d) Mixed fertilizersA mixed fertilizer contains 2 or more fertilizer elements. The fertilizer formula indicates the composition of the mixture indicated as NPK. For example, a 10-10-10 or N10P10K10 contains 10 per cents of each of nitrogen (N), phosphoric acid (P₂O₅) and potash (K₂O). The other consists of other elements such as calcium, sulfates, chlorides, inert material and some micro-nutrients.

c) Potassium fertilizersThe principal potash fertilizer materials are potassium chloride with 47-61% potash (K₂O), potassium sulfate with 47 to 52% and the manure salts with 19 to 32%.According to potassium content, soils could be classified as:▪ Poor soils with potassium content less than 100ppm▪ Moderate soils with potassium content of 100-300ppm▪ Rich soil with potassium content greater than 300ppm.Another classification is also used, where soils are divided into:• Poor soils with potassium content less than 250ppm• Moderate soils with potassium content of 250-400ppm• Moderately rich soils with potassium content of 400-550ppm• Rich soils with potassium content greater than 550ppm.

b) Phosphate fertilizersPhosphorus usually is in the form of phosphate, mostly of calcium. It must be dissolved in the soil solution to be taken up by the plants. Phosphorus uptake by the plants is in the form of orthophosphate (H₂PO₄⁺) or in the form of HPO₄⁻⁻.The phosphatic fertilizers are:Triple superphosphate with 23 to 48% phosphoric acid.Ammonium phosphate, chiefly monoammonium phosphate with 11% nitrogen and about 48% phosphoric acid. It has a tendency to increase soil acidity.Superphosphate with 16 to 20% of P₂O₅.other materials such as bone meal and finely ground raw-rock phosphate.

a) Nitrogenous fertilizersNitrate fertilizers are materials with the nitrogen combined in the nitrate form that is readily utilized by plants such as in sodium nitrate. Sodium nitrate tends to make the soil alkaline.Ammonium fertilizers such as ammonium sulfate, ammonium phosphate and others carry the nitrogen in the ammonium form, which is less readily leached in the soil than the nitrate form although soluble in water. Ammonium sulfate tends to make the soil acid because of the sulfate ion.Fertilizers that contain nitrogen in the amide form include urea and calcium cyanamide. These simple nonprotein compounds dissolve in water, while the nitrogen is converted to ammoniacal or nitrate forms by bacteria.

Insufficient potassium in tobacco will reduce the burning quality. The leaves will have a poor color and flavor. Potash usually is abundant in soils of volcanic origin.

It also insures the development of well filled kernels and stiff straw in cereals, encourages growth in legumes, assists in chlorophyll formation and is particularly helpful in the production of starch or sugar-forming crops.

Deficiency of this element results in plants of poor color, poor quality and low productivity.

It could be noticed that there is a certain level of selectivity for the absorbed ions, and the cations and ions are absorbed independently, as well, some of them are absorbed more readily than others such as the ammonium, potassium and nitrates that could be absorbed in greater quantities than needed for normal growth. Such consumption is called Luxury consumption. It should be aware that excessive consumption of nitrates by some forage crops may cause poisoning to animals. The same could be noticed for selenium when excessively consumed by some Astragalus spp.

Contact theory assumes that on the root hairs that carry negative charges hydrogen ions are found which will be directly exchanged with the ions found on the surface of the soil particles without movement to the soil solution. It is also assumed that this exchange requires energy and the absorption will be stopped when the activity of cells is ceased due to the absence of oxygen or significant reduction in temperature.

Soil solution theory. The capillary water or the soil solution is considered the environment where ionic exchange takes place. CO₂ released by roots with water will form carbonic acid H₂CO₃ which ionizes to give hydrogen ions that replace the adsorbed ions on the surface of the clay particles that will be transferred to the soil solution to be absorbed by the plant fine roots.

there is the public perception that inorganic fertilizers "poison the soil" and result in "low quality" produce.

