Impacts Of Different Tillage Measures On Soil Microorganism And Enzymatic Activity Of Dry Farmland Of The Loess Plateau

To verify the influence of different tillage measures on the edaphon content andsoil enzyme activity, and check how to effectively and accurately apply PLFA methodto measure the edaphon content, and rely on the long-term location test of theprotective tillage of farmland bean and wheat dual-sequence crop rotation bred byLongzhong Loess Plateau, this paper sets six tillage measures: conventional tillage (T),no-till with straw cover (NT), conventional tillage with straw incorporated (TS),no-till with straw cover (NTS),conventional tillage with plastic mulch (TP), andno-till with plastic mulch (NTP). After the crop harvest in August of2014, itmeasured the activity of the polyphenol oxidase, catalase, sucrose, alkalinephosphatase, and urease of the each processed surface soil.The main research conclusions are as follows:1. The improved extraction method based on the conventional methodshows the better extraction effect.The edaphon extracted through different extraction methods has13phospholipids fatty acid signatures. Its peak height, corr.area, relative percentagecontent relative to the internal peak, and corr.(%) max became obviously higherthrough the improved extraction method. Those with the improved method wereobviously71.86%and444.02%higher than the conventional method and traditionalmethod respectively. The peak height extracted through the improved method was61.75%and764.04%higher than the conventional method and traditional methodrespectively. Besides, the maximum corr.(area) through the improved method was191.14%and1111.84%higher than the conventional method and traditional methodrespectively. Moreover, the corr.(%) max through the improved method was149.18%and920.63%higher respectively.2. Under crop rotation, the bacteria in the surface soil with different tillagemeasures shows the highest relative percentage content, followed by the fungus,while the actinomycetes shows the lowest relative percentage content.The variation amplitude of the relative percentage content of the bacterial,fungus and actinomycetes in the surface soil of the wheat and pea rotate is76.49%-85.84%and79.46%-86.90%,9.44%-15.95%and9.23%-14.80%,.73%-8.22%and2.82%-6.90%respectively. 3. Under different crop rotation sequence, the tillage measures havedifferent effect on the relative percentage content of the soil bacteria, fungus andactinomycetes.In the wheat land, compared with other tillage measures, the soil bacteria underthe no-tillage measure, the fungus under TS and the actinomycetes under NTS showthe highest relative percentage content respectively. In the pea rotati land, comparedwith other tillage measures, the bacteria under NTP, the fungus under the no-tillagemeasure and the actinomycetes under conventional tillage show the highest relativepercentage content respectively.4. PLFAs constitution of the soil bacterial has different response to tillagemeasure and crop rotation sequence.In the wheat land, three floras under T and TS can be ranked according to therelative percentage content as follows: Gram-no bacterium> Gram-positivebacterium> Gram-negative bacterium; three floras under other tillage measures canbe ranked according to the relative percentage content as follows: Gram-positivebacterium> Gram-no bacterium> Gram-negative bacterium. However in the pearotati land, three floras under T, no tillage, and TS can be ranked according to therelative percentage content as follows: Gram-no bacterium> Gram-positivebacterium> Gram-negative bacterium; they are ranked under other tillage measures asfollows: Gram-positive bacterium> Gram-no bacterium> Gram-negative bacterium.5. The protective tillage can promote the activity of the polyphenol oxidase,sucrose, and urease of the surface soil of the wheat, as well as the activity of thecatalase and alkaline phosphatase of the surface soil of the pea rotati.In the wheat land, under different tillage measures, the polyphenol oxidaseactivity of the soil is ranked as follows based on the sized: NTP>NTS>NT>TP>TS>T;that under NTP is remarkably higher than the one under other tillage measures(p<0.05); that under NTS is obviously higher than the one under the conventionaltillage. The soil urease activity shows obvious different. Based on its size, it can beranked: NTS>NTP>TP>NT>TS>T. Its activity under NTS and NTP is obviouslyhigher than that under other measures. The soil sucrose activity can be ranked:NTP>NTS>NT>TS>TP>T. Its activity under NTS and NTP is obviously higher thanthat under the T, TS and TP; its activity under no tillage is obviously higher than thatunder the T and TP; its activity under TS is obviously higher than that under theconventional tillage. In the pea rotari land, the catalase activity of the soil shows obvious activity.Based on its size, it is ranked: NTP≈NT>TS≈NTS≈TP>T. The catalase activity ofthe soil under TP and T is the highest, and obviously higher that that under othermeasures. Moreover, the alkaline phosphatase activity presents remarkable different.It is ranked as follows based on the size: NTS>NTP>NT>TP≈TS>T. The activityunder NTS, NTP and no tillage is remarkably higher than that under TP, TS and T.