What is the agriculture developments during Song Dynasty

Compared with the Tang Dynasty, Song made greater development in agriculture. The farm land is 2.5 times larger than that of in the Tang Dynasty, and the production yield is much larger too. The use of farm implements with sharp steel edges began to extend to the whole nation. Special agriculture book Nong Qi Pu recorded all the farm implements at that time which was the most complete book at that time. Construction of sea walls, canels and water tunnels were conducted many times, which created good condition to develop agriculture. For the lack of gains, the Tang Dynasty once ordered to reduce making wines. While in the Song Dynasty, the government encouraged to do so for rich gain stock.