They can be :• naturally-occurring compounds such as peat or mineral deposits (Chilean sodium nitrate, mined "rock phosphate" and limestone)• or manufactured through natural processes such as composting)• or chemically-synthesized inorganic fertilizers such as ammonium nitrate, potassium sulfate, and superphosphate, or triple superphosphate.

Fertilizers are compounds given to plants to promote growth and better crop quality; they are usually applied either via the soil, for uptake by plant roots, or by foliar feeding, for uptake through leaves.

Integrated Nutrient Management (INM): Combining organic, inorganic, and biofertilizers for balanced nutrient supply.4R Nutrient Stewardship: Right source, right rate, right time, right place.Crop Rotation and Cover Crops: Enhances soil fertility and reduces the need for external fertilizers.

Nutrient Loss: Leaching, volatilization, and runoff lead to lower efficiency.Soil Degradation: Imbalanced use of fertilizers causes soil acidity and nutrient depletion.Water Pollution: Nitrate leaching leads to eutrophication of water bodies.

Yield Increase: Higher productivity of staple crops (e.g., rice, maize).Quality Enhancement: Protein content in cereals and oil content in oilseeds.Economic Benefits: Better returns on investment with improved crop yield.

d. Crop-Specific FertilizationCereals (e.g., Wheat, Rice, Maize): High nitrogen demand during vegetative growth.Legumes (e.g., Soybean, Chickpea): Focus on phosphorus and potassium due to nitrogen fixation.Oilseeds (e.g., Mustard, Sunflower): Sulfur and boron are critical for high oil yield.Cotton: Requires balanced NPK with emphasis on potassium for fiber quality.

c. Timing of Fertilizer ApplicationSplit applications for better nutrient uptake (e.g., basal and topdressing in rice). Matching fertilizer use with crop growth stages:Nitrogen during vegetative stages.Phosphorus and potassium during reproductive stages.

b. Fertilizer Application Methods• Broadcasting: Spreading fertilizers evenly over the soil surface.• Band Placement: Applying fertilizers in rows or near plant roots for efficient uptake.• Foliar Feeding: Spraying liquid fertilizers on crop foliage for quick absorption.• Fertigation: Applying water-soluble fertilizers through irrigation systems.

a. Soil Testing• Importance of analyzing soil nutrient levels and pH.• Avoid over-fertilization to reduce environmental risks.

• Potassium (K):• Improves disease resistance, water use efficiency, and crop quality.• Common sources: Potash (Muriate of Potash - MOP).

• Phosphorus (P):• Aids in root development, flowering, and seed formation.• Critical during early crop growth stages.• Common sources: Single superphosphate (SSP), diammonium phosphate (DAP).

• Nitrogen (N):• Stimulates vegetative growth and chlorophyll synthesis.• Essential for cereals and leafy crops.• Common sources: Urea, ammonium nitrate, anhydrous ammonia.

• Replenish soil nutrients removed by intensive cropping.• Support high-yield crop varieties.• Enhance overall crop quality (e.g., protein content, oil yield).

Crops grown on a large scale for food, fiber, feed, or industrial use.

The block may be the presence of an inhibitor or the absence of a hormone or other growth-promoting substance; both inhibitors and promoters may be present, with the former predominating.

in most species it seems to be a block to the physiological processes involved in germination.

A newly ripe seed, is not germinating-ripe, but is in a state of dormancy and fails to respond to these conditions.

In germinating seeds, the embryo ruptures the seed coat (about 2 days after being wetted) and the radicle or the embryonic root is the first organ to emerge, which is soon followed by the plumule or the young shoot.

The energy consumed during germination may amount to ½ the dry weight of the seed. The germination of 35 kilograms of wheat utilizes the equivalent of oxygen found in 25 M³ of air.

Energy is supplied by respiration and the oxidation of carbon and hydrogen into carbon dioxide and water.

