Soil pollution is a condition in which soil become rich in pollutants, contaminants and toxic materials and it poses threat to human life, agriculture, animals and other macro and microorganisms. In other words, soil pollution is the beginning of death of soil, failing to sustain any kind of production in terms of agriculture and wildlife on it. Arable land turns into desert land and threats food security ultimately.
Reasons of Soil Pollution
The reason of soil pollution is both natural and man-made. Global warming, climate change are regarded as natural factors of soil pollution while, excess usage of fertilizers, pesticides, weedicides and herbicides is damaging the natural order of soil, thus polluting it and making it weak. It is a global phenomenon that soils are becoming less and less productive and fertile due to degrading organic matter.
Natural Causes of Soil Pollution
Among many, common natural causes of soil pollution is the natural amassing of compounds in soil resulting from imbalances between atmospheric deposition and leaking away with precipitation water. This is common in arid environments where concentration and accumulation of per-chlorate in soils results in soil pollution.
In some cases, thunderstorm also creates environment for soil pollution. This happens when chlorine source or metallic objects present in the soil use energy generated from thunderstorm to generate per-chlorate in the soil.
Man-made Causes of Soil Pollution
Accident leaks and spills.
Agricultural activities resulting in release of pesticide, fertilizer etc.
Transport activities releasing toxic smoke and emissions.
Cracked paint chips.
The storage of waste in landfills.
Soil Erosion Causing Death of Soil to Sustain Agriculture
Soil erosion is another factor causing soil pollution. The United Nations Food and Agricultural Organization (FAO) stated recently that 75 billion tons of soil which is almost equivalent to 10 million hectares of land is lost due to erosion, water-logging and salination annually. On top of it, additional 20 million hectares of land is abandoned and not under any cultivation due to poor quality soil and degradation.
In Arid Agriculture or dryland farming systems, selection of proper crop is critical to generate healthy revenue. For selection of appropriate crop for your farm, there are numerous factors to be considered before actually entering into farming business. While farmers of irrigated land may select their crops on the basis of profitability, a dryland or arid farmer has to select appropriate crop considering two factors. These are
Adaptability in arid environment
Thus an arid farmer has a lot on stake when it comes to farming. Any deviation in regular pattern of rainfall can bring loss to farmer’s investment. Agriculture is gambling, but arid agriculture is far more than just gambling. This article will discuss important factors that should be kept in mind before starting any agriculture activity in any arid zone of the world.
1. Ocular Screening of the Land
To start farming in arid lands, an ecological skimming should be carried out. This is not a technical thing. It just include a deep ocular scrutiny and other approaches to acquire evidences on the biotic factor that have direct or indirect link with the plant growth and its yield, climatic conditions prevailing in the surrounding area, soil properties, infrastructural needs and accessibility. Summarizing, the rule should be to know your farm then select the right crop.
2. Disease History of the Area
Here it is important to mention that a biotic scan will aid in knowing any symptoms of diseases prevailing in the area. In the case of diseases, disease resistant varieties can be selected for farming and susceptible crops may be omitted.
Soil is the baseline for any kind of agricultural activities. Without soil, sustainable agriculture that feed billions of people and other organisms on earth is not possible. That is why; soil is studied under its own branch termed as ‘soil science’. This article will guide you through a brief introduction of soil science as subject and career in soil science field.
Before moving ahead, let’s discuss what is soil science? It is the branch of agriculture science that deals with the study of soil as a natural resource. In this, we study the soil from all aspects including soil formation, management, classification and mapping, chemical, physical and biological properties, soil fertility and problems related to soil and exploring solutions to solve the its problems, diseases of soil etc.
Sometimes, few other terms are used in place of soil science like pedology and edaphology where pedology means formation, chemistry, morphology, and classification of soil while edaphology studies influence of soil on organisms, especially the plants.
Career is Soil Science
A person who studies soil and do practicals based on soil theory is known as Soil Scientist. Technically, a soil scientist studies the earth crust from upper surface. His/her concern is with few inches of top soil of earth. The main focus of a soil scientist is with the physical, chemical and biological properties, soil genesis and morphology. If you are planning to become a soil scientist, keep in mind that you should have a strong academic background in biological and physical sciences along with a good grip on mathematics.
