# Soil Mobility and Residual Effects of Herbicides Applied on Corn Straw

## TL;DR

This study examines how corn straw and dry periods affect the mobility and effectiveness of pre-emergence herbicides in controlling weeds.

## Contribution

The study identifies how different herbicides respond to straw cover and dry periods, guiding better herbicide selection and management.

## Key findings

- Diclosulam and sulfentrazone remain effective under straw and dry conditions.
- Flumioxazin and S-metolachlor lose efficacy in the presence of straw.
- Straw cover reduces residual activity of some herbicides like flumioxazin.

## Abstract

The efficacy of herbicides is directly related to its
availability
in biological targets. The presence of straw cover on the soil, coupled
with dry period conditions following pre-emergence herbicide application,
has raised concerns regarding pre-emergence herbicide efficacy, mainly
because of the increased potential for herbicide retention and degradation.
This research aimed to elucidate how different levels of corn straw
and dry periods impact the mobility and residual activity of key pre-emergence
herbicides used in cultivation systems with soil coverage. The results
showed that diclosulam and sulfentrazone maintained their mobility
and efficacy in controlling Commelina benghalensis L., regardless of straw cover or dry periods. However, the residual
activity of diclosulam was slightly reduced by straw, while sulfentrazone
remained effective 42 days after herbicide application. In contrast,
the presence of straw negatively affected the mobility and efficacy
of flumioxazin and S-metolachlor, reducing their effectiveness in
controlling C. benghalensis L, regardless
of dry periods. The residual activity was also negatively affected
by straw on the soil, particularly in the case of flumioxazin. Herbicides
with greater stability under straw and dry conditions, such as diclosulam
and sulfentrazone, exhibit more consistent performance, while flumioxazin
and S-metolachlor molecules require complementary management strategies
to maintain efficacy. Thus, farmers should consider the amount of
straw on the soil and the possibility of dry periods when selecting
pre-emergence herbicides. From an environmental perspective, the distinct
physicochemical properties of the evaluated herbicides determine their
mobility, persistence, and potential risk of contamination through
leaching and surface runoff. Understanding these interations supports
the development of integrated weed management and environmental protection
strategies in agricultural systems conservation.