Agriculture

5. Density of Water: Water is less dense as ice than as a liquid, which affects plant life.

At the same temperature of 0°C, the density (mass per volume) of ice is 0.9187 grams per cubic centimeter (g cm^-3 or g/cm³) while that of liquid water is 0.9998 g cm^-3 (Cohen et al. 2003).

The lesser density means that ice contains lesser mass (quantity of matter) per unit of volume.

It also means that the molecules of water are less compressed per unit volume of ice.

The above densities indicate that with the same volume under identical gravitational force, ice will be lighter and liquid water will be heavier compared to each other.

On Earth, a cubic centimeter of ice will weigh 0.9187 grams (or 918.7 kg per cubic meter) while the same volume of liquid water will weigh 0.9998 grams (or 999.8 kg per cubic meter) at a temperature of 0°C.

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4. Water has a high heat of vaporization and boiling point.

Water has the unique property of being able to exist in either of three states: solid, liquid, and gas or steam or water vapor.

The transformation from one to another involves changes in hydrogen bonding and energy levels.

The rule applies that “energy is required for a bond to form, and energy is released when a bond is broken” (Mader 1993).

However, despite its low molecular weight (m.w.= 18.02), water is a liquid at ordinary temperatures and pressure; it does not readily change to ice or steam.

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3. The specific heat of the water as a liquid is high. The temperature of water increases as it absorbs heat and decreases as it releases heat.

However, the temperature of liquid water rises and falls more slowly than those of most other liquids.

Stated another way, water absorbs heat without an immediate rise in temperature. It also retains its temperature much longer than other substances.

This high specific heat of water prevents abrupt changes in temperature and helps the body maintain temperatures that are relatively constant.

Otherwise, plants and other living organisms, which contain large amounts of water, will easily become susceptible to overheating or underheating.

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The ammonium sulfate fertilizer or sulfate of ammonia ((NH₄)₂SO₄; sulfate is also spelled sulfate) is sometimes called ammosul or further abbreviated as AS or AMS.

It is a chemical compound that is primarily used as a nitrogen fertilizer with other minor uses.

It occurs in crystals with a particle size that is variable, colored white to beige (IPNI 2012).

It is a two-in-one synthetic fertilizer that supplies both the essential elements nitrogen and sulfur.

Also interchangeably called 21-0-0 or 21-0-0-24S, it contains 21% nitrogen and 24% sulfur.

All of the nitrogen that is supplied by the ammonium sulfate fertilizer is in the positively-charged ammonic form (NH₄⁺, ammonium ion) just like in urea (CO(NH₂)₂, 46% N), anhydrous ammonia (NH₃, 82% N), and aqua ammonia or ammonium hydroxide (NH₄OH, 20-41% N).

But the sulfur is in the oxidized sulfate form carrying a negative electrical charge.

Upon conversion into ammonic nitrogen in the soil, it behaves according to its properties regardless of the fertilizer source.

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The buddha belly bamboo (Bambusa ventricosa) naturally produces big seeds, with sizes similar to thorny bamboo or kawayan tinik (Bambusa blumeana), bayog ( Bambusa sp.) And botong (Gigantochloa levis).

These plant species are among those recommended for growing bamboo to mitigate global warming and for commercial purposes.

But with little effort and patience, you can produce a dwarf clump which is ideal as a bamboo bonsai and as a landscape specimen.

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This type of photosynthesis was named after the plant family Crassulaceae.

According to Hopkins (1999), it may have evolved ahead of the C4 cycle based on its presence in primitive ferns and Welwitschia.

The Crassulacean Acid Metabolism is similar to C4 photosynthesis based on their having both C3 and C4 cycles of CO2 fixation and reduction.

However, they differ in that in C4 photosynthesis the C3 and C4 cycles occur spatially in two different cells, that is, CO2 is initially fixed via the C4 cycle in the mesophylls cell followed by C3 cycle in the bundle sheath cells.

But in CAM photosynthesis, C3 and C4 cycles occur both spatially in different parts of the same cell (Moore et al. 2003) and temporally, that is, C4 cycle at night and C3 cycle during daytime.

Plants exhibiting this mechanism of photosynthesis referred to as CAM plants, open their stomata at night to allow the passage of CO2 from the atmosphere but close them during the day to conserve water.

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C3 Photosynthesis.

This type of photosynthesis employs solely the C3 Cycle by which carbon dioxide goes through chemical reactions to form carbohydrates.

The C3 cyclic reactions also include the regeneration of the CO2-acceptor chemical substrate. Plants exhibiting this mechanism of photosynthesis are called C3 plants.

The C3 cycle is also called the photosynthetic carbon reduction (PCR) cycle and Calvin Cycle, after Melvin Calvin, an American biochemist.

Calvin headed the research effort at the University of California which, with the use of radiolabeled ¹⁴CO2, finally detailed the sequential reactions leading to the conversion of inorganic, atmospheric CO2 into carbohydrates and other organic compounds.

For this work, he won the Nobel Prize in Chemistry in 1961.

The C3 photosynthesis is only the first to be understood.

Other mechanisms, referred to as C4 photosynthesis and CAM photosynthesis, were later discovered.

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In agriculture, plants are grouped into various crop classifications.

Agricultural crops are plants that are grown or intentionally managed by man for some purpose.

They are classified using various terms worldwide.

But, do we need these classifications to survive, to live a decent and joyful life, or to perform our daily chores?

The answer should be in the negative. Not directly anyway.

We continue to survive because of the oxygen, the energy harvested from the sun which is converted into a usable form, and the other nutrients that plants provide, whether or not they are named or classified into certain groups.

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Stem vegetables (vegetable crops) are those food plants from which edible botanical stems are harvested for use in culinary preparations.

They can be divided further into those with edible stems that are above ground and those with modified underground stems.

Swollen modified stems, such as bulbs, tubers, corms, and rhizomes, serve as the main food storage organs.

Crop plants that are grown for their starchy roots, tubers, and corms are called root and tuber crops.

They are generally placed under the domain of agronomy.

But as to human consumption, they can be considered vegetables under horticulture.

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What is urea?

Urea is a nitrogen-containing fertilizer and a chemical compound with the formula CO(NH₂)₂ (or H₂N.CO.NH₂).

The molecule has two –NH₂ groups joined by a C=O or carbonyl functional group.

It is also called carbamide.

It is very soluble in water but insoluble in ether, with a melting point of 132°C (Walker 1988).

That it is a fertilizer should be the common reply to the question.

Synthetic urea is largely used as such in crop agriculture to supplement the essential major element nitrogen (N).

According to Soh (2006), the usage of urea as fertilizer accounts for more than 90% of total production.

But there are plenty more as to what is urea.

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