Allelopathic Effects of Cover Crops Allelopathy refers to the beneficial or harmful effects of one plant on another plant, both crop and weed species, from the release of biochemicals, known as allelochemicals, from plant parts by leaching, root exudation, volatilization, residue decomposition, and other processes in both natural and agricultural systems. Cover crops is one of the practices recommended by the Illinois Nutrient Loss Reduction Strategy to improve water quality at home and downstream by reducing nitrogen and phosphorus levels in our lakes, and rivers. different types ofLoss plants Cover crops arestreams, recommended by Many the Illinois Nutrient fall under the cover crop umbrella water such asquality ryegrass, Reduction Strategy to improve at brassicas, home and legumes, sudan, winter peas, etc. and phosphorus levels in our downstream by reducing nitrogen lakes, streams and rivers. Many different types of plants fall under the cover crop umbrella such as ryegrass, brassicas, legumes, sudan, winter peas, etc.
Grower Insight
When it came time to pick a winter cover crop for our trial system at Pleasant Plains, we turned to the most widely used cover crop in our area – cereal rye. Cereal rye can be seeded later in fall than other cover crops and still provide considerable dry matter, an
REDUCED STRIP TILL
TILLAGE
TOXICITY
24
MED
AGGRESSIVE STRIP TILL
LOW
extensive soil-holding root system, significant reduction of nitrate leaching and exceptional weed suppression. A good stand is critical for a successful cover crop, making cereal rye an easy choice for local producers. Plot seeding began after corn harvest on October 1, 2014. The cereal rye received a half inch rain that night for an excellent germination for our 2015 trials. Trials were established to compare conventional tillage to strip till versus strip till with a cover crop of cereal rye. Four hybrids with varying phenotypic characteristics were tested to provide an array of hybrid responses. We expected nutrition to provide the primary solution for profitable cover crop management. Thus, extensive nutrient treatments were added to tillage/cover crop trials to study the yield significance of nutrient product, placement and timing of each practice. Nitrate soil tests were performed to evaluate cover crops’ role of sequestering unused nitrogen remaining or mineralized after harvest. Spring tests did reveal the nitrate levels in the soil were cut in half when evaluating the use of a cover crop in a no till system. Thus, cover crops may assist with improving water quality as predicted.
NO TILL
HIGH
AGGRESSIVE STRIP TILL
LOW