Faculté des Sciences de la Nature et de la Vie AH 19... · 2020. 5. 2. · In semi-arid area, the rainfed agriculture is the most practice developped, ... What are the consequences

Faculté des Sciences de la Nature et de la Vie

Département des sciences agronomiques

Master I: Aménagement Hydro Agricole

Anglais hydro agricole

Mme: LABAD Ryma

[email protected]

Année universitaire: 2019/2020

Meteorogical factors

Precipitation Wind Temperature

--

--

-

---

HAC

Agricultural practices

K+NH4+

PO4

H+

Ca+2Mg2+

Water ressources

Module semestriel,

Coefficient: 2

Crédit: 3

Objectif

✓ Savoir déterminer les propriétés

et les caractéristiques des eaux

et mesurer leurs qualité,

✓ Savoir choisir l’eau adéquate

pour des fins agronomiques.

✓ Savoir utiliser les ressources en

eau disponibles.

Contenu et programme

Chapter 1: Meteorology,

bioclimate and climate

change

Chapter 2: Soil fertility

Chapter 3: Cultural

practices

Chapter 4: Water ressources

Chapter 5: Crops

requirments

Chapter 6: Water

productivity

Mode d’évaluation

Semestrial exams

Anglais

hydro

agricole

Chapter 1

Meteorology, bioclimate and climate

change

LABAD R. 2019/2020

Introduction

With progressing earth history, the parameters of climate such as temperatureand precipitation have globally changed.

The change in the temperature and precipitation could affect developpment ofcultures specially in rainfed agriculture.

Agricultural production depends on many factors such as: water, soil andclimate.

Rainfed agriculture described farming practices that reposed on rainfall as onlysource of water.In semi-arid area, the rainfed agriculture is the most practice developped,because water is a limited factor for agricultural production .

Therefore, the chnage in climate provided modification in the amount ofprecipitation. This modification can affect a yield production, specially in rainfedagriculture.

LABAD R. 2019/2020

What is climate change?

Climate change means the variability of wheather phenomenaassociated with an increase in average temperature.

Wheather ??

Is the combination of the current meteorological components as:

• Temperature: is a primary factor affecting the rate of plantdevelopment.

• Wind direction and speed: have significant influence on cropgrowth. Wind influences crop production in physiological andmechanical ways.

• Amount and type of precipitation: include rain, snow and hail.

• Sunshine hours: is an indicator of the annual number of sunshinehours in the region. According to requirements of cultures, thisparameter is very important.

LABAD R. 2019/2020

Source: Climatic Research Unit, University of East Anglia, UK

The climate is a weather average over a period. At least thirty years

(30 years)

The climate change is a significant variation of temperature during a

long period

What is climate change?

LABAD R. 2019/2020

Climate variability reflects a different weather values recordedbetween seasons.

Cumulative precipitations and average temperatures of Setif, during 2014/2015-2015/2016 seasons

S1 S2

LABAD R. 2019/2020

How we can measure the components of weather ?

Thermometer for temperature

Barometer for air pressure

Meteorological station

Sling psychrometer for relative hymidity

Rain gauge for rainAnemometer for wind speed

LABAD R. 2019/2020

Climatic change softwares

Clic – MD climate change with Montly Data.

C-ROADS WORLD CLIMATE helps people to

understand the long-term climate impacts of actions

that reduce greenhouse gas emissions. You can use it

to rapidly test strategies for tackling climate change.

LABAD R. 2019/2020

video

What are the causes of climate change?

Causes of climate change

Natural causes Causes caused by humain

There are a number of natural factors responsible for climate

change as (Karmakar et al., 2016):

➢ Continental drift

➢ Volcanos

➢ Ocean currents

➢ Earth’s tilt

➢ Comets and meteoritesLABAD R. 2019/2020



Natural causes Causes caused by humain

Climate change is caused by humain activities as industrialization,

deforestation and pollution. These activities increase the emission of

carbon dioxyde, water vapor, methane and nitrous oxide. All these

greenhouse gases persist in the atmospher for long years.

LABAD R. 2019/2020



Natural causesCauses caused

by humain

How greenhouse gases affect climate change?