Fats which occur mainly in the cotyledons of oil-bearing seeds and in the embryos of cereal seeds will split by lipases into fatty acids and glycerol, which in turn undergo chemical changes to form sugars to build up carbohydrates and fats in the seedling.

Proteins are broken into amino-acids then build protein in the seedling.

Glucose will be transported to the growing sprout by diffusion from cell to cell.

Rice is an exception where the seed may germinate under a water surface level of 15cm.

most legumes will require as high moisture content as about 75%.

25 to 75%

Abundant water is necessary for rapid germination.

germination of 90 to 100%

• increase the labor cost for production and• reduces the crop yield and• contaminates the current crop as well as the seed and the soil in the following seasons.

High quality seed is essential for successful crop production.

higher biological activity occurs under no-tillage, an indicator of a healthier soil.

more earthworms, arthropods, (acarina, collembola, insects), more micro- organisms (rhyzobia, bacteria, actinomicetes), and also more fungi are found under no- tillage as under conventional tillage.

the more favorable soil moisture and temperature conditions under no- tillage also have a positive effect on micro- organisms of the soil.

micro- organisms do not die because of famine under this system (as is the case under bare soils in conventional tillage) because they will always find organic substances at the surface to supply them with food.

Due to the fact that no mechanical implements are used that destroy the "nests" and channels built by micro- organisms, higher biological activity occurs under the no- tillage system.

raise soil compaction inducing a decrease in macrofauna activity.

Reduced tillage affords limitation of erosion by increasing structural stability and resistance against stress from vehicle load and by permitting the development of earthworm community.

Minimizing soil disturbance reduces mineralization of organic matter (OM) and can result in larger storage of soil OC relative to conventional tillage.

he maintenance of a vegetal cover reduces soil erosion and improves soil infiltration and Organic matter content.

Under no- tillage, higher values of organic matter, nitrogen, phosphorus, potassium, calcium, magnesium and also a higher pH and cation exchange capacity, but lower Al values are measured.

no- tillage has positive effects on the most important chemical properties of the soil.

In no- tillage a higher soil moisture content and lower soil temperatures as well as higher aggregate stability have been measured.

Under no-tillage, higher infiltration rates have been measured compared to conventional tillage and this results in a drastic reduction of erosion.

An increase in soil density in no-till system was found in near the soil surface layers when compared to plowing.

It is well assumed that cultural practices mainly affect macro-porosity, i.e. pores larger than 30 micrometer (in diameter) that can be formed by soil tillage, soil fauna and roots of crops.

Conservation agriculture dramatically reduces soil erosion maintains or even increases the organic matter content in the soil and keeps the soil temperature at low levels.

Alongside serious environmental impacts, the longevity of the soil as a viable means of production is also threatened.

damages the integrity of the soil, hampering its ability to retain moisture and necessitating heavy usage of fertilisers.

immediate benefits in yield and weed control

• Primary and secondary tillage. Primary tillage is usually conducted after the last harvest, when the soil is wet enough to allow plowing but also allows good traction.• Reduced tillage.• Intensive tillage.• Conservation tillage.• Zone tillage.

On irrigated areas with bad drainage, plowing to a depth of 30cm is adequate if hard pans are not found. If hard pans do exist, then plowing to a depth of 50cm might be necessary.

In semi-arid and semi-humid areas, deep plowing should not be practiced unless in the case of the first fall plowing for spring crops or fields to be fallowed. All other practices should be surface tillage to a depth of 10cm without inverting the soil.

an experiment was conducted on wheat and potato also did not reveal significant differences in yield between the different depths of plowing

⮚ The depth of plowing must be the same in all parts of the field.

⮚ The runs of the machinery must always be straight.

⮚ The borders of the field are plowed in perpendicular direction to the furrows.

⮚ On lands with a slope, plowing should be done perpendicular to the slope and not parallel to it in order to prevent soil erosion. On such soils, early plowing is not desirable.

