BENEFITS OF SOIL ORGANIC MATTER

SOM

• Soil Organic matter encompasses all organic components of a soil:– Fresh residues– Decomposing

organic matter

– Stable organic matter

– Living organisms

I.CHEMICAL BENEFITS

Benefits1.Nutrient Supply

Organic matter is a reservoir of nutrients that can be released to the soil. Each percent of organic matter in the soil releases 20 to 30 pounds of nitrogen, 4.5 to 6.6 pounds of P2O5, and 2 to 3 pounds of sulfur per year.

The nutrient release occurs predominantly in the spring and summer, so summer crops benefit more from organic-matter mineralization than winter crops. Organic matter is the source of 90-95 percent of the nitrogen in unfertilized soils.

2.Contribution to CEC

Organic matter contributes to the cation exchange capacity, often furnishing 30-70 percent of the total amount. The large available surfaces of humus have many cation exchange sites that adsorb nutrients for eventual plant use and temporarily adsorb heavy metal pollutants ( lead, cadmium, and the like), which are usually derived from applied waste waters. Adsorption of these probably helps clean contaminated water.

3.Chelate

Organic matter acts as a chelate. A ligand is any organic compound that can bond to a metal (usually iron, zinc, copper, or manganese) by more than one bond and form a ring or cyclic structure by that bonding, called a chelate (keylate). The soluble chelates probably help mobilize these micronutrients metal ions increasing their availability to plants and general mobility in soils. The chelate mechanisms are not fully known at present.

II. PHYSICAL BENEFITS

1.Water Holding Capacity

2. Organic matter behaves somewhat like a sponge, with the ability to absorb and hold up to 90 percent of its weight in water. A great advantage of the water-holding capacity of organic matter is that the matter will release most of the water that it absorbs to plants. In contrast, clay holds great quantities of water, but much of it is unavailable to plants.

2. Soil Structure Aggregation

Organic matter causes soil to clump and form soil aggregates, which improves soil structure. With better soil structure, permeability (infiltration of water through the soil) improves, in turn improving the soil's ability to take up and hold water.Soil structure is defined by the way individual particles of sand, silt, and clay are assembled. Single particles when assembled appear as larger particles. These are called

aggregates Classes and Types of soil structure1. Very fine or very thin;2. Fine or thin;3. Medium;4. Coarse or thick;5. Very coarse or very thick.

3.Soil Quality

• Soil quality is the capacity of soils

within landscapes to sustain

biological productivity, maintain

environmental quality, and promote

plant and animal health.

• Protecting soil quality like

protecting air quality and

water quality should be

fundamental goal of our

Nation’s Environmental Policy

http://www.directseed.org/soil_quality.htm

http://www.nrsl.umd.edu/research/NRSLResearchAreaInfo.cfm?ID=14

Poor Good

4. Erosion Prevention

This property of organic matter is not widely known. Data used in the universal soil loss equation indicate that increasing soil organic matter from 1 to 3 percent can reduce erosion 20 to 33 percent because of increased water infiltration and stable soil aggregate formation caused by organic matter.

Most soil organic matter is in the topsoil. When soil erodes through water movement, organic matter is removed with it. Appropriate tillage practices particularly on sloping soils can reduce erosion and organic matter losses such as contour ploughing.

5. Mulch When left on top of soil as a mulch, organic matter reduces erosion, shades

the soil (which prevents rapid moisture loss), and keeps the soil cooler in

very hot weather and warmer in winter.

6.Compaction • Higher organic matter levels tend to reduce the risk of soil compaction. Soil compaction is the

compression of soil due to outside pressure. The effect of soil compaction is an increase in the density of a soil and a corresponding reduction in the amount of air present in the spaces between soil particles. This process can be caused by a number of factors and may be harmful or beneficial depending on the circumstances.