Should you Choose Soil Science?
It is a million dollar question. Soil science is not just another branch of agriculture. There should be some per-requisites that should be present in a person if he/she wants to become a soil scientist. This includes;
Love of nature
Love with soil
Happy working outdoors for hours in harsh environments
Understanding of geographies and maps
Want to become an integral part of decision making processes related to soil
How to become a Soil Scientist?
There are graduate programs dealing with soil science that are offered to students who are willing to join soil science field. Agricultural universities are the ones offering these programs. To be consider as a soil scientist, he/she must have earned at least bachelor degree not diploma is soil science. The graduate then can study further and earn masters or even PhD degrees in soil science.
Globally, two choices are favorite for soil scientists. They may choose to study simple soil science or environmental soil science. The first prepare students to become advisor or consultant mostly with large corporations, companies and government agencies, while the later prepare students to have prosperous career in environmental positions to deal with quality of soil and water, soil relation to water, assessment of soil properties during construction, recreational facilities and waste disposal.
Soil scientist works both on desk and in fields. However, a soil scientist without frequent field visits cannot becomes a perfect scientist. They have to visit recurrently to the farm lands, mountains and uneven terrains with spades and shovels in hands to collect soil sample. Another important thing is that, soil scientists have to work often with non-soil science professionals. So they have to be open minded by attitude to accept ideas.
On global scale, the demand of soil scientists is increasing day by day due to land degradation by erosion, desertification and urbanization. Both public and private options are open for a soil scientist thus opening vide avenues of career in soil science for the scientists. Below is a list showing various career options for a soil scientist.
Research jobs in government and private labs
Teaching jobs at undergraduate and graduate level in colleges and universities
Jobs in pesticide, weedicide and herbicide companies
Marketing manager for an agricultural firm at district level
Soil scientist in mapping and interpretation of soil matters
Land planning officer
Crop production specialists
Government and private farm advisor
P.S. This is not a complete list. Comments are welcome below to highlight other job opportunities available for a soil scientist.
Cite this Article in APA Style as:
[box type=”note” align=”aligncenter” ]Rahman, M. A. (2017, September 10). Introduction and Career in Soil Science [Blog Post]. Retrieved from http://aridagriculture.com/2017/09/10/introduction-and-career-in-soil-science[/box]
In arid and dryland farming, water has premium importance. It is available in scarce quantity, so its usage should be carried out in a wise manner. In this regard, understanding soil chemistry and soil-water relationship is of utmost importance especially for arid and dryland farming systems. This article will highlight various types of soil water or precisely the combinations of water that is available in connection with the soil particles that give birth to new and innovative soil-water relationship.
Soil chemistry is complex. Understanding soil needs in-depth analysis of various factors. One of these is the soil-water relationship. The interaction of water with soil is always the element of interest for agriculturists and especially soil scientists all around the globe. The study of soil-water relationship gives birth to a phenomenon called as ‘types of soil water’. Soil scientists classified this relationship in various categories which I will discuss later in this article. Firstly, it is important to understand the behavior of soil when it receives water.
Suppose the soil is dry. You add water to the soil by any means say for example through irrigation, or rainfall. The water gets in touch with the soil and is distributed all around the particles of soil. The water around the soil particles is held through adhesion and cohesion forces. By the action of these forces, air gets displace that is present in pore spaces and water enters in these pores and fill them. The pore spaces are of various sizes. When all these pores get filled whether they are small, medium or large, we call that soil is saturated and it is now at maximum capacity of retention.
Types of Soil Water
It is difficult to define what the exact soil water definition is, but for the sake of easy understanding of students and general readers, soil scientists classify various kinds of soil water into following categories.
1. Gravitational Water
It is the simplest type of soil-water relationship. In this, when soil gets water, water moves freely under the action of gravitational force and drains out of the soil. This happens, when the capillary capacity of soil is fulfilled and additional water comes under the gravitational pull. This additional water then starts moving freely through the macro-pores of soil particles and this is termed as gravitational water.
