Phosphorus Balance on Paddy Soils Reclaimed from the Salinized Waste Land, Northern Jiangsu

Abstract

The present experiments on the reclamation of saline soil by rice plantation were carried out in 1969–1977, in the coastal areas of northern Jiangsu Province. The soils were derived from the loessial deposit of the old Huanghe River, and underlaid by marine mud. Solonchak soils of the experimental areas may be divided into two groups according to their salt content: (l) Heavily salinized soils containing soluble salts 2.5–6 %. Large areas of such soils remain waste, while the depressions of which are covered by salt tolerant plants such as reed, cogongrass, etc. (2) Cultivated saline soils. They are provided with drainage ditches for lowering the water table, and used for barley, wheat or cotton. However, during the drought spring season, plant seedlings usually appear burned by high concentration of soluble salts in surface soil. Cultivated saline soils contain about 0.1–0.2 % of soluble salts. The present experiments were laid on the heavily salinized soils, covering an acreage about 25 hectares.