Historical review of Agronomy both as a discipline and a specialty and its reframing: Taking Agroecology as its core theoretical subject Review on slow-release fertilizer Landscape characters of agricultural ecology system in Huangta small watershed Qingshishan watershed agro-ecology information system and its application with the support of Geographic Information System(GIS) Development trend and enlightenment of overseas agro-ecology Application of ecological thinking in reconstructing traditional agronomy: a case study of agro-ecosystem management as core applied subject Study on the agricultural environmental bearing capacity in the mid-south parts of Hebei Province