WASTES IN RELATION TO AGRICULTURE AND FORESTRY 



67 



wafers, although commonly returned to rivers, 

 may — with efficient irrigation management — be so 

 saline that alternative methods of disposal should 

 be considered. Since some crop plants are 10 times 

 as salt tolerant as others, the drainage water, al- 

 though too saline for general use, often has pro- 

 ductive potential for crops with especially high 

 salt tolerance. Bermudagrass pastures and seed 

 crops of some other grasses can be grown with 

 waters too saline for general agricultural use. The 

 further concentration of the original drainage 

 waters by using them on a second salt-tolerant crop 

 may be an important step in disposing of large 

 volumes of saline waste waters. 



Salinity Reconnaissance 



There is a pressing need for rapid and effective 

 methods of evaluating conditions in extensive land 

 areas. Such information is needed in planning irri- 

 gation districts, drainage districts, conservation 

 districts, and river basins. Remedial measures are 

 more expeditiously applied as knowledge of the 

 nature and extent of the problems increases. The 

 occurrence and intensity of soil salinity, the prev- 

 alence of moisture excesses or shortages, and dis- 

 ease infestations are kinds of problems where 

 extensive evaluation is helpful. The use of remote 

 sensing techniques appears to offer unusual 

 advantages. 



Limited research in this area has been underway 

 for several years by the U.S. Department of Agri- 

 culture in the Lower Rio Grande Valley of Texas. 

 The earlier studies using aerial infrared color film 

 sensitive to wavelengths in the range of 0.5 to 0.9 

 micron showed tonal contrasts that correlated well 

 with measured soil salinity. Recent results reveal 

 an excellent correlation between leaf temperature 

 of cotton plants and salinity in the 0- to 5-foot 

 profile. 



The Department of Defense and the National 

 Aeronautics and Space Administration have de- 

 veloped information through their research and 

 development programs that makes possible the use 

 of optical and thermal techniques in aerial map- 

 ping of large areas and in detection of environ- 

 mental conditions important to agriculture. 



Little is known, however, of the specific effects 

 of plant and soil environmental factors on the op- 

 tical characteristics of land cover and of their re- 

 lation to specific agricultural problems. This phase 

 is now receiving direct attention in the research 



and development programs of the U.S. Depart- 

 ment of Agriculture and several land-grant uni- 

 versities. Fundamental studies seek to establish 

 the mechanisms whereby these environmental 

 factors affect the optical properties of plant ma- 

 terials and of the soil. From this information, 

 photogrammetry techniques and identification and 

 interpretation procedures are being developed for 

 use in the solution of many land-management 

 problems involving salinity and the status of soil- 

 moisture conditions. 



Organic Wastes 



The Chinese developed procedures for full utili- 

 zation of agricultural wastes centuries ago {69). 

 The peasants diligently collected all wastes — hu- 

 man, animal, and plant — made "patties*" out of 

 them, and allowed them to dry in the sun. The pat- 

 ties were then stacked until distributed to the fields 

 at the proper time. Although this old Chinese art 

 provided for full use of organic wastes, the pro- 

 cedure has never found favor in the United States. 



The point to be emphasized is that organic 

 wastes can be used, but we rightly insist on us 

 technology that takes into account health hazards, 

 social acceptability, and economic feasibility. 



Research that pertains to organic wastes may 

 have one or more of the following six objectives : 



1. To better characterize organic was 



2. To improve evaluation of the effects of 

 organic wastes in the environm 



3. To minimize production of organic 

 wastes. 



4. To minimize adverse effects in the man- 

 agement of organic wastes. 



5. To develop waste management and 

 posal procedures and facilities with 

 high economic feasibility. 



6. To develop technology with hig 

 nomic feasibility for utilization 

 wastes. 



Animal Wastes 



Research was underway in the State agi 

 experiment stations on the characterizatioi 

 tiling, and utilization of animal manures 

 the turn of the century. The Cornell ( N 

 station reported on such research in ind 



the Ohio stal ion in 1907 ,; . 



research was oriented towards the use 



