Nutirients

FERTILIZER RECOMMENDATION FOR MAJOR CROPS   N P K PADDY (kg/ha) Upland(Modan) PTB 28,29 and 30 High-yielding short duration varieties 40 60 20 30 30 30 Wet land (All regions) High-yielding short duration varieties High-yielding medium duration varieties Local varieties H4 Mashuri 70 90 40 70 50 35 45 20 45 25 35 45 20 45 25 COCONUT (Adult palm)kg/palm/annum. General recommendation (a) Average management (b) Good Management (c) For reclaimed clayey soils (as in Kuttanad) 0.34 0.50 0.25 0.17 0.32 0.35 0.68 1.20 0.90 Hybrid and high yielding palm (a) For irrigated areas (b) Rainfed 1.00 0.50 0.50 0.32 2.00 1.20         RUBBER From 1st year to 4th year :-10:10:4:1.5 NPK Mg mixture at the following rates: 3rd Month 225g / plant 9th Month 450g / plant 15th Month 450g / plant 21st Month 550g / plant 27th Month 550g / plant 33rd Month 450g / plant 39th Month 450g / plant From 5th year till tapping begins 12:12:12 NPK Mixture @ 125 kg /ha during April – May and September – October (Where mulching was practiced during initial years) 15:10:6 NPK Mixture @ 200 kg /ha during April – May and September – October (Where mulching was not practiced during initial years) Mature Rubber under tapping 10:10:10 NPK Mixture @ 300 kg /ha or 900 g / plant March -April or 15:15:15 NPK Mixture @ 200 kg /ha or 17:17:17 NPK Mixture @ 175 kg /ha or 19:19:19 NPK Mixture @ 160 kg /ha   N P K  TAPIOCA (kg per hectare) H.97, H.226 75 75 75       H.165, H.1687, H.2304 100 100 100       M4 and Local 50 50 50 SWEET POTATO (kg/ha ) 75 50 75 SESAMUM (kg/ha ) 30 15 30 GROUNDNUT (kg/ha ) 10 75 75 BANANA (g/plant)       Nendran (irrigated ) 190 115 …

The production, accumulation and degradation of organic matter are greatly dependent on climate. Temperature, soil moisture and topography are the major factors affecting the accumulation of organic matter in soils. Organic matter tends to accumulate under wet or cold conditions where decomposer activity is impeded by low temperature or excess moisture which results in anaerobic conditions. Excessive slope may encourage the erosion of the top layer of soil which holds most of the raw organic material that will eventually become humus.

Humus refers to organic matter that has been decomposed by bacteria, fungi, and protozoa to the final point where it is resistant to further breakdown. Humus usually constitutes only five percent of the soil or less by volume, but it is an essential source of nutrients and adds important textural qualities crucial to soil health and plant growth. Humus also hold bits of undecomposed organic matter which feed arthropods and worms which further improve the soil. Humus has a high cation exchange capacity that on a dry weight basis is many times greater than that of clay colloids. It also acts as a buffer, like clay, against changes in pH and soil moisture. Humic acids and fulvic acids, which begin as raw organic matter, are important constituents of humus. After the death of plants and animals, microbes begin to feed on the residues, resulting finally in the formation of humus. With decomposition, there is a reduction of water-soluble constituents including cellulose and hemicellulose and nutrients such as nitrogen, phosphorus, and sulfur. As the residues break down, only complex molecules made of aromatic carbon rings, oxygen and hydrogen remain in the form of humin, lignin and lignin complexes as humus. While the structure of humus has few nutrients, it is able to attract and hold cation and anion nutrients by weak bonds that can be released in response to changes in soil pH. Lignin is resistant to breakdown and accumulates within the soil. It also reacts with amino acids, which further increases its resistance to decomposition, including enzymatic decomposition by microbes. Fats and waxes from plant matter have some resistance to decomposition and persist in soils for a while. Clay soils often have higher organic contents that persist longer than soils without clay as the organic molecules adhere to and are stabilised by the clay. Proteins normally decompose readily, but when bound to clay particles, …