• Reasons to Avoid Soil Compaction1. Causes nutrient deficiencies 2. Reduces crop productivity 3. Restricts root development 4. Reduces soil aeration through reduce the cultivation.5. Decreases soil available water 6. Reduces infiltration rate 7. Increases bulk density 8. Increases sediment and nutrient losses 9. Increases surface runoff 10. Damages soil structure ,through reroute the traffic.

• 11. Breakup the hard layers.• 12.Amend the soil .

7. Reduced Surface Crusting

• Higher organic matter levels tend to reduce the risk of soil capping particularly on fine textured soils through an improved soil structure.

8.Porosity • Porosity or pore space refers to the volume of soil voids that can be filled by water

and/or air. It is inversely related to bulk density. Porosity is calculated as a percentage of the soil volume:

• Bulk density x 100 = % solid space Particle density

• 100% – % Solid Space = Percent Pore Space• Loose, porous soils have lower bulk densities and greater porosities than tightly

packed soils. Porosity varies depending on particle size and aggregation. It is greater in clayey and organic soils than in sandy soils. A large number of small particles in a volume of soil produces a large number of soil pores. Fewer large particles can occupy the same volume of soil so there are fewer pores and less porosity.

• Pores of all sizes and shapes combine to make up the total porosity of a soil. Porosity, however, does not tell us anything about the size of pores.

HUMUS• Newly-formed humus=• a) combination of

resistant materials from the original plant tissue,

• b) compounds synthesized as part of the microorganisms' tissue which remain as the organisms die. (Fulvic and Humic Acid)

• humus is mostly resistant to further microbial attack- N and P are protected from ready solubility

Leaf Humus

9.Humus

Humus buffers the soil against a rapid change in acidity, alkalinity, and salinity; and damage by pesticides and toxic heavy metals.

Rachel says, "Humus is as good as it gets, nutritionally. However, humus cannot support healthy life on its own. It should make up only a certain percentage of ideal soil. Colorado State University has compiled a comprehensive guide to identifying the composition of your soil, which will help you figure out how much humus you need."

Ingredients of Humus

• Healthy humus contains everything a plant needs to thrive. Nitrogen and oxygen are present in abundance, along with various amounts of potassium, magnesium and other minerals. Adding 1 cubic foot of clay every 3 or 4 months will help infuse trace metals and other inorganic compounds as well as naturally regulating the acidity of the humus soil. In all, humus contains more than 25 minerals and nutrients that plants need for proper growth.

Humus is Alive

• Humus is not just soil, it is a community of living things. Organic matter is a breeding ground for many types of microbes, including bacteria and fungi which break down plant material, and for other microorganisms that help plants roots absorb necessary nutrients. Earthworms have long been known to loosen the soil for plant roots. Recent research indicates that earthworms may serve to eliminate unwanted pathogens from the soil as well.

Stable Organic Matter -Humus

• Thus, soil organic compounds become stabilized and resistant to further changes by microorganisms

• Stabilized organic matter acts like a sponge and can absorb six times its weight in water

Humus consists of different humic substances:

1.Fulvic acids: the fraction of humus that is soluble in water under all pH conditions. Their colour is commonly light yellow to yellow-brown.

2.Humic acids: the fraction of humus that is soluble in water, except for conditions more acid than pH 2. Common colours are dark brown to black.

3.Humin: the fraction of humus that is not soluble in water at any pH and that cannot be extracted with a strong base, such as sodium hydroxide (NaOH). Commonly black in colour.

Functions of humus:1. Improved fertilizer efficiency , Nutrients in organic matter are not readily

leached from the soil.2. longlife N - for example, urea performs 60-80 days longer;3. improved nutrient uptake, particularly of P and Ca;4. stimulation of beneficial soil life;5. provides magnified nutrition for reduced disease, insect and frost impact;6. salinity management - humates “buffer” plants from excess sodium;7. organic humates are a catalyst for increasing soil C levels.8. Supply plant-available phosphorus and plant-available sulfur when soil humus

is present (25% or more) 9. Furnish 30% to 70% of a soil’s cation exchange capacity. The higher a soil’s

cation exchange capacity, the greater its ability to hold onto nutrients until needed by the plant and microbes.

