FOR 2060 1st Edition Lecture 9Outline of Last Lecture I. NitrogenII. The Nitrogen CycleA. Nitrogen FixationB. Nitrogen Mineralization C. Nitrogen Immobilization Outline of Current Lecture III. Nitrogen CycleA. AmmoniumB. Nitrification C. Denitrification IV. NutrientsV. LoggingCurrent LectureIII. Nitrogen Cycle Ammonium is an inorganic form of nitrogen that plants are able to take up. It is a cation (positive charge) and soil has a negative charge, so ammonium adsorbs (is attracted) to the soil particles. There is very little leaching because of the strong association between the ammoniumand the soil. It can also be taken up by plants since this is a common source of available nitrogen. The ammonium can also volatize at a high pH. Volatilization only occurs at high pH andcause nitrogen gas and water to be produced. Ammonium can also be rapidly converted to nitrate under most conditions; therefore it does not accumulate in the soil. Nitrification is a two-step process. First the ammonium is converted to nitrite by the nitrosomonas bacteria; then the nitrite is converted to nitrate by the nitrobacter bacteria. Nitrate has a negative charge so it will repel the soil, which is also negative. This makes the nitrate very mobile and highly susceptible to leaching and denitrification losses. It is common in plant uptake and the most common mineral form of nitrogen in most soils. Leaching of nitrate can be a major problem. The nitrate is very mobile so it moves and can move into the waterways, causing human health problems (blue baby syndrome). These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Denitrification is an anaerobic process that plants can facilitate when they have depleted all of their oxygen. It happens a lot in wetlands, where there is saturated soil, high organic matter, and a high pH. It can be a major pathway of nitrogen loss. IV. Nutrients The biggest pools of nutrients are in the soil. The nitrogen is in the overstory, understory, forest floor, and in the mineral soil. The bulk of the nitrogen is stored on the forest floor and in the mineral soil. In trees the most nitrogen in the leaves, which fall to the ground and create litter on the forest floor. Management practices that erode the litter and soil have the potential to greatly reduce the nutrient capital of ecosystems. V. Logging In the early days of logging only large, sound logs were taken out. The canopy, branches, and less-valuable timber were left in place. There was a long rotation time because you are leaving alot of the trees. But as demand increased for forest products this practice changed by increasingthe intensity of production. There were shorter rotations, whole tree harvesting, complete tree harvesting, and clear-cutting. Clear-cutting or stem harvesting is a very common practice today. All stems are removed from the site and the logging slash (tops and branches) is left behind. A long rotation gives the site time to recover, but a short rotation does not give the soil time to recover. The short rotation reduces the productivity of the site. Stem harvesting allows the site time to recover so the site remains productive. Whole tree harvesting degrades the site becausemore and more nutrients are removed each time and the site is not given time to recover. As you shift from stem harvesting to whole tree harvesting you see a major decline in nitrogen, phosphorous, potassium, and calcium in the