9/21/2015DMA: Chapter 8 Hartmann's Plant Science, 4th edition 1 CHAPTER VII Soil and Water Management Plant Science: Pages 195-221

04/19/23 DMA: Chapter 8 Hartmann's Plant Science, 4th edition

1

CHAPTER VII

Soil and Water Management

Plant Science: Pages 195-221


2

• Introduction

• To a large extent, crop productivity is determined by the way soil is managed.

• Soil management is the combination of tillage, cropping systems, and soil treatments that either complement or compete with each other.


3

Land Preparation

•The purpose of land preparation are to:

1.Level the land where needed.

2.Incorporate crop residues, green manure and cover crops.

3.Prepare and maintain a seedbed in good tilth.

4.Help control weeds, diseases and insects.

5.Improve the physical condition of the soil.

6.Help control erosion where needed


4

Land Preparation

•Tilth is the physical condition of the soil in respect to its capability to grow a specific crop.

•Tillage is defined as the mechanical manipulation of soil to provide a favorable environment for crop growth.

•Tillage is done any time soil conditions permit.

•Objective: seedbed should provide seeds with an environment conductive to rapid germination and growth (fine seed bed).


5

Land Preparation

•Tilth. حراثة


6

Land Preparation (Tillage).


7

Land Preparation = Seedbed.


8

Land Preparation (Plowing)

•Generally, the first step in seedbed preparation is to plow the land.

•Plows invert the soil and cover the trash, but they often leave the soil in large liner lumps that must be reduced in size.

•A farmer has the choice between two types, the moldboard or the disk plow each adapted to certain soil characteristics.


9

Land Preparation •Moldboard plows are used when the soil is sufficiently moist to allow the plow to pass through easily. •The ideal moisture content for plowing loam soil is about 2 or 3 % below field capacity.

The disk plow consists of a series of large disks 60-75 cm in a diameter that cut the soil by rotating as the plow moves forward. •The disk plow are best adapted to dry hard soils.


10

Land Preparation (Moldboard plow)


11

Land Preparation (Moldboard plow)


12

Land Preparation (Disk plow)


13

Land Preparation (Disk plow)

14

Land Preparation (Disk Harrow) •Disk harrows have general purpose of tillage = implements consisting of gangs طقم of concave disks. •Disk harrow are used to reduce the size of larger soil clods by fracturing them by cleavage and pressure.

•Disking) harrowing) generally follows plowing, but under some conditions disking can eliminate the need for plowing.


15

Land Preparation (Harrowing) •The function of the harrow is to further reduce the size of soil clods left after disking, to smooth the soil surface and to do small scale leveling. Harrowing also kills any small weeds. •The principle types of harrows include: –Spike-tooth, –Spring-tooth, –chain or drag and –cultipackers.- Rotivators.


16

Land Preparation (Spring-tooth harrow)


17

Land Preparation (Spike-tooth harrow)


18

Land Preparation (Lister)

•In some areas, row crops are planted on ridge formed by listers.

•A lister is a plow equipped with a two moldboards that cuts a furrow slice two ways on both directions.

•Some farmers flatten the tops of the ridges with a roller or a drag.


19

Land Preparation (Lister)


20

Land Preparation (Cultivation)

•Cultivation is the tillage between seedling emergence and crop harvest. •The main reason for cultivation is to –control weeds, –improve soil aeration, –the conservation of soil moisture and –loosening compacted soils.


21

Land Preparation (Cultivation)

•Cultivation equipment can be divided into three main classes:

1.Row-crop cultivators.

2.Field cultivators.

3.Rotary hoes.

4.Rototillers.


22

• Land Preparation (Row-crop cultivators)


23

Land Preparation (Row-crop cultivators)


24

Land Preparation (Field cultivators)


25

Land Preparation (Rotary hoes)


26

Land Preparation (Roto-tillers)


27

• Land Preparation (Deep Tillage)

•Some farmers use deep tillage to improve problem soils.

•Extra heavy equipment is used for deep tillage when soil is dry and before seedbed preparation.

•Equipment include: Slip plow, deep moldboard plow and ripper or deep chisel.

•Deep tillage is expensive and it does not materially increase crop yields.


28

Land Preparation (Deep tillage)


29

• Land Preparation (Slip plow)


30

• Land Preparation (Minimum Tillage)

•Using large machine in tillage compacts the soil.

•To avoid soil compaction, minimum tillage is recommended.

•Yield differences between minimum and normal tillage is small.

•The saving in reduced fuel costs and machinery cost is appreciable with minimum tillage.


31

• Land Preparation (Minimum tillage)


32

Land Preparation (Minimum tillage)


33

Land Preparation (Land leveling) •Irrigated land generally needs to be leveled, especially if row crops are grown.=Furrows •Land is leveled to permit water to flow and spread evenly over the soil surface without causing erosion. •Land should be leveled in rainy season because leveling is injurious to wet soil.


34

Land Preparation (Soil Fumigation) •To grow some crops, the soil has to be fumigated before seedbed preparation. •These are high-value crops with a potential for pest damage severe enough to justify the cost of treatment. •The most widely used soil fumigant is methyl bromide, a colorless, odorless and toxic gas. •Steam or solar fumigations are used instead of chemicals.