10. Reduce Soil Erosion 11. Organic matter is a carbon (food) supply for beneficial soil microbes.

III. Biological Benefits

1.Soil Biota

• The soil contains a vast array of life forms ranging from submicroscopic (the viruses), to earthworms, to large burrowing animals such as gophers and ground squirrels. Microscopic life forms in the soil are generally called the "soil microflora" (though strictly speaking, not all are plants in the true sense of the word) and the larger animals are called macrofauna

2.Soil Microorganisms

• Soil microorganisms occur in huge numbers and display an enormous diversity of forms and functions. Major microbial groups in soil are bacteria (including actinomycetes), fungi, algae (including cyanobacteria) and protozoa.

3.Nutrient Cycling by Soil Microbes

• Soil microbes exert much influence in controlling the quantities and forms of various chemical elements found in soil. Most notable are the cycles for carbon, nitrogen, sulfur and phosphorus, all of which are elements important in soil fertility, and as we know today, may be involved in global environmental phenomena.

4. Bioremediation

• Bioremediation may be defined as the controlled use of microorganisms for the destruction of chemical pollutants. A large number of processes have been developed to handle various wastes and for the cleanup of spilled organic materials. At the heart of all of these processes lies the premise that the metabolic activities of bacteria or fungi can be used to degrade many of the organic chemicals of commerce (solvents, pesticides, hydrocarbon fuels, etc.).

Functions of Soil Micro organisms S.no Function Microorganism Involved

1 Maintenance of soil structure Bioturbating invertebrates and plant roots, mycorrhizae and some other micro-organisms

2 Regulation of soil hydrological processes Most bioturbating invertebrates and plant roots

3 Gas exchange and carbon sequestration (accumulation in soil)

Mostly micro-organisms and plant roots, some C protected in large compact biogenic invertebrate aggregates

Functions of Soil Micro organisms S.no Function Microorganism Involved

4 Soil detoxification Mostly micro-organisms

5 Nutrient cycling Mostly micro-organisms and plant roots, some soil- and litter-feeding invertebrates

6 Decomposition of organic matter Various saprophytic and litter-feeding invertebrates (detritivores), fungi, bacteria, actinomycetes and other micro-organisms

Functions of Soil Micro organisms S.no Function Microorganism Involved

7 Suppression of pests, parasites and diseases Plants, mycorrhizae and other fungi, nematodes, bacteria and various other micro-organisms, collembola, earthworms, various predators

8 Sources of food and medicines Plant roots, various insects (crickets, beetle larvae, ants, termites), earthworms, vertebrates, micro-organisms and their by-products

9 Symbiotic and asymbiotic relationships with plants and their roots

Rhizobia, mycorrhizae, actinomycetes, diazotrophic bacteria and various other rhizosphere micro-organisms, ants

Functions of Soil Micro organisms S.no Function Microorganism Involved

10. Plant growth control (positive and negative) Direct effects: plant roots, rhizobia, mycorrhizae, actinomycetes, pathogens, phytoparasitic nematodes, rhizophagous insects, plant-growth promoting rhizosphere micro-organisms, biocontrol agents Indirect effects: most soil biota

IV Environmental Benefits of SOM

Compost• Compost is natural, inexpensive and good for the environment. By using

food scraps and garden vegetation as compost, you:

Compost • Compost use can result in a variety of environmental benefits. The

following are a few of the most important benefits• 1. Compost enriches soils • 2.Compost helps cleanup contiminated soils • 3. Compost helps prevent pollution

• 4.Using compost offer economic benefits. • 5. Compost contains macro and micronutrients often absent in synthetic fertilizers.• 6. Compost releases nutrients slowly—over months or years, unlike synthetic

fertilizers Compost enriched soil retains fertilizers better. Less fertilizer runs off to pollute waterways.

• 7. Compost buffers the soil, neutralizing both acid & alkaline soils, bringing pH levels to the optimum range for nutrient availability to plants.

