Phosphate rich organic manure
Encyclopedia
Phosphate rich organic manure is a type of fertilizer
used as an alternative to diammonium phosphate
and single super phosphate.
Phosphorus
is required by all plants but is limited in soil, creating a problem in agriculture
. In many areas phosphorus must be added to soil for the extensive plant growth that is desired for crop production. Phosphorus was first added as a fertilizer in the form of single super phosphate (SSP) in the mid-nineteenth century, following research at Rothamsted Experimental Station
in England
.
The world consumes around 140 million tons of high grade rock phosphate mineral today, 90% of which goes into the production of diammonium phosphate (DAP). Excess application of chemical fertilizers in fact reduces the agricultural production as chemicals destroy natural soil flora and fauna. When DAP or SSP is applied to the soil only about 30% of the phosphorus is used by the plants, while the rest is converted to forms which cannot be used by the crops [x1,X2], a phenomenon which is known as phosphate problem to soil scientists
.
Directly mixing finely ground rock phosphate mineral into organic manure produces a fertilizer known as phosphate rich organic manure (PROM). Research indicates that this substance may be a more efficient way of adding phosphorus to soil than applying chemical fertilizers. Other benefits of PROM are that it supplies phosphorus to the second crop planted in a treated area as efficiently as the first, and that it can be produced using waste solids recovered from the discharge of biogas
plants.
Phosphorus in rock phosphate mineral is mostly in the form of tricalcium phosphate
, which is water insoluble
. Phosphorus dissolution in the soil is most favorable at a pH
between 5.5 and 7. Ions of aluminum, iron
, and manganese
prevent phosphorus dissolution by keeping local pH below 5.5, and magnesium
and calcium
ions prevent the pH from dropping below 7, preventing the release of phosphorus from its stable molecule. Microorganisms produce organic acid
s and heat, allowing the slow dissolution of phosphorus from rock phosphate dust added to the soil, allowing more phosphorus uptake by the plant roots. Organic manure can prevent ions of other elements from locking phosphorus into insoluble forms. The phosphorus in phosphate enhanced organic manure is water insoluble, so it does not run into ground water or runoff [x] any more than that from chemical fertilizers.
Most phosphate rocks can be used for phosphate rich organic manure. It was previously thought that only those rocks which have citric acid
soluble phosphate and those of sedimentary origin
could be used. Rocks of volcanic origin
can be used as long as they are ground to very fine size.
Organic manure should be properly prepared for use in agriculture, reducing the C:N ratio to 30:1 or lower. Alkaline and acidic soils require different ratios of phosphorus.
PROM is known as a green chemistry
phosphatic fertilizer. Addition of natural minerals or synthetic oxides in water insoluble forms that contain micronutrients such as copper
, zinc
, and cobalt
may improve the efficiency of PROM. Using natural sources of nitrogen, such as Azolla, may be more environmentally sound.
Fertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...
used as an alternative to diammonium phosphate
Diammonium phosphate
Diammonium phosphate is one of a series of water-soluble ammonium phosphate salts which can be produced when ammonia reacts with phosphoric acid...
and single super phosphate.
Phosphorus
Phosphorus
Phosphorus is the chemical element that has the symbol P and atomic number 15. A multivalent nonmetal of the nitrogen group, phosphorus as a mineral is almost always present in its maximally oxidized state, as inorganic phosphate rocks...
is required by all plants but is limited in soil, creating a problem in agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
. In many areas phosphorus must be added to soil for the extensive plant growth that is desired for crop production. Phosphorus was first added as a fertilizer in the form of single super phosphate (SSP) in the mid-nineteenth century, following research at Rothamsted Experimental Station
Rothamsted Experimental Station
The Rothamsted Experimental Station, one of the oldest agricultural research institutions in the world, is located at Harpenden in Hertfordshire, England. It is now known as Rothamsted Research...
in England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
.
The world consumes around 140 million tons of high grade rock phosphate mineral today, 90% of which goes into the production of diammonium phosphate (DAP). Excess application of chemical fertilizers in fact reduces the agricultural production as chemicals destroy natural soil flora and fauna. When DAP or SSP is applied to the soil only about 30% of the phosphorus is used by the plants, while the rest is converted to forms which cannot be used by the crops [x1,X2], a phenomenon which is known as phosphate problem to soil scientists
Soil science
Soil science is the study of soil as a natural resource on the surface of the earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to the use and management of soils.Sometimes terms which...
.
Directly mixing finely ground rock phosphate mineral into organic manure produces a fertilizer known as phosphate rich organic manure (PROM). Research indicates that this substance may be a more efficient way of adding phosphorus to soil than applying chemical fertilizers. Other benefits of PROM are that it supplies phosphorus to the second crop planted in a treated area as efficiently as the first, and that it can be produced using waste solids recovered from the discharge of biogas
Biogas
Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Organic waste such as dead plant and animal material, animal dung, and kitchen waste can be converted into a gaseous fuel called biogas...
plants.
Phosphorus in rock phosphate mineral is mostly in the form of tricalcium phosphate
Tricalcium phosphate
Tricalcium phosphate is a calcium salt of phosphoric acid with the chemical formula Ca32. It is also known as tribasic calcium phosphate or "bone ash" ....
, which is water insoluble
Solubility
Solubility is the property of a solid, liquid, or gaseous chemical substance called solute to dissolve in a solid, liquid, or gaseous solvent to form a homogeneous solution of the solute in the solvent. The solubility of a substance fundamentally depends on the used solvent as well as on...
. Phosphorus dissolution in the soil is most favorable at a pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
between 5.5 and 7. Ions of aluminum, iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
, and manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
prevent phosphorus dissolution by keeping local pH below 5.5, and magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
and calcium
Calcium
Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
ions prevent the pH from dropping below 7, preventing the release of phosphorus from its stable molecule. Microorganisms produce organic acid
Organic acid
An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are relatively stronger acids. The relative stability of the conjugate...
s and heat, allowing the slow dissolution of phosphorus from rock phosphate dust added to the soil, allowing more phosphorus uptake by the plant roots. Organic manure can prevent ions of other elements from locking phosphorus into insoluble forms. The phosphorus in phosphate enhanced organic manure is water insoluble, so it does not run into ground water or runoff [x] any more than that from chemical fertilizers.
Most phosphate rocks can be used for phosphate rich organic manure. It was previously thought that only those rocks which have citric acid
Citric acid
Citric acid is a weak organic acid. It is a natural preservative/conservative and is also used to add an acidic, or sour, taste to foods and soft drinks...
soluble phosphate and those of sedimentary origin
Sedimentary rock
Sedimentary rock are types of rock that are formed by the deposition of material at the Earth's surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle and accumulate or minerals to precipitate from a solution....
could be used. Rocks of volcanic origin
Volcanic rock
Volcanic rock is a rock formed from magma erupted from a volcano. In other words, it is an igneous rock of volcanic origin...
can be used as long as they are ground to very fine size.
Organic manure should be properly prepared for use in agriculture, reducing the C:N ratio to 30:1 or lower. Alkaline and acidic soils require different ratios of phosphorus.
PROM is known as a green chemistry
Green chemistry
Green chemistry, also called sustainable chemistry, is a philosophy of chemical research and engineering that encourages the design of products and processes that minimize the use and generation of hazardous substances...
phosphatic fertilizer. Addition of natural minerals or synthetic oxides in water insoluble forms that contain micronutrients such as copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
, zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
, and cobalt
Cobalt
Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
may improve the efficiency of PROM. Using natural sources of nitrogen, such as Azolla, may be more environmentally sound.