⮚ The depth of plowing heavy soils must be changed from year to year.

⮚ For growing small grains, plowing to a depth of 15-25cm is enough and 25cm for cotton.

⮚ If a hard pan is formed as result of continuous use of heavy machinery and plowing to a constant depth, then chiseling when the soil is dry might be beneficial as well as planting of leguminous crops may improve the structure of the soil.

⮚ Seeds of smaller size require better mellowing of the soil.

⮚ Early fall plowing is desirable for growing crops of winter or spring habit, such operation promotes the moisture accumulation during winter. If the land is intended to be fallowed, then shallow plowing to control weeds may be practiced but without inverting the soil.

⮚ Light soils should not be plowed deeply. After plowing rolling would be desirable.

⮚ Add the organic fertilizers before plowing. Low organic matter content leads to the adhesion of clay and silt particles, which results in bad aeration, bad drainage and weak growth of plants. Organic fertilizers in light soils will improve physical and chemical properties.

Do not plow heavy soils unless they are friable enough, otherwise soil clumps will be formed that are difficult to mellow, beside the great resistance that will face the plow.

harrow

Disc harrow

For light tillage with little surface disturbance.

For Pulverizing cloddy soils in friable state, it breaks soil crust and be used together with a plough or harrow).

• This implement can penetrate to a depth of 50 cm to loosen deep soil layers and promote water movement and root growth.

• It is a form of a chisel plough designed to penetrate to a greater depth.

V. some modified chisels could be used for harrowing the soil.

IV. soils with fertility concentrated in the surface layer.

III. the soils that are characterized by a very dry surface layer and wet deeper layers.

II. the shallow soils that do not exceed 20-25cm.

I. the alkaline and the saline soils, since plowing with such an implement does not invert the soil layer where the salts are accumulated to the zone where the roots are mostly distributed.

It is usually set at 20 to 30cm deep. The maximum depth is 60cm.

• After field preparation, a marker is run in both the directions. The seedlings are transplanted at the intercepts.

• Crops like tobacco, tomato, chillies are planted with equal inter and intra-row spacing so as to facilitate two-way intercultivation.

• Sugarcane is planted in the furrows or trenches.

• After the secondary tillage, these crops are sown without any land treatments.

• These operations are crop specific.

• Broadcasting: Suitable for large fields.• Drilling: Ensures even spacing.• Transplanting: For certain crops or pastures.• Direct Seeding: Economical and efficient.

• Land Clearing – Remove weeds and debris.• Tillage – Loosen soil using plows or tillers.• Leveling – Ensure uniform soil height.• Moisture Management – Ensure adequate soil moisture.

• Create a favorable soil structure• Facilitate seed germination• Promote root development

Purpose:• Leveling the soil surface.• Breaking clods and pulverizing the soil.• Weed control and moisture conservation.

Follows primary tillage and refines the soil for planting. Involves shallow ploughing (5–15 cm) for seedbed preparation and leveling.

Purpose:• Break up compact soil layers.• Improve soil structure and drainage.• Incorporate organic matter into the soil.

Purpose:• Break up compact soil layers.• Improve soil structure and drainage.• Incorporate organic matter into the soil.

The first operation after the harvest of the previous crop, involving deep soil penetration.

optimizing soil preparation and ensuring healthy plant growth.

1. Preservation of soil structure  2. Accumulation and preservation of soil moisture

Cutting of creeping or spreading grass and inversion

Deep ploughing and inversion

Incorporation of manures, fertilizers and plant residue

Objectives: • Break compact soil layers. • Incorporate residues, organic matter, and fertilizers. • Improve aeration and water infiltration. • Prepare the field for secondary tillage. • Inversion of soil • Uprooting of weeds and stubbles

The first major soil-working operation after the last harvest. It is done to loosen the soil, turn it over, and bury crop residues and weeds.

Objectives of Tillage

a practice made before sowing or planting of crop.

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