Compost binds soli particles 1. Compost helps sandy soil retain water and nutrients.2. Compost loosens tightly bound particles in clay or silt soil so roots can spread,

water drain & air penetrate.3. Compost alters soil structure, making it less likely to erode, and prevents soil

spattering on plants—spreading disease.4. Compost can hold nutrients tight enough to prevent them from washing out, but

loosely enough so plants can take them up as needed.5. Compost makes any soil easier to work.

Compost brings and feeds diverse life in the soil

• Compost bacteria break down organics into plant available nutrients. Some bacteria convert nitrogen from the air into a plant available nutrient.

• Compost enriched soil have lots of beneficial insects, worms and other organisms that burrow through soil keeping it well aerated.

• Compost may suppress diseases and harmful pests that could overrun poor, lifeless soil.

Compost increases soil’s ability to retain water &

decreases runoff. 1. Compost encourages healthy root systems, which decrease runoff2. Compost can reduce or eliminate use of synthetic fertilizers3. Compost can reduce chemical pesticides since it contains beneficial

microorganisms that may protect plants from diseases and pests.4. Only a 5% increase in organic material quadruples soils water holding

capacity.

Compost and pH

• The composting process is relatively insensitive to pH within the range commonly found in mixtures of organic materials, largely because of the broad spectrum of microorganisms involved. The preferred pH is in the range of 6.5-8.0. pH does become a consideration with raw materials containing a high percentage of nitrogen. A high pH, above 8.5, encourages the conversion of nitrogen compounds to ammonia

Compost and time

• The time required to transform raw materials into compost depends on many factors. Proper moisture content, C:N ratio and frequent aeration ensure the shortest composting period. A well-managed composting operation should produce quality compost within four months

Co-composting • Co-composting refers to composting that includes more than one organic

material. Some co-composting operations determine the portions of each material by trial and error to obtain a compostable mixture. The trial and error method could cause problems later. To obtain the best ingredients for composting within the optimum time period without excessive odors, follow a mixing procedure based on the physical and chemical characteristics of the composting materials.

Compost enriches surface area • Grinding, chipping, and shredding materials increases the surface area on

which the microorganism can feed. Smaller particles also produce a more homogeneous compost mixture and improve pile insulation to help maintain optimum temperatures .If the particles are too small, however, they might prevent air from flowing freely through the pile.

Compost and moisture content

• Microorganisms living in a compost pile need an adequate amount of moisture to survive. Water is the key element that helps transports substances within the compost pile and makes the nutrients in organic material accessible to the microbes. Organic material contains some moisture in varying amounts, but moisture also might come in the form of rainfall or intentional watering.

Compost provides oxygen flow

• Turning the pile, placing the pile on a series of pipes, or including bulking agents such as wood chips and shredded newspaper all help aerate the pile. Aerating the pile allows decomposition to occur at a faster rate than anaerobic conditions. Care must be taken, however, not to provide too much oxygen, which can dry out the pile and impede the composting process.

• A minimum oxygen concentration of 5% within the pore spaces of the composting material is recommended for a wellmanaged compost facility (air contains about 21% oxygen).

Compost and temperature

• Microorganisms require a certain temperature range for optimal activity. Certain temperatures promote rapid composting and destroy pathogens and weed seeds. Microbial activity can raise the temperature of the pile’s core to at least 140° F. If the temperature does not increase, anaerobic conditions (i.e., rotting) occur. Controlling the previous four factors can bring about the proper temperature.

Types of home-composters to buy or make

1. plastic bins with ventilation holes or slits2. plastic bins without ventilation3. metal drums with holes punched in the side

and the base removed4. rotating drum units (tumblers)5. enclosures made from timber (planks or

sleepers), bricks or chicken wire.

Tips for composting

1. Choose a shady spot in the garden to start your compost heap or to position your compost bin.

2. Add to your compost in layers of food scraps, garden clippings and paper.

3. Keep your compost moist, but not wet, and aerate it about once a week

4. Dig it into your garden or spread it on top as mulch. Your compost should be ready when it is dark and crumbly, after about four months.

