AGROMETEOROLOGY AND IT’S IMPORTANCE FOR EFFECTIVE DRM ACTIVITIES

ByAlmaz Demessie

M.Sc. IN TROPICAL AGRICULTURAL DEVELOPMENT(Uk) Senior Agro meteorologist and Early Warning expert, UNDP/GEF LDCF project Focal Person

Disaster Risk Management and Food Security SectorOffice tel: +251-114430578, Mobile tel: +251 -911-197120

E-mail: demessiead@gmail.com

Strengthening the existing Early Warning Activities in terms of data collection, interpretation and information dissemination in order to establish timely response mechanism”, organized by DRMFSS and supported by UNDP/GEF LDCF project December 4 – 5, 2015, Debre

Zeit

INTRODUCTION Agrometeorology is the application of

meteorological knowledge, information and data to weather sensitive problems in agriculture. Amongst other things this includes problems dealing with the effect of weather, climate and their variability.

 

Introduction cont’d….• An agrometeorological service is of great

importance for countries with a primary agricultural economy. It supplies forecasts of adverse weather conditions like frost, heavy rainfall, drought, late onset and early cessation of rainfall, erratic distributing of rainfall, extreme maximum and minimum temperatures, strong wind, excess moisture and could cover, and information, which is important for sowing, application of pesticides, for harvesting, etc.

Introduction cont’d….• Agricultural meteorology deals with the

interaction between meteorological and hydrological factors, on the one hand, and agriculture in the widest sense, including horticulture, animal husbandry and forestry, on the other. Its objective is to discover and define such effects, and then to apply knowledge of weather to practical agricultural use. Its field of interest extends from the soil layer of deepest plant and tree roots, through the air layer near the ground in which crops grow and animals live, to the higher levels of the atmosphere of interest in aerobiology, the latter with particular reference to the effective transport of seeds, spores, pollen and insects.

Introduction cont’d….• In addition to natural climate and

its local variations, agricultural meteorology is also concerned with modifications in the environment.

The services which meteorologists can provide to agriculturists

It may be grouped broadly as follows: - 

a. To co-operate with and seek advice from agricultural services in all matter of common interest;

 b. To supply as far as practicable, any available meteorological data required by agricultural scientist in their research experimental and advisory work;

 

The services which meteorologists Cont’d…

c. To advice on the best utilization of weather and climate data in attaining such objective as improving agricultural production introducing new species of plants and animals and increasing the area in efficient farming use;

The services which meteorologists Cont’d…

d. To assist agricultural and allied interests in combating unfavorable weather and climate.

 eg. - artificial modification

of climate- wind breaks, shelter-

belts, irrigation and glass house- afforestation (by

planting trees)  

The services which meteorologists Cont’d…

e. To assist in the fight against agricultural pests and diseases by considering both the environmental factors during their life histories and the meteorological factors which may influence the effectiveness of the protective measures taken;

f. To advise on the protection of agricultural products, in storage and in transit, against damage.

The services which agriculturists can provide to meteorologists

It may be grouped broadly as follows:-a) To co-operate with and seek advice from

Meteorological Services in all matters of common interest;

b)  To supply meteorologists with such ecological data on the life-histories of plants and animals, and of the pests, as may serve a guide for preparing corresponding weather forcasts and for formulating climatological advice on such matters as the introduction of new plants and animals;

c) To encourage the implementation of continuous and comprehensive national surveys of important agricultural pests, so that their relationships with weather factors in different regions may be studied further;

d) To supply, as far as practicable, statistical data on crop yields, etc, adequate for investigation of reliable crop-weather relationships;

e) To co-operate with Meteorological Services in establishing standard agrometeorlogical stations and in collecting other relevant data.

Joint services by meteorologists and agriculturalists

Meteorologists and agriculturists should co-operate towards making meteorological and climatological information “an operational tool” in every farmer’s day to day activities and in his weekly, seasonal and long-range planning. This jointly developed and furnished services should include:

a)  Operationally useful forecasts of meteorological variables that are important to current farming operations together with an agricultural interpretation of such forecasts;

                    b) Education programmes for farmers

to demonstrate the usefulness of weather information for agricultural planning and operations;

  c) Joint research projects on agriculture-weather relationships and their applications to farming practices.

                    The six main points governing relationship

between weather and agriculture1. Soils

Weather is important factor in creating and determining the nature of soil

Climate and weather affect i. Chemical physical and mechanical properties of

the soilii. The organism it contains.iii. Its capacity for retaining and giving up heat.Iv Types of nutrient (e.g Rainfall not only adds

chemical contents to soil and washes soil nutrients).

V State of soil ( it is affecting cultivation, pest control and harvesting).

   

2. PlantsDevelopment and growth of plants depend on environmental condition at every stage. Un understanding of inter relation between the environment(ground cover, surface slop, degree of shelter, ect) and the local micro climate, in the crop and around the crop may result actions aimed at the long term improvement of the growth situation .

