Everyone knows that an excess of the above salts in a soil is injurious to plants, and if the percentage exceeds certain limits the plants are destroyed. One is often asked how much salt may a soil contain and yet grow good crops. This question is by no means as simple as it looks, because it usually happens that the three salts under consideration are found in association possibly with others. The proportions of each will vary so much that it is probably impossible to decide to what extent each one is responsible for injury. The farmer knows that soils are derived from the decomposition of rocks, and anything which the soils contain, apart from the organic matter, must be found in the rocks from which they are derived, although usually in very different chemical forms. The granite and diorite rocks from which the soils in the agricultural areas are chiefly derived, contain among other things certain compounds of sodium, calcium, magnesium, and potassium. From these original, insoluble chemical compounds soluble ones formed during the process of decomposition of the rocks. Some of these are good for plants, while others are injurious if in excess of certain limits. Some are much more soluble in water than others. If there is a heavy rainfall, the rain washes out the soluble salts as they are formed, so that we do not have the same accumulation in wet districts as we do in country with a limited rainfall. If we take any area of land in the eastern Districts, say near Beverley, or York, or Northam, we find the country in its natural state covered with forest or scrub growth, which largely absorbs the limited amount of rain which falls, and salty patches are rare and confined to special hollows receiving drainage, or surface water. This is because the soluble salts are more or less evenly distributed throughout the soils, on the hillsides through the whole extent of the country.

Everyone knows that an excess of the above salts in a soil is injurious to plants, and if the percentage exceeds certain limits the plants are destroyed. One is often asked how much salt may a soil contain and yet grow good crops. This question is by no means as simple as it looks, because it usually happens that the three salts under consideration are found in association possibly with others. The proportions of each will vary so much that it is probably impossible to decide to what extent each one is responsible for injury. The farmer knows that soils are derived from the decomposition of rocks, and anything which the soils contain, apart from the organic matter, must be found in the rocks from which they are derived, although usually in very different chemical forms. The granite and diorite rocks from which the soils in the agricultural areas are chiefly derived, contain among other things certain compounds of sodium, calcium, magnesium, and potassium. From these original, insoluble chemical compounds soluble ones formed during the process of decomposition of the rocks. Some of these are good for plants, while others are injurious if in excess of certain limits. Some are much more soluble in water than others. If there is a heavy rainfall, the rain washes out the soluble salts as they are formed, so that we do not have the same accumulation in wet districts as we do in country with a limited rainfall. If we take any area of land in the eastern Districts, say near Beverley, or York, or Northam, we find the country in its natural state covered with forest or scrub growth, which largely absorbs the limited amount of rain which falls, and salty patches are rare and confined to special hollows receiving drainage, or surface water. This is because the soluble salts are more or less evenly distributed throughout the soils, on the hillsides through the whole extent of the country.

When the land is ring-barked, cleared and broken up, natural vegetation no longer utilises the larger proportions of the rainfall, which entering the ground dissolves more or less of the salts, and as it soaks through the soil and gradually flows down the hillsides to the lower land, and the water carries the salts with it. In the summer time heavy evaporation takes place from the lower lands, the salt being left behind. After a few years this naturally results in large increase of salts in the hollows, and they are known as salt pans, samphire flats, or salt lakes.

When the land is ring-barked, cleared and broken up, natural vegetation no longer utilises the larger proportions of the rainfall, which entering the ground dissolves more or less of the salts, and as it soaks through the soil and gradually flows down the hillsides to the lower land, and the water carries the salts with it. In the summer time heavy evaporation takes place from the lower lands, the salt being left behind. After a few years this naturally results in large increase of salts in the hollows, and they are known as salt pans, samphire flats, or salt lakes.