The Amount of Potassium Nitrate for Plants

Plant Nutrient Use

• Potassium nitrate contains 13 percent nitrogen and 44 percent potassium oxide. Before applying potassium nitrate to soil, growers should research the amount of nutrients the crops they grow use and then add the amount of potassium nitrate needed to meet the nutrient requirements. Because potassium nitrate contains more potassium than nitrogen, plants that use more nitrogen than potassium might need some potassium nitrate and some additional nitrogen fertilizer. Adding enough potassium nitrate to meet high nitrogen demands could introduce an excess of potassium.

Soil Testing and Nutrient Contents

• Testing the plants' soil is helpful. Different soils contain different amounts of nutrients, which determine the amount of potassium nitrate that may help plants grow. Potassium nitrate is especially beneficial for soil that lacks lots of potassium and a small or moderate amount of nitrogen. Often a university or nursery laboratory can recommend amounts of nitrogen and potassium to add to soil after soil test results are known.

Nutrient Deficiency Symptoms

• Too little nitrogen in soil can cause slow growth and pale or yellowish leaves. A potassium deficiency causes yellowish or spotted older leaves, too. If plants exhibit these nutrient-deficiency symptoms, then adding potassium nitrate may combat the problem.

Safe Fertilizer Use

• Always add fertilizer in amounts equal to or less than its manufacturer instructions because excessive fertilizer can damage plants and cause pollution. For example, too much nitrogen can make plants intolerable for cattle to eat, cause too much leafy growth and lead to not enough flower or fruit production. Fertilizer runoff also gets into bodies of water and causes damaging algae blooms. Potassium nitrate is water soluble and leaches nitrate when gardeners use it in excessive amounts.