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Dravid Hosein And DENICIA DUMONTWATER LOGGING&SOIL COMPACTION what is Water logging?Waterlogging refers to the saturation of soil with water. Soil may be considered waterlogged when the ground water in the water table is too high to allow a premeditated activity such as agriculture to take placeCAUSESWaterlogging occurs whenever the soil is so wet that there is insufficient oxygen in the pore space for plant roots to be able to adequately respire. Other gases detrimental to root growth, such as carbon dioxide and ethylene, also accumulate in the root zone and affect the plants.

Plants vary in their demand for oxygen. There is no static level of soil oxygen that can identify waterlogged conditions for all plants, a plants demand for oxygen in its root zone will vary with its stage of growth.

Key pointsWaterlogging occurs when roots cannot respire due to excess water in the soil profile.Water does not have to appear on the surface for waterlogging to be a potential problem.Improving drainage from the inundated paddock can decrease the period at which the crop roots are subjected to anaerobic conditions.While raised beds (see Raised Bed Cropping fact sheet) are the most intensive management strategy, they are also the most effective at improving drainage.Waterlogged soils release increased amounts of nitrous oxide (N2O), a particularly damaging greenhouse gas.

Symptoms and causes

Lack of oxygen in the root zone of plants causes their root tissues to decompose. Usually this occurs from the tips of roots, and this causes roots to appear as if they have been pruned. The consequence is that the plants growth and development is stalled. If the anaerobic circumstances continue for a considerable time the plant eventually dies.Most often, waterlogged conditions do not last long enough for the plant to die. Once a waterlogging event has passed, plants recommence respiring. As long as soil conditions are moist, the older roots close to the surface allow the plant to survive. However, further waterlogging-induced root pruning and/or dry conditions may weaken the plant to the extent that it will be very poorly productive and may eventually die.

Many farmers do not realise that a site is waterlogged until water appears on the soil surface however, by this stage, plant roots may already be damaged and yield potential severely affected Effect and impacts of waterlogging

Suffocation of Plant roots. Fall of productivity by about 20% in those areas affected. Pasture loss through drowning. Fungal disease. Nitrogen deficiency. Access problems for machinery/stock. Erosion in higher rainfall areas and soil structure decline, as soil is washed away Damage to StructureWaterlogging causing excess water to surface

Countries affected by waterloggingPakistanAustralia Trinidad & TobagoGuyana

discussionFungal disease can be brought about by waterlogging and can infect agricultural crops which can further lead to the disease spreading to the consumer of the crops. Low levels of oxygen in the root zone trigger the adverse effects of waterlogging on plant growth. When plants are growing actively, root tips begin to die within a few days of waterlogging. The shallow root systems that then develop limit the uptake of nutrients (particularly nitrogen) and water, particularly when the soil profile starts to dry in spring. As a result plants may ripen early and grains may not fill properly.Nitrogen is lost from waterlogged soils by leaching and denitrification (degassing). Denitrification leads to the gaseous loss of nitrous oxide (N2O) into the atmosphere, which is a major greenhouse gas. These losses, together with the lowered ability of plants to absorb nutrients from waterlogged soil, cause the older leaves to yellow. Waterlogging also directly reduces nitrogen fixation by the nodules of legume crops and pastures.The livelihood within a community can be jeopardized if agricultural land within a community is water logged as the soil become nitrogen deficient, nitrogen is need for a plants proper growth. There crops yield are lowered in quality as well ah greatly delayed. how CAN WATERLOGGING CAN BE SOLVED?Solving waterloggingDrainage can be improved on many sites and is the first thing to consider once a waterlogging problem has been identified. Options might vary from shallow surface drains (i.e. Spoon- and W-drains) to more intensive drainage using wide-spaced furrows, to the intensive drainage form of raised beds. The efficiency of surface drainage increases in that order as does the degree of management. Consult your local adviser for further advice.What is soil compaction?Soil compaction is when the soil particles are pressed together, increasing the pore space between them.

CAUSESThere are several forces, natural and man-induced, that compact a soil. This force can be great, such as from a tractor, combine or tillage implement, or it can come from something as small as a raindrop. Listed below are several types of soil compaction and their causes. Raindrop impact This is certainly a natural cause of compaction, and we see it as a soil crust (usually less than 1/2 inch thick at the soil surface) that may prevent seedling emergence. Rotary hoeing can often alleviate this problem.

Tillage operations Continuous moldboard plowing or disking at the same depth will cause serious tillage pans (compacted layers) just below the depth of tillage in some soils. This tillage pan is generally relatively thin (1-2 inches thick), may not have a significant effect on crop production, and can be alleviated by varying depth of tillage over time or by special tillage operations.Wheel traffic This is without a doubt the major cause of soil compaction. With increasing farm size, the window of time in which to get these operations done in a timely manner is often limited. The weight of tractors has increased from less than 3 tons in the 1940's to approximately 20 tons today for the big four-wheel-drive units. This is of special concern because spring planting is often done before the soil is dry enough to support the heavy planting equipment.

Minimal Crop Rotation The trend towards a limited crop rotation has had two effects:1.) Limiting different rooting systems and their beneficial effects on breaking subsoil compaction.2.) Increased potential for compaction early in the cropping season, due to more tillage activity and field traffic.CONSEQUENCES:-Compacted soil is dense and has low porosity. Compaction preferentially compresses large pores, which are very important for water and air movement in the soil. Infiltration is then reduced and erosion is increased.

Compaction causes an increase in the soils penetration resistance. There is little root penetration in soil above 300 psi (pounds per square inch), except if there are cracks and macrospores in the soil that can be followed by plant roots. More energy is expended when tilling compacted soil.

WHAT CAN BE DONE TO REDUCE AND PREVENT SOIL COMPACTION?Avoid working wet soil. Soil is most susceptible to compaction when its saturated and cannot absorb any more water. Use the quick field test method above to access the soil conditions, andbegin planting or working the soil only if the proper conditions exist.Reduce tillage. Crop residue can intercept raindrops and prevent the soil surface from sealing and compacting.Compacted soil is a harsher environment for soil organisms, especially earthworms, to live in.

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Compaction affects nutrient uptake. Denitrification rates can increase in compacted soil due to limited aeration. Manure ammonia volatilization losses have been found to increase when liquid manure is surface applied to compacted soils because of reduced infiltration. Phosphorus and potassium uptake can be reduced if root growth is inhibited.Use the right implements. The degree of compaction is determined by the moisture content of the soil, as well as the weight of the equipment in the field. Reduce the weight on each axle, choose wider tires and adjust air pressure to reduce the load on the soil surface.

Introduce rotary hoeing - this method can help alleviate this problem.

COUNTRIES AFFECTED BY SOIL COMPACTIONSNetherlandsEurope

CitationCompaction-Soil Management Series 2. University of Minnesota Extension, BU-7400