Changes in soil structure and biological activity on some meadow hay plots at Cockle Park,Northumberland

Summary The accumulation of organic matter to form an organic horizon on one of the Palace Leas meadow hay plots has resulted from the effects of ammonium sulphate application over a period of 86 years. Associated with this accumulation is a reduction in biological activity, deterioration in hydrologic conditions and an increase in soil bulk density. The primary cause of the organic matter accumulation has been acidification. The worsening of hydrologic conditions as a result of the development of an organic horizon and soil structural deterioration may encourage fur ther accumulation of organic matter.