Even before planting the influence of weather should be considered in terms of seed quality and viability.

   Plants contd Post harvest operation, such as drying of

grains and other crops, and the capacity to maintain the quality of harvested fruit, vegetable and other farm products affected by seasonal weather. Weather and climate are important in the occurrence forest, bush and grass fires, knowledge of them is important for the defence against such hazards.

                   3.Farm animalsWeather affects animals in the following

ways:-

a.directb. crops on which they feedc. soil on which they are keptd. their geographical distributione.yield and quality of animal productf. preparing these products and their

capacity for storage and transport

4. Diseases and pests of crops and animals

a.weather influences susceptibility of plants and animals to attack by pests and diseases

b.nature, number, spread and activity of pests and diseases

c. has impact upon the effectiveness of control measures

d.on the amount and toxicity of spray on harvested crops

5. Farm buildings and equipment

a. weather conditions should be considered while planning farm buildings particularly designing animal housing and storage space for agricultural products

b. It also influences the choice, up-keep and best use of farm machinery.

6.Artificial modification of meteorological and hydrological regimes

Irrigation, mulching, wind breaks and shelter belts.

Agrometeorological observations

The effect of weather on agriculture can not be determined by observing only the weather. In addition to meteorological observation therefore, agrometeorologists began observing plants, soils domestic animals, the occurrence of pests and disease etc. Modern agrometeorology needs and uses data from both observations of the weather and of agriculture.

Agrometeorological observations - Plant development (phenology)

- State of the plant- Plants yield- Plants height- Damage from adverse meteorological phenomenon- Extent of weeds- Soil moisture in the field of crops- State of soil surface- Health of domestic animals- Productivity of domestic animals- Occurrence of diseases etc.

Depending upon their applicability and use, the agro-meteorological observations can be divided into two main groups:-

 a. Observations made for specific research projects.

b.   Observations used as permanent (routine) in a network of agro-metrological stations

Observations to be carried out at agro-meteorological stations.

I. Observations of the physical environment a)      Temprature and humidity of the air; b)      Wind; c)      Sunshine and radiation; d)      Clouds, hydrometeors and other water-

balance factors(including hail, dew, fog, soil and water evaporation, plant transpiration, runoff and water table);

 

e)      Evaporation and water-balance measurements

 f)       Soil temperature. g) Soil moisture  Additional observations contribute towards

better understanding of soil-moisture conditions:

-         Field capacity of the soil;-         Permanent wilting point; and-         Depth of the groundwater 

    II. Phenological Observation In the developmental process from

the germination of seeds, plants show several visible external changes, which are a result of the environmental conditions. These external changes are called phenological phases (stages) of plant development and the observations are called phenological observations.

- Definitions and methods of observation of individual phenological phase

Eg. Sprouting:-This is defined as when seeds have developed shoots and the first leaves have unfolded in different spots on the plots, the sprouting stage has begun. Uniformly of emergence is described qualitatively by the following criteria.

Good - over 90% of the entire field is uniformly emerged.

Fair - below 90% but above 75% of the entire fields is Uniformly emerged.

Poor - below 75% of the entire field is uniformly emerged.

Selection of fields for phenological observation

Phenological observations should not be made on crops involved in agricultural experiments, such as testing fertilizers irrigation experiments etc. The phenological observations however can be performed in the control plots of such experiments, where all conditions are the same as in the surrounding area.

Times of phenological observation

The phenological observations should be performed three times a week. If one of the selected days is an official holiday, the observations should be performed a day earlier or later.

Method of phenological observation

The method of performing phenological observations depends on the way a crop is cultivated.

III. OBSERVATIONS ON THE STATE OF THE CROPS 

A. General assessment of the state of the plant

-                     Excellent stae:- the plants are strong, healthy, well rooted and well-developed. The density the sowing area is optimal for the local conditions, and there are no missing plants. All parts of the plants, and especially the reproductive ones, are in excellent condition. There are no weeds. Such a state is typical for years with very good meteorological conditions and a yield much higher than normal years is to be expected;

-                     Very good state:- the state could not be assessed as excellent only because of some minor shortcomings-some plants are not too healthy or strong; there are missing plants in some parts of the field; there are some weeds; there is slight damage from adverse meteorological phenomena, pests. Neverthless, the expected yield from the crops is still above average for the area;

-                     Normal state:- a normal yield is expected;-                     Unsatisfactory state:- a yield below normal is to be expected;-                     Bad state:- a very poor yield is to be expected.

