摘要：Farm ers and lo cal de vel op ment or gani za tions around the worlduse and pro mote a va ri ety of tech nolo gies to in crease foodproduction. But the high cost of in or ganic fer til iz ers and otherag ro chemi cals of ten drives farm ers to rely on lo cally avail ableresources in stead of pur chased, ex ter nally pro duced in puts.So- called low ex ter nal in put ag ri cul ture (LEIA) has spread rap -idly to dif fer ent parts of the globe as a chal leng ing al ter na tiveto—or, more fre quently, a com ple ment to—Green Revo lu tiontech nolo gies (see 2020 Vi sion Brief No. 55). LEIA farm ing typi -cally re lies on cover crops, ani mal ma nure, and im proved fal low man age ment to main tain soil or ganic mat ter con tent; em ployscon ser va tion meas ures (ter races, wind breaks, hedges) to con trolsoil ero sion; and ap plies cul ti va tion meth ods (con tour farm ing,mini mum till age, in te grated pest man age ment [IPM]) to en -hance en vi ron mental out comes while con trib ut ing to house holdfood se cu rity. The com mon ele ment among these prac tices isthat farm ers of ten es chew ag ro chemi cals and other off- farm in -puts, and in stead de velop in te grated crop ping and live stocksys tems—in clud ing agroforestry- based sys tems—that per mitim proved nu tri ent cy cling and bio logi cal con trol of pests anddis eases. The goal of pol icy, re search, and ex ten sion should be to help LEIA farm ers achieve "sus tain able in ten si fi ca tion,"which re fers to the si mul ta ne ous in crease in re turns to land andla bor (in the short run) and the main te nance of soil nu tri ent bal -ances (in the long run).
