Applied Soil Physics
Applied Soil Physics CSS 340
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This 57 page Class Notes was uploaded by Rosalind O'Connell on Saturday September 19, 2015. The Class Notes belongs to CSS 340 at Michigan State University taught by Alvin Smucker in Fall. Since its upload, it has received 90 views. For similar materials see /class/207206/css-340-michigan-state-university in Soil Science at Michigan State University.
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Date Created: 09/19/15
Soil Heterogeneity among profiles and roots WELCOME to Applied Soil Physics CSS 340 Soil Physical Conditions and their Control of Sustainable Soil and Plant Production Row Crops Turfgrass and Cellulosic Biomass Includin Environmental Applications Spring 2012 Applied Soil Physical Properties CSS 340 2 Credits 212 Spring 2012 Instructors Wei Zhang and Alvin Smucker Telephone 3550271 ext 1251 Email or telephone for best time appointments Email smuckermsuedu Prerequisites CSS 210 and working knowledge of math and physics If this knowledge is missing then read Appendices B and C pp 379 410 in Soil Physics text book by Scott located in Reading Room on 2nd oor of PSSB and Angel Website for CSS340 Ask the instructor for additional background reading materials This course meets for 90 minutes from 1240 to 210 in room 148 PSSB Mondays and Wednesdays Selected Readings gt Text Agricultural and Environmental Soil Physics by Daniel Hillel gt Website sources of all lectures and assigned readings plus books in the PSSB Reading Room on 2nd oor Course Outline Powerpoint lecture notes and Laboratory Sessions and Guidelines for Writing Laboratory Reports and other linkages to websites are on the above Angel website for CSS340 Course Obiectives 1 CSS340 is designed to identify key physical properties that control the transport of soil water solutes organics gases and thermal conditions affecting plant growth and development 2 CSS340 is designed to introduce students to a range of soil physical property measurements important for agricultural environmental and turf grass majors in a manner that assists students to solve real world problems 3 Ecosystem management modi cations of soil physical heterogeneity Recent journal articles and book publications Course Evaluations Quizzes Given at the beginning of selected class lectures 15 Therefore be prepared for a possible quiz before each class lecture by reading the assigned reading for each lecture before each class lecture Exam 1 Lectures 15 25 Laboratory Sessions Reports and Problem Sets 25 Final Exam Lectures 6 12 lab sessions and reading assignments 35 Lecture 1 10 Introduction 11 12 13 14 15 16 17 18 19 Historical First soil science book Civilization depends on the soilplant atmosphere continuum for survival Soil is the foundation matrix of life Concealment of roots Course goals Three general soil stresses to plant growth De nition of Soil Physics SoilPlantAtmosphere Continuum SPAC 10 Introduction to Applied Soil Physics 11 Historically the importance of soil has been expressed by many civilizations Ancient Hebrews reported that God created us from the components of the soil Clay catalysis of protein synthesis Ancient Greeks considered soil and water are two of the four primary constituents of nature earth wind water and re 12 In 1883 Dokouchow was the author of the rst Soil Science book Russian Tchernozim So how does the soil t into this Whole paradigm 13 Soil is the foundation matrix of life Unfortunately even though we know more about the soil many in our postmodern societies take the SPAC much too casually 14 Today as throughout history we ultimately depend upon the dynamic nature of the soilplant rootatmosphere continuum SPAC for our survival Ironic dilemma of SPAC is that 80 of what we know about plants is based upon the above ground portions of the plant At least half of all photosynthetic carbon is used below ground in the soil and by dark respiration 15 Concealment of plant roots by the soil introduces an obvious complication into the SPAC studies of root and soil relationships Furthermore dif culties arise from the random and highly variable nature of the roots in soil profiles One of the paradoxes of soil and the plant root system interrelationships is that the very environment which supports root growth often becomes too hostile and actually inhibits normal root function Unfavorable soil conditions restricting the performance of roots are a common reason why crop yields and plant quality are much lower than their potential maximum based upon their genetic characteristics incident solar radiation and thermal conditions permit RS Russell 1980 The Plant Root System Their Function and Interaction with the Soil Example Roots of the same plant often experience widely contrasting soil environments which are subject to hourly changes by the weather and with soil depth These environments often negate genetic differences and completely alter species dependent rooting patterns of the two environments the atmosphere above ground and the soil in which plants grow the soil is much more complex Weaver 1926 the soil 111 How many cells are n V552quot 80 of the reductions in plant productivity for 8 different crops resulted from physiochemical