Soils - Part 9 addressed how soil testing works and the proper method of taking soil samples. The purpose of soil testing is to provide a rational basis for making fertilizer recommendations. The impact of not having the optimum crop nutrition can be yield loss, economic expense and environmental contamination. For many years, it has been widely known that fertilizer recommendations for a given crop often vary widely, depending on who is making the recommendation. With the development of site- specific nutrient management, more emphasis is being placed on soil sampling as a basis for predicting response to applied fertilizer. This lesson will explain several approaches to making fertilizer recommendations and will discuss why recommendations may vary widely when different approaches are used to interpret soil tests.
[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.]
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Soil means different things to different people. To some, soil is something that must be swept away; to others it is just a material that sticks to your shoes. In both instances, soil is associated with unpleasantness. To the engineer, soil is something to be moved, manipulated or built upon. To the farmer and rancher, soil is the source of nutrients which crops use to produce the grain and with it the livestock needed to produce a profit on the farm and in agribusiness. For some of us, soils provide recreation through the development of landscapes or vegetable gardens. For all of us, soils are the medium that provides the food production that has been so successful in feeding our population.
[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.]
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Soil may look simple; however, it is an extremely complex system. It is most often described by its physical, chemical and biological properties and processes. Soil is organic or inorganic; inert or active; living or non-living. Soil contains many organisms: bacteria, nematodes, fungi, earthworms, and small animals. From a physical perspective the soil constitutes the building blocks upon which we walk, construct buildings, grow crops and filter natural and manmade compounds. Soil’s physical, chemical and biological properties and processes interact to enhance its value as a natural resource.
[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.]
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To most gardeners, organic matter is like Husker football—everybody is a fan, but not everybody understands the details of the game. Anyone who uses a soil should have an interest in its organic matter content because so much about the soil is influenced by its organic matter content. In this lesson, we will increase our knowledge about soil organic matter to be able to understand its importance.
[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.]
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Soil pH is one of the most important chemical characteristics of the soil. For example, soil pH can affect availability of plant nutrients. In addition, the soil pH can affect the performance of preemergence herbicides, activity of microorganisms, the need for lime, soil bacteria activity, the best crop to be grown, and other characteristics.
[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.]
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Nitrogen (N) is one of the most abundant elements on earth, and after carbon (C), hydrogen (H), and oxygen (O), it’s the element living creatures need most. The atmosphere over each square foot of the earth’s surface — which is 78 percent dinitrogen (N2) gas — contains approximately 6,000 pounds of nitrogen. However, most of the earth’s nitrogen (98 percent) is in rock, sediment, and soils. The amount of nitrogen in rocks is about 50 times more than that in the atmosphere, and the amount in the atmosphere is approximately 5,000 times more than in soils (Stevenson, 1982).
[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.]
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Phosphorus fertilizers are second only to nitrogen in importance for growing crops in Nebraska; however, the principles affecting efficient phosphorus use are totally different. Nitrogen is a mobile nutrient, both in the plant and in the soil, while phosphorus moves very little in the soil. Additionally, total plant requirements are much lower for phosphorus than for nitrogen. For example, leaves commonly contain 10 times more nitrogen than phosphorus. However, phosphorus is concentrated in the grain so that only about 2.5 times more nitrogen is removed in harvested grain compared to phosphorus.
Potassium (K) is an essential plant nutrient. Next to nitrogen, crops absorb potassium in greater amounts than any other nutrient. It is a vital component of numerous plant functions including nutrient absorption, respiration, transpiration, and enzyme activity. Potassium is unique because it does not become part of plant compounds, but remains in ionic form in the plant. Potassium remaining in plant residues after harvest and in manure are quickly returned to the soil when water leaches through the plant residue.
[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.]
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Sixteen elements are known to be essential for plant growth. These are divided into two groups: macronutrients — those elements used in relatively large quantities and micronutrients — those needed in very small amounts.
Macronutrients | ||
Carbon (C) | Nitrogen (N) | Calcium (Ca) |
Hydrogen (H) | Phosphorus (P) | Magnesium (Mg) |
Sulfur (S) | Potassium (K) | Oxygen (O) |
Micronutrients | ||
Zinc (Zn) | Copper (Cu) | Boron (B) |
Iron (Fe) | Manganese (Mn) | Molybdenum (Mo) |
Chlorine (Cl) |
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[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.]
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During the first seven lessons, we have discussed a variety of topics related to soils, ranging from their formation to how nitrogen reacts in the soil. In Soils - Part 8, we are going to shift gears and discuss some common fertilizers and their characteristics. These will include the common nitrogen and phosphorus fertilizers, as well as many fertilizers that provide micronutrients to the soil. In this chapter, no attempt is made to judge the value of each type of fertilizer.
[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.]
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Soil tests are part of a four-step process of determining and providing nutrients to agronomic crops. The four steps are:
1) soil sampling,
2) soil analysis,
3) result interpretation and decision making, and
4) fertilizer application.
This chapter will focus on Steps 1 and 3 — soil sampling and result interpretation and decision making. It will not examine specific laboratory procedures or address fertilizer application issues. Until very recently, soil testing was conducted on a field basis. Site-specific management and the associated technologies of fertilizer application and yield monitoring are enabling agriculture management to reduce the area associated with each soil test to the subfield level. The article, "Soil Testing and Nutrient Recommendations," from Nutrient Management for Agronomic Crops in Nebraska, includes further information on soil testing.
[This lesson, as well as the other nine lessons in the Soils series, is taken from the "Soils Home Study Course," published in 1999 by the University of Nebraska Cooperative Extension.]
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