Water retention in soil can be understood as the water retained by the soil after it runs through the soil pores to join water bodies such as groundwater or surface streams. Pores in the soil can be defined as the air-spaces that exist in between soil particles.
Water retention is mainly dependant on the particle size of the soil. The finer the soil particles, the higher the chance that water molecules shall hold on to soil particles, such as in clay, as opposed to sandy soil, that has large and coarse particles that are not cohesive.
The water retention by soil is critical for plants and acts as the chief source of moisture for it in almost all habitats. Other than percolation through the soil, soil moisture can also deplete due to evaporation directly from the soil and by transpiration by plants.
As based on the size of the soil particles, there are four classificatory systems for the identification of soils (J. Mariamma, 2010) –
- US Bureau of Soil Classification
- International Classification
- M.I.T Classification
- Indian Standard Classification
The Indian Standard classificatory system was formulated originally for the classification of soils primarily for engineering purposes. This is because the draft for soil classification was prepared by the Soil Engineering Sectional Committee and was approved by the Civil Engineering Division Council.
The final draft was adopted by the Bureau of Indian Standards on December 19th, 1970. This system divides soils into three broad categories based on the properties of soil particles (Bureau of Indian Standards, 2004) –
i) Clay – the particles are microscopic to sub-microscopic and exhibit plasticity, allowing it to retain the most water.
ii) Silt – the particles are fine grains, but exhibit less plasticity, making this form retain lesser water.
iii) Sand and Gravel – aggregates of comparably larger particles that are coarse and loosely bound thus lacking cohesion. The least water retention is possible in this form of soil.
Different topographic and climactic patterns result in varied behaviour of soils and thus require a variety of approaches to analyze and implement soil management techniques for water retention. Soil can sometimes pose problems for not being as desired, and these problems can broadly be grouped under chemical and physical problems (National Agricultural University, NAU, 2013).
Chemical problems include high salinity or acidity in soils, along with the presence of other toxic chemicals such as phosphorous in soil (NAU, 2013). This problem becomes especially pertinent in agriculture where crop yield or productivity could dwindle due to chemicals used in the agricultural process such as pesticides and herbicides.
Among a large gamut of solutions and applications, the most common one is the use of ecologically beneficial green manure. Agricultural soil should also be frequently and properly drained to achieve effects such as the leaching of saline moisture in soils.
The physical problems can involve soil that is not able to contain much water due to lack of cohesion or due to a rigidity that can occur owing to encrustation, or a very clayey surface. Shallow depth of soil, soil that is too clayey, or the presence of hard opaque surfaces underneath can also present problems to water retention and there can be water-logging when too much water is added to soil.
These require artificial solutions to soil management that frequently involves the mixing of soil with other different forms of soil. Incorporating organic matter and regulating drainage are also frequently applied solutions.
There are various methods to enhancing the water retention capacity of soil. Some methods are more traditional, and also conventional, while some involve the utilization of technology. While most of technological investment regarding water retention in soils involves technologies for enumeration and generation of data, technological solutions can vary from simple, affordable, everyday solutions to solutions utilizing high-end technology.
Some of the simple solutions include application of organic solutions such as drought resistant crop varieties and organisms that increase the fertility of soil, management and design of irrigation according to soil properties, application of biochar – produced from biomass for low-cost carbon sequestration in soil – making soil less porous, use of the roots of plants that grip soil, and application of natural by-products such as poultry litter that provide greater cohesiveness to soil.
The solutions can also range towards using complex technologies such as mapping the global water cycle in relation to water retention in soil, and preparation of dietary fibres that have high water-holding capacity from food sources used in soil. There is however, a leaning in technological progress in engineering water retention in soil to introduce organic elements in the soil instead of inorganic matter.
Recent Posts
Petrol in India is cheaper than in countries like Hong Kong, Germany and the UK but costlier than in China, Brazil, Japan, the US, Russia, Pakistan and Sri Lanka, a Bank of Baroda Economics Research report showed.
Rising fuel prices in India have led to considerable debate on which government, state or central, should be lowering their taxes to keep prices under control.
The rise in fuel prices is mainly due to the global price of crude oil (raw material for making petrol and diesel) going up. Further, a stronger dollar has added to the cost of crude oil.
Amongst comparable countries (per capita wise), prices in India are higher than those in Vietnam, Kenya, Ukraine, Bangladesh, Nepal, Pakistan, Sri Lanka, and Venezuela. Countries that are major oil producers have much lower prices.
In the report, the Philippines has a comparable petrol price but has a per capita income higher than India by over 50 per cent.
Countries which have a lower per capita income like Kenya, Bangladesh, Nepal, Pakistan, and Venezuela have much lower prices of petrol and hence are impacted less than India.
“Therefore there is still a strong case for the government to consider lowering the taxes on fuel to protect the interest of the people,” the report argued.
India is the world’s third-biggest oil consuming and importing nation. It imports 85 per cent of its oil needs and so prices retail fuel at import parity rates.
With the global surge in energy prices, the cost of producing petrol, diesel and other petroleum products also went up for oil companies in India.