Certain gases in the atmosphere block

heat from escaping. Long-lived gases that

remain semi-permanently in the

atmosphere and do not respond

physically or chemically to changes in

temperature are described as "forcing"

climate change.

LABAD R. 2019/2020

What are the consequences of climate change on agriculture?

The most important effect of climate change on agriculture can be explained on

the soil. Therefore, the impact of climate change on soils is a slow complex

process.

Impact of climate change on soil physical parameters

Soil water can be fluctuated by a number through climate change:

▪ Precipitation cause rapid changes in soil water since the time- scale for response

is usually within a few hours.

▪ Temperature increase resulting in greater evapotranspiration loss of water from

the soil and lastly the type of land use.

The integral influence of climate- hydrology- vegetation- land use changes

are reflected by the field water balance and soil moisture regime (Varallyay

and al., 2008).

LABAD R. 2019/2020

What are the consequences of climate change on agriculture?

The components of the field water balance and soil moisture regime ( Karmakar et al., 2016)

LABAD R. 2019/2020

What are the consequences of climatie change on agriculture?

Impact of climate change on biological parameters:

Soil organic matter:

Organic matter improuves soil quality through the influences in soil structure, water

retention and nutrient storage. Also organic matter play a particularly role for soil

micoorganisms.

According to some scientifics, the changes recorded in the last decades have already

modified soil temperature and soil moisture. Therefore the decline in organic matter level

was observed associated to soil erosion.

When the level of arganic matter decline the activitie of faune and flora of the soil decrease,

consequently degradation phenomena of nutrient and pesticides decrease.

LABAD R. 2019/2020

What are the consequences of climatie change on agriculture?

Impact of climate change on soil chemical parameters:

The salinization and alcalization of soil can be decreased in area when the

evapotranspiration increased and rainfall decreased.

LABAD R. 2019/2020

How to write a material and methods and results parts

When the methods used in the experiment are presented, the use of present simple is necessary.

Because in this part an author have to axplain different ways or axes of scientific research

work. Also, in results part, the use of present simple is required.

The present simple The present continous

We use the present simple to talk about

things in general. We use it to say that

something happens all the time or

repeatedly, or that something true in

general.

I/ we/ you/ they: drive, work, present,

show

He, she, it: drives, works, presents,

shows

We use the present continous when

the action is started but not yet

finished.

I: am + ing

She, he, it: is + ing

We, you, they: are + ing


Exercise

An experiment was conducted in Semi arid area of Algeria during 2017/2018

season. The technic practices is direct seeding. And vegetal materials used is

barley and lens. The followings tables present a differents operations of

experiment, climatic conditions and yield of culture.

1/ Write two paragraphs:

- Material and methods

-Results.

-2/ Discuss the effect of climatic variability on the yield.

LABAD R. 2019/2020


Exercise

Barley Lens

Seeding 21/11/2016 Seeding 13/12/2016

Up grain

Tillering stage (Feb) Ramification (March)

Physiological maturity (May) Developpment of pods (May)

Grain maturity Pod abortion

Harvesting : 18/06/2017

Yield recorded: 22.25 q/ha

No yield recorded

Table 1: Development steps of cultures

Month T (°C) P (mm)

Nov 13.34 47.3

Dec 10.71 97.0

Janu 7.34 141.9

Feb 11.98 6.0

Mar 13.01 10.9

Apr 15.58 2.6

May 19.79 10.9

Table 2: Climatic conditions

LABAD R. 2019/2020

Chapter 2

Soil fertility and agricultural practices

Introduction

Soil is the loose surface material consisting of inorganic particles and organic matter that

covers most of the land surface. Soil provides the structural support and the source of water

and nutrients for plants used in agriculture.

Crop production capacity is greatly influenced by soil quality. Soil quality is determined by

physical and chemical characteristics.

Soil physical characteristics Soil chemical characteristics

Soil quality

1/ Soil physical characteristics

Many of the physical properties such as texture, slope, and soil depth, cannot be

modified by the farmer. But, these factors determine the suitability of the soil for

agricultural production.

