老墙土是指整修猪圈墙、牛栏墙、厕所墙、旧屋墙时扒下来的土。墙土里本来就含有一些难溶性的磷、钾等,经过长期的理化作用,便转化为易溶性的速效养分。同时,人们日常生活中的污水、污物以及人畜排泄物渗入土中,其中的含氮化合物经氨化和硝化作用而形成硝酸,进而与钾结合 Old wall soil refers to the renovation of sty wall, noodle fence, toilet walls, the walls of the old house Grilled down the soil. Wall soil already contains some insoluble phosphorus, potassium, etc., after a long period of physical and chemical effects, it will be converted to readily soluble nutrients. At the same time, people’s daily life, sewage, dirt and human and animal waste into the soil, which nitrogen compounds by ammonification and nitrification to form nitric acid, and potassium combined