The Effect of Acid Soil Soils with a pH of less than 7.0 are acid. The lower the pH, the more acid the soil. When soil pH falls below 5.5, plant growth is affected. Crop yields decrease, reducing productivity. Soils provide water and nutrients for plant growth and development. Essential plant nutrients include phosphorus, nitrogen, potassium, and sulfur. Plants require other elements such as molybdenum, in smaller quantities. Some elements e.g. allumunium and manganese, are toxic plants. Nutrients become available to plants when they are dissolved in water. Please are not able to take up phosphorus, nitrate, potassium, and sulfate ions in solution. The solubility of nutrients changes with pH. In acid soils, (low pH), molybdenum become less soluble and aluminium becomes more soluble. Therefore, plant growth may be affected by either a deficiency of molybdenum or too much aluminium. Both crop and pasture plants are affected by acid soils. There may be a range of symptoms. Crops and pastures may be poorly established resulting in patchy an uneven growth. Plant leaves may go yellow and die at the tips. The root system of the plant may be stunted. Crop may yield less. Plant vary in their sensitivity to low pH. Canola and lucerne are very sensitive to acid soils so they do not grow well. Lupins and triticale are tolerant to soils of low pH so they still perform well. Land can become unproductive if acid soil is left untreated. Incorporating lime into the soil raises the pH. Therefore, liming soil can reverse the effects of acid soil on plants and return a paddock to productivity. "Therefore, plant growth may be affected by either a deficiency of molybdenum or too much aluminium." (Paragraph 4) The underlined word is closest in meaning to ....

Question

The Effect of Acid Soil

Soils with a pH of less than 7.0 are acid. The lower the pH, the more acid the soil. When soil pH falls below 5.5, plant growth is affected. Crop yields decrease, reducing productivity.

Soils provide water and nutrients for plant growth and development. Essential plant nutrients include phosphorus, nitrogen, potassium, and sulfur. Plants require other elements such as molybdenum, in smaller quantities. Some elements e.g. allumunium and manganese, are toxic plants.

Nutrients become available to plants when they are dissolved in water. Please are not able to take up phosphorus, nitrate, potassium, and sulfate ions in solution.

The solubility of nutrients changes with pH. In acid soils, (low pH), molybdenum become less soluble and aluminium becomes more soluble. Therefore, plant growth may be affected by either a deficiency of molybdenum or too much aluminium.

Both crop and pasture plants are affected by acid soils. There may be a range of symptoms. Crops and pastures may be poorly established resulting in patchy an uneven growth. Plant leaves may go yellow and die at the tips. The root system of the plant may be stunted. Crop may yield less.

Plant vary in their sensitivity to low pH. Canola and lucerne are very sensitive to acid soils so they do not grow well. Lupins and triticale are tolerant to soils of low pH so they still perform well.

Land can become unproductive if acid soil is left untreated. Incorporating lime into the soil raises the pH. Therefore, liming soil can reverse the effects of acid soil on plants and return a paddock to productivity.

"Therefore, plant growth may be affected by either a deficiency of molybdenum or too much aluminium." (Paragraph 4)

The underlined word is closest in meaning to ....