As this water can be regarded as surplus, it is not useful for the plants. It has zero atmospheric tension. In case where movement of gravitational water is more towards downward, there is a good chance that some useful nutrients needed by plants may leached out. On the other hand, in case where gravitation water’s downward movement is slow or less, then in that case, it affects the soil aeration.
2. Hygroscopic Water
This type of soil water is tightly held with the surface of the soil particles in the form of a thin film. It is held under the influence of adhesive and cohesive forces. Mostly, it is in vapor form. This type of water is held by the soil with a force which is estimated to be 31 atmosphere from the outer side and 10,000 atmosphere towards inner side of hygroscopic water film. (At sea level, 1 atmosphere is 15 pounds per square inch). In general, this type of water is not of any use to the plants.
3. Capillary Water
Third type of soil water is capillary water. This water is held by the surface tension forces. It is in the form of continuous film around the soil particles and in the spaces of capillary. Capillary water is that water which is held in soil in excess of hygroscopic water. However, it is less than the point where gravitation water category starts. This means, capillary water is a type that exists between hygroscopic and gravitation water. In the scenario when capillary water exceeds the point of gravity pull, then in that case, water will move downwards and drainage situation occurs.
The capillary water is actually loosely held water. It ranges from 31 atmosphere to 1/3 atmosphere tension. It is capable of moving within the soil. It is useful for the pant as the plant food nutrients gets dissolved in capillary water.
4. Water Vapors
Last in the types of soil water is the water available in vapors form. It is of least importance as compare to the first three. This is because; water vapors are present in the soil atmosphere in the gaseous form. This does not allow the plant to use it directly. Water vapors are important for maintain healthy soil chemistry. This type of water not only helps in maintaining the optimum temperature in the soil, but also allows healthy intake of nutrients by the plant.
Water is precious for arid agriculture and dryland farming. Understanding the soil-water chemistry is important in chalking out irrigation methodologies for arid agriculture.
Cite this article in APA Style as;
[box type=”note” align=”aligncenter” ]Rahman, M. A. (2017, September 09). Various Types of Soil Water [Blog Post]. Retrieved from http://aridagriculture.com/2017/09/09/various-types-of-soil-water/[/box]
Agriculture in dryland or arid lands is carried out in harsh environment. Water being the chief resource in crop growth, is scarce in drylands. To cope with this situation, there are certain agronomic procedures in dryland agriculture that are applied to have sustainable production in efficient manner.
Soil and water are two basic factors that are vulnerable to harsh environment in arid or dryland agricultural systems. These two factors require conservation measures to have sustainable crop production. Otherwise crop failure occurs. In modern day agriculture, agronomic and mechanical means are used to conserve soil and water. Mechanical measures are supposed to back or support the agronomic measures especially where slope surpasses the tolerable limit and runoff results in accelerated erosion. Thus, water being the scarce resource in dryland agriculture needs special attention of the agronomists and agricultural engineers to have supportable livelihoods of the farmers.
This article is focused on the agronomic procedures in dryland agriculture that are essential in terraced or inter-bunded areas. In reality, the agronomic measures enhance the utility obtained from all types of mechanical structures applied in an area. Below are few necessary measures that should be taken for resource conservation to achieve optimal crop production in dryland or arid agriculture system.
It is a common observation that the soils in arid or dryland agriculture systems are very low in organic matter. Increasing the organic matter is somewhat expensive for the poor farmers. So, most common agronomic procedures in dryland agriculture are the leaving of crop residue in situ in the fields after harvesting the crop.
Being an agriculturist, I am big opponent of applying chemical or synthetic fertilizer in dryland or arid agriculture systems to increase fertility of soil. This is because; these fertilizers act as competitors to crops and consume already scarce moisture in soil in their transformation. This also impacts the natural activities of microorganisms and destruct soil structures.
Soil in dryland or arid agriculture systems should be supplemented by organic farm manure or compost. Using cow/buffalo waste or poultry residue are good examples of manures, while utilizing dead leaves and kitchen waste are good examples for composting. These are very helpful in increasing soil-temperature, soil-air and soil-moisture relationship along with enhanced soil micro organismic activities.
