我国土壤资源的现状及特点 (20).ppt

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1、3.5 Functions and Regulations of Soil Organic Matter3.5 土壤有机质的作用与调节 The relationship between SOC content and crop yieldLi et al.,(2016)researched the relationship between SOC content and crop yield of wheat and maize during 2008-2012.Correlation between SOC content and yield15141312111098-10123451.F

2、unctions of the SOM (1)Effects on soil fertilityProvide nutrients for plants uCarbon nutrition:The carbon cycle is the basis of the earths ecological balance.The amount of carbon dioxide emission from soil reach to 1.351011 tons every year,which is equivalent to the need for plants photosynthesis;u

3、Nitrogen nutrition:Organic nitrogen accounts for 80%of the soil total nitrogen.This organic nitrogen can be released through the mineralization process of SOM;uPhosphorous Nutrition:Organic phosphorus accounts for 20%-76%of the total soil phosphorus.uOther nutrients:K,Na,Ca,Mg,S,Fe,Si and other nutr

4、ient elements.1.Functions of the SOMOrganic matter produces organic acid and humic substances during the mineralization and humification process.It can increase the solubility of mineral nutrients.Organic acid and humic substances can complex with some metal ions(eg,Zn)and preserve it in soil soluti

5、on and prevent it to form the sedimentation,which can improve their efficiency.At the same time,reducing the fixation and increasing the efficiency of phosphorus.Promote nutrient availability (1)Effects on soil fertility1.Functions of the SOMSodium humic acid can promote plant root growth;SOM also c

6、ontains vitamins and hormones,which can promote plant growth and enhance plant resistance.Promote plant growth and development (1)Effects on soil fertility1.Functions of the SOMHumus is hydrophilic colloid,which is loose and porous,that can absorb a lot of water;Humic colloid has a large surface are

7、a and surface energy,which can absorb a lot of nutrient cations;Humic colloid is an organic weak acid,which can buffer the alkali in soil,humus can be in complexation with metal ions to form humate,which has the function of amphoteric colloid,so it has a strong ability to buffer the acid and alkali.

8、lImproving soil water and fertilizer conservation ability and buffering capacity (1)Effects on soil fertility1.Functions of the SOMIt can improve the structure of soil,make the dispersed soil particles agglomerate into soil aggregate;Improve the structure of sand and clay soil,it can alter the prope

9、rties that sand soil is excessive sand and clay soil is excessive stickiness;It can deepen the soil color because of humus has darker color itself,increased the heat absorption capacity of soil and improved soil temperature.lImprove the physical properties of soil (1)Effects on soil fertility1.Funct

10、ions of the SOMSOM-Soil muscleThe soil is groaning？(2)The function of OM in ecological environment1.Functions of the SOMComparison of carbon storage capacity of different systems (Pg,1Pg=1015 g)Comparison of carbon sequestration capacity under different ecosystems(Pg,1Pg=1015 g)Perennial 560SOM 1500

11、Atmosphere(1980 y)760Ocean 38500 Lithosphere 6560000Changsheng Li,Biogeochemistry:Scientific fundamentals and modeling approach.2015 (2)The function of organic matter in ecological environment1.Functions of the SOMThe effects of SOM on heavy metal pollution Complexation:Organic matter can reduce hea

12、vy metal pollution by binding them in stable organomineral complexes.For example,the binding capacity of humic acid to metal ions is 200-600 mol g-1.Humic acid can affect the existing form of heavy metal ions through complexation and reduction activity.For example,humic acid can reduces the toxic Cr

13、 6+to Cr 3+,and forms stable chelates which can reduce plant and animal absorption and utilization.(2)The function of organic matter in ecological environment1.Functions of the SOMEffects of OM immobilization on pesticides pollutionHumus can dissolve and absorb organic pollutants.Effects of SOM on t

14、he global carbon pool balanceSOM is an important carbon pool for global carbon balance.The global SOM pool is about 2.5 to 3 times as compared to the terrestrial ecosystem.(2)The function of organic matter in ecological environment1.Functions of the SOM (1)Approaches to increasing SOM contentReasona

15、ble rotation system2.Regulations of SOMApplied organic fertilizerSOM content was increased and maintained at a higher level through rotation or conversation tillage.We can apply manure,compost and organic combined with inorganic fertilizer to enhance SOM content.Planting green manureStraw and biocha

16、r amendment We should pay more attention to the C:N ratio,degree of grinding,the depth of straw returned,soil moisture and the amount of fertilizer application and other factors during the straw and biochar amendment.Sesbania,milk vetch and alfalfa and so on;Planting green manure in the fallow seaso

17、n or intercropping;Adaptation to the local conditions,rational utilization.(1)Approaches to increasing SOM content2.Regulations of SOM (2)Regulation the decomposition rate of SOM We can regulate the C:N ratio of soil through applied mineral nitrogen fertilizerWe can also regulate the environmental f

18、actors(eg,soil moisture,air condition,and soil heat)to influence the mineralization and humification coefficient of SOM through tillage and management approaches.C:N=25:1,decomposition rate is appropriateC:N25:1,decomposition rate will be decreasedC:N25:1,decomposition rate will be increased2.Regulations of SOMThank you