Introduction to Turfgrass Management
Introduction to Turfgrass Management CS 200
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This 5 page Class Notes was uploaded by Demarco Hansen on Thursday October 15, 2015. The Class Notes belongs to CS 200 at North Carolina State University taught by Daniel Bowman in Fall. Since its upload, it has received 22 views. For similar materials see /class/223658/cs-200-north-carolina-state-university in Crop and Soil Sciences at North Carolina State University.
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Date Created: 10/15/15
Soils and Cultivation Soils are defined as the loose surface of the earth or that material which nourishes and supports growing plant orthe material which supports foundations roads etc But common sense tells us that soils are the solid medium in which plants grow Functions of Soils A Plant support A Supplies H2O Oxygen A Supplies Nutrients A Protection from stresses A Magic symbiotic relationships A unknown chemicalssubstances Where Do Soils Come From Parent Rock breaks down into smaller rocks then gravel then further into sand sized particles Sand is further broken down into silt sized particles To this point it is mainly a matter of subdividing the original parent rock This means that the chemical composition of sand and silt is very similar to the parent rock Clay on the other hand is very different In addition to being much smallerthan the other particles it has unique structures and is unlike the parent rock material Clay has a very large surface area surfaces are where things happen in a soil Clay is chemically very reactive and dominates the soil in terms of its effect on soil processes Weathering is the process that converts parent rock material into a soil It is a very long term process Several different components contribute to weathering including the type of parent material climate temperature rainfall freezethaw cycles plants and microorganisms Soil Components A Solids sand silt and clay organic matter Pore spaces waterfilled airfilled Balance of Aeration and Moisture Characteristics of Soils A Physical Properties A Chemical Properties Nutrition A Reactivity pH A Organic Matter A Biological Activity Soil Class Soils are usually composed of several or many separates The proportions of the component separates determines the soil class For example a soil might contain 20 clay 40 silt and 40 sand This mixture is classi ed as a loam based on the soil textural triangle Soil texture is very important but so is soil structure Soil Structure How the soil particles are arranged and associated with each other is called soil structure Individual particles aggregate together glued by attractive forces and by microbial activity plus organic matter Soil structure can improve a poor soil texture Soil Porosity Pores exist between individual soil particles These may be either large unac or small IIIIL which is largely determined by the size of the individual particles and aggregates Pore size is important because it determines permeability and percolation rate Soil Percolation In ltration A Percolation is how quickly water moves through a soil A Infiltration is how quickly water moves into a soil from the surface A Both depend on pore structure Both are important considerations in water management and drainage design Soil Porosity Macropores are large enough to drain after being lled with water from rain or irrigation Air enters after water drains which is very important for root health A Micropores are small enough to hold water against the downward force of gravity This water is what the plant uses Soil Aeration Soil aeration is one ofthe most important factors affecting turf health Poor aeration can lead to root death The black layer often found in putting greens is due to poor aeration A You can improve aeration by encouraging good soil structure and by cultivation Soil Compaction Soil compaction occurs when forces such as tire or foot traffic compress the soil and alter pore structure Bulk density increases macropores decrease in ltration decreases aeration decreases Compaction is most a problem when soils are wet A similar problem is caused by shearing forces or puddling of soil surfaces Soil Compaction A Soil compaction is 39 b 39 quot a traffic quot 39 a soils and cultivation Soils can be modi ed to resist compaction but it s not as simple as it sounds The old dogma about adding a little sand to lighten a heavy soil isjust plain wrong But pure sands are great for resisting compaction A Cultivation is practiced in many forms Soil Cultivation A Cultivation before planting is pretty easy as long as the soil is not too wet Cultivation after planting is the basis of an entire equipment industry Pieces include hollow and solid tine aeri ers water injectors air injectors slicers spikers wing blades What does cultivation do The idea is to increase the surface area or increase the macropore space to facilitate in ltration and percolation and to increase air diffusion into the soil Core cultivation especially solid tine can create compaction around the holes A plow layer can occur when same tine depth is always used Soil Cation Exchange Capacity CEO is a measure of how negatively charged a soil is and is related to clay content Sands have very low CEC s silts somewhat higher but clays usually have very high CEC s Cation exchange sites occur at the surface ofa soil particle and are negatively charged They attract cations such as NH4 K Ca Mg etc CEO is important because it represents a reservoir of some nutrients for the plant Cations stick fairly tightly to the sites but on occasion come offand go into solution in the soil water These cations can then be absorbed by the plant roots Soil Reactivity Soil reactivity is a measure of how acid a soil is or soil pH Soil pH affects root function and nutrient availability and must be monitored by the turf manager A Most soils have pH s between 5 and 9 with somewhere around 65 being ideal for most grasses A Many of our soils are quite acid Why Soil pH Many of our soils are highly weathered This means that most of the basic cations K and especially Ca and Mg have been washed out of the soil They are replaced by protons H which are the basic unit of acidity A This contrasts to younger soils which are less weathered and more neutral Soil pH A How do we control soil pH Ifthe soil is acid we need to raise the pH towards neutral The most common way is to lime the soil Lime is calcium carbonate or calcium plus magnesium carbonate The amount required will depend on the soil and should be determined by a soil analysis A Lime granule size is important also Lime can be applied either preplant high rates can be used all at once or to a mature turf But then lower rates are necessary Do not apply more than 4050 pounds of lime perthousand square feet to an existing turf Water in after application Several to many applications may be required Soil Nutrients A C H 0 from the air water A The rest from the soil A C HOPKNS CaFe ClZn MoB CuMn Mg A See Hopkins Cafe Closin Mob Comin with Machine Guns A Many nutrients are in adequate supply in the soil and do not need to be added Some are readily lost from the soil or are present but not available These need to be added as fertilizer N P sometimes K Fe rarely S The only way to tell ifyour soil has special needs or even routine needs is by a soil test using a reputable lab Home chemistry kits are not usually practical or accurate Samples should represent an entire use area Collect 12 or more cores 4 6 deep and mix them together A total of about a quart is usually more than enough for the lab
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