Effects of Plants, Organic Matter, and Earthworms on Soil Physical ...

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Effects of Plants, Organic Matter, and Earthworms on Soil Physical ...

ong>Effectsong> ong>ofong> ong>Plantsong>, ong>Organicong> ong>Matterong>, ong>andong> ong>Earthwormsong> on Soil Physical PropertiesIntroduction to ong>Organicong> Crop Production, 24 January 2009The following treatments are designed to demonstrate how plant roots, soil organic matter, ong>andong>earthworms interact in forming soil aggregates ong>andong> increasing water infiltration rate. Each groupis assigned one ong>ofong> the treatments, with the instructor being Group VI. Within your group answerthe following questions:1. How do you expect the soil in your treatment to be affected compared to the control(Group VI)?2. The effects that we will be showing will be for only a few weeks. How would a completelack ong>ofong> tillage ong>andong> increasing organic matter for several years likely be different from thisshort-term demonstration?Procedure:TreatmentGroup Soil Wheat Compost ong>Earthwormsong>VI yes no no noI yes yes yes yesII yes no yes noIII yes yes no noIV yes no yes yesV yes yes no yes1. Each group will prepare the soil mixture to be used as indicated in the chart. Large clodsong>ofong> soil should be broken up ong>andong> large pieces ong>ofong> organic matter removed. If compost is tobe added, one ‘double hong>andong>ful’ per pot should be thoroughly mixed with the appropriateamount ong>ofong> soil, ong>andong> enough compost to cover the soil about 1 inch should be added tothe surface.2. After the soil has been prepared, fill the pots ong>andong> add a liter ong>ofong> water. This should beplenty ong>ofong> water to germinate the wheat seed. If wheat seed are to be added to yourtreatment, they should be planted (about 0.5 inch deep) before adding water.3. If earthworms are to be added to your treatment, add water first ong>andong> let the water drainbefore you add earthworms. Add ~5 earthworms per pot for the appropriate treatments.4. Look at the differences in the structure ong>ofong> the soil among treatments. Are theredifferences between those treatments receiving compost ong>andong> those not receivingcompost?5. After several weeks we will evaluate how quickly water infiltrates these differenttreatments ong>andong> we will examine soil structure in each ong>ofong> the pots.


6. Firmly place a 4 inch PVC pipe into the soil, about 1 inch.7. Set a stopwatch, pour 1 liter ong>ofong> water into the pipe, ong>andong> time how long it takes for thewater to reach the soil surface inside the pipe.8. After the water has infiltrated the soil, remove excess water from the saucer, ong>andong> gentlyremove soil from pot into large, black tray.9. Carefully break open the soil for each treatment. Are there differences in soil structuredepending upon whether pots had earthworms, wheat, or compost? Which ong>ofong> these hada more consistent effect on soil structure ong>andong> rate ong>ofong> water infiltration?

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