In total, during the 15-year period between 1989 and 2004, approximately $100 million in grants were allocated to IPM projects in Asia that used the FFS approach under the guidance of FAO There are two major reasons why it is difficult to make generalisations about the costs and benefits of IPM field schools. وإجمالا ًوخلال فترة الخمسة عشرعامًا بين 1989 و 2004 خُصِصَ ما يقارب من 10 ملايين دولار لبرامج مكافحة الآفات في آسيا والتي أستخدمت تقنيات مثل مدارس الحقل للمزارعين تحت أشراف منظمة الأمم المتحدة للغذاء والزراعة.