soil stresses John Boyer Science 1982 Breman 2002 has identi ed annual yield losses among most major cereal crops exceed 10 billion due to drought Breman also demonstrates accompanying land degradation resulting from inadequate vegetative cover on doughty soils adversely affects 25 of the world39s total land area and 19 of the world s population Reality is that the grim gure of 940 million people who experience daily hunger andor starvation mandate extraordinary science that will bring releaf to the human race and environmental sustainability to soil water and other natural resources What is our responsibility as global citizens to improve the world food supply and other plant life on this planet Iillious Billions Population increment 80 397 8 60 6 4O nnuul lllLl39LllldllK l39opulmmn we 20 Population size 2 0 I I I I r 1 39 r0 1850 lilll 1 l 11 1750 1800 1900 1950 2003 2033 Longterm world population growth 17502050 Source United Nations Population Division The World at Seven Billion Dr Wittwer former Director of the Michigan Agricultural Experiment Station AgBioResearch Station at MSU predicted maize yields could approach 900 buac That s 50400 lbsac 56500 kgha State average for Michigan is 145 buac 1600 Of potential or 16 of predicted potential yield Record yields in Iowa approached 356 buac 4000 0f predicted maximum yields For Example Yields per acre of Phaseolus vulgaris dry beans in Michigan Statewide yields 1270 lbs per acre 21 bua 1984 Research yields 4670 lbs per acre 5230 kghectare 368 greater than current yields 120 podsplant Klp Protein 41 Cullers Irrigated with 02 to SW 03 inchesd July September on s01 Mlssourl with clay pan below root zone Mr Cullers produced 139 bu soybeans per acre Average soybean yield in Michigan is 40 bua 8340 pounds per acre 9341 kgha Mr Cullers also produced 346 bu 20760 pounds of corn grain per acre Roots of maize which recolonize previous soil macropores developed by maize roots of previous crops develop many more disease lesions arrows in B than maize roots which occupy bulk soil A or recolonize root induced macropores RIMs developed by alfalfa species Healthier roots of maize following other crops may be one of the major factors contributing to the positive contribution referred to as the rotation effect Digital microcamera with lights for recording root numbers intersecting clear plastic minirhizotron tubes in soils Electronic controller and digital Video camera for minirhizotron digital camera Roots of maize which recolonize previous soil macropores developed by maize roots of previous crops develop many more disease lesions arrows in B than maize roots which occupy bulk soil A or recolonize root induced macropores RIMs developed by alfalfa species Healthier roots of maize following other crops may be one of the major factors contributing to the positive contribution referred to as the rotation effect 1 A No of roots mquot d 400 300 200 100 710039 200 300 400 Kalamazoo loam KBSLTER Alfalfa O2m O4m 06m O8m 40m Growth Death 1989 1990 1991 1992 1993 2000 1500 5 I g 1000 o I 500 39 I I I f I I I 00 01 02 03 04 05 06 07 08 MPa Ci 0 u L Lolly 2 Rootsm 2 t 0 kPa O 50 cm A D 80 cm 1500 A 100 cm moo 23 of roots died soo o I I I F I I I 00 01 02 03 04 05 00 07 08 Water potential MPa Excellent soil water contents cause roots to grow and absorb water and nutrients Dry soils kill plant roots 16 Course goals 1 To identify for you those soil physical stresses which restrict the growth of plants 2 To identify and discuss problematic areas which can be ameliorated so that plant growth is leastlimiting and how soils retain the maximum nutrient and water contents without contaminating the environment As an educator I have two goals in this course First goal 1 Provide considerable information and a few principles which will enable you to become a satis ed professional who assumes 0 Information eg learning to remember 0 Develop basic knowledge and experiences 0 Wisdom that transforms information into knowledge and gives you an opportunity to gain considerable con dence in the discipline of soil biophysical and hydrological sciences Second goal 2 Develop correct prognoses during your identi cation of speci c problem areas encountered in the elds lawns golf courses parks grassland and forested areas 17 Three general soil stresses to plant growth 1 Biological stresses Includes disease caused by a biological or causal organism Types a Allelopathic suppression of plants b Competitive weedsintercropping c Symbiotic Rhizobium nodules 2 Chemical stresses Shortage or imbalance of nutrients or toxic levels of some heavy metals or nonessential elements in any region of the soil a Crop yields are frequently limited by inadequate supplies of essential nutrients b Soil chemists have discovered ways of alleviating these chemical stresses during the past 50 years by using the proper balance of inorganic fertilizers crop rotations with legumes high biomass cover crops and organic amendments c d No doubt that fertilizers have been the greatest contribution by soil science to the historic increases in crop production Yet it has led to local contamination of surface and ground waters particularly when excessive runoff and percolation within the soil pro le that leads to leaching More