All farms that have as part of their production system the disturbance of soil will have to manage weeds. Weed control ranks as the number one barrier to organic agricultural production (Kristiansen, Sindel and Jessop, 2007). Farmers practicing more conventional forms of crop production have more tools at their disposal to address weed control than organic farmers. And, while NANIH is not a certified organic grower, we do follow organic and permaculture growing practices. Some of the challenges created by weeds include: competition of light, water, and soil nutrients. Some of the methods of weed control available to organic vegetable growers include: cover cropping, use of herbicides, tillage, solarization, mechanical removal, and various types of mulching. We use no genetically engineered varieties or organisms on our farm.
Moreover, despite the fact that ecologically friendly growing methods, such as organic farming, have grown dramatically over the past 10 years there has been little research done on improving organic and sustainably managed farms’ ability to effectively control weeds. It is estimated that controlling weeds on small, intensely managed farms such as ours can cost as much as 30-50 percent of production costs.
We are proposing to study the effectiveness of using non-chemical means of controlling weeds in market vegetable production. Specifically, we are proposing to use chipped wood mulch to control weeds in small fruit and vegetable production. A study by Olkowski and Klitz (1981) showed that wood chip mulch can be effectively used to significantly reduce weed stands. And, according to a 2007 publication by Chalfer-Scott, the advantages of using wood chips versus plastic mulch include: improved soil structure; enhanced gas transfer; enhance water infiltration and retention; prevention of erosion and compaction; providing nutrients; suppress pathogens and pests; enhanced beneficial organisms; increased biodiversity; neutralize pollutants; reducing economic loss; more visually pleasing produce resulting in increased sales; and ease of application.
Project objectives from proposal:
The experimental design will be a completely randomized design with 2 mulch treatments, replicated five times, established on 20 test plots approximately 200 ft.2 The treatments will include blended hardwood mulch applied at a depth of 4 inches; double shredded hardwood bark at a dept of 4 inches; and control (no mulch). All plots will be rain-fed. Multiple vegetables and herbs will be planted including garlic, peppers, onions, zinnias, eggplant, kale, melons, cucumbers, squash, and asparagus. Harvestable and marketable yield for each of these crops will be recorded at harvest time for each experimental plot.
Weed infestation will be determined by monitoring the populations and identification of the species as follows: assigning scores using visual estimates of the observed percentage of weed coverage in each plot; and obtaining a count of the individual weed plants growing in a 1.332 sample area of each plot. We will also identify and record all weed species growing in the plots.