IE20110484U1 - Agricultural product - Google Patents

Abstract

ABSTRACT There is provided a fertilizer composition comprising a calcium oxide (CaO) particulate having an average particle size diameter of from about 2 to 8 mm.

Description

Title: Agricultural Product Field of the invention The invention relates to agricultural fertilizer for supply to soil to provide nutrients and optimum soil conditions to stimulate growth _of plants. More particularly the invention relates to inorganic calcium based fertilizers.

Background to the Invention Healthy plants require macro-nutrients including nitrogen (N), phosphorus (P), and potassium (K), calcium (Ca), magnesium (Mg) and sulfur (S), and trace nutrients include iron, (Fe), manganese (Mn), zinc (Zn), copper (Cu), cobalt (Co), molybdenum (Mo), and boron (Bo). Both macro and trace nutrient availability is controlled by soil pH. In slightly to moderately alkaline soils, molybdenum and macro-nutrient (except P) availability is increased, but trace element levels are reduced and thus plant growth may be affected. In acid soils, micro—nutrient availability (except Mo and B0) is increased. Nitrogen is supplied as ammonium (NH4) or nitrate (N03) in fertilizer, and dissolved N will have the highest concentrations in soil with pH 6-8. Concentrations of available N are less sensitive to pH than concentration of available P. Soil pH is important for the crop growing process and the pH affects plant nutrient availability by controlling the chemical forms of the nutrient. The optiumum pH range for most plants is between 6 and 7.5. In order for P to be available for plants, soil pH needs to be in the range 6.0 and 7.5. If pH is lower than 6, P starts forming insoluble compounds with iron (Fe) and aluminium (Al) and if pH is higher than 7.5 P starts forming insoluble compounds with calcium (Ca). Most nutrient deficiencies can be avoided between a pH range of 5.5 to 6.5, provided that soil minerals and organic matter contain the essential nutrients to begin with.

Calcium is a particularly important essential nutrient required for healthy plant growth. it is required for various structural roles in the plant cell wall and membranes, it is a counter-cation for inorganic and organic anions in the vacuole, and the cytosolic Ca2+ concentration ([Ca2+]cyt) is an obligate intracellular messenger coordinating responses to numerous developmental cues and environmental challenges. in Ireland and other countries where there are relative high levels of rainfall, rain leachs basic cations from the soil with the result that acidic ions are concentrated, thus lowering the pH of the sool below optimum growing conditions. A|3+ and H+ cation concentrations concurrently increase.

|E110484.

When plants grow in acid soils, they are generally nutrient deficient and more susceptible to toxic forms of inorganics salts of metals such as aluminium or manganese. Aluminium toxicity is a particular concern, since Ali” cation is partcularly soluble at acidic pH and causes severe root damage. Aluminium interferes with normal calcium uptake, binds to phosphate to interfers with normal plant cell processes and causes root stunting. Furthermore, in soils of below pH 4, hydrogen ions can damage root cell membranes. In soils with high content of Manganese (Mn) containing minerals, Mn toxicity can become a problem at pH 5.6 and below. Mn, like aluminum becomes increasingly more soluble as pH drops, and Mn toxicity symptoms can be seen at pH's below 5.6.

Mn is an essential plant nutrient, so plants transport Mn into leaves. Classic symptoms of Mn toxicity are crinkling or cupping of leaves.

Traditionally, pulverized or ground limestone is used as a soil conditioner to neutralize acidic soils.

Limestone is a type of sedimentary rock consisting of calcite and aragonite which are polymorphs of calcium carbonate. However, limestone has poor solubility in water and is only slightly soluble even in weak acid solutions.

Calcite can be either dissolved or precipitated by groundwater, depending on several factors, including the water temperature, pH, and dissolved ion concentrations. Calcite exhibits an unusual characteristic called retrograde solubility, in which it becomes less soluble in water as the temperature increases.

While ground limestone is effective at pH correction of acid soils, limestone is slow to breakdown in the soil. This means that the neutralising effects of the limestone are relatively slow and that it takes quite some time before beneficial levels of calcium accumulate in the soil.

Therefore, it is an object of the invention to provide an alternative to ground limestone fertilizer that addresses these deficiencies.

