Definition

Organic materials are materials that can be renewed, recycled, revamped by soil bacteria into elements that can be used by plants without polluting the soil and water. Soil organic matter is an accumulation of the remains of plants and animals that have undergone some weathering and the re-establishment. Such organic materials in the active decay and fall prey to attack micro bodies. As a result these materials change continues and unstable so that should always be updated through the addition of the remains of plants or animals.

Source of Organic Materials

The primary source of organic material is plant tissue of roots, stems, twigs, leaves, and fruit. Organic matter produced by plants through photosynthesis process so that the element carbon is the main constituent of the organic material. The element carbon is in the form of polysaccharide compounds, such as cellulose, Hemicellulose, starch, and pectin substances and lignin. Addition of nitrogen is the most elements in organic materials accumulated as an important element in the microbial cells are involved in the reform process of soil organic matter. This plant tissue will decompose and be transported to the lower layer and incorporated with the soil. Plants not only a source of organic material, but the source of organic material of all living things.

Secondary sources of organic material is fauna. Fauna first to use organic materials only then plants also contribute organic materials. Soil organic matter than can be derived from the original network can also be derived from the rocks.

Difference sources of organic material such land will provide different effects contribute to the soil. It is closely related to the composition or structure of the organic material. Content of organic materials in each type of soil is not the same. This depends on several things, namely: the type of vegetation in the area, the soil microbial populations, soil drainage conditions, precipitation, temperature, and soil management. The composition or composition of plant tissue will be much different from animal tissue. In general, animal tissue would be destroyed faster than the plant tissue. Plant tissue largely composed of water that vary from 60-90% and an average of about 75%. Part solids approximately 25% from 60% carbohydrate, 10% protein, 10-30% lignin and 1-8% fat. Judging from the composition of the element carbon is the largest part (44%) followed by oxygen (40%), hydrogen and ash respectively about 8%. Ash composition itself consists of all the absorbed nutrients and plant required except C, H and O.

Humus

Humus is one form of organic material. Original network form of plant or animal's body had not yet decayed continue to experience attacks that use micro bodies as sources of energy and body building materials. Results weathering original material by micro-called humus.Humus body usually dark and is found primarily in the top layer of soil. Definition of humus that is the fraction of soil organic matter more or less stable, most of the rest of the plant and animal residues that have been the decomposition.

Humus is organic material forms a more stable, in the form of organic material is accumulated in the soil much. Humus has the largest contribution to the durability and soil fertility. Humus is active and is like clay, which is negatively charged. But unlike most of the crystalline clay, humus is always amorphous (irregular shape).

Humus is a complex compound decayed somewhat resistant (resistant), brown, amorphous, colloidal nature and derived from plant or animal tissue that have been modified or shaped by a variety of micro bodies. Humus is not completely resistant to the bacteria work. They are unstable, especially in the event of regime change in temperature, humidity and aeration. humus in the soil helps reduce the bad influence of clay on soil structure, in this case to stimulate granulation humus soil aggregate. Humus ability retain water and nutrient ions clay exceeds capacity. High holding power (saving) the nutrient is due to the high cation exchange capacity of humus, because the topsoil has several active groups, especially carboxyl groups. Thus the nature of existence with humus in the soil will help improve soil productivity.

The nature and characteristics Humus

As a colloidal · like clay but amorfous.

· Surface area and absorption capacity far exceeds the clay.

· Cation exchange capacity of 150-300 g me/100, clay me/100 only 8-100 g.

· Power jerap water 80-90% of their weight, only 15-20% clay.

· Power cohesion and plasticity is low, thereby reducing clamminess of clay and soil aggregate assist granulation.

· Misel humus composed of lignin, poliuronida, and proteins clay accompanied by C, H, O, N, S, P and other elements.

· Negative charge comes from the-COOH and-OH sticking on the outskirts where the Ion H can be replaced by other cations.

· Has ability to increase available nutrients such as Ca, Mg, and K.

1. Is a micro-remains a source of energy.

2. Darker colors provide on the ground.

Factors Affecting Soil Organic Materials

Among the many factors that affect the levels of organic matter and soil nitrogen, an important factor is the depth of soil, climate, soil texture and drainage.

The depth of the layer determines the level of organic matter and N. Highest levels of organic material found in the top layer thickness of 20 cm (15-20%). The more down organic matter content decreased. This is because of the accumulation of organic material is concentrated in the layer aboveFactors influencing climate are temperature and rainfall. Getting into the cold regions, levels of organic matter and N higher. At the same conditions the level of organic matter and N increased 2 to 3 times each annual temperatures average fell 100C. effective when the humidity increases, levels of organic matter and N also increases. It shows a soil organism activity constraints.

Soil texture is also quite a role, the higher the number the higher clay content of organic matter and soil N, if the other conditions the same. Sandy soil allows good oxidation so that the organic material needed..

