Evaluation of Soil Quality in Vegetables Planted in Plastic Mulch Vs. No-till in Polyculture Cover Crop.

Organic vegetable production in Missouri relies heavily on tillage as a form of weed control due to the prohibition of herbicide use.  Studies have shown that both continual tillage and the use of polyethylene film contribute to the degradation of soil quality, whereas introducing no-till strategies paired with cover crops can help improve soil organic matter content and reduce soil erosion.  These improvements to soil quality can subsequently lead to increased productivity and yields. 

Still, no-till practices are challenging to implement on organic vegetable farms because of the issue of weed control.  For this research, we are examining three different seasonal vegetable crops and seven organic growing systems that utilize either no-till or tillage and rely on either polyethylene, straw, fabric, or rolled cover crop for weed-suppressing mulch to determine which systems provide best practices for weed control, soil quality, and profitability. 

2013 was the first year of the study and research revealed that the highest yields came from tilled plots with no cover crops planted for all three crops (lettuce, tomatoes, broccoli) with fabric providing the most effective mulch for the spring and summer crops.  However, based on daily soil moisture measurements, results showed that no-till plots were the most successful at conserving soil moisture compared to the tilled plots that were covered with mulch.  

At this time, it is not surprising to see that plots with tilled soils are producing the highest yields in our trials.  In an organic vegetable system, tillage provides temporary weed control and prepares a fluffy bed for seeding or transplanting.  No-till plots had compacted soils and cover crop debris that impeded the mulches.  However, we have yet to analyze data for soil quality and this information will help us compare the soil health benefits of no-till versus tilled plots.