Statements of the Invention According to the present invention, as set out in the appended claims, there is provided a fertilizer composition comprising a calcium oxide (CaO) particulate having an average particle size diameter of from about 2 to 8 mm. The inventors have designed fertilizer comprising the CaO particulate fertilime or ”White Rhino FertilimeTM".

In a related aspect of the invention, there is provided a method of preparing a calcium oxide (Ca0) particulate having an average particle size diameter of from about 2 to 8 mm comprising the steps of: |E1‘l0484 (i) caicining limestone in a kiln to form a lump particulate having an average particle size diameter of from about 40 to 100 mm; (ii) crushing the limp particulate formed in step (i) and screening to collect a fraction having an average particle size diameter of from about 2 to 8 mm; (iii) repeating step (ii) as required.

The skilled person will appreciate that limestone is primarily calcium carbonate lCaCO3).

When heated, CaCO_=, decomposes to Ca0 (also known as quicklime) which is an office white, highly alkaline solid in lump form having an average particle size diameter of from about 40 to 100 mm.

This material has been used in the part as an_ agricultural fertilizer. However, Ca0 has not been used as a fertilizer or indeed has not been used in fertilizer compositions in particulate form having an average particle size diameter of from about 2 to 8 mm. The particle size of the CaO particulate of the invention means the material is still suitable for spreading. The skilled person will also appreciate that calcination reactions usually take place at or above the thermal decomposition temperature (for decomposition and volatilization reactions) or the transition temperature (for phase transitions). Typically temperatures are between 850- 1000 degrees centigrade.

Accordingly, in a third aspect of the invention, there is provided for use of a calcium oxide (CaO) particulate having an average particle size diameter of from about 2 to 8 mm as a fertilizer or a pH correction material.

TM") product of the The CaO particulate or fertilime (known as "White Rhino Fertilime invention has several advantages over and above using limestone lump particular in fertilizer and/or pH correction applications. First, the CaO particulate of the invention, when applied to agricultural soil, displays a much faster breakdown time. This results in significantly more calcium availability for soil improvement in a shorter time period. Accordingly, the soil benefits from application far sooner that when traditional lime fertiiizers are used as the rate of breakdown and availability of the calcium material is increased. Traditional limestone can take up to 2 years to fully break down to become available for the soil. Second, the CaO particulate of the invention has a higher total neutralizing value (TNV) than traditional lime fertilizers. The TNV is a measure of the ability of a material to neutralize soils and indeed raise soil pH. The Ca0 particulate of the fertiiime or White Rhino Fertilimem product of the invention has a TNV of170, whereas traditional C30 lump particulate has a TNV of 100. The highly alkaline nature of the fertilime or White Rhino Fertilimem product of the invention arises from the reaction of its main constituent Ca0, with water. As Ca0 reacts with ground and atmospheric moisture, calcium hydroxide (Ca(OH)z) is generated. The hydroxide thus formed quickly raises the pH of the surrounding medium, for example, soil.

Further advantages arise from the inherently higher calcium content of the fertilime product of the invention when compared to traditional limestone or Ca0 ferlizers. Typically, fertilime ("White Rhino Ferti|imeTM") has a calcium content of 65% w/w, whereas traditional Ca0 lump particulate has a calcium content of 65% w/w and ground limestone has a calcium content of

Claims (5)

Claims

1. A fertilizer composition comprising a calcium oxide (Ca0) particulate having an average particle size diameter of from about 2 to 8 mm.

2. A method of preparing a calcium oxide (Ca0) particulate having an average particle size diameter of from about 2 to 8 mm comprising the steps of: (iv) calcining limestone to form a lump particulate having an average particle size diameter of from about 40 to 100 mm; (v) crushing the limp particulate formed in step (i) and screening to collect a fraction having an average particle size diameter of from about 2 to 8 mm; (vi) repeating step (ii) as required.

3. Use of a calcium oxide (Ca0) particulate having an average particle size diameter of from about 2 to 8 mm as a fertilizer or a pH correction material.

4. A composition as substantially hereinbefore described with reference to the accompanying examples.

5. A process as substantially hereinbefore described with reference to the accompanying examples.