recently emphasis has been focused toward lower fertilizer inputs and minimum tillage with the goal of developing more sustainable agricultural systems e One should recognize however that fertilizers eliminate only one natural soil limitation of crop production Consequently other limiting components of the soil require modi cations when nutrition is adequate i The next challenge for organic farming is the excessive tillage required to control weeds pests and plant diseases 3 Physical stresses gaseous liquid or solid limitations to root growth and plant productivity a Causes are heavy machinery frequent traf c and excessive tillage when soils are too wet b During the next 12 to 14 class periods and two laboratory exercises we will identify a portion of these physical stresses Unavailable water Hygrusmplc Wallar E 39m to plants 3 Fur pic Eue glent E an Wllld i P l i E 1 III w t g 1 I 5quot aer Avallable nu E water to g 391quot Field Emuw plants E rawliailmalwmrEr39 V cm I mm mm 11min may ll 1 Water Fllllrn TII39I Il mess m m Relationship between soil water film thickness and moisture tension or matric potential 4PM Source Physical Geography net Within the soil system the storage of water is influenced by several different forces The strongest force is the molecular force of elements and compounds found on the surface of soil minerals The water retained by this force is called hygroscopic water and it consists of the water held within 00002 millimeters of the surface of soil particles The maximum limit of this water around a soil particle is known as the hygroscopic coefficient Hygroscopic water is essentially nonmobile and can only be removed from the soil through excessive heating Matric force holds soil water from 00002 to 006 millimeters from the surface of soil particles This force is due to two processes soil particle surface molecular attraction or adhesion of water molecules to mineral surfaces and the cohesion that water molecules have to each other 1 Note that wilting coefficient 4D increases as texture becomes finer Field capacity 2 Field capacity 6V increases 7 32 until as texture becomes finer until silt loams then levels O 39 24 Avallablz water 3 Greatest plantavailable H20 capacity PAWC occurs with medium rather than finetextured soils 1llI39ll tin g coefficient Soil water content 3 volume 96 Unavailable water Sand Sandy Loam Silt Clay Clay loam loam loam Fineness of texture I General relationship between soil water characteristics and soil texture Rememberthese are representative curves amp individual soils will likely have values different from those shown Brady and Well 2004 p 157 18 De nitions Soil Physics is the study of the physical properties of the soil and the relation of these properties to agricultural environmental and engineering uses Soil Biophysics is the multidisciplinary studies of the biological root microbial and mesofaunal interactions with all soil soil physical parameters Soil Hydrology is the study of soil water content ow retention availability solubility and transport Within the soil matrix Soil Volume and Mass Relationships within a Threephase System Read Course textbook Chapter 1 Hillel pp 317 on Angel website Reviewread Three Phase Soil System listed on the course website Begin solving the problem set on the Angel website 19 SoilPlantAtmosphereContinuum SPAC 191 Soil is the weathered and fragmented outer layer of the earth s mantel that has been modi ed by climate and cultivation 192 Soil is a complex system With multiple components each having multiple variables Polyphasic heterogeneous particulate disperse porous 1 Polyphasic solid liquid and gas 2 Heterogeneous The soil has many inter and intraphasic properties that change with time and space Soil water retention characteristic graph for a wellstructured loam soil Soil Matric Water Potential bars 1quot U 12 09 06 03 G 1 atmosphere 1023 cm water 760 mm Hg 010 020 030 040 Volumetric Water Content cm3cm3 X 100 3 Particulate size shape chemical nature and composite texture 4 Disperse the colloidal nature and interfacial activity gives rise to swelling shrinking aggregation adsorption hydration ion exchange etc EX Area of up to 800 m2 g391 of 21 clay 5 Porous soil particle arrangements give rise to particles and pores that transmit or retain soil solutions gases and thermal gradients 193 Plant a biological conduit between the soil and atmosphere which requires ATP energy to absorb x translocate and emit compounds 0 Carbon compounds eg enzymes sucrose plant growth regulators PGRs etc o Ions o Liquids plant extracts 0 Gases CO2 and 02 194 Multiple sourcessinks and gradients in SPAC systems 1 Soil water ux to roots and water uptake 2 Ion uptake by plant roots 3 Ion accumulations by plants 4 Advectiveconvective ion retention uxes 5 Xylem and phloem transport Within plants 6 Transpiration of water from leaf surfaces 7 Plant temperature control 8 Root growth and death Air 500ba0 Leaves Clearly the major portion ofthe overall potential difference in the SPAC occurs between the leaves and the atmosphere Fig 196 Variation of water potential along the transpiration stream Hillel 2004 p 375 195 Examples of dynamic SPAC Water Approximately 100 times more water is absorbed from the soil and transported to the