Soil herbicides

Soil. Herbicides and pesticides arc of course metabolized in the soil to which they are applied, and there are many reports of isolating degrading organisms from such sites. Little work has yet been presented where the biodegradation of these compounds has been successfully stimulated by a bioremediation approach,... 

Soil estimated persistence of 2 months (Kearney et al. 1969 quoted, Jury et al. 1987) persistence of 2 weeks in soil (Edwards 1973 quoted, Morrill et al. 1982) persistence of about 3 weeks in soil (Herbicide Handbook 1989) selected field t,/2 = 5 d (Augustijn-Beckers et al. 1994 Hornsby et al. 1996). 

RTC803 Soil - herbicides Certified values for 9 herbicides... 

Trifluralin has been marketed since 1961. It is a selective soil herbicide that acts by entering the seedlings in the hypocotyl region and disrupting cell division. It adsorbs in the soil and so is resistant to leaching, having a long residual activity. Trifluoralin is much more stable under aerobic than anaerobic... 

Weed-killers (herbicides) are the chemical tools for controlling weeds harmful to crops. They include a great variety of types both in the chemical sense and with respect to their mode of action. According to their mode of application, we may distinguish foliar herbicides and soil herbicides, and according to the time of application, pre- and postemergent herbicides. 

The salts and esters of 2,4-D are systemic foliage herbicides, with moderate soil herbicidal action. They are applied postemergence mainly in cereals, maize, rice, sugar cane and on pastures at a rate of 0.280-2.3 kg/ha active ingredient for the selective control of dicotyledonous weeds. At an application rate of 2.3 kg/ha, it is decomposed in about a month in the soil. 

Alachlor is a selective preemergence soil herbicide with action similar to that of propachlor. With its poorer solubility in water it needs more soil moisture than propachlor to exert its action, and irrigation must be used in a dry spring to obtain a satisfactory herbicidal action. On a molar basis, alachlor is twice as efficient as propachlor, and its activity lasts 2-4 weeks longer (Evans et al., 1968). 

Metolachlor is a selective preemergence soil herbicide, effective at a rate of... 

Diphenamid is a selective preemergence soil herbicide. It is absorbed through the roots, rapidly translocated to all above-ground parts of the plant and metabolised (Lemin, 1966 Golab et al.. 1966 Bingham and Shaver, 1971). 

Naptalam is a preemergence soil herbicide with systemic action and some hormone action. It can be used selectively at rates of 4.5 kg active ingredient/ha in cucurbits, soybean, potatoes and peanuts. It is not persistent, being degraded within 3-8 weeks in the soil. 

The herbicidal properties of profluralin (CGA 10 832,14) were first described by Taylor (1973). It is a selective, preplanting incorporated soil herbicide, applied at a rate of 0.75-1.5 kg active ingredient/ha. At this rate its action lasts for one year, and it is used mainly for the control of annual grass weeds and several broad-leaved weeds. It is well tolerated by cotton, sunflower and peanut. In soybean profluralin is, besides chlomidin, the dinitroaniline herbicide that can be most safely used in overdose amounts (Harvey, 1973), and it is very effective against Setaria faberi. It can also be used selectively in several vegetables. 

Terbutol is mainly a soil herbicide, but it is also effective postemergence for the control of grass weeds. It has a selective action in cotton, maize, tomato and soybean, and is recommended for the control of crab grass in established turf. It is particularly effective for the control of Digitaria spp. 

Propham is a selective soil herbicide used preemergence for the control of grass weeds in beet, cabbage, peas and lettuce. 

CEPC is a preemergence selective soil herbicide for the control of mono- and dicotyledonous weeds. 

The crystalline substance, slightly soluble in water and readily soluble in organic solvents, is a soil herbicide. It is effective against annual grass weeds in sugar beet and legumes at a rate of 6-8 kg/ha. The lDjo for rats is 3000 mg/kg. 

Proximpham is a selective soil herbicide, but it is absorbed also through the leaves. It is used in beet, onion, vegetables and ornamental plant cultures for the control of Compositae, Labiatae and Cruciferae weeds, which are tolerant to the other phenylcarbamates. 

Molinate is a selective pre- and postemergence soil herbicide mainly for the control of grass weeds and particularly for Echinocloa spp. (Smith and Fox, 1965). It is applied either before planting to water-seeded or shallow soil-seeded rice, or post flood on other types of rice culture. Applied at its recommended rate of 2-4 kg active ingredient/ha, its action lasts over the whole crop period (Swain, 1974). 

DCU is a soil herbicide used at rates of 2-50 kg active ingredient/ha for preemergence treatment in sugar beet, cotton, oil flax, potato, carrots and medicinal herb cultures. In Hungary it is used in combination with Pyramin for weed control in sugar beet (Ubrizsy and Gimesi, 1969). 

Methazole is a selective herbicide which can be used both as a residual soil herbicide and as a contact foliage-acting herbicide for the control of certain grasses and many broad-leaved weeds. 

DMPA is a preemergence soil herbicide which has been used in turf for the control of crab grass Digitaria spp.), and in soybeans, peas, beans and onions against grass weeds (Roberts et ai, 1966), but it has been superseded today. 

Chlorsulfuron is a residual soil herbicide. Its half-life in the soil is 1-2 months. 

Stearman, G. K., Wells, M. J., Adkisson, S., and Ridgill, T., Supercritical fluid extraction coupled with enzyme immunoassay analysis of soil herbicides, Analyst, 120, 2617-2621, 1995. 

D. Sampling directly after agrochemical treatment of soils (herbicides, pesticides, fertilizers, lime etc.) should not be performed. 

A wide range of different chemical compounds are currently in use in the EU. More than 600 single, active compounds are applied by farmers on stable cultivated agricultural soil. Herbicides... 

G.K. Stearman, M.J.M. Wells, S.M. Adkisson, T.E. Rid-gill, Supercritical Fluid Extraction Coupled with Enzyme Immunoassay Analysis of Soil Herbicides , Analyst, 120, 2617-2621 (1995). 

---