NEM 10V Lecture Notes - Lecture 56: Nematology, Soil Texture, Carbon Cycle

25 views2 pages

sangriarat247

6 May 2018

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Nematology

Plants:

Rhizosphere

• Soil is a mixture of several different components including:

1. organic matter,

2. water

3. oxygen

4. inorganic rock materials.

• Soil texture is the measure of the volume proportions of:

1. Sand

2. Silt

3. clay.

• Soil texture determines the porosity or water holding capacity of the soil.

• It also determines the soil permeability or rate at which water moves through it.

• Soil samples can be analyzed to determine their suitability for crop growth.

• This consists of determining the amount of sand, silt, clay, and organic matter present as

well as available nutrients.

• The pH of soils has a lot to do with the availability of nutrients.

• Lime can be added to raise soil pH, and elemental sulfur can be added to lower pH.

• Soil contains macronutrients including:

1. K,

2. Ca

3. P

4. Mg

5. micronutrients including Zn, Mn, Fe, Al, B, and S that are important for plant

growth.

find more resources at oneclass.com

Unlock document

This preview shows half of the first page of the document.
Unlock all 2 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Rhizosphere: soil is a mixture of several different components including, organic matter, water, oxygen, inorganic rock materials. Soil texture is the measure of the volume proportions of: sand, silt, clay. Soil texture determines the porosity or water holding capacity of the soil. It also determines the soil permeability or rate at which water moves through it. Soil samples can be analyzed to determine their suitability for crop growth: this consists of determining the amount of sand, silt, clay, and organic matter present as well as available nutrients. The ph of soils has a lot to do with the availability of nutrients. The warming action on earth"s atmosphere is referred to as the greenhouse effect: plants and animals cannot use pure nitrogen gas found in the atmosphere. It must first be fixed into a useable form: lightning can fix nitrogen gas allowing nitrogen to combine with oxygen to form nitrate.

Related Questions

The following questions are related to measuring saturated flow in a given soil. Use the formula for saturated soil discharge and the table below to answer the questions. Be sure and show your work.

Calculate K_sat (cm/sec) using the following measurements (5pts):

A = 113in², t = 15 sec, Q = 150ml, Îh = 66cm, L = 125cm

Using the information from the table below and your calculated K_sat, what is the likely soil texture? (5pts)

K (cm/s)

10²

10¹

10^-1

10^-2

10^-3

10^-4

10^-5

10^-6

10^-7

10^-8

10^-9

10^-7

Relative permeability

Pervious

Semi-Pervious

Impervious

Aquifer

Good

Poor

None

Unconsolidated Sand and Gravel

Well sorted gravel

Well sorted sand or sand & gravel

Very fine sand, silt, loess, loam

Unconsolidated Clay and Organic

Peat

Layered clay

Fat/Unweathered clay

You were assigned by the local soil conservation district to take some field measurements to help assess the soil water conditions of a given area for potential agricultural usage. The diagram below schematically shows the distribution and depth of tensiometers and lysimeters (used to determine soil moisture content). Data from each tensiometers and lysimeters group is taken from the bottom ( ). Use the table of field data to answer the following questions.

	Î¨_Tot (kPa)	Soil Wetness (cm³/cm³)	Air Porosity (%)	Soil Water Condition
Group A	-20	0.28	15
Group B	-50	0.18	32
Group C	-35	0.22	24
Group D	-25	0.25	22
Group E	-45	0.15	35
Group F	-30	0.12	28

In the space provided in the above data table, label the likely soil water conditions as related to maximum retentive capacity, field capacity, wilting coefficient, and hygroscopic coefficient. (12 pts)

Cation exchange capacity (CEC) is the sum of all exchangeable cations (e.g., Na+, Ca2+, K+) that a soil can adsorb. These cations are positively charged ions and are held on the negatively charged surfaces of soil particles (e.g., clay and organic matter) and can be replaced by other positively charged ions in the soil solution. Since they are readily exchanged with other cations, they are also easily available to plants. The CEC of a soil is dependant on the composition (e.g., types and amounts of clay and organic matter) of the soil (permanent charge) and the pH (pH-dependent charge).

The proportion of the CEC occupied by non acid-forming cations (Ca2+, Mg2+, K+ and Na+) is termed the percent base saturation. It is important to note that these cations are not bases and do not necessarily form bases. Cations including Al3+ and Fe3+ are considered acid-forming cations as they can hydrolyze water. The
percent base saturation can be calculated as shown in Equation 1.

Consider the method presented in your textbook for determining the CEC for a soil. Similar measurements were conducted for soil samples collected from a Gray Luvisol in BC (forested area; see Table 1 a brief summary of the soil properties). For these measurements, 100 g subsamples of oven-dried soil from each horizon were leached with 400 mL of a NH4+ salt solution (leachate 1). The NH4+ displaces all of the cations adsorbed to soil surfaces. Leachate 1 was analyzed for Ca, Mg, K and Na (Table 2). The excess NH4+ remaining in the soil was removed using alcohol and then the sample was leached again with a 400 mL of a K+ salt solution (leachate 2). Similar to above, the K+ displaces all of the NH4+ from the soil surfaces.

Determine the CEC of the soil sample collected from each soil horizon presented in Table 2.

NEM 10V Lecture Notes - Lecture 56: Nematology, Soil Texture, Carbon Cycle

Document Summary

Get access

Related Documents

BIOL 119 Lecture Notes - Lecture 1: Arbuscular Mycorrhiza, Potential Energy, Membrane Protein

[BIOL 119] - Final Exam Guide - Ultimate 118 pages long Study Guide!

ESS361H1 Lecture Notes - Lecture 3: Bulk Density, Thermal Conductivity, Thermal Diffusivity

Related Questions