atmosphere by plants than is retained by the plant during one season of growth A corn plant contains approximately one liter of water at physiological maturity while nearly 100 liters have transpired across the leaf surfaces during the growing season Calculations If each corn plant transpires 100 litersseason and if there are 34848 corn plants per acre and we know there are 378 liters per gallon then 100 X 34848 378 921905 gallonsacreseason Therefore nearly a million gallons of water are required to produce an acre of corn each year Calculation for next Wednesday s class If 280 mm of rainfall and supplemental irrigation were added to an acre of corn would there be adequate water for the corn crop 1 2 SoilPlantAtmosphere Continuum H20 flow takes place in the soilplantatmosphere continuum SPAC from soil regions where water potential energy is higher less negative to soil regions where water potentials are more negative This H20 flow includes a H20 movement in soil towards the root b liquidvapor movement across the roottosoil contact zone c absorption into roots amp across membranes to vascular tubes of the xylem d transfer through xylem up the stem amp branches to the leaves e evaporation in the intercellular spaces within the leaves f vapor diffusion through stomatal cavities amp out the stomates to the air directly in contact with the leaf surfaces g vapor movement to the larger atmosphere that carries away the H20 that was extracted from the soil by the plant roots 196 PlantAvailable H20 1 As long as the transpiration rate of the plant is not too high and 2 3 hydraulic conductivity of the soil is adequate and the density of roots is sufficient the plant can extract H20 at a rate needed for normal growth When the rate of extraction drops below the rate of transpiration the plant experiences a net loss of H20 a if the rate of soil H20 uptake cannot be increased the plant may suffer loss of turgor and normal growth will be disrupted b if this situation persists the plant wilts and will die Recall that soil texture influences the amount of H20 that remains in the soil at a given matric potential lJm Soil Matric Water Potential bars Soil water retention graph for a wellstructured loam soil 15 1392 1 atmosphere lt 1023 cm water 09 760 mm Hg 06 03 0 I I I I 010 020 030 040 Volumetric Water Content cm3cm3 X 100 Due to the smaller pore sizes amp greater surface area 9V in the clayey soil is gt the 9V in the sandy soil Clayey soil Soil matric water potential bars Sandy soil G Water content Saturated Fig 68 The effect of texture on soilwater retention Hillel 2004 p 115 PlantAvailable H20 cont d As water infiltrates into the soil by moving across the soil surface it proceeds into and through the soil profile by a process called internal drainage Gravity lJg influences most of this type of H20 flow Then as water flow ceases the matric forces lpm retain this water at a soil water status often referred to as field capacity Saturated soil all pores lled w H20 Field capacity following drainage by gravitational force mg mm 1030 cbar wilting coef cient tum becomes strong enough that plants can no longer extract H20 from soil mm 1500 cbar Hygroscopic coef cient when soils become air dry amp considerable H20 still in soil mm 3100 cbar Saturation Saturated m l I00 I 40 mL 5quot Cl Walcr new apathy mo Aw mm mm w M Hygmmlm m L Sam Pm space Volumes of Water and alr assoclated Wltn 5100 g Sllce of Boll SOlldS W a Wellrgranulated Sllt loam at dlfferent molsturelevels EvadyStWell ZUUA p 155 PlantAvailable H20 cont d 4 As infiltration proceeds and internal drainage of H20 due to gravity lJg and matric potential tum ceases the amount of H20 remaining in the soil is commonly referred to as field capacity 5 This is how texture influences the amount of plant available water content PAWC 6 Additionally PAWC of a soil can be marginally increased by increasing the soil s organic matter content 050 9 040 Field capacity g quot 5 m i 030 8 5 i E o t 020 3 Permanent wilting g percentage E I 0 IO l l l i I l 0 i 2 3 4 5 6 7 soil organic matter by weight Effects of soil organic matter content on the field capacity and wilting percentage for a number of silt loam soils showing how PAWC can be increased Brady and Weil 2004 p158 110 Water Use Efficiency WUE Lack of PAW to meet plant ET demands can lead to drought stress This stress affects physiological processes 1 cell growth 239 wall synthesis amp protein synthesis 3 stomatal opening amp CO2 assimilation 4th respiration 5th proline amp sugar accumulation One measure of drought stress on crops amp plants is WUE which can be defined as WUE dry matter produced DMIactual evapotranspiration AET WUE seed yield SYIAET ex tons DMIacin of H20 evapotranspired lb or bu grainlacin of H20 89 bushels of corn per acre inch of water lost by ET WUE cont d WUE varies with climate soil amp crop factors but between 200 800 kg H20 is used to produce 1 kg DM or 200 800 lb H20 is used to produce 1 lb DM Example WUE calculation Scott p 347 amp 349 assume 196 of seasonal AET to grow 8450 lblac soybean DM WUE 8450 lblac I 196 431 lblac in H20 since 1 acin 27150 gal amp 1 gal 834 lb 1 ac in 226000 lb so 226000 lb H20l431 lb DM 524 lb H20 lostlb DM produced
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