1.1 Soil texture:

Is the arrangement of particles that make up the soil. Soil particles are classified according

to their size:

Clay ˂ 0.002 mm

Silt 0.002- 0.05 mm

Sand ˃ 0.05 mm

Determining soil texture is important in agriculture as many different soil textures have

potential benefits and drawbacks for different plants. For example, sandy soil will drain

well and promote root growth, but dry out quickly. Clay will hold in moisture but will

often become so compacted that plants will not receive a sufficient amount of oxygen.

1.2 Slope:

presence of slope causes soil erosion. In the field, is not easy to determine slop value when there

are many slope length.

Soil movement under slope Slope types


1.3 Soil depth:

Soil depth determines the potential rooting depth of plants to be grown and any restrictions

within the soil that may hinder rooting depth. One crop may require 3 feet of soil, while

another may require 4 feet. Any discontinuities in the soil from layers of sand, gravel, or

even bedrock can physically limit rooting depth and hinder irrigation.

Texture variation, important slope and variability of soil depth can modify a

suitability of the soil for agricultural production


Chemical characteristics that affect soil quality are: acidity, organic matter content and

supply of essential plant nutrients. In general, if physical properties are satisfactory, the

chemical properties can be modified by adequate use of agricultural limestone, manures,

commercial fertilizers, green manure plow downs.

2/ Soil chemical characteristics

The relation between soil chemical characteristics

Organic matter and soil pH are key soil parameters. These two factors affect soil functions and

plant nutrient availability.

Soil pH is determined by concentration of hydrogen ions (H+). It is a measure of soil solution’s

(soil water together with its dissolved substances) acidity and alcalinity, on a scale from 0 to

14.

2/ Soil chemical characteristics

The soil pH influences solubility and

availability of plant nutrients,

performance of pesticides and organic

matter decomposition.

The pH scale (Mc Caulay and al., 2017)

3/ Effect of chemical characteristics on nutrient availability

A soil’s ability to hold and supply nutrients is related to its cation and anion exchange

capacities, the number of parking spaces for nutrients on soil particles. Cation and anion

exchange capacities are influenced by soil pH. As described in Plant Nutrition and Soil

fertility, cation and anion exchange capacity are largely determined by the soil particles and

soil organic matter.

Soils with high amounts of clay and organic matter have a higher cation exchange capacity.

Soil pH affects nutrients availability because the H+ ions take up space on the negative charges

along the soil surface, displacing nutrients.

Potassium, sulfur, calcium and magnesium are more available at higher pH. The micronutrients

are more available at lower pH.

3/ Effect of chemical characteristics on nutrient availability

3-1/ How managing soil pH ?

To manage soil pH, the addition of amendments, fertilization and tillage practices, soil

organic matter levels and crop selection should all be considered. The longevity of soil pH

change brought about by management greatly depends on the treatment. Changes can occur

within a season or last for decades.

Therefore, the presence of organic matter in the soil is a key to manage soil functions.

3-2/ Soil organic matter

Soil organic matter serves multiple functions in the soil, including nutrient retention, water

holding capacity and soil aggregation and is a key indicator of soil quality.

Plant roots and fauna as: rodents, earthworms, mites and microorganisms contribute to the

movement and breakdown of organic matter in the soil.

Soil organic matter content depends on the balance between organic residue addition and

the rate of decomposition.

To add organic matter in the soil, it is necessary to:

-Respect good growing conditions,

-crops or cover crops rather than fallow,

-leaving plant residue on the field.

Soil organic matter decomposition rates depend on soil organic matter form, soil texture

and drainage, carbon: nitrogen ratios of organic materials, climate and cropping

practices.

Soil organic matter is the combination of plant and animal residues at various stages of

decomposition and cells and tissues of soil organisms. The consistent benefit of soil organic

matter is that it buffers soil pH change. Soil organic matter offers many negatively charged

sites to bind H+ in an acidic soil, or from which to release H+ in a basic soil, in both cases

pushing soil solution towards neutral. Whether soil organic matter changes soil pH in the long

term depends on many factors.

Soil organic matter forms are :

Disolved organic matter (DOM),

Particulate organic matter (POM),

Humus.

Soil texture:

Soils high in clay and silt are generally

higher in SOM content than sandy

soils. This is attributed to restricted

aeration in finer-textured soils,

reducing the rate of organic matter

oxidation, and the binding of humus to

clay particles, further protecting it

from decomposition. Additionally,

plant growth is usually greater in fine-

textured soils, resulting in a larger

return of residues to the soil.

