Using cover crops to alleviate compaction in organic grain farms

Organic producers rely on mechanical operations for weed management, creating compacted areas that favor weedy species thus forming a cycle of tillage, compaction and increasing weed populations. In an effort to address the concerns of organic grain farmers from Illinois, we explored the effect of selected cover crops in compacted and non-compacted areas of their farms on weed populations, yields and soil properties in a participatory on-farm research approach. The experimental layout was a split-plot arrangement of compaction and cover crop treatments with two replications set up at four locations in Illinois. The main plot treatments were compacted (CP) versus non-compacted areas (NCP), and the sub-plot consisted of four levels of cover crops treatments: a control without a cover crop (C), forage radish (Raphanus sativus L.) (FR), forage radish and buckwheat (Fagopyrum esculentum Moench) (FRbw); and forage radish with hairy vetch (Vicia villosa Roth) and cereal rye (Secale cereale L.) (FRhvr). Farmers planted soybean (Glycine max (L.) Merr.) in 2012, and corn (Zea mays L.) in 2013 in the same plots as in 2012. Cover crop density was determined every fall prior to winterkill and spring before termination by tillage. Weed density, along with their biomass and species identification were collected prior to cash crop planting and during the growing season, while cash crop yields were determined every fall. Soil sampling was conducted each fall and spring prior to cover crop planting and termination. Penetration resistance (PR), bulk density (BD), water aggregate stability (WAS), total carbon (TC), nitrate (N-NO3), ammonia (N-NH4), bray phosphorus (P), and pH was determined each sampling time. Additionally, texture and Proctor determinations were conducted once at the beginning of the study. Greater PR and BD values in the CP areas verified compaction; these plots also had increased WAS, TC, P, and pH when compared to NCP areas. Cover crop treatments affected soil properties but did not alleviate compaction. Cover crops treatment additionally did not influence WAS or available nitrogen. The FR cover treatment decreased TC by 6% in the FR in comparison to the control, and the FRbw and FRhvr treatments potentially improved phosphorus cycling as decomposed FRbw increased P by 17% and still growing FRhvr decreased P by 11% in comparison to the control. Additionally, FRhvr reduced weed counts and biomass in comparison the no cover crop control, but this treatment decreased soybean yields in 2012 by 20% in the NCP. Our findings suggest the rotations with cover of forage radish/hairy vetch/rye can significantly suppress weed populations yet can potentially decrease yields, especially in dry years, and that cover crops have the potential to improve nutrient cycling, but the long term effects of the practice on compaction and carbon sequestration in Midwest organic grain systems requires further research.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Crop Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Welch, Rachel Yoso

• cover crops
• organic
• corn
• soybean
• compaction
• soil properties
• weeds
• yields

Statement dc:rights

• Copyright 2015 Rachel Welch

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/78411

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/78411