Composting is easy

1. Choose a shady spot in the garden to start your compost heap or to position your compost bin. There are many types of composting bins available – some require mixing and some don’t

2. Add to your compost in layers of food scraps, garden clippings and paper.

3. Keep your compost moist, but not wet and aerate it about once a week.

4. When your compost is dark and crumbly (about four months) dig it into your garden or spread it on top as mulch.

What to put in your compost

1. Compost needs a ratio of three 'brown' (carbon-rich) to approximately one ‘green’ (nitrogen-rich) amounts of material. You can also add egg shells, tea bags and even dust from the vacuum cleaner to your compost.

2. Brown: leaves, twigs, sawdust, shredded paper.

3. Green: fruit and vegetable peelings, grass clippings, soft prunings and leaves.

What u not add in compost

1. diseased plant material,2. meat scraps and bones,3. dairy products,4. bread,5. cake or6. pet droppings.

Composting Process

• Composting converts Composting converts organic waste such as leaves, kitchen scraps and garden wastes…, into a valuable product whi h h d i th hich, when used in the garden, results in healthier plant growth healthier plant growth when added to garden soil

How the Composting Process Works

1.Organisms involved in the composting process

2.Variable components in the composting process

3.Types o f ma terials (feedstocks) that can be composted

4.Home composting systems 5.Uses of compost

Compost conserve resources

1. Water2. Energy and fuel3. Composting could save your money4. Compost reduces green house gases 5. Compost improves soil quality

Decrease in SOM

1.Burning of natural vegetation and crop residues

• Burning destroys the litter layer and so diminishes the amount of organic matter returned to the soil. The organisms that inhabit the surface soil and litter layer are also eliminated. For future decomposition to take place, energy has to be invested first in rebuilding the microbial community before plant nutrients can be released. Similarly, fallow lands and bush are burned before cultivation. This provides a rapid supply of P to stimulate seed germination. However, the associated loss of nutrients, organic matter and soil biological activity has severe long-term consequences.

2. Overgrazing • Overgrazing destroys the most palatable and useful species in the plant

mixture and reduces the density of the plant cover, thereby increasing the erosion hazard and reducing the nutritive value and the carrying capacity of the land.

3. Removal of crop residues

• Many farmers remove residues from the field for use as animal feed and bedding or to make compost . Later, these residues return to contribute to soil fertility as manures or composts. However, residues are sometimes removed from the field and not returned. This removal of plant material impoverishes the soil as it is no longer possible to recycle the plant nutrients present in the residues

4.Tillage Practices • Tillage is one of the major practices that reduces the organic matter level in the

soil. Each time the soil is tilled, it is aerated. As the decomposition of organic matter and the liberation of C are aerobic processes, the oxygen stimulates or

speeds up the action of soil microbes, which feed on organic matter.• Tillage induced flush of decomposition of organic matter ( Source Glanz

1995)Type of tillage Organic matter lost in 19 days ( kg/Hect)

Mouldboard plough + disc harrow (2x) 4300

Mouldboard plough 2230

Disc Plough 1840

Chiesel Plough 1720

Direct Seeding 860

5.Drainage • Decomposition of organic matter occurs more slowly in poorly aerated

soils, where oxygen is limiting or absent, compared with well-aerated soils. For this reason, organic matter accumulates in wet soil environments. Soil drainage is determined strongly by topography - soils in depressions at the bottom of hills tend to remain wet for extended periods of time because they receive water (and sediments) from upslope. Soils may also have a layer in the subsoil that inhibits drainage, again exacerbating waterlogging and reduction in organic matter decomposition

6. Fertilizer and pesticide use

• Initially, the use of fertilizer and pesticides enhances crop development and thus production of biomass (especially important on depleted soils). However, the use of some fertilizers, especially N fertilizers, and pesticides can boost micro-organism activity and thus decomposition of organic matter. The chemicals provide the microorganisms with easy-to-use N components. This is especially important where the C: N ratio of the soil organic matter is high and thus decomposition is slowed by a lack of N.