Drainage:

Poorly-drained soils typically

accumulate higher levels of SOM than

well-drained soils. This is due to poor

aeration causing a decline in soil

oxygen concentrations. Many soil

microorganisms involved in

decomposition are aerobic (oxygen-

requiring) and will not function well

under anaerobic conditions (oxygen-

limiting).

3-3/ Factors that affect decomposition of soil organic matter

The carbon: nitrogen ratio of

organic material affects

microorganism activity and

subsequent decomposition rates.

Organic materials with carbon:

nitrogen ratios greater than 30:1

generally decompose slowly and

tend to accumulate, whereas those

with carbon: nitrogen less than 24:1

decompose quickly. To obtain a

desired balance between SOM

decomposition and accumulation,

different crops can be planted in

rotation or organic materials can be

mixed

Climate

It affects growth conditions of soil

microorganisms.

A combination of warm and moist soil

is ideal for decomposition and rapid

release of nutrients.

Decomposition can be faster at higher

temperatures, but adequate soil

moisture becomes critical. At very low

temperatures, decomposition is limited

by both temperature and water

availability, such as in cold deserts and

in arid and semi-arid areas.

Cropping practices : all practices are made by farmer


Soil organic matter decomposition increases as the combination of temperature and

soil moisture increases within conditions favorable for most microbial growth.


Decomposition of organic matter is due essentially to microorganisms activity. It produces

dioxide of Carbone in the soil. Consequently, to evaluate soil biological activity, the rate of

Carbone dioxide is a key.

Organic matter decomposition cycle


How to evaluate organic matter in the soil ?

Organic matter in the soil is not evaluated directly in laboratory. In the first, Carbone dioxide

must be measured.

Different methods can be used in laboratory. The first one used is ANNE method, when the

dioxide of Carbone is measured by sulphuric acid. After that, the following formula can be

used:

OM (%) = OC (%) * 1.724

The amount of organic

matter

Type of soil

˂ 1 Very poor content of OM

1 to 2 Poor content of OM

2 to 4 Average content of OM

˃ 4 Rich content of OM

Schafer, 1975

4/ The effect of agricultural practices on soil fertility

Conservation agriculture (CA) is one concept for resource conservation and mitigation

of adverse climatic impacts that has higher profitability.

This technology involves minimum soil disturbance, providing a soil cover through

crop residues or other cover crops and crop rotations for achieving higher productivity

Agricultural practices: are all operations practiced and techniques used for

agricultural production. For example: irrigation, fertilization and mechanization.

They are a relationship between mechanization and soil fertility.

Depends on the type of agricultural equipments used, minimum tillage and direct

seeding as conservation agriculture or conventional agriculture can be practiced.

Conventional tillage is based on using of mechanical equipment and soil disturbance

to a greater depth. Traditional or conventional tillage needs the use of disc harrows or

plows on soils and seedbed preparation methods.


Soil organic matter has tremendous benefits on soil chemical, biological and

physical properties, which in turn affect the productive capacity of soils. Any

decline in soil organic matter will create deficiencies in nutrients, soil structure

destabilization, and a reduction in the productive potential of soil. Hence,

conservation tillage, including no tillage as a means to sequester Carbone in soils

and revert degradation processes. In the other hand, there is a direct relationship

between conventional tillage and erosion.

Conservation or minimum tillage systems refer to a range of soil tillage management

practices that minimize degradation of soil and water resources. But soil cultivation

with either plow or disc is reducing soil quality affecting the sustainability of farming

systems.


How to write Results and discussion

Results: present a significant results using present simple and present continuous.

Discussion:

It is comparison between different results worldwide that are presented in the

literature.

In generally, in discussion part past simple and past continuous are used to explain

and compare results.

Present perfect

Have + past

participle

Used to talk about a

recent action in the

past

Past simple

•Regular verbs: + ed

•Irregular verbs

Used to talk about action

happened in the past

Past perfect

Had + past participle

Used to talk about an

action happened before

another

How to write Results and discussion

Discussion part needs the use of conjunctions and prepositions to relate a

sentences.

