Soil Fertility Management PDF

SOIL FERTILITY MANAGEMENT PHYSICAL PROPERTIES AND ITS PROCESSESS Soil physical properties relate to the physical characteristics of soil, including its texture, structure, porosity, temperature, density, and color. These properties influence the behavior of soils and their suitability for vari...

SOIL FERTILITY MANAGEMENT PHYSICAL PROPERTIES AND ITS PROCESSESS Soil physical properties relate to the physical characteristics of soil, including its texture, structure, porosity, temperature, density, and color. These properties influence the behavior of soils and their suitability for various uses. Soil fertility often refers to the ability of soil to provide essential nutrients to plants in adequate amounts for optimum growth. Organic matter plays a vital role in soil fertility by impacting the physical properties of soil and the processes that underpin them. Here's how organic soil fertility impacts physical properties and the relevant processes: 1. Soil Structure: Organic matter, when decomposed, produces substances that bind soil particles (sand, silt, clay) into aggregates. These aggregates improve the soil structure, making it crumbly and well-aerated. This aids in root penetration and encourages healthy root development. 2. 2. Water Holding Capacity: Organic matter acts like a sponge, holding water and making it available to plants for a longer time. This enhances the soil's ability to retain moisture and reduces the need for frequent irrigation. 3.Soil Aeration: The decomposition of organic matter by microorganisms creates channels and spaces in the soil. This improves soil aeration, providing oxygen to plant roots and supporting aerobic soil organisms. 4. Soil Temperature: Organic matter, especially when used as mulch on the soil surface, can regulate soil temperature. It can reduce the temperature extremes by providing insulation, benefiting plant growth  5. Soil Erosion Control: Well-structured soils, rich in organic matter, are less prone to erosion. The aggregates prevent the detachment of soil particles, and the improved water infiltration reduces surface runoff, thus preventing soil erosion. 6.Bulk Density: Soils rich in organic matter usually have a lower bulk density. Lower bulk density means the soil is less compacted and allows for better root growth and penetration 7. Water Infiltration: The presence of organic matter improves water infiltration rates by preventing soil crusting and increasing the number of channels in the soil. Processes Involved: 1. Decomposition: Organic materials added to soil—like compost, manure, or plant residues—are broken down by a range of soil organisms, including bacteria, fungi, and earthworms. This process releases nutrients and produces humus, a stable form of organic matter that contributes to soil structure. 2. Humification: It's the process of forming humus from decomposed organic material. Humus improves soil's water holding capacity and cation exchange capacity 3. Mineralization: The conversion of organic nitrogen, phosphorus, and sulfur to inorganic forms. This process makes these nutrients available for plant uptake. 4. Nutrient Cycling: As organic materials decompose, they slowly release nutrients back into the soil. This slow release ensures a steady supply of nutrients for plants over time. 5.Biological Activity: The presence of organic matter enhances the biological activity in the soil. A more active soil biota can improve soil structure, nutrient cycling, and overall soil health. In summary, organic soil fertility plays a critical role in improving and maintaining the physical properties of soil. It promotes healthier plant growth, better water retention, and can even mitigate some of the impacts of soil degradation. Soil Chemical Properties Organic soil fertility is centered around the premise that naturally derived organic materials (such as compost, manure, and cover crops) are essential for maintaining and enhancing the chemical, physical, and biological properties of soils. The chemical properties of the soil play a crucial role in its fertility, affecting the availability of nutrients to plants and the soil's overall health. Chemical Properties Influenced by Organic Soil Fertility: 1. Soil pH: Organic materials can influence soil pH, which in turn affects nutrient availability. Decomposing organic matter can produce organic acids, which may slightly acidify the soil, but the addition of certain organic materials like hardwood ash can raise pH. 2. Cation Exchange Capacity (CEC): This is the soil's ability to hold and exchange positively charged ions (cations) such as calcium, magnesium, potassium, and hydrogen. Organic matter can increase the CEC of the soil, allowing it to retain more nutrients. 3. Base Saturation: It's the proportion of the soil's CEC occupied by basic cations (e.g., Ca²⁺, Mg²⁺, K⁺). Organic matter decomposition can influence the balance of these cations. 4. Nutrient Content: Organic soil amendments like compost and manure can directly add essential nutrients (like N, P, K, and micronutrients) to the soil. 5. Organic Carbon Content: Regular addition of organic matter increases the organic carbon content of the soil, which plays a foundational role in soil fertility. 6. Soil Salinity: Organic matter can influence the salt content of the soil. While organic matter itself doesn't typically contribute much salt, the breakdown of certain materials can lead to salt accumulation in some cases. Processes Affecting Chemical Properties in Organic Soil Fertility: 1. Mineralization: The conversion of nutrients from an organic form (found in organic materials) to an inorganic form that plants can uptake. As microbes break down organic materials, nutrients like nitrogen become available to plants. 