On the ground with poor drainage, where the excess water, oxidation is hampered by poor aeration conditions. This causes the levels of organic matter and soil N berdrainase higher than both. Besides soil and vegetation cover of the lime in the soil also affects soil organic matter levels. Forest vegetation will be different with pasture and farmland. These factors are interrelated, so difficult to judge for yourself (Judge et al, 1986).

Role of Organic Materials for Soil

Important role of organic materials to create soil fertility. The role of soil organic matter is in relation to changes in soil properties, namely physical, biological, and chemical properties of soil. Organic material is in the soil-forming granulation and very important in the formation of stable soil aggregates. Organic materials are solid materials that make soil aggregate no peerless. Through the addition of organic material, soil that had been heavily into crumb structure are relatively mild. Vertical movement of water or infiltration can be improved and the soil can absorb water more quickly so that the surface flow and erosion is minimized. Similarly, the soil aeration for the better because the soil pore space (porosity) increases due to aggregate formation.Organic materials commonly found in surface soil. The numbers are not large, only about 3-5% but their influence on soil properties is huge. About half of the cation exchange capacity derived from organic materials. He is the source of plant nutrients. Besides the organic material is a source of energy for most soil organisms. In the role of organic materials is determined by the source and composition, because the smoothness of the decomposition, and the results from the decomposition itself.

Organic Materials Influence on Soil Physical Properties

· Increasing the capacity of the soil retain water. This can be attributed to the nature of the polarity of the negatively charged water and the subsequent positive associated with soil particles and organic materials. Affect groundwater soil microorganisms and plants on it. Optimum water content for plants and microorganisms is 0.5 bar / atmosphere.· Color soil becomes brown to black. This increases the absorption of solar radiation energy which then affect the temperature of the soil.

· Stimulates granulation aggregate and memantapkannya

· Lower plasticity, cohesion and other bad qualities of clay.One role of organic material that is as Granulator, which improve soil structure. According to Arsyad (1989) the role of organic material in a stable aggregate formation occurs because the soil easily form complexes with organic materials. This effectively takes place through mechanisms:

· Addition of organic matter can increase soil microorganism populations, such as mushrooms and truffles, for organic materials used by soil microorganisms as a constituent body and energy sources. Miselia or hifa these fungi are able to unite the land into aggregate grains, while the bacteria function as a unifying cement aggregate.

· Increasing physical prime grain by miselia mushrooms and aktinomisetes. In this way the formation of structures without the clay fraction may occur in the soil.· Improvement chemically clay beads through the bond portions of the organic compounds that form long chains.

· Improvement chemically clay beads through a bond between the negative clay with the negative (karbosil) of organic compounds with the intermediate base and hydrogen bonding.

· Improvement chemically clay beads through a bond between the clay and the negative positf part of the organic compounds form the polymer chain.

The influence of organic matter in soil chemical properties

Enhance jerap and cation exchange capacity (CEC). About half of the cation exchange capacity (CEC) derived from soil organic matter. Organic materials can increase the cation exchange capacity of two to thirty times larger than colloidal minerals, which include 30 to 90% of the energy jerap a mineral soil. Increased CEC due to the addition of organic materials due to decay of organic material will produce humus (organic colloids) which has the surface can hold nutrients and water so that it can be said that the provision of organic material can save water and fertilizer are provided in the ground. Increasing CEC increase soil's ability to withstand nutrient elements.Elements N, P, S bound in organic form or in the body of microorganisms, so avoid washing, and then available again. Unlike with commercial fertilizers which are usually added in significant amounts because it is water soluble so that the period of rain occurred a very high loss, nutrients stored in organic residues did not dissolve in water so released by microbiological processes. Lost due to washing is not as serious as what happened in commercial fertilizers. As a result the content of nitrogen is stable at intermediate level and reduce the danger of weaknesses and strengths. Organic material serves as a nutrient enhancer N, P, K to the plants of the mineralization by microorganisms. Mineralization is the opposite of immobilisasi. Mineralization is the transformation by microorganisms from an element in the organic material into inorganic, such as nitrogen in the proteins into ammonium or nitrite. Through mineralization, nutrients become available to plants.

Increasing the easy exchange of cations and dissolving some of the mineral nutrients by acid humus. Organic material can sustain the supply and availability of nutrients with a simple cation exchange. Nitrogen, phosphorus and sulfur bound in the form of organic humus and acid decomposition of organic material will extract nutrients from the rock minerals. Affect the acidity or pH. The addition of organic materials can increase or even decrease the pH of soil, this depends on the type of soil and organic material added. Decrease in soil pH due to addition of organic material can occur due to decomposition of organic material produces many dominant acids. While an increase in pH due to addition of organic material that occurs in acid soil where soil aluminum content is high, due to organic material of Al as a compound binding complex that no longer hydrolyzed.