Addition Cause Consequences

In addition to

As well as

Similar to

To

For

Because of

On account of

Owing to

That’s why

Consequently

As a consequence

As a result

Therefore

GR crop frequency, by itself or in interaction with tillage, affected rhizosphere

MBC in only two of 20 site years and had no effects in bulk soil. Therefore,

including GR crops in rotation usually had no significant effects on MBC.

Increasing GR crop frequency (or increased use of in-crop glyphosate) increased

MBC in the two cases where changes were observed. Both sites had abnormal

seasonal precipitation in the years in question: Lethbridge received 44x normal

precipitation in June of 2002 and Lacombe had only 16% of normal precipitation in

July of 2003 (Harker et al., 2005). In addition, while the soils at both sites were

loam in texture, the soil at Lacombe had the highest organic matter (8.3%) and sand

content (43%) of all sites, and the soil at Lethbridge had the highest pH (7.8) of all

sites (Harker et al., 2005).

Discussion

In conclusion, significant effects of high GR crop frequency on soil MBC,

bacterial functional diversity, or dehydrogenase enzyme activity were observed in

only two or three of 22–40 cases under LDS or CT systems over a wide range of

growing conditions, and in most cases the effects were not consistent.

These soil and climatic differences may have contributed to the results. A slight

shift in weed community as a result of a high frequency of in-crop glyphosate use

(Harker et al., 2005) may also have influenced these results by altering plant root

substrates available to soil microorganisms. In most other studies, glyphosate

applied at recommended rates has been observed to have no significant effects on

soil MBC (Olson However, this was still only three of 22 cases)

Exercise

Write a paragraph to compare organic matter evolution under no tillage and conventional

tillage and explain role of organic matter in soil stability. Use some prepositions and

conjunctions.

Water resources and agricultural productivity

Introduction

Earth water resources, including rivers, lakes, oceans, and underground aquifers,

are under stress in many regions. Humans need water for drinking, sanitation,

agriculture, and industry. So, contaminated water can spread illnesses and disease

vectors, so clean water is both an environmental and a public health issue.

The water cycle

Risk of water pollution

How does water move through the ground and interact with sediments and rock?

Type of agricultural water use

There are two main ways that farmers use agricultural water to cultivate crops:

▪Rain-fed farming

▪Irrigation

Rain-fed farming: is the natural application of water to the soil through direct

rainfall.

Application of rain-fed water in agriculture can reduce contamination of food

products. But, when it is irregular in the time, the production level decrease. So the

use of artificial water applications is required.

What is the artificial water applications ?

Irrigation is the artificial water application to the soil through various systems.

Irrigation is used in areas where rainfall is irregular or dry times or drought is

expected.

The use of artificial water application or irrigation can cause problem of

contamination. Because many water sources can be exploit. Such as: groundwater,

surface water, rivers, lakes or even other sources, such as treated waste-water or

desalinated water.

Type of irrigation Systems

There are many different types of irrigation systems, depending on how the

water is distributed through the field.

Surface irrigation

Water is distributed over and across land by

gravity, no mechanical pump involved.

Source FAO

Type of irrigation systems



Localized irrigation

Water is distributed under low pressure, through a piped network and applied to

each plant.




Drip irrigation

A type of localized irrigation in

which drops of water are

delivered at or near the root of

plants. In this type of irrigation,

evaporation and runoff are

minimized.




Sprinkler irrigation

Water is distributed by overhead

high-pressure sprinklers or guns from

a central location in the field or from

sprinklers on moving platforms.




Center pivot irrigation

Water is distributed by a system of

sprinklers that move on wheeled towers

in a circular pattern. This system is

common in flat areas.




Lateral move irrigation

Water is distributed through a series of pipes, each with a wheel and a set of sprinklers,

which are rotated either by hand or with a purpose-built mechanism. The sprinklers

move a certain distance across the field and then need to have the water hose

reconnected for the next distance. This system tends to be less expensive but requires

more labor than others.

Documents

Faculté des Sciences de la Nature et de la Vie AH 19... · 2020. 5. 2. · In semi-arid area, the rainfed agriculture is the most practice developped, ... What are the consequences