Ken Janovicek

Increasing Crop Diversity Mitigates Weather Variations and Improves Yield Stability

Cropping sequence diversification provides a systems approach to reduce yield variations and improve resilience to multiple environmental stresses. Yield advantages of more diverse crop rotations and their synergistic effects with reduced tillage are well documented, but few studies have quantified the impact of these management practices on yields and their stability when soil moisture is limiting or in excess. Using yield and weather data obtained from a 31-year long term rotation and tillage trial in Ontario, we tested whether crop rotation diversity is associated with greater yield stability when abnormal weather conditions occur. We used parametric and non-parametric approaches to quantify the impact of rotation diversity (monocrop, 2-crops, 3-crops without or with one or two legume cover crops) and tillage (conventional or reduced tillage) on yield probabilities and the benefits of crop diversity under different soil moisture and temperature scenarios. Although the magnitude of rotation benefits varied with crops, weather patterns and tillage, yield stability significantly increased when corn and soybean were integrated into more diverse rotations. Introducing small grains into short corn-soybean rotation was enough to provide substantial benefits on long-term soybean yields and their stability while the effects on corn were mostly associated with the temporal niche provided by small grains for underseeded red clover or alfalfa. Crop diversification strategies increased the probability of harnessing favorable growing conditions while decreasing the risk of crop failure. In hot and dry years, diversification of corn-soybean rotations and reduced tillage increased yield by 7% and 22% for corn and soybean respectively. Given the additional advantages associated with cropping system diversification, such a strategy provides a more comprehensive approach to lowering yield variability and improving the resilience of cropping systems to multiple environmental stresses. This could help to sustain future yield levels in challenging production environments.

Early corn seedling growth response to phenolic acids

Phenolic (vanillic, p-coumaric, ferulic and p-hydroxybenzoic) acids inhibited corn seedling radicle elongation in bioassay studies, especially at solution concentrations exceeding 1.0 × 10−4M. Radicle growth inhibition among hybrids was different when p-coumaric or ferulic acids were assayed, suggesting that corn sensitivity to phenolic acid phytotoxicity may be hybrid dependent. Key words: Allelopathy, phenolic acids, radicle growth inhibition, corn, Zea mays L., hybrid response

Early corn seedling growth response to acetic, propionic and butyric acids

Corn (Zea mays L.) responses to crop rotation, tillage practice and/or plant residue placement may be due to differential production of acetic, propionic and butyric acids which are associated with the anaerobic decomposition of plant residues. To evaluate early corn growth response to acetic, propionic and butyric acids, a series of bioassays was conducted in which seeds of three commercially available corn hybrids, Pioneer 3737, Pioneer 3949 and Hyland 2260, were germinated and allowed to develop in solutions containing these acids alone or in combination at four concentrations (1.0 ×10−4 M, 1.0 × 10−3 M, 5.0 ×10−3 M, and 1.0 × 10−2 M) which were adjusted to two solution pH levels (4.5 and 7.5). None of the acids or acid mixtures tested affected seed germination. However, all three acids inhibited corn radicle growth. The magnitude of inhibition was butyric > propionic > acetic. Reducing solution pH tended to increase the degree of radicle growth inhibition. Particularly with propionic and butyric acids...

Frost seeding increases spring cereal yield

Abstract: Short growing season and mid-summer heat and drought are limiting factors for spring cereal production in Canada, suggesting that higher and more stable yields may be possible if the seeding date occurred earlier in the spring. Field trials were conducted in southern Ontario in 2003 and 2004 to compare development and yield potential of frost (early April) and conventional (late April–early May) seeded hard red spring wheat (Triticum aestivum L.), spring barley (Hordeum vulgare L.), and oat (Avena sativa L.) established using commercially available no-till planting equipment. Frost seeding had lower plant populations than conventional seeding, with pre-tillering plant population reductions for frost seeding averaging 44 plants m-2 (12%) for wheat and 27 plants m-2 (10%) for oats. In spite of lower plant population, frost seeding yields were higher than conventional seeding, with yield increases averaging 0.66 Mg ha-1 (24%) for wheat, 0.72 Mg ha-1 (20%) for oats, and 0.36 Mg ha-1 (11%, 2004 only) for barley. Frost seeded cereals had earlier occurrence of key phenological stages with average heading dates for frost seeded wheat and barley occurring 5 d earlier. Frost seeded cereals also had a longer vegetative period, which, along with earlier heading dates, contributed to increased yields for frost seeded cereals.