Silty soils cropping

The stmcture of the soil can be easily damaged by harmful operations, e.g. heavy traffic in wet conditions orploughing when the soil is too plastic. Overworking poorly stmctured silty soils can lead to surface capping after a period of intense rain followed by surface drying. Srrrface capping can lead to crop failrrre if it occims after drilling a small seeded crop and also increases the risk of water erosion. 

More than three-quarters of all the farm soils in this country have available water capacities between 60 and 100 mm (12-20% by volume) within the root range of most crops (about 500 mm depth). Sandy, gravelly and shallow stony soils have less than 60 mm (12%), whereas deep silty soils, very fine sands, warpland, organic and peaty soils have well over 100 mm (20%) of available water within root range. The available water capacity of the topsoil is often different from that of the subsoil. This should be taken into consideration when calcrrlating the amount present within the root range of a crop. 

Controlled Studies. Three field sites were established in 1981 to more accurately examine enhanced carbamothioate degradation in soils with controlled herbicide histories (18-20). Soils and sites included a Sharpsburg silty clay loam at Mead (Typic Argiustoll, pH 6.4, 2.9% organic matter), Crete silty clay loam (Udic Argiustoll, pH 6.6, 2.7% organic matter) at Clay Center, and a Tripp very fine sandy loam at Scottsbluff. Soils at each location were annually cropped to corn and treated with the same annual pesticide treatments from 1981 through 1985. No carbamothioate pesticides had been previously applied. 

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