1 Scope
This standard specifies the quality requirements, test methods, inspection rules, packaging, marking, storage and transportation of plug seedling substrate of vegetables.
This standard is applicable to the quality judgment of commercial plug seedling substrate of vegetables mainly composed of decomposed organic materials and natural minerals.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 601 Chemical reagent - Preparations of standard volumetric solutions
GB/T 1250 Rules for expression and judgment of limiting values
GB/T 6679 General rules for sampling solid chemical products
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB 7859 Determination of PH value in forest soil
GB 7865 Determination of exchangeable calcium and magnesium in forest soil
GB 8172 Control standards for urban wastes for agricultural use
LY/T 1229 Determination of hydrolyzable nitrogen in forest soil
LY/T 1233 Determination of available phosphorus in forest soil
LY/T 1236 Determination of available potassium in forest soil
LY/T 1237 Determination of organic matter in forest soil and calculation carbon-nitrogen ratio
LY/T 1243 Determination of cation exchange capacity in forest soil
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
substrate
mixed lightweight material that can replace the soil, provide suitable nutrients and pH for crops cultivation, and have good water retention, fertilizer retention, ventilation performance and root fixation, including such constituents as turf, vermiculite, perlite, wood chips, crop straws, livestock excrement, barks and mushroom dregs
3.2
bulk density
dry weight of substrate of unit volume, g/cm3
3.3
ventilatory porosity
space occupied by air in substrate, which is expressed as the volume percentage (%) of the substrate
3.4
water retention porosity
space occupied by moisture in substrate, which reflects the water retention capacity of the substrate to some extent, and is expressed as the volume percentage (%) of the substrate
3.5
general porosity
sum of all pores (water retention pores and ventilatory pores) in substrate, which is expressed as the volume percentage (%) of the substrate
3.6
water air ratio
ratio of ventilatory porosity to water retention porosity in substrate
3.7
cation exchange capacity
adsorption capacity of cations in solution by a negatively charged substrate colloid by virtue of electrostatic attraction, which is expressed as the potential CEC (counted based on NH4+), cmol/kg
3.8
granule size
diameter of substrate grains, mm
3.9
electric conductivity
content of soluble salts in substrate, mS/cm
3.10
buffer capacity
capability of substrate of mitigating the sharp changes in pH, which may maintain the relative stability of the substrate pH
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Quality requirements
5 Test methods
6 Inspection rules
7 Packaging, marking, storage and transportation
Annex A (Normative) Determination method for bulk density of substrate
Annex B (Normative) Determination method for porosity of substrate
Annex C (Normative) Determination method for relative moisture content of substrate
Annex D (Normative) Determination method for electric conductivity of substrate
Annex E (Normative) Operation specifications for emergence rate test
