WASTES IX RELATIOX TO AGRICULTURE AND FORESTRY 



71 



at a number of locations on the Great Plains soon 

 after the turn of the century (77) . 



The first intensive research in this practice was 

 started under cooperation between the U.S. De- 

 partment of Agriculture and the Nebraska agri- 

 cultural experiment station in 1937. Cooperative 

 research on this use of plant residues was under- 

 way in Idaho, Iowa, North Dakota, South Caro- 

 lina. Texas, and Washington by the early forties. 



The research proved conclusively that adequate 

 residue cover is an effective use for this waste in 

 controlling wind and water erosion (139) . 



Use of plant residues as a mulch affected the 

 chemical, microbiological and physical character 

 of the soil surface. 



Leaving crop residues on the surface may in- 

 crease or depress yields. Proper residue manage- 

 ment requires maintaining an adequate supply of 

 soil nitrogen, controlling weeds, and adapting suit- 

 able cropping sequences. 



Eesearch has developed machinery capable of 

 effectively managing residues on the soil surface 

 and of planting field grains and so} T beans directly 

 into deep mulch without prior tillage. 



Eesearch on chemical weed control has greatly 

 abetted research on the feasibility of stubble mulch 

 farming. 



Plant residues do sometimes aid in the carryover 

 of crop diseases and harmful insects. Eesearch has 

 not yet solved these problems inherent in the use 

 of mulches. 



Trash in Forests 



As pointed out in "Organic Wastes'' in appen- 

 dix II, some 25 million tons of logging debris are 

 left in the woods annually. This is a serious fire 

 hazard. Eesearch is underway to develop ways of 

 disposing of this trash alternative to controlled 

 burning, but the probabilit}' of discovering an eco- 

 nomically feasible method is not bright. Burning 

 costs only $1 per ton; chipping costs $12 a ton. 



Processing Wastes 



In "Organic Wastes'' in appendix II, data were 

 presented indicating that the annual effluent of 

 organic wastes from the pulp, paper, and wood 

 fiber industry was equivalent in BOD to that 

 the raw sewage from a population of 216 million 

 people. It is obvious that research towards devel- 

 oping processes that would lessen such waste pro- 



duction would be an important contribution to 

 abatement of stream pollution. 



Over the past 25 years, many of the proce- 

 steps in the manufacture of pulp paper and wall- 

 board have been studied towards better recovery 

 of byproducts and consequent decrease in stream 

 pollution. In recent years, pulping factories have 

 begun to use wood chips from sawmills and veneer 

 mills. This use of a byproduct is now involved in 

 25 percent of all pulp produced in the United 

 States. In kraft pulping, chemicals are now recov- 

 ered and oxygen-depleting substances are removed 

 by sedimentation to minimize stream pollution. 

 Wastes from the older sulfite plants are still a 

 problem. 



In newly built sulfite mills, use of the mag- 

 nesium-base pulping process developed by forest 

 products research eliminates much of the polluting 

 effluent (123). A new polysulfide modification of 

 the kraft process results in greater pulp yields, less 

 waste, and reduced air and water pollution. 



Cheese whey fermentation processes that lessen 

 amount of polluting eilluent have been developed, 

 and are in industrial use. The first process that can 

 successfully dry the acid cottage cheese whey has 

 been developed recently (51). This process lessens 

 waste effluent and is being rapidly utilized. 



A technique for recovering sugar from pear 

 processing wastes has been developed, enabling the 

 recovered syrup to be used for canning. 



A process for recovery of feed and fertilizer 

 values from chicken feathers was developed and 

 is in general use (28) . 



Processes for decreasing the amount of wastes 

 from wool scouring have been found (J+l. 4 ! 



The cost of farm and ranch produce and, par- 

 ticularly, timber products is such that every effort 

 must be made to improve technology that increases 

 product yields and reduces wastes. Since these 

 wastes have potential economic value for produc- 

 tion of boards, paper, animal feeds, and chemicals. 

 the research problems are not so much ones of 

 waste disposal or elimination for esthetic r 

 as they are of finding and developing products 

 high economic value. Thus, a large part o\ 

 product development research in the TJ.S irt- 



tuent of Agriculture and the State agricultural 

 experiment stations ultimately contributes to - 

 hit ion abatement. 



