Farmers who use herbicides to control weeds have great flexibility in the timing of applications. Farmers who use cultivation to remove weeds do not have much flexibility. Cultivation must be done when weeds are small. If a field is too wet for a tractor to enter, cultivation cannot be done and the weeds continue to grow and cause crop yield loss. Recent research shows that the wet field problem is common and that relying on cultivation instead of herbicides results in a yield loss of about 26% one-third of the time.
“Wet weather during the early part of the growing season was the major reason that mechanical weed control was difficult in some years.
This variability fit our observations of the trials that there was a large range in annual grain yields in the organic systems depending on how favorable the weather was for mechanical weed control.
The field crew reported problems controlling weeds in the organic systems in 1993 and 1998 at Elkhorn and 1993, 1996, 2000, and 2001 at Arlington.
Based on the above summary, we estimate that the frequency of weed control problems and subsequent reduced yields in low-input row crops is roughly 34 out of every 100 cases and the corresponding relative yield is approximately 74%.”
Authors: Posner, J. L., et al.
Affiliation: Department of Agronomy, University of Wisconsin.
Title: Organic and conventional production systems in the Wisconsin integrated cropping systems trials: I. productivity 1990-2002.
Source: Agronomy Journal. 2008. 100:253-260.