Project 3: Influence of mulch on soil physical properties

Project 3: Influence of mulch on soil physical properties
Mulching is an effective erosion control practice, protecting soil surfaces from erosive action of falling raindrops and abrading wind. Mulches can also slow down water and wind movement at the surface. The mulches depending on colour of the mulching material increase or decrease the amount of absorbed radiation and also restrict the outgoing heat from the surface and thus change the energy balance. Mulches are used to keep soils warmer once temperature begins to drop in the winter. They also conserve water by restricting the soil evaporation. Mulching is an important component of many agricultural land use systems particularly in dry lands.
Objectives
1. To identify the influence of mulch on soil temperature
2. To identify the influence of mulch on soil moisture
Materials required
• Agricultural fields with mulching
o Paddy / wheat straw may be used as a mulch material
o Plastic (clear, white, or black) mulches or paper mulches
o Any other type of mulch
• Agricultural field with no mulching
• Simple thermometers
• Spoon for soil collection
• Cans for sampling

Methodology:
Temperature study
• Find two crop fields of the similar soil types and crop, of which one has been mulched (with straw, plastic or paper) and the other one is without mulch.
• Insert thermometers in the mulched and unmulched soil up to a depth of 5 cm (2 inches) at 8, 12, 16 and 20 hrs and record the soil temperature
• Record the diurnal temperature variations and compare which soil condition will warm or cool more rapidly
Moisture study
• Weigh eight 250 ml empty cans
• Note the irrigation dates in mulched and unmulched fields
• In the same mulched and unmulched field, collect soil samples at a depth of 5 cm (2 inches) in cans with the help of a spoon at same time used in soil temperature 7 days interval after the date of irrigation
• Weigh the moist soils with can
• Dry the samples and measure soil moisture contents after subtracting can weight.
Soil moisture (%) =
• Compare which soil condition will retains or conserves more moisture
Relevance:
The specific heat of water is 1.0 calorie per gram while the specific heat of soil is about 0.2 calories per gram. This means with the same energy input, the soil temperature will increase five times more than the water temperature. Mulched soils conserve water that contributes to slower warming.