B. Density of the sowing area

C. Height of the plants

D. Observation of damage to plants by unfavorable weather phenomena

i. Unfavorable weather phenomena to plants 

The following are the main weather factors that adversely affect crops.

               a.   Abnormal rainfall condition.   Direct damage to fragile plant organs, like flowers; soil erosion;

water logging; drought and floods; land slides; impeded and drying of agricultural product; conditions favorable to crop and livestock pest development; negative effect on pollination and pollinators etc.

 

b. Abnormal wind condition.·  Physical damage to plant organs

or whole plants(e.g. defoliation, particularly of shrubs and trees); soil erosion; excessive evaporation. Wind is an aggravating factor in the event of bush or forest fires.

 

c. Abnormal air moisture.· High values create conditions

favorable to pest development; low values associated with high evaporation and often one of the most determinant factors in fire outbreaks.

d.  High tempratures·  Increased evaporation; induced

sterility in certain crops. High temperatures at night are associated with increased respiration loss. “Heat waves”, lengthy spells of abnormally high temperatures are particularly harmful.

 e.   Low temperatures

– Destruction of cell structure(frost); desication; slow growth, particularly during cold waves; cold dews.

f.  High cloudiness·  Increased incidence of diseases; poor growth.

g.   Hail

·    Hail impact is usually rather localized, but the damage to crops particularly at critical phenological stages may be significant. Even light hail tends to be followed by pest and disease attacks.

h.    Lightning·   Lightning causes damage to buildings and the loss of farm animals. It is also one of the causes of wildfire.

i.   Snow·   Heavy snowfall damages woody plants. Un-seasonable occurrence particularly affects reproductive organs of plants.

j.Volcanic eruptions, avalanches and earthquakes· The events listed may disrupt infrastructure and cause the loss of crops and farmland, sometimes permanently. A recent example of carbon dioxide and hydrogen sulphide emissions from a volcanic lake in Cameroon caused significant loss of human life and farm animals.

 k.  Air and water pollution

· Air pollutants affect life in the immediate surrounding of point sources. In combination with fog, some pollutants have more marked effect on plants and animals. Occurrences of irrigation water pollution have been reported.

E. Damage from Plant pathogensi) Plant pathogens

Plant diseases are caused by different pathogens in groups of viruses, fungi, nematodes, bacteria etc like organisms.

Meteorological conditions influence not only the development of an epidemic over a single growing season, but also the survival of the pathogen until the next season.

ii) The influence of climate on pest and disease

Climate determines the distribution of pest like the distribution of vegetation over the area. In other word climate sets the limits of occurrence of pest. The development of pest depends upon three factors that are environment, host and pathogen.

 Disease triangle or disease triode

P- Pathogen  

H- Host

Time

E- Environment

iii) Classification of plant disease: - Based on the severity of the occurrence or intensity of attack the plant disease classified as follows -         Sporadic-         Endemic-         Epidemic

iv) Role of weather in the development of pest

Temperature - influence all metabolic (physiological or biochemical) reactions

- Influence incubation period (time interval between infection and first appearance of disease symptom in the host)

E.g. Wheat stem rustTemperature Incubation period

24°C 5 days13°C 12 days4.5°C 21 days

Humidity –temperature and humidity together influences the process of infection, incubation period, and sporulation and determines the number of disease cycles in one crop-growing season.

  Rainfall - if it is little with sunny intervals

it would create favourable condition for decease whereas if it is heavy it is not favourable for disease development, it washed out the spores.

 

Wind -if it is calm and the rainfall occurs, it would favour the disease but if it is strong it dried the leaf no condition for germination.

  Light - intense light condition is

not favorable for fungi but deem and moist condition is favourable.

Insect pests responses to climate variabilityExamples

African armyworm (spodoptra exemta)  The first outbreaks in east Africa are often in Tanzania at the end of

the year, and later outbreaks are further and further north, reaching Ethiopia by the middle of the year (The infestation period at different areas of the country is mid-April-July). Downwind displacement would take moths towards and into the Inter Tropical Convergence Zones(ITCZ), so that most of the insects, whether caterpillars or moths would be near the ITCZ, where rains fall and grasses grow. Moreover, the following generations would move with the ITCZ as shown by catches from a network of moth traps over east Africa.

Locusts  Over most parts of the African Savanna, grasshoppers

and locusts destroy many farmlands every year. The locusts generally originate in the Sahara desert margins where there is enough moisture for breeding and for vegetative growth to feed the larvae. The locusts fly in swarm’s southwards with the northeasterly winds during the day when temperatures are between 20 and 40°C. Locusts find it impossible to hold to a course if the wind speed exceeds 16 to 20 Km/hour.

Quelea

The red-billed quelea is mainly distributed in the Ethiopian rift valley where sorghum is grown abundantly. The depredation of sorghum by the red-billed quelea at its milky stage is very high.

The seasonal movement patterns of queleas for breeding are influenced by rainfall. Queleas are dependent on ripening grass seeds for breeding and these become available six to eight weeks after the onset of the main rains.

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