As as for purpose of this invention it is possible, to manufacture with simple method, it makes the medicinal effect of the agricultural chemical active ingredient show at the same time over long term, it means that decreasing environmental load, spreading to the whole paddy field uniformly the chemical injury which is pulled up by the agricultural chemical active ingredient the granular agricultural chemical formulation which or it can lighten prevent, due to simple spreading method offers the possible uniform diffusivity granular agricultural chemical formulation. As a uniform diffusivity granular agricultural chemical formulation, it contains with the acidic agricultural chemical active ingredient and the cationic surface active agent and the basic substance, it contains the non collapse type granular agricultural chemical composition which does not collapse at underwater within 30 minutes, mass ratio of the particle above grain size 3mm 80 mass % the gradation which is above and immediately after dropping to the water surface, has the character which floats, but the granular composition which within 30 minutes collapses in the water surface is offered. As for the acidic agricultural chemical active ingredient things such as pKa2 - 7, in addition as for the cationic surface active agent gels at underwater, or or those which show swelling property are desirable.本発明の目的は簡便な方法で調製することができ、且つ長期にわたり農薬活性成分の薬効を発揮させるとともに、環境負荷を低減し、農薬活性成分により引き起こされる薬害を軽減又は防止しうる粒状農薬製剤を、簡便な散布法により水田全体に均一に拡散させることが可能な均一拡散性粒状農薬製剤を提供することである。均一拡散性粒状農薬製剤として、酸性農薬活性成分とカチオン界面活性剤と塩基性物質とを含有し、30分以内には水中で崩壊しない非崩壊型粒状農薬組成物を含有し、粒径3mm以上の粒子の質量割合が80質量%以上である粒度分布と水面に投下した直後には浮遊する性質を有するが、30分以内に水面で崩壊する粒状組成物が提供される。酸性農薬活性成分はpKa2~7のものが、またカチオン界面活性剤は水中でゲル化するか、あるいは膨潤性を示すものが好ましい。