35

• Land Preparation (Soil Fumigation using chemicals)


36

• Irrigation (Methods of Application)

•In areas where 300 mm of rain falls during growing season, an average 400 mm of supplementary irrigation is needed.

•Some factors that determine the method of irrigation system include:

•Climate.

•Type of crops.

•Cost of water.

•Slope of field.

•Physical properties of soil.

•Water quality.

•Water availability

•Drainage capability

•Salinity.


37

Irrigation (Methods of Application) •Border or flood method is used where the topography is flat an level. A uniform down slope of 0.1 to 0.4 percent is used. •This method is used with drilled or broadcast crops such as cereal grains. •The land needs to be graded and levels and this depends upon: –Topography. –Cropping system. –Cost. •Excessive percolation and inadequate wetting of the soil in different areas should be avoided.


38

• Irrigation (Border or flood method)


39

Irrigation (Methods of Application) •Furrow irrigation is a modification of flooding-water is confined to furrows rather than wide checks. Water is used more efficiently. •Furrow irrigation is frequently used for row crops, orchards and vineyards. •The length of furrow varies from 30 m to 450 m. Long furrows cause greater loss of water because of deep percolation and excessive soil erosion. •Furrow spacing is determined by the plant row length.


40

Irrigation (Furrow irrigation method)


41

Irrigation (Furrow irrigation method)


42

Irrigation (Methods of Application) •Sprinkler irrigation is often used when flood or furrow irrigation is impractical. •Sprinklers are selected over other methods because: –Excessive high or low soil permeability. –Germination rate of small seed crops. –Soil topography. –Water cost + farmer budjet. •There are several types of sprinklers including: the permanent set, the hand set, the wheel line, the hose drag and the central pivot.


43

Irrigation (The permanent set sprinkler irrigation method)


44

Irrigation (The wheel line sprinkler irrigation method)


45

Irrigation (The central pivot sprinkler irrigation method)


46

Irrigation (Methods of Application) •In drip irrigation small amounts of water are allowed to trickle slowly into the soil through mechanical devices called emitters wetting the soil without runoff. •In this system, a control station will filter the water, will add fertilizers and will regulate the pressure and timing of application.

•The system uses less water than other methods but the system is expensive.


47

Irrigation (The drip irrigation method)


48

Irrigation (The drip irrigation method)


49

Mineral Nutrition •Fertilizers have probably increased crop yields and reduced hunger more than other single agricultural practice. •In addition to supplying nutrients to crops to increase yields, fertilizers can also cause marked changes in soil characteristics, some beneficial, some not. •Seventeen chemical elements are known to be essential for the growth of the most plants and few others are used under

certain conditions.


50

Mineral Nutrition •For essential element, it must met the following criteria 1.A plant must be unable to complete its life cycle in the absence of the element. 2.The function of the element must not be replaceable by another element. 3.The element must be directly involved in plant metabolism.

• How do plants absorb nutrients from the soil?

•Nutrients do not simply

flow into the cytoplasm

of a plant cell in the

absorbed water.

•It is important to

emphasize that the

plant nutrients are

charged forms (ions)

of the elements


51


52


53


54

Mineral Nutrition

Based on this seventeen chemical elements are known to be essential elements and they include:

–Non mineral Nutrients :

•Carbon (C), Hydrogen (H) and Oxygen. They are supplied by air and water.

–The mineral nutrients and they are divided into three groups:

•Macronutrients, they are required by plants in large amounts and they include:

–Primary macro: Nitrogen (N), Phosphorus (P), Potassium (K),

–Secondary macro: Calcium (Ca), Magnesium (Mg), and Sulfur (S).

•Micronutrients, they are required in low amounts and they include:

–Boron (B), Chlorine (Cl), Copper (Cu), Iron (Fe), Manganese (Mn), Sodium (Na), Zinc (Zn), Molybdenum (Mo), and Nickel (Ni).


55

Mineral Nutrition •Nitrogen is a major component of proteins, hormones, chlorophyll, DNA, vitamins and enzymes essential for plant life. •In nature, nitrogen exists in several forms that plants can have access to. Plants absorb nitrogen only as inorganic nitrate ions (NO3-) and, in few cases, as ammonium (NH4+). •The transformation of organic matter to the mineral or inorganic form by microorganisms is called mineralization. The conversion of the mineral form to the organic form is known as immobilization.


56

Mineral Nutrition (The Nitrogen Cycle)


57

• Mineral Nutrition

Nitrogen fertilizers are applied as solid, liquid or gases.

Ammonia, or azane, is a compound of nitrogen and hydrogen with the formulaNH3. It is a colourless gas with a characteristic pungent smell

•Nitrogen fertilizers must not be placed directly over foliage because they burn the leaves.

•Continued use of nitrogen fertilizers can affect the pH of the soil. Fertilizers containing ammonium ions are residually acid. Fertilizers contain basic cation and nitrate are residually basic.