Contour tillage is an agronomic practice if the land slope is more than the normal level. The objective is to reduce erosion and prevent runoff. It is generally recommended that all mechanical practices like ridging, ploughing, harrowing, sowing and trenching should be done on the contour. Moreover, these practices should be implemented across the direction of the slope especially where the land holding are small. Though, the procedure looks simple, but is quite effective against the forces that cause the soil erosion. Moreover, it also increases the time of concentration of water, so that more water seeps into the soil.
Dead furrows are very important when all tillage operations are completed. It is beneficial to leave a yawning dead furrow at least every 10 m interval. It should be ensured that this dead furrow remains in that position till crop harvest. The advantage of dead furrow is to reduce the velocity of runoff that results in water conservation.
In normal season, there are marginal lands that do not produce good annual income from crops. These soils are in-fact best suited for dryland horticultural crops like tamarind, olive, guava etc. These kinds of land help in growing such trees that have economic value and become assets to generate handsome profit. Another option is to grow such varieties of trees that are fast growing and usable as fodder, timber or fuel for the local community. Thus dryland become good source of income for local inhabitants.
Regular weeding is not only a requirement in arid or dryland agriculture, but also it should be made a habit. Weeds compete for moisture and nutrients with crops. Mechanical weeding and line sowing along with using appropriate size of blade harrow eradicate the weeds. Hand hoes are useful for weeding within the rows.
Growing Drought Tolerating and Early Maturing Varieties
It is wise to cultivate those varieties of crops in dryland or arid farming systems that have genetic character with the ability to endure shortage of water and drought circumstances. Similarly, it is worthy to select such crop varieties having shorter period of life cycle i.e. their seed to seed cycle is less. This will reduce the water requirements of the crop. These two measures are revenue generating in the drought-prone areas.
Arid agriculture or dry land agriculture is used quite often universally. However, these are poorly defined and understood. The word ‘Arid” is used for an area that is characterized by low volume of rainfall i.e. less than 10 inches of rain fall per annum. Arid agriculture is sometimes referred to as dry land agriculture. From farming perspective, arid agriculture has great importance. This is mainly because most of the regions in the world are Arid, where agricultural system lack irrigation facilities. More precisely, arid agriculture refers to as the cultivation of crops where irrigation facilities are absent and evaporation of moisture from soil exceeds rainfall.
It is interesting that rain fed agriculture and arid agriculture are sometimes consider same and used interchangeably. However, there lies massive difference between the two. Rain fed agriculture includes the arid or dryland agriculture. But arid agriculture is generally defined as growing of crops where lack of availability of moisture hampers the crop production to part of the year.
A study of world atlas shows that large chunk of the earth is arid. So, arid agriculture is adept in many parts of the globe. The countries in the Middle East, South America, the steppe lands of Eurasia, major part of Australia and southern and southwestern parts of United States bear arid climate. The weather conditions are harsh with high temperature and less availability of water. Rainfall is sporadic in arid areas. This causes flash floods when it happens because dry climate of arid areas makes the soil tough and compact that it cannot easily absorb rain water. Thus flood occurs. On the other hand, the organic matter in the soils of arid regions is low resultantly the fertility of the soil is affected. Soil erosion is a common problem in arid agriculture.
Despite of all these facts, the mankind has developed technologies to cope and sustain under harsh climate of arid nature. Arid agriculture has economic importance because if no cropping is practice in these areas, then more pressure will be exerted on other limited productive parts of the world that will eventually result in food insecurity situation. So, arid agriculture or dryland agriculture cannot be neglected of its harsh environment.
There are ways in which arid agriculture can be made productive by altering farming practices and adapting smart water conservation technologies. Mulching, growing trees at farm borders, constructing small dams, leveling the farm land, growing heat tolerant crops, avoiding formation of hard crust on soil surface, growing small structured variety of crops to minimize transpiration, usage of smart irrigation strategies like drip, furrow or sprinkler etc. are few practical ways that can ensure sustainable arid agriculture in any part of the world.