2. Immobilization: The opposite of mineralization. In this process, soil microbes take up inorganic nitrogen from the soil and convert it into their own organic forms, making it temporarily unavailable to plants. 3. Humification: The process of transforming organic substances into humus, a stable and complex organic compound that plays a vital role in soil fertility. 4. Decomposition: The breakdown of organic materials by soil microorganisms, releasing nutrients back into the soil. 5. Chelation: Organic molecules can form stable complexes with metal ions, making certain micronutrients more available to plants. 6. Soil Buffering: Organic matter can help buffer or moderate changes in soil pH, maintaining a more stable environment for plants and microbes. Understanding and managing the chemical properties of the soil in organic farming systems is crucial for long-term soil health and productivity. Organic soil fertility practices aim to maintain a balance, ensuring nutrient availability for crops while also building and preserving the soil's organic matter and overall health. Biological Properties Organic soil fertility revolves around the idea that soil health can be maintained and improved through the incorporation of organic matter and the fostering of biological activity within the soil. This contrasts with inorganic or synthetic fertilization methods, which might not consider the long-term health and sustainability of the soil system as a whole. Biological Properties Affected by Organic Soil Fertility: 1. Soil Microorganisms: Healthy soil teems with billions of microorganisms like bacteria, fungi, protozoa, and algae. These organisms play a vital role in decomposition, nitrogen fixation, and nutrient cycling. 2. Soil Fauna: This includes larger organisms like earthworms, nematodes, arthropods, and various insects. They help in organic matter decomposition, soil aeration, and aggregation 3. Mycorrhizal Associations: These are symbiotic relationships between certain fungi and plant roots. The fungi help the plants take up nutrients, especially phosphorus, and in return, the plants supply the fungi with carbohydrates. 4. Decomposers: Organisms such as certain fungi and bacteria play a vital role in breaking down complex organic molecules into simpler forms, making nutrients available for plant uptake. Processes Influenced by Organic Soil Fertility: 1. Decomposition: As organic materials (like compost, manure, plant residues) are added to soil, they are broken down by soil microorganisms. This releases nutrients in a form plants can use. 2. Nutrient Cycling: Microorganisms help in converting nutrients from one form to another, ensuring they're available for plant uptake. For example, bacteria in the soil can convert atmospheric nitrogen to a form plants can use. 3.Soil Structure Formation: Organic matter and the activities of soil fauna, especially earthworms, create soil aggregates. Good soil structure improves water infiltration, root penetration, and reduces soil erosion. 4. Soil Carbon Sequestration: Organic matter is rich in carbon. By improving organic soil fertility, carbon is stored in the soil, playing a role in combating climate change. 5.Suppressing Soil-Borne Diseases: Some beneficial soil organisms, when thriving in organically-managed soils, can suppress harmful pathogens. This can reduce the need for chemical pesticides. 6. Water Retention: Organic matter can absorb and hold water, making soils more resilient during drought periods. 7. pH Buffering: Organic matter can help buffer against rapid pH changes, ensuring a more stable environment for plants. Advantages of Focusing on Organic Soil Fertility: 1. Sustainability: Organic management practices usually promote long-term soil health, ensuring that future generations have fertile ground to cultivate. 2. Biodiversity: Encouraging a rich soil ecosystem means a variety of organisms can thrive, creating a more resilient system. 3. Reduced Chemical Inputs: By relying on organic materials and natural processes, there's less dependence on synthetic fertilizers and pesticides. 4.Economic Benefits: Over the long term, organically managed soils can be more productive and may reduce the costs associated with inputs. In conclusion, organic soil fertility relies heavily on understanding and harnessing natural processes and the biological properties of the soil. By fostering these processes, we can achieve sustainable agricultural systems that are productive and environmentally friendly. Soil nutrient cycles Soil fertility is crucial for supporting healthy plant growth and maintaining ecosystem functions. Organic soil fertility refers to the natural means of maintaining or improving the soil's ability to supply nutrients to plants, primarily through the breakdown of organic matter and the activity of soil organisms. Organic fertility practices aim to maintain a balance of macro and micronutrients in the soil, improve soil structure, and foster a vibrant soil biota. Understanding how organic soil fertility impacts nutrient cycles requires understanding the following components: 1. Organic Matter Decomposition: Organic matter (like fallen leaves, dead plants, animal manure, etc.) undergoes decomposition by bacteria, fungi, and other microorganisms. This decomposition process releases essential nutrients back into the soil. 2. Nutrient Mineralization: As microorganisms break down organic matter, nutrients that were part of the organic compounds are converted into inorganic forms that plants can absorb. This process is called mineralization. 