Introduction
Soil supports the process of main lives on the earth, maintains the balance of the ecosystem, provides necessary food for human beings, and plays an irreplaceable role in the food security and ecological environment construction in the current time. How to coordinate and give play to such functions of soils as production, environmental protection, ecological engineering construction and global change mitigation has become an important task for modern pedology to contribute to the sustainable development of human society.
The soil health is an inherent attribute of soils, which cannot be obtained directly by human observation. There are no unified international standards for the soil health assessment methods. There are rich and diverse biological groups in soil, which play an important role in the formation and improvement of soil structure, the accumulation and turnover of organic matters, the fixation and transformation of nutrients, the fixation and degradation of pollutants, and the spread and control of soil-borne diseases. The soil food web is a complex network of relationships of feeding and being fed among different biological groups in the soil ecosystem, and it is the main path reflecting the material circulation and energy flow in the ecosystem, and also an important biological index to measure soil health. For the purpose of this document, by selecting main biological functional groups occupying different trophic levels in the soil food web, such as plant roots, bacteria, nematodes and earthworms, the soil health is characterized from different aspects with the green bean root morphology test method, luminescent bacteria bioassay, nematode community bioassay or earthworm bioassay. This document can provide a simple and practicable guide for the soil health assessment on different types of soils such as grain fields, vegetable fields, orchards and grasslands.
Biological test methods for comprehensive characterization of soil health
1 Scope
This document gives the principles for biological test methods (green bean root morphology test method, luminous bacteria bioassay, nematode community bioassay and earthworm bioassay) for the comprehensive characterization of soil health, the sampling and tests as well as the requirements for the test reports.
This document is applicable to biological tests of soil health in cultivated land, garden plots and grasslands.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 15441-1995 Water quality－Determination of the acute toxicity - Luminescent bacteria test
GB/T 36197-2018 Soil quality - Guidance on sampling techniques
HJ/T 166-2004 Technical specification for soil environmental monitoring
NY/T 52-1987 Method for the determination of soil water content
3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
soil health
ability of soil as a life system to sustain the productivity of soil system, biodiversity and environmental services
Note: Healthy soils are free of potential risks of soil-borne diseases and heavy metal exceeding the standard, and have diverse edaphone soil communities, which are conducive to increasing soil productivity and ultimately keeping soil from degradation.
3.2
soil health assessment
overall qualitative and quantitative assessment performed for soil health by means of biological factors such as green beans, luminescent bacteria, nematodes, and earthworms
3.3
bioassay
method that the system uses biological reactions to test the effects or hazards caused by one or more pollutants or environmental factors alone or in combination
3.4
community
collection of species groups gathered in the same area at the same time
Note: For the purpose of this document, the community mainly refers to the nematode community and earthworm community.
3.5
luminescent bacteria
luciferase gene-contained bacteria that is able to emit visible light under normal physiological conditions
4 General
This document includes four biological testing methods, among which, the green bean root morphology test is mainly aimed at testing the health of soil related to soil-borne diseases, the luminescent bacteria bioassay is mainly aimed at testing the health of contaminated soil, the nematode community bioassay is mainly aimed at testing the health of degraded grassland soil, and the earthworm bioassay is mainly aimed at testing the comprehensive health of soils in orchards and vegetable fields and upland soil. In practice, if it is required to use multiple bioassays mentioned in this document, the luminescent bacteria biological test method shall be used firstly to evaluate the pollution degree of the soil to be tested, and the health level of the soil shall be determined based on the test result obtained by this method. If the soil tested with this method is healthy, the health level of the soil shall be the lowest level obtained by the other methods.
5 Biological tests
6 Test reports
Foreword i
Introduction i
1 Scope
2 Normative references
3 Terms and definitions
4 General
5 Biological tests
6 Test reports
Annex A (Informative) Test devices and selection of sampling points and samples
Bibliography