The organic soil matter includes all the dead plant material and all creatures, live and dead. The living component of an acre of soil may include 900 lb of earthworms, 2400 lb of fungi, 1500 lb of bacteria, 133 lb of protozoa and 890 lb of arthropods and algae. Most living things in soils, including plants, insects, bacteria and fungi, are dependent on organic matter for nutrients and energy. Soils have varying organic compounds in varying degrees of decomposition. Organic matter holds soils open, allowing the infiltration of air and water, and may hold as much as twice its weight in water. Many soils, including desert and rocky-gravel soils, have little or no organic matter. Soils that are all organic matter, such as peat (histosols), are infertile. In its earliest stage of decomposition, the original organic material is often called raw organic matter. The final stage of decomposition is called humus.

Micronutrients include iron, manganese, zinc, copper, boron, chlorine and molybdenum. The term refers to plants’ needs, not to their abundance in soil. They are required in very small amounts but are essential to plant health in that most are required parts of some enzyme system which speeds up plants’ metabolisms. They are generally available in the mineral component of the soil, but the heavy application of phosphates can cause a deficiency in zinc and iron by the formation of insoluble phosphates. Iron deficiency may also result from excessive amounts of heavy metals or calcium minerals (lime) in the soil. Excess amounts of soluble boron, molybdenum and chloride are toxic.

Most sulfur is made available to plants, like phosphorus, by its release from decomposing organic matter. Deficiencies may exist in some soils and if cropped, sulfur needs to be added. A 15-ton crop of onions uses up to 19 lb of sulfur and 4 tons of alfalfa uses 15 lb per acre. Sulfur abundance varies with depth. In a sample of soils in Ohio, United States, the sulfur abundance varied with depths, 0-6 inches, 6-12 inches, 12-18 inches, 18-24 inches in the amounts: 1056, 830, 686, 528 lb per acre respectively.

Magnesium is central to chlorophyll and aids in the uptake of phosphorus. The minimum amount of magnesium required for plant health is not sufficient for the health of forage animals. Magnesium is generally available, but is missing from some soils along the Gulf and Atlantic coasts of the United States due to leaching by heavy precipitation.

Calcium is 1 percent by weight of soils and is generally available but may be low as it is soluble and can be leached. It is thus low in sandy and heavily leached soil or strongly acidic mineral soil. Calcium is supplied to the plant in the form of exchangeable ions and moderately soluble minerals. Calcium is more available on the soil colloids than is potassium because the common mineral calcite, CaCO3, is more soluble than potassium-bearing minerals

The amount of potassium in a soil may be as much as 80,000 lb per acre, of which only 150 lb or 2 percent is available for plant growth. When solubilised, half will be held as exchangeable cations on clay while the other half is in the soil water solution. Potassium fixation occurs when soils dry and the potassium is bonded between layers of clay. Under certain conditions, dependent on the soil texture, intensity of drying, and initial amount of exchangeable potassium, the fixed percentage may be as much as 90 percent within ten minutes. Potassium may be leached from soils low in clay.

Phosphorus is the second most critical plant nutrient. The soil mineral apatite is the most common mineral source of phosphorus. While there is on average 1000 lb of phosphorus per acre in the soil, it is generally in unavailable forms. The available portion of phosphorus is low as it is in the form of phosphates of low solubility. Total phosphorus is about 0.1 percent by weight of the soil, but only one percent of that is available. Of the part available, more than half comes from the mineralisation of organic matter. Agricultural fields may need to be fertilised to make up for the phosphorus that has been removed in the crop. When phosphorus does form solubilised ions of H2PO4–, they rapidly form insoluble phosphates of calcium or hydrous oxides of iron and aluminum. Phosphorus is largely immobile in the soil and is not leached but actually builds up in the surface layer if not cropped. The application of soluble fertilisers to soils may result in zinc deficiencies as zinc phosphates form. Conversely, the application of zinc to soils may immobilise phosphorus as zinc phosphate. Lack of phosphorus may interfere with the normal opening of the plant leaf stomata, resulting in plant temperatures 10 percent higher than normal. Phosphorus is most available when soil pH is 6.5 in mineral soils and 5.5 in organic soils.