3. Nutrient Immobilization: Sometimes, microorganisms will absorb inorganic nutrients, making them temporarily unavailable to plants. This is called immobilization. Over time, as these microbes die and decompose, the nutrients will be mineralized and become available again. 4. Nitrogen Fixation: Certain bacteria, especially those associated with leguminous plants, can convert atmospheric nitrogen into ammonia, which plants can use. This process augments the soil's nitrogen content without the need for synthetic fertilizers  5. Mycorrhizal Associations: Mycorrhizal fungi form symbiotic relationships with many plant roots. These fungi extend their hyphae into the soil, effectively increasing the root's nutrient absorption area. In return for carbohydrates from the plant, these fungi help the plant absorb phosphorus, nitrogen, and other micronutrients. 6. Soil Structure and Aggregation: Organic matter and the biological activity it fosters can significantly improve soil structure. Well-structured soil has good pore spaces, ensuring adequate air and water movement. This is vital for root health and for facilitating nutrient transport 7. pH and Nutrient Availability: Organic matter can influence soil pH. Many nutrients are more available to plants at specific pH levels, so maintaining the right pH is essential for nutrient uptake. 8. Organic Mulching: Organic mulches, such as straw or wood chips, can protect the soil from erosion, conserve moisture, and gradually break down, contributing to soil organic matter and releasing nutrients.  9. Soil Food Web: The interactions between different organisms in the soil – from bacteria and fungi to earthworms and insects – play a significant role in nutrient cycling. For instance, earthworms ingest organic matter and excrete nutrient-rich casts, making nutrients more available to plants. 10.Limiting Soil Erosion: Organic practices, like cover cropping or no-till farming, can prevent soil erosion, which otherwise can deplete the topsoil of its nutrient-rich layer. Carbon Dioxide and Soil The carbon cycle illustrates the role of soil in cycling nutrients through the environment. More carbon is stored in soil than in the atmosphere and above-ground biomass combined. Soil carbon is in the form of organic compounds originally created through photosynthesis in which plants convert atmospheric carbon dioxide (CO2) into plant matter made of organic carbon compounds, such as carbohydrates, proteins, oils, and fibers. Thus, if no new plant residue is added to the soil, soil organic matter will gradually disappear. If plant residue is added to the soil at a faster rate than soil organisms convert it to CO2, carbon will gradually be removed from the atmosphere and stored (sequestered) in the soil. Cultivation aerates the soil, triggering increased biological activity 2.5 Philippine National Standard - PNS/BAFS 183:2020 Organic Soil Amendments 1 Scope. This Standard applies to organic fertilizers, organic soil conditioners, microbial inoculants, and organic plant supplements. The emphasis on how to minimize contamination from microbiological, physical, and chemical hazards is in accordance with the relevant provisions under the Philippine National Standard (PNS) on the Code of Practice for the Production of Organic Soil Amendments 2 3.4 organic soil amendments - include all the products within the scope of the Standard, i.e. organic fertilizer, organic soil conditioner, microbial inoculant, and organic plant supplement 3 3.5 pathogens - organisms that can cause negative effects on human health 3. raw materials - naturally-occurring materials used in the production of organic soil amendments 4. 4.1 Organic Fertilizer - any product in solid or liquid form, derived from plants or animals that has undergone substantial decomposition that can supply available nutrients to plants with a total Nitrogen (N) - Phosphorus (P2O5) - Potassium (K2O) content of five to ten percent (5-10%). 5. 4.2 Organic Soil Conditioner - any product in solid or liquid form, derived from plants or animals that has undergone substantial decomposition that can supply available nutrients to plants with a total N- P2O5 - K2O content of 2.5 to less than five percent (2.5 - < 5%). 6. 4.4 Organic Plant Supplement - any compound of organic origin in liquid or solid form that has a total N-P2O5-K2O content of not less than 0.5% to not more than 10%. for solid and to less than 5% for liquid. These include but are not limited to: FPJ (Fermented Plant Juice), FFJ (Fermented Fruit Juice), FAA (Fish Amino Acid), FE (Fish Emulsion), Seaweed Extracts, Vermi Tea, Compost Tea, and the like. Minimum requirements Raw materials. Raw materials to be used for the production of organic soil amendments should be in accordance with the list of permitted raw materials for the production of organic soil amendments as listed in the National List of Permitted Substances for Organic Agriculture. 5.2.1.2 For solid organic fertilizer, all specifications in Table 1, except actual MC, should be in dry weight basis 5.2.1.3 For solid and liquid organic fertilizer, organic soil conditioner, and organic plant supplement containing microbial inoculants, the Genus should be verifiable and stated in the label. Specifications for organic fertilizer, organic soil conditioner, and organic plant supplement Specifications Organic Fertilizer (Solid) Organic Fertilizer Organic Soil Conditioner Organic Plant (Liquid) (Solid and Supplement (Solid Liquid) and Liquid) Total N-P2O5- K2O, % 0.5 - 10% for Solid 5 - 10% 5 - 10% 2.5 -