling injury. An optimal target canola plant population of >40 plants m −2 has been reported for the region (Swanepoel et al., ), although no economic impact for plant populations as low as 25 plants m −2 has been reported elsewhere (French, Seymour, & Malik, ). Planting canola with 10 kg N ha −1 with a disc opener that does not have the ability to separate seed from fertilizer has resulted in suboptimal plant populations of <40 plants m −2 .…”

“…However, the control treatment resulted in intermediate plant performance between the disc and tine treatments. Other reasons for canola to perform better with a tine opener might include soil disturbance that affect seedto-soil contact, residue load on the row, and seedbed quality (Grant et al, 2002;Swanepoel et al, 2018Swanepoel et al, , 2019. However, performance of seed furrow openers seems to be crop specific.…”

“…Different planting and fertilization strategies are necessary for canola and wheat production. A previous study on canola establishment with different furrow openers mounted on a seed drill in the Western Cape Province reported that disc openers resulted in a lower yield (Swanepoel et al., ). However, mechanisms of reduced productivity could only be ascribed to multiple reasons, including hairpinning (pushing residue into the furrow without cutting through residue), crop residue handling, and chemical or physical injury from fertilizers, and more research is warranted.…”

“…No-tillage is a practice widely followed by canola (Brassica napus L.) producers (Morrison, Harker, Blackshaw, Holzapfel, & O'Donovan, 2016;Swanepoel, le Roux, Agenbag, Strauss, & MacLaren, 2019). This necessitates the use of seed drills that place seed directly in soil, without prior soil preparation actions.…”