As the BBC marks its centenary, Adam Henson and Margherita Taylor step back in time at Cogges Farm in Oxfordshire to look at farming 100 years ago and to chart the radical changes which have shaped our countryside – from the appearance of the first tractor to the changing role of women in agriculture.Adam gets behind some serious horse power to tend the land while Margherita tries her hand at pickles and preserves and discovers how women made their mark beyond the farmhouse kitchen. Farmer Helen Browning, Chief Executive of The Soil Association, reveals the heroines who inspired her while 90-year-old author and retired farmer Bryan Edgley reminisces on how farming has changed in his lifetime.We also meet 10-year-old Isabella in the first of Countryfile's Ramble appeal films whose life has been transformed thanks to her remarkable specially-trained assistance dog Storm, who's helping her with her autism. And Charlotte Smith investigates if trade deals with the likes of Australia could undermine the UK's drive to be carbon neutral.