Soil fertility investigations on farmers' fields [antikvár]

lUTROroPTION During the last tvo deoades PAO has assisted memter oouptriea in oarrying out large soalo soil fertility surveys with the purpose of increasing agricultural production quickly by the introduction or expansion of the use of mineral fertilizers. The first step in such operations is to find out for each area which types and quantities of fertilizers are required under the given fanning conditions in order to obtain substantial yield Increases in suoh a way that fertilizer use is profitable and econo-Dically sound. The method followed in this voTk was originally oonoeived in India around 1947 imder the name of "simple trials on farmers' fields" (l2) and has since been used in many countries as it was found to be the quickest and most effective method to obtain the required large soale information on possible crop increases and fertilizer needs. Before this time, small unreplioated trials on farmers' fields had already been oonduoted in Xeatem countries for spooial purposes. In Germany this type of experiment, called atreirversuobe ("dispersed experiments") had been used exten-¦ivoly for testing now plant varieties under looal farm conditions. Alternatively trials of this kind WOM used for the calibration of soil test data and in general for testing the praotioal value of new methods. It was important to know how •ffeotive a new method, usually developed on the well-tended fields of experimental ¦tations, would bo if applied on average farmers' fields. When this type of large-scale fertiliser experimentation was Initiated in India, many data on fertilizer responses were available in several tropical countries, for oash orops as well as for food orops. However, these data for food orops originated almost exclusively from experimental stations, where growing conditions wore quite different from those on farmers' fields. Purtheimore, in a large country like India there were not nearly enough experimental stations to cover even the noat important ¦oil types and farm conditions. TAider those oiroaaastanoes and under the ever-inoreasing pressure for more food produotion, simple fertilizer trials on farmers' fields proved to be a quick and direct means of developing fertilizer recommendations whioh are valid and eoonoaioally profitable under existing farm Conditions. This makes possible the immediate use of fertilizer and increased yields without necessitating large ohangea in farm praotioea. Since this start in India, dispersed experiments have been used inoroasingly under the auspices of PAO in the less developed areas of more than 40 oouatries, assisting Member Qovemments in laying a sound basis for their fertilizer polioy. It is typical of the present sittiaticn that in the 1969 Conference of Member Nations whioh guides the work of PAO, fertilizer use and fertilizer polioy were mentioned ¦ore frequently by the cotintry delegates than any other aspeot of agricultural development. At the time this guidebook is written, fertilizer trials and demonstrations laid out and harvested on faraers' fields by PAO-guided projects number between 30,000 and 40,000 eaoh year. Considering the great number and wide distribution of these operations it is surprising how little the principle and method of dispersed experiments and its great merits for large-scale development work is known and recognized in aoademio circles. Hardly any of the young specialists with excellent university training who join PAO know anything of the principle of dispersed experiments nor of their present application. Nearly all beoome enthusiastic when they learn how this method oan oontribute to the solution of problems whioh ooncem huge areas of the less developed regions.