Summerfallow

• Summerfallowing accelerates the loss of organic matter. Aeration of the soil associated with tillage, and the increase in soil temperature and moisture results in increased organic matter decomposition. Since little In the way of residues are added to the soil, a net loss of organic matter occurs. Research has shown that as the frequency of fallow increases, the amount of soil organic matter decreases

Maintenance of SOM

1. Compost• Composting is a technology for recycling organic materials in order to

achieve enhanced agricultural production. Biological and chemical processes accelerate the rate of decomposition and transform organic materials into a more stable humus form for application to the soil. Composting proceeds under controlled conditions in compost heaps and pits.

Composting of manure and other materials will:1. help stabilize nutrients2. reduce the amount to spread (volume can be reduced by 30%-60%)3. produce a better-smelling final product

2.Cover Crops1. They prevent erosion by anchoring soil and lessening the impact of raindrops.2. They add plant material to the soil for organic matter replenishment.3. Some, e.g. rye, bind excess nutrients in the soil and prevent leaching.4. Some, especially leguminous species, e.g. hairy vetch, fix N in the soil for future use.5. Most provide habitat for beneficial insects and other organisms.6. They moderate soil temperatures and, hence, protect soil organisms.

3.Green Manure

• Green manures are grown to add nutrients and organic matter to the soil. Green manures are incorporated into the

soil while green or shortly after flowering.

4. Crop Rotation • Crop rotation is an integral part of the crop production system. The greatest

benefit to a good crop rotation is increased yields. A well-planned crop rotation will help with insect and disease control and aid in maintaining or improving soil structure and organic matter levels. Using a variety of crops can reduce weed pressures, spread the workload, protect against soil erosion and reduce risk. Legume crops in the rotation have become more valuable with the increased cost of nitrogen. Research and experience have proven that a good crop rotation will provide more consistent yields, build soil structure and increase profit potentia

5. Crop Residue

6.Zero Tillage • Avoiding mechanical soil disturbance implies growing crops without mechanical

seedbed preparation or soil disturbance since the harvest of the previous crop. The term zero tillage is used for this practice synonymously with terms such as no-till farming, no tillage, direct drilling, and direct seeding.

7. Agro forestry and Alley Cropping • Agroforestry is a collective name for land-use systems where woody perennials

(trees, shrubs, palms, etc.) are integrated in the farming system (FAO, 1989). Alley cropping is an agroforestry system in which crops are grown between rows of planted woody shrubs or trees. These are pruned during the cropping season to provide green manure and to minimize shading of crops (FAO, 1993).

8. Balanced Ferilization• Fertilizers should be applied in sufficient quantities and in balanced

proportions. The efficiency of fertilizer use will be high where the organic matter content of the soil is also high. In very poor or depleted soils, crops use fertilizer applications inefficiently. When soil organic matter levels are restored, fertilizer can help maintain the revolving fund of nutrients in the soil by increasing crop yields and, consequently, the amount of residues returned to the soil.

9. Improved Vegetative Stands• In many places, low plant densities limit crop yields. Wide plant spacing is often

practised as “a way to return power to the soil” or “to give the soil some rest”, but in reality it is an indicator that the soil is impoverished. Plant spacing is usually determined by farmers in relation to soil fertility and available water or expected rainfall (unless standard recommendations are enforced by extension). This means that plants are often spaced widely on depleted soils in arid and semi-arid regions with a view to ensuring an adequate provision of plant nutrients and water for all plants.

10. Protection from fire

• Burning affects organic matter recycling significantly. Fire destroys almost all organic materials on the land surface except for tree trunks and large branches. In addition, the surface soil is sterilized, loses part of its organic matter, the population of soil microfauna and macrofauna is reduced, and no ready-to-use organic matter is available for rapid restoration of the populations.

