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The rice paddies natural no-tillage system of soil microbes and organic matter turnover

Author: ZhangLei
Tutor: XieDeTi;WeiChaoFu
School: Southwest Agricultural University
Course: Soil
Keywords: no-tillage organic matter decomposition turnover microbe
CLC: S154.3
Type: PhD thesis
Year: 2002
Downloads: 623
Quote: 5
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Abstract


Being a protective tillage, the no-tillage means getting rid of not only the tillage before sowing, but also the intertill after sowing, and leaving the plant residue after harvesting. Under its principle, limited tillage is carried out only on the sowing lines which occupy 25% of the field. So it’s also called zero-tillage, chemical-tillage, and no-plowtillage etc.There are different types of no-tillage according to different types of leaving the plant residue. The type is temporarily called root-no-tillage with only the root left in soil and direct drilling; sowing directly and placing the past plant stalk orderly over the soil is called mulch-no-tillage. They are both of the content when refers to no-tillage generally and are adapted to keep moist in or keep from soil erosion in drying land.Academician Hou Guangjiong, who summarized the experiences from peasants in Sichuan province, promoted the no-tillage and ridge culture in 1982 that has two sides of meaning of its name: one is simulating the physical and ecological characteristics of originally moist soil; the other means rhat the basic characteristic of perfect soil fertility is no-tillage.The key of no-tillage is the supply the past crop residue to soil. Not only couldn’t the quantity of soil organic matter and organic N be lifted up, but also did it lead, to soil erosion and output declining under nc-ti!!age system without crop residue adding. By the crop residue input, priming effects of soil irJcrobe will take place, and decomposition and bio-fixation give rise to soil organic matter arid M in the up layer of soil. On the other hand, tillage accelerate; the organic matter mineralization and leads to the quantity of organic matter decreasing in..Or 10cm.layer which is about 1/2 of soil organic matter under no-tillage. So the pool of soil organic matter in soil become bigger anci bigger under no tillage while smaller and smaller under tillage.The no-tillage and culture focus more on creating better conditions for microbe decomposing the crop residue compared with no-tillage. There are four principle in it: 1) successive capillary water circulation; 2) successive no-tillage; 3) successive multiple crop rotation; and 4) successive "ridge and furrow culture". By these devices taken, the soil accumulate more organic matter in shorter period compared with general no-tillage.As we all know: the chief part in decomposing the plant residue is soil microbe. It’s microbe’s metabolism that promotes the turnover of substance and organic matter in soil. The study about the turnover of organic matter in soil is the same as the study about the relationship between the microbes and organic decomposition in some extent. But there is few report on exactly the relationship till now. The no-tillage and ridge culture is just the good example to study it. And the models of the turnover and circulation of organic matter in no-tillage and ridge culture are be used as a base and a start to the relationships.This study takes the relationships between the turnover of organic matter and microbe as its goat by researching the course of plant residue decomposition and mineralization. First, the dynamics of soil properties in different period during a year from the long-term no-tillage and ridge culture experiment field are researched in order to get the general dynamic properties of organic matter,chemical substances, microbe, pH and Eh in soil. The plant residue decomposing simulated experiment in containers is managed according to those general properties afterward with aims to test and verify them. Besides this, the possibility to accelerate the plant residue decomposing by inoculate promoting strains, such as cellulose decomposing microbe and nitrogen-fixating bacterium, is also be consulted. Then, in order to pursue effect of soil humidity to the relationship between the turnover of organic matter and the micro flora, the no-tillage and ridge culture simulated experiment is carried out to find out the exactly reasons for the high level of organic matte

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CLC: > Agricultural Sciences > Agriculture as the foundation of science > Soil > Soil Biology > Soil microbiology
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