The role of organic matter to improve soil chemical properties can not be separated in terms of the decomposition of organic materials, because this process changes the chemical composition of organic material from the complex compound into simpler compounds. The process that occurs in the decomposition of the remaining reforms plant or animal by miroorganisme land or other enzymes, increased biomass of organisms, and the accumulation and final release. Accumulation of plant and animal residues in soil organic matter in the other consisting of carbohydrates, lignin, tannins, fats, oils, wax, resin, compound N, pigments and minerals, so it can add nutrient elements in soil.

Influence of Organic Materials in Soil Biology Nature

The number and metabolic activity of soil organisms increases. In general, the provision of organic materials can improve the growth and activity of microorganisms. Organic material is a source of energy and food for the microorganisms that live in the soil. Soil microorganisms interact with their need for organic materials organic materials provide carbon as an energy source for growth.

Body activities in assisting micro decomposition of organic material increases. Fresh organic material added to the soil will be digested by the various existing micro-organism in soil and subsequent didekomposisisi if environmental factors support the process. Decomposition means that the reforms undertaken by a number of microorganisms (biological elements in the soil) of complex compounds into simpler compounds. The results of the decomposition of more stable compounds called humus. The more organic material is the more micro population in the soil body.

Role of Organic Materials for Plants.

Organic materials play a crucial role in the ground. For organic materials derived from plants that remained, containing nutrient elements needed for plant growth. Organic matter affects soil structure and tend to keep raising the desired physical condition. The role of organic material there is is direct to the plant, but mainly affects plants through changes in soil characteristics and features.

Direct Influence of Organic Materials in Plants

Through the study found that some growth substances and vitamins can be absorbed directly from organic material and can stimulate plant growth. Once considered one that only amino acids, alanine, and glycine are absorbed by plants. N compounds such absorption was relatively lower than other N forms. No doubt that the organic material contains a number of substances and vitamins to grow and at certain times can stimulate the growth of plants and micro bodies.

This organic material is an inorganic source of nutrients for plants. So the growth rate of plants for a long period comparable to the supply of organic and inorganic nutrients. This indicates that the major direct role of organic materials is to supply nutrients for plants. The addition of organic matter into the soil to add nutrients both macro and micro are needed by plants, so that fertilization with inorganic fertilizers used by farmers can be reduced in quantity because the plants have a nutrient elements from organic materials added to soil it. Plant nutrient efficiency increases when the soil surface covered with organic material.

Indirect influence of Organic Materials in Plants

Contribution of organic materials on plant growth is its impact on the physical properties, chemical and biological from the ground. Soil organic matter affect the majority of the physics, biology and chemistry in the soil. Organic material has a chemical role in providing N, P and S for the plant's role in influencing the biological activity and microfauna mikroflora organisms, and physical role in improving soil structure and others.

This will affect the growth of plants growing on the land. The magnitude of this effect varies depending on changes in each environmental factor. In connection with the results of decomposition of organic material and humus properties it can be said that the organic material will greatly affect the nature and characteristics of the soil. Indirect role of organic material for the plant include:
· Increasing the availability of water for plants. Organic materials can increase the water holding capacity due to soil organic matter, especially who have been minted with the ratio C / N levels of C 20 and 57% water can absorb 2-4 times the weight. Because the water content, the organic material that has become especially humus can be a buffer for the availability of water.

· Forming complex with micro elements that protect these elements from the washing. Elements N, P, S bound in organic form or in the body of microorganisms, so avoid washing, and then available again.

· Increasing soil cation exchange capacity CEC increase soil's ability to increase the holding nutrient elements.

· Improving soil structure Soil organic material containing loose structure, and when mixed with minerals will provide crumb structure and easy to do the processing. Such soil structure is the physical nature of the good soil for plant growth media. Textured clay soil, sand, or a clot will provide physical properties better when mixed with organic materials.

· Reduce erosion

· Improve soil aggregation. Organic material is in the soil-forming granulation and very important in the formation of stable soil aggregates. Organic material is the material aggregate land pemantap no peerless. Through the addition of organic material, soil that had been heavily into crumb structure are relatively mild. Vertical movement of water or infiltration can be improved and the soil can absorb water more quickly so that the surface flow and erosion is minimized. Similarly, the soil aeration for the better because the soil pore space (porosity) increases due to aggregate formation.

· Stabilizing the temperature. Organic materials can absorb the high heat and can also be a heat insulator because it has a heat conductivity is low, so that the optimum temperature needed by plants for growth can be properly fulfilled.

· Increasing the efficiency of fertilization

In general, the provision of organic materials can increase plant growth and production. Similarly, the role in tackling soil erosion and land productivity. The addition of organic material would be better if accompanied by appropriate planting patterns, such as crop patterns between the intercropping system. Management of land or land that is suitable to support the creation of a conservation of soil and water and provide for human benefit.