field- level crop production models responding to 

 various weather sequences, testing and calibrating 

 these for a selected number of varieties of important 

 crop species; and (3) conduct field trials of selected 

 indicator varieties on various soil types in selected 

 climatic sites within the range of adaptability of the 

 species. These trials would serve to calibrate the 

 models, define the range of their reliabilities, and 

 establish the forms in which the weather data should be 

 collected. 



4. Farm and Land-Use Planning for 

 Sustained Food Production 



Increases in world food production must be based on 

 the sustained, productive use of inherently limited 

 land and water resources over time. Unfortunately, 

 erosion and flooding continue to destroy soil 

 productivity and reduce food production in many parts 

 of the world. Poor land and water management increase 

 the uncertainties of food production, while causing 

 damage both upstream and downstream of cultivated 

 areas. 



Farm and land-use planning is essential to increase 

 food production, conserve natural resources, and create 

 an agricultural society with an acceptable quality of 

 life. And, even beyond that, planning must be 

 undertaken for entire watersheds as integrated units 

 for the interaction of forest, range, and cropland, and 

 for the balance between cultivated and 

 municipal/industrial land use. 



Here we describe activities related to farm and 

 land-use planning on which the United States has much 

 to offer. 



Land Classification . Despite land surveys and 

 classification that go back many decades, some 75 

 percent of the worlds land has not yet been 

 inventoried. Even where soil survey information is 

 available, it is often not used for planning purposes. 



Methods for developing land-use classification from 

 soil survey information are well known. The systems 

 developed by FAO and various countries are somewhat 

 different but comparable. The U.S. Soil Taxonomy, 

 derived from work at USDA (1975), is particularly 

 useful, although it calls for less than optimum amounts 

 of weather data for making decisions on land-use 

 capability. 



Water and Soil Conservation . Rainfed agriculture 

 is the principal source of the world's food. History 

 is replete with examples of the disastrous effects that 

 failure to control erosion and sedimentation has had on 

 human welfare. Unwise cropping practices have resulted 



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