They raised petrol and diesel prices by Rs 10 a litre in just over a fortnight beginning March 22 but hit a pause button soon after as the move faced criticism and the opposition parties asked the government to cut taxes instead.
India imports most of its oil from a group of countries called the ‘OPEC +’ (i.e, Iran, Iraq, Saudi Arabia, Venezuela, Kuwait, United Arab Emirates, Russia, etc), which produces 40% of the world’s crude oil.
As they have the power to dictate fuel supply and prices, their decision of limiting the global supply reduces supply in India, thus raising prices
The government charges about 167% tax (excise) on petrol and 129% on diesel as compared to US (20%), UK (62%), Italy and Germany (65%).
The abominable excise duty is 2/3rd of the cost, and the base price, dealer commission and freight form the rest.
Here is an approximate break-up (in Rs):
a)Base Price | 39 |
b)Freight | 0.34 |
c) Price Charged to Dealers = (a+b) | 39.34 |
d) Excise Duty | 40.17 |
e) Dealer Commission | 4.68 |
f) VAT | 25.35 |
g) Retail Selling Price | 109.54 |
Looked closely, much of the cost of petrol and diesel is due to higher tax rate by govt, specifically excise duty.
So the question is why government is not reducing the prices ?
India, being a developing country, it does require gigantic amount of funding for its infrastructure projects as well as welfare schemes.
However, we as a society is yet to be tax-compliant. Many people evade the direct tax and that’s the reason why govt’s hands are tied. Govt. needs the money to fund various programs and at the same time it is not generating enough revenue from direct taxes.
That’s the reason why, govt is bumping up its revenue through higher indirect taxes such as GST or excise duty as in the case of petrol and diesel.
Direct taxes are progressive as it taxes according to an individuals’ income however indirect tax such as excise duty or GST are regressive in the sense that the poorest of the poor and richest of the rich have to pay the same amount.
Does not matter, if you are an auto-driver or owner of a Mercedes, end of the day both pay the same price for petrol/diesel-that’s why it is regressive in nature.
But unlike direct tax where tax evasion is rampant, indirect tax can not be evaded due to their very nature and as long as huge no of Indians keep evading direct taxes, indirect tax such as excise duty will be difficult for the govt to reduce, because it may reduce the revenue and hamper may programs of the govt.
Globally, around 80% of wastewater flows back into the ecosystem without being treated or reused, according to the United Nations.
This can pose a significant environmental and health threat.
In the absence of cost-effective, sustainable, disruptive water management solutions, about 70% of sewage is discharged untreated into India’s water bodies.
A staggering 21% of diseases are caused by contaminated water in India, according to the World Bank, and one in five children die before their fifth birthday because of poor sanitation and hygiene conditions, according to Startup India.
As we confront these public health challenges emerging out of environmental concerns, expanding the scope of public health/environmental engineering science becomes pivotal.
For India to achieve its sustainable development goals of clean water and sanitation and to address the growing demands for water consumption and preservation of both surface water bodies and groundwater resources, it is essential to find and implement innovative ways of treating wastewater.
It is in this context why the specialised cadre of public health engineers, also known as sanitation engineers or environmental engineers, is best suited to provide the growing urban and rural water supply and to manage solid waste and wastewater.
Traditionally, engineering and public health have been understood as different fields.
Currently in India, civil engineering incorporates a course or two on environmental engineering for students to learn about wastewater management as a part of their pre-service and in-service training.
Most often, civil engineers do not have adequate skills to address public health problems. And public health professionals do not have adequate engineering skills.
India aims to supply 55 litres of water per person per day by 2024 under its Jal Jeevan Mission to install functional household tap connections.
The goal of reaching every rural household with functional tap water can be achieved in a sustainable and resilient manner only if the cadre of public health engineers is expanded and strengthened.
In India, public health engineering is executed by the Public Works Department or by health officials.
This differs from international trends. To manage a wastewater treatment plant in Europe, for example, a candidate must specialise in wastewater engineering.
Furthermore, public health engineering should be developed as an interdisciplinary field. Engineers can significantly contribute to public health in defining what is possible, identifying limitations, and shaping workable solutions with a problem-solving approach.
Similarly, public health professionals can contribute to engineering through well-researched understanding of health issues, measured risks and how course correction can be initiated.
Once both meet, a public health engineer can identify a health risk, work on developing concrete solutions such as new health and safety practices or specialised equipment, in order to correct the safety concern..
There is no doubt that the majority of diseases are water-related, transmitted through consumption of contaminated water, vectors breeding in stagnated water, or lack of adequate quantity of good quality water for proper personal hygiene.
Diseases cannot be contained unless we provide good quality and adequate quantity of water. Most of the world’s diseases can be prevented by considering this.
Training our young minds towards creating sustainable water management systems would be the first step.
Currently, institutions like the Indian Institute of Technology, Madras (IIT-M) are considering initiating public health engineering as a separate discipline.
To leverage this opportunity even further, India needs to scale up in the same direction.