WASTES IN RELATION TO AGRICULTURE AND FORESTRY 



59 



The data from these studies are used effectively 

 by educational institutions in teaching conserva- 

 tion courses and by action agencies in explaining 

 to potential cooperators the need for and the ad- 

 vantages from application of the practices to these 

 lands. 



These findings point out the need for application 

 of effective conservation practices to land areas 

 and show the tremendous reductions that can be 

 made in sediment yield. In addition to preserva- 

 tion of the soil resource for food production, such 

 measures are necessary to preserve the storage ca- 

 pacity in water reservoirs; to protect the beauty 

 and utility of recreational areas, particularly those 

 that are water based; to reduce highway mainte- 

 nance costs; and to mitigate the damage inflicted 

 during urban and industrial expansion. 



Slopes once scarred by gullies have been healed 

 by establishment of grasses and legumes. Contour 

 stripcropped fields have added to the beauty of the 

 rural landscape. 



Clarifying Silted Water 



Investigations of the ground water acquirer of 

 western Texas and Oklahoma and eastern New 

 Mexico have shown that natural recharge is so 

 small that pumping is essentially a mining opera- 

 tion. Depletion of this aquifer exceeds 4 million 

 acre-feet annually. Natural recharge is about 75,- 

 000 acre- feet a year. Simple arithmetic reveals the 

 future of the aquifer. During the average year, 

 about 1.5 million acre-feet of runoff water is col- 

 lected in shallow playa lakes that have almost im- 

 permeable lake bottoms. This water, which is 

 almost always wasted by evaporation, is a potential 

 source for recharge through reverse operation of 

 irrigation wells. 



A study of recharge through multiple-purpose 

 wells showed a drastic reduction of well pumping 

 rates caused by clogging of the acqui fer pore space 

 by the clay and silt in the playa lake water. Pump- 

 ing of the wells removed little of the sediments. 

 The need to clarify the. water before recharge 

 thereby became urgent. Numerous chemical floccu- 

 lants have been studied in an effort to develop an 

 economical clarification system. The flocculatiou 

 potential of polyeleetrolytes has been intensively 

 investigated for several years under cooperative 

 research with the Government of Israel through 

 authorization in P.L. 83-480 (116) in Israel. From 

 these studies a model clarification svstom has been 



developed and tests made on the Texas High 

 Plains. Early results indicate 90 percent of sedi- 

 ments can be removed; however, considerable re- 

 search remains to be done before commercial 

 operation is warranted. 



Resume 



The vast magnitude of sedimentation problems 

 is mitigated by their subtle nature. Many people 

 are so accustomed to seeing muddy water that they 

 become indifferent to its presence. 



Sediment in the waters of many of our streams 

 and their associated reservoirs can never be elimi- 

 nated, but abatement of this water pollutant 

 should go forward to the full extent practical. 

 There must be ever-continuing improvement in 

 technology that will warrant economically feasible 

 plans and procedures for curbing and controlling 

 the sediment burden entering and being trans- 

 ported by our streams. 



Plant Nutrients 



Major concern over the effects of plant nutrients 

 in surface waters as a precondition to eutrophica- 

 tion is rather recent. Research on the behavior of 

 such nutrients as phosphorus and nitrogen in soils 

 and soil solutions has been underway for over a 

 century. 



In 1834, at the age of 20, Jolrn Bennett Lawes 

 was given the management of the family estate. 

 This family farm was called Rothamsted. It cov- 

 ered 250 acres near the village of Harpenden, 

 England. While at Eton and Oxford. Lawes be- 

 came interested in the new science of chemistry. 

 Working in his home laboratory, he discovered 

 that treating bone black with sulfuric acid made 

 the product more effective as a phosphatic fertil- 

 izer. This suggested using the same treatment on 

 apatite and other mineral phosphates. In L842, he 

 obtained a patent for, and began manufacturing, 

 superphosphate. 



In 1843, Joseph Henry Gilbert, a chemist, joined 

 Lawes at Rothamsted. They started their histori- 

 cally famous soil fertility experiment that is still 

 underway. The effects on crop yields of chemical 

 fertilizers providing nitrogen, phosphorus, and 

 potassium were evaluated with comparable levels 

 of plant nutrients provided in barnyard manures. 

 The tremendous value of chemicals as sources of 

 soil fertility soon became apparent. 



