WASTES IN RELATION TO AGRICULTURE AND FORESTR 



Most all research in this area lias been empirical. 

 There is an urgent need for fundamental studies 

 on the energetics involved in the detachment and 

 movement of soil particles by raindrop splash and 

 flowing water. Surface sealing and related phe- 

 nomena that result in decreased infiltration need 

 to be understood in order to be corrected. Water 

 intake and movement through soil during freezing 

 and thawing is especially important, but the inter- 

 play of forces involved is inadequately understood. 

 Control practices need to be developed and inte- 

 grated into systems that will reduce runoff a maxi- 

 mum amount and provide for the removal of sur- 

 face drainage without appreciable erosion. 



There is an urgent need for new concepts and 

 procedures for identifying critical sediment 

 son ices and predicting sediment delivery from 

 areas affected by climatic factors, soils, geology, 

 topography, stream channel characteristics, and 

 watershed protection measures. Special emphasis 

 must be given to developing better technology for 

 stabilizing and revegetating gullies, spoil banks, 

 roadbanks, strip mines, overgrazed rangelands, 

 forest burns, and badly disturbed construction 

 sites. 



Research towards diminution of forest fires and 

 overgrazing of rangelands would greatly con- 

 tribute to reducing sediment delivery. 



Criteria for engineering design of sediment 

 traps and debris basins could stand much improve- 

 ment. 



There needs to be a much better understanding 

 of sediment transport in tortuous upstream tribu- 

 taries, with emphasis on better understanding of 

 the hydraulic forces necessary for design and 

 maintenance of stable stream channel systems. 



Limited information is available on the role of 

 sediment as a transporting agent for pesticides 

 and other chemicals. 



Since comprehensive river basin planning is 

 moving forward rapidly under the leadership of 

 the Water Resources Council, expansion of effort 

 to gain new or better information and technology 

 on sediment problems in upstream watersheds 

 should keep pace. 



Plant Nutrients 



Surface Water 



Plant nutrients, as here used, are inorganic 

 chemicals essential for the mineral nutrition of 



plants. When present in surface waters they 

 may become contaminants in that they pro- 

 vide for unwanted growth of aquatic plants. 

 Nitrogen and phosphorus are the two elements 

 principally involved, but potassium is some- 

 times involved. 



The algae "blooms" that frequently develop 

 in nutrient-laden waters cause an off-taste and 

 an unpleasant odor to the water. When streams 

 and lakes reach the "green soup" stage of algae 

 growth, the odor of decaying plants becomes 

 offensive, fish are killed because of reduced 

 oxygen content of the water, and there is in- 

 terference with boating, swimming, and water 

 skiing. 



These nutrients enter surface water by dis- 

 charges of raw or treated sewage, some in- 

 dustrial wastes, and runoff and seepage from 

 land. Barnyards and feedlots yield nutrients. 

 Use of chemical fertilizers on lands is some- 

 times suspected as being a significant source 

 of plant nutrients found in streams and lakes. 

 Such growths can ruin farm ponds. They harm 

 the usefulness of the permanent pools of up- 

 stream watershed structures. Along with other 

 water weeds, they can seriously impair the 

 flow in irrigation and drainage ditches. 



Detergents used in households and industry pro- 

 vide an abundance of soluble phosphate to sewage 

 effluent. Evidence indicates that sewage delivery 

 of phosphate amounts to 2 pounds per person per 

 year. If the sewage effluent from 1 million people 

 enters a stream with an average annual flow of 

 5,000 cubic feet per second, the average phos- 

 phorus content will be 0.2 p.p.m. This level is more 

 than ample to enable excellent growth of algae 

 without the phosphorus from other sources. 



Each 1,000 tons of suspended sediment can be 

 expected to carry about 1,000 pounds of phos- 

 phorus, most of which is in the adsorbed or fixed 

 state unavailable for plant growth. Depending on 

 the source, usually not more than 10 percent of the 

 phosphorus on sediment is available for plant nu- 

 trition. Sediment derived from subsoils low in 

 phosphate may actually deactivate much of the 

 soluble phosphorus in a stream. 



Phosphorus is moving into streams from agri- 

 cultural lands. Many years o{ research by soil - 

 cntistS using ly si meters and other techniques show- 

 that only infinitesimal amounts of phosphorus 



