manual of classification agricultural and forestry research revision vi classifications used in the current information system issued by us department agriculture cooperative state education extension service science resources development december 1998 2 contents topic area problem subject investigation field descriptions 3 i natural environment rpas 101 135 ii plants their systems 201 216 iii animals 301 315 iv engineering support 401 405 v food non products processing quality delivery 501 512 economics markets policy 601 611 vii human nutrition safety health well being 701 723 viii family community 801 805 ix administration communication 901 903 4 soil appraisal 102 plant water nutrient relationships 103 management saline sodic soils salinity 104 protect from harmful effects elements 111 conservation efficient use 112 watershed protection forest