11. Crop residue management

1. Add soil organic matter, which improves the quality of the seedbed and increases the water infiltration and retention capacity of the soil, buffers the pH and facilitates the availability of nutrients;

2. sequester (store) C in the soil;3. provide nutrients for soil biological activity and plant uptake;4. capture the rainfall on the surface and thus increase infiltration and the

soil moisture content;5. provide a cover to protect the soil from being eroded;6. reduce evaporation and avoid desiccation from the soil surface.

12. Integrated Pest Management • As with balanced fertilization, proper pest and disease management

results in healthy crops. Healthy crops produce optimal biomass, which is necessary for organic matter production in the soil. Diversified cropping and mixed crop-livestock systems enhance biological control of pests and diseases through species interactions. Through integrated production and pest management farmers learn how to maintain a healthy environment for their crops.

13. Applying animal manure or other carbon-rich wastes

• Any application of animal manure, slurry or other carbon-rich wastes, such as coffee-berry pulp, improves the organic matter content of the soil. In some cases, it is better to allow a period of decomposition before application to the field. Any addition of carbon-rich compounds immobilizes available N in the soil temporarily, as micro-organisms need both C and N for their growth and development. Animal manure is usually rich in N, so N immobilization is minimal. Where straw makes up part of the manure, a decomposition period avoids N immobilization in the field.

14.Mulch or permanent soil cover • One way to improve the condition of the soil is to mulch the area requiring

amelioration. Mulches are materials placed on the soil surface to protect it against raindrop impact and erosion, and to enhance its fertility (FAO, 1995). Crop residue mulching is a system of maintaining a protective cover of vegetative residues such as straw, maize stalks, palm fronds and stubble on the soil surface

15. REDUCED SOIL EROSION AND IMPROVED WATER QUALITY

• When the soil is protected with mulch, more water infiltrates into the soil rather than running off the surface. This causes streams to be fed more by subsurface flow rather than by surface runoff. The consequence is that the surface water is cleaner and resembles groundwater more closely compared with areas where erosion and runoff predominate. Greater infiltration should reduce flooding by increased water storage in soil and slow release to streams. Increased infiltration also improves groundwater

recharge, thus increasing well supplies.

16.Reduced water logging • However, in case of waterlogging, organic matter plays also an important

role. The bioturbating activity of the macrofauna leaves various so-called conducting macropores in the soil, which are responsible for the drainage of water to deeper soil layers.

17. INCREASED BIODIVERSITY

• Conventional agriculture tends to reduce aboveground and belowground diversity. Thus, it brings about significant changes in the vegetation structure, cover and landscape. The change in vegetal cover during the conversion of forest and pastures to cropping affects plants, animals and micro-organisms

18. Manures • Livestock manure is an excellent source of organic matter for the soil.

Applying manure to the soil will provide other benefits, such as a greater diversity and activity of organisms and better soil structure.

19.Sanitation measures• Sanitation measures can be used to help prevent the introduction of pests onto

the farm, to prevent the movement of pests within the farm, and to remove overwintering or breeding sites for pests on the farm.

• Start with pest-free plants; inspect plants brought onto the farm to prevent the introduction of pests.

• Removal or incorporation of crop residue can eliminate overwintering sites for some pests.

• Infested plants should be removed and composted, buried, or otherwise destroyed as soon as possible.

• .

19.Sanitation measures Removal of weeds and natural vegetation bordering crops may eliminate alternate

hosts for some insect pests. Bear in mind that these areas may also harbor natural enemies; therefore, the grower must carefully assess the potential threat from pest insects in these areas before mowing or removing any plants.

When working in an infested area, clean equipment and clothes before going to another area of the farm. Pests such as whiteflies and spider mites can be carried on workers' clothes and spread to new areas.

20.Liming

The main purpose of liming is to raise soil pH and supply calcium and sometimes magnesium for plant growth. Other benefits from liming acid soils include increased biotic activity, enhanced mineralization of nutrients from soil organic matter, improved soil structure, decreased potential for aluminum toxicity, and increased availability of other nutrients, especially phosphorus.