Diuron and Simazine Losses to Runoff Water in Mediterranean Vineyards

Abstract

The Mediterranean climate is characterized by a hot and dry summer where occasional storm events induce erosion and runoff. The high leaching potential of pesticides to surface waters under such climate conditions are not in relation to the main body of data that originated from summer‐rain row‐crop scenarios. In this 2‐yr study we monitored runoff discharge and concentrations of the two soil applied herbicides diuron [3‐(3,4‐dichlorphenyl)‐1,1‐dimethylurea] and simazine [6‐chloro‐N2,N4‐diethyl‐1,3,5‐triazine‐2,4‐diamine] from two field sites—one tilled and one no‐till—cropped with grapevine (Vitis vinifera L.; Cinsault and Aramon, respectively). Despite a time lag of 140 d in 1994 between chemical application and first runoff event, diuron concentrations in overland flow exceeded 200 µg L−1 at the no‐till site. In 1995 the first strong rainfall‐runoff event following application carried >87 and 60% of the respective seasonal simazine and diuron loss at both sites, although it accounted for <17 and 7% of the total runoff volume at the no‐till and tilled site, respectively. At the no‐till site, seasonal diuron loss during 1995 was 1.71% of applied; the corresponding value for simazine was 1.25%. Only 0.68 and 0.79% of the respective applied diuron and simazine mass were washed from the tilled field, reflecting differences in runoff volume between sites. Pesticide losses depended primarily on runoff volume and intensity. Event average herbicide concentrations in surface runoff followed an exponential decay over time. Estimated first order rate coefficients were at least twice as large as those derived from soil samples using the alcoholic solvent extraction technique. The decreasing water availability with time compared with the herbicide content at the soil surface indicated an increasing adsorption with time.

The role of storm flows in concentration of pesticides associated with particulate and dissolved fractions as a threat to aquatic ecosystems - Case study: the agricultural watershed of Save river (Southwest of France)

“…Our findings revealed that more than 59% of pesticides are transported during storm events into river systems. Results obtained by previous studies indicate that pesticide transport and losses are related to some phenomena which generally appear close to the application periods (Brown et al, 1995;Lennartz et al, 1997). Moreover, the characteristics of rainfall, runoff volume and storm events have a great impact on pesticide transport and losses (Muller et al, 2003).…”

Effect of kaolinite and Ca-montmorillonite on the alleviation of soil water repellency

“…Yields are reduced by the patchy growth and the delay in germination reduces the effective growing seasons (McKissock et al 2000). The water repellency of the topsoil reduces the infiltration capacity of the soil matrix, which can lead to enhanced overland flow and associated soil erosion and nutrient washout (Lennartz et al 1997). This may be particularly the case where heavy rainstorms follow prolonged dry periods, a combination of events that is increasing in frequency and intensity as a consequence of climate change (Cebulak et al 2000).…”

Spatial Simulation of Agricultural Practices using a Robust Extension of Randomized Classification Tree Algorithms

“…This catchment suffers from serious herbicide pollution of the surface water. Studies on the pollution process show that this pollution should be in relationship with the high risk of herbicide leaching by run-off during the heavy rainfall events that are typical of the area's sub-humid Mediterranean climate (Lennartz et al, 1997;Louchard et al, 2001). They assign a crucial role to the vineyard weed control practices (WCP), which determine both the type and amount of herbicide applied and the evolution of soil surface characteristics that affect the soil's hydraulic conductivity (Leonard and Andrieux, 1998;Hebrard et al, 2006).…”