•Many plants deficient in nitrogen show pale green to yellow leaves in lower leaves since it is mobile.

http://en.wikipedia.org/wiki/Chemical_compound

http://en.wikipedia.org/wiki/Nitrogen

http://en.wikipedia.org/wiki/Hydrogen

http://en.wikipedia.org/wiki/Chemical_formula

http://en.wikipedia.org/wiki/Gas

http://en.wikipedia.org/wiki/Pungent

http://en.wikipedia.org/wiki/Odor


58

Mineral Nutrition (Nitrogen burns leaves)


59

Mineral Nutrition (Nitrogen deficiency symptoms).


60

Nitrogen fixation can be carried out by several groups of bacteria. The bacteria that are of greatest agricultural importance are named rhizobia. •These bacteria infect legumes such as –The vegetable crops peas and beans and –The agronomic crops soybean and alfalfa •They enter the root through root hairs and form growths on the root called nodules


61

• The plant supplies the bacteria with organic nutrients (e.g., carbohydrates), and in return the bacteria supply the plant with ammonium.

• In general, a species of rhizobia infects only one species of legume. Thus:

• 1.Pea rhizobia do not form nodules on bean plants and soybean rhizobia do not form nodules on alfalfa.

• 2.When a legume is first grown in the field, it is very important to supply an appropriate rhizobial inoculant.


62


63


64

Complete Flowers

• Complete flowers usually have four parts—sepals, petals, stamens, and pistil—which are usually borne on a receptacle (Fig. 8-36).

• The sepals are the leaflike scales that encircle the other flower parts.

• Most often the sepals are green, The sepals collectively are called the calyx.

• The petals are the next whorl of colored floral leaves inward from the sepals. The collective term for petals is corolla.

• Sepals and petals collectively are called the perianth.


65

• The next whorl of floral organs in a complete flower is the male part, or stamen. Each stamen consists of

1. A filament and 2. An anther; the anther produces the pollen.

• The pistil, the central female component of the flower, is composed of three parts:

1. The stigma, the receptive surface that receives the pollen;

2. The style, a tube connected to the stigma; and 3. The ovary, attached to the lower end of the style.

• The ovary contains undeveloped ovules that are attached to a placenta; the ovules develop into seeds after pollination and fertilization.


66

Incomplete FlowersIncomplete flowers lack of one or more of the four parts:

sepals, petals, stamens, or pistil. - Flowers with both stamens and pis tils are called

Perfect flowers. - Flowers with stamens only and no pistils are called

Staminate flowers; - Those with pistils but no stamens are called

Pistillate flowers. - Staminate or pistillate flowers are by definition

Imperfect flowers.


67

• Plants having both staminate and pistillate flowers borne on the same plant are termed monoecious (e.g., corn) (Fig. 8-40). As corn

• If the pistillate and

staminate flowers are borne on separate individual plants (male and female plants), the species is called dioecious. (e.g., date palm and pistachio)


68

Some flowers, like the tulip, are borne singly on a stalk and are called solitary, but others are arranged in multiples or in clusters known as

inflorescences (see Fig. 8-37).


69

FRUITS• A fruit is a matured ovary plus associated parts;

it is generally a seed-bearing organ, but there are parthenocarpic fruits that are seedless.

• Fruit may 1. Protects seeds 2. Helps disseminate نشر seeds.

• Fruits develop after pollination and fertilization.

• The ovary wall, which is called the pericarp, can develop into different structures.


70

Simple Fruits• Simple fruits have a

single ovary formed from one flower.

Aggregate and Multiple Fruits

• Aggregate fruits develop from many ovaries on a single flower. (strawberry)

• Multiple fruits develop from many individual ovaries fused into a single structure borne on a common stalk. (fig)


71

SEEDS• A seed is a mature ovule. The three basic parts are 1. The embryo, 2. The food storage tissue (endosperm, cotyledons, or

perisperm = the nutritive tissue surrounding the embryo in certain seeds as beet,), and

3. The seed coats.

• The embryo is a miniature plantlet formed within the seed from the union of the male and female gametes during fertilization.

• Basically, the embryo has two growing points: – Radicle, which is the embryonic root, and – Plumule, which is the embryonic shoot.


72

• Food can be stored in the form of 1. Starch, 2. Fats, or 3. Proteins.

• There may be one or two seed coats (testa), which form from the integuments, the outer layers of the ovule.

• The scar that remains after breaking the seed from the stalk is called the hilum, and the small opening near the hilum is the micropyle. The ridge on the seed is the raphe (Fig. 8-4).


73

Monocots and dicots plants differ in many anatomical details:

Fig 35-1. A comparison of monocots and dicots. These two groups of angiosperms are named for the number of cotyledons, or seed leaves, present on the embryo of the plant. Monocots include orchids, bamboos, palms, lilies, and yuccas, as well as the grasses, such as wheat, corn, and rice. A few examples of dicots are roses, beans, sunflowers, and oaks (which are all eudicots, the largest class of angiosperms with the dicot-type anatomy).

Documents

9/21/2015DMA: Chapter 8 Hartmann's Plant Science, 4th edition 1 CHAPTER VII Soil and Water Management Plant Science: Pages 195-221