A Filtration

Soil filtering systems are used to deplete Biological Oxygen Demand (BOD), consume or remove such biostimulants as phosphates and nitrates, provide long term storage of heavy metals, and deactivate pathogens and pesticides. Soils suitable for use as filtering systems have permeability slow enough to allow adequate time for purification of water percolating through the soil system.

A balance of air, water, and nutritive substances at a favorable temperature is important to a healthy micro-bial population and an effective filtration system.

Figure 5-1 Relationship between microbial respiration rate and temperature

Figure 5-2 Relationship of microbial respiration rate to temperature and moisture

Maximum rate

Figure 5-1 Relationship between microbial respiration rate and temperature

Maximum rate

10 20 30 40 50 Soil temperature (°C)

Figure 5-2 Relationship of microbial respiration rate to temperature and moisture

Soil moisture content (%)

For example, overloading the filtration system with wastewater that has high amounts of suspended solids causes clogging of soil pores and a reduction of soil hydraulic conductivity. Management and timing of wastewater application are essential to maintaining soil filter systems. Climate, suspended solids in the wastewater, and cropping systems must be considered to maintain soil porosity and hydraulic conductivity.

The wastewater application rate should not exceed the waste decomposition rate, which is dependent on soil temperature and moisture content. Periods of wetting and drying increase microbial decomposition and byproduct uptake by the crop and decrease potential soil pore clogging. In areas where the temperature is warm for long periods, the application rates may be higher if crops or other means of using the by-products of waste decomposition are available.

Tillage practices that maintain or improve soil tilth and reduce soil compaction and crusting should be included in the land application part of agricultural waste management systems. These practices help to maintain soil permeability, infiltration, and aeration, which enhances the biological decomposition processes.

Organic Gardeners Composting

Organic Gardeners Composting

Have you always wanted to grow your own vegetables but didn't know what to do? Here are the best tips on how to become a true and envied organic gardner.

Get My Free Ebook


Post a comment