WVU Organic Research Project
Weed Control Research at the Organic Farm
Rakesh S. Chandran, Kimberly Salinas and Matthew Madeira
Division of Plant and Soil Sciences
West Virginia University
Weed management is an important component of cultural practices in organic agricultural systems. Weeds compete with crops affecting their yield and quality. A study was conducted in 2000 and 2001 to evaluate different strategies for weed control in an organic horticultural garden. Twenty pepper seedlings were transplanted in 6' by 12' plots managed under conventional practices to date. Weed management treatments included:
1) Hand Cultivation 2) Plastic Mulch 3) Straw Mulch (2") 4) Straw Mulch (4") 5) Straw Mulch (8") 6) Untreated Control
Field experiments were designed as a randomized complete block with four replications. Plots that received the hand cultivation treatment were maintained weed free by weekly hand cultivation. In 2001, peppers were harvested for fresh weights upon fruit maturity. Pepper count and fresh weights were tallied for the duration of the study. Upon termination of the study, pepper shoot fresh weights and root dry weights were recorded. All data were analyzed using the statistical procedure Analysis of Variance. Mean separation was carried out using Least Significant Differences (LSD) at a 5% probability level.
Results from Study of 2000
Pepper yield. Plastic mulch resulted in maximum pepper yield with increases of ~150% compared to 8" straw mulch and 50% compared to hand cultivation. Approximately, a twenty-fold increase was noted in yield compared to untreated plots. The efficacy of plastic mulch to increase pepper yield was due to weed control and perhaps due to moisture conservation. Effects on conserving soil moisture by plastic mulch may have resulted in increased pepper yields compared to cultivated plots. Pepper number/plot. A trend similar, as with pepper yield, was noticed with number of peppers harvested during the growing season. Plastic mulch resulted maximum pepper number/plot with increases of ~125% compared to 8" straw mulch and 100% compared to hand cultivated plots. Plastic mulches also resulted in a thirty-fold increase in pepper number compared to untreated plots. Pepper growth. Data collected on growth characteristics of pepper supported yield data implying that there was a direct correlation between these variables. Shoot growth was influenced more than any other growth parameter by the weed control treatment. Increased shoot growth, in turn, resulted in increased yields. Hand cultivated plots and plastic mulched plots resulted in similar total root production by peppers. However, root length was affected by these treatments, where the plastic mulch caused pepper roots to grow longer than hand cultivated peppers. These differences may have been due to moisture distribution patterns in the soils as affected by the various mulch treatments. Overall, the research in 2000 generated sufficient data to obtain some preliminary information on weed control in organic gardens. The experiment in 2001 will determine the consistency of results obtained in 2000 and also generate information on low input transition systems.
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