| The excessive application of chemical fertilizer and low utilization efficiency in potato production not only cause the waste of nutrient resources,but also cause a series of environmental and ecological problems,which is threatening the sustainable development and ecological security of potato.The organic nutrient substitution for chemical nutrient can effectively reduce the input of chemical fertilizer,improve the utilization rate of fertilizer,and exhibit remarkable effect on the prevention and control of agricultural non-point source pollution.Therefore,under the background of the green development demand of potato industry,organic fertilizer replacement of chemical fertilizer partially has become an increasingly concerned research field.The northern foot of Yinshan Mountain in Inner Mongolia is an important potato producing area in China,but the research on organic fertilizer instead of chemical fertilizer under local potato planting mode,climate conditions and soil environment condition has not been carried out systematically.In order to avoid the problems caused by single potato cropping system,the potato-wheat rotation mode has formed in local potato production,the research on the sustainable development of potato obviously can not get rid of the whole rotation system.Moreover,there are great differences between wheat root absorption ability,growth characteristics and potato,and the effect of organic fertilizer substitution on wheat growth and yield in the northern foot of Yinshan not clear.Therefore,it is of great theoretical significance and practical value to systematically study the effects of organic fertilizer substitution on soil physical and chemical properties,microbial community structure,crop growth and yield in farmland.It is not only the basis of chemical fertilizer input reduction and efficiency promotion in potato prodution,as so do in potato-wheat rotation system and healthy soil culture in this area.On the basis of the above scientific problems,the effects of 100%(T0),30%(T1),60%(T2)and 80%(T3)chemical fertilizer on soil physicochemical and biological properties,crop growth,yield and nutrient uptake as well as utilization in potato-wheat rotation system and farmland in later wheat season were studied.The main findings are as follows:1.compared with the application of 100%chemical fertilizer,the replacement of 60%by organic fertilizer can significantly increase the content of alkali-hydrolyzed nitrogen,available phosphorus and available potassium in soil during tuber expansion stage of potato season.The organic fertilizer replacement fertilizer can sTableilize the soil available nutrient supply in the late wheat season,and the soil organic matter content increased significantly with the increase of rotation years.2.compared with 100%chemical fertilizer treatment,the replacement of 60%by organic fertilizer significantly improved the bacterial diversity and richness in soil.the dominant flora in the soil bacterial community in the potato season is classified as amoeba(Proteobacteria),actinomycetes(Actinobacteria),acinetobacter(Acidobacteria),chlorophyta(Chloroflexi)and mycoplasma(Bacteroidetes).Moreover,the germinal phylum(Gemmatimonadetes),patescibacteria,verruca microphylla(Verrucomicrobia),rocardi phylum(Rokubacteria),etc.could also be detected in soil samples in each year.There was no change in the dominant phylum during the second and third year in wheat seasons of rotation,but organic fertilizer instead of chemical fertilizer increased the abundance of green bended phylum(Chloroflexi)and pseudo-bacterium(Bacteroidetes).3.in the potato season at the first year of rotation,there was no significant difference in soil enzyme activity between organic fertilizer replacement treatment and 100%chemical fertilizer treatment.However,in the wheat season at the second and third years of rotation,compared with 100%fertilizer treatment,60%organic fertilizer replacement increased soil alkaline phosphatase,urease activity and promoted the sTableility of soil sucrase,dehydrogenase and catalase activity.4.in potato season,potato weight per plant when organic fertilizer replaced 60%fertilizer was significantly higher than 100%chemical fertilizer treatment,potato yield increased 8%-12%,yield sTableility was the highest.In wheat season,the organic fertilizer replacement 60%fertilizer significantly increased wheat grain number and yield relative to 100%chemical fertilizer.Although the yield increase under 60%organic fertilizer replacement treatmentwith the increase of rotation years,the yield sTableility coefficient of the organic fertilizer replacement 60%fertilizer was always the highest under the treatment.5.in potato season,compared with 100%fertilizer treatment,the substitution of 60%fertilizer by organic fertilizer can increase the dry matter assimilation rate and nutrient accumulation in potato tuber expansion period,and significantly increase the partial productivity of nitrogen fertilizer,phosphorus fertilizer and potassium fertilizer.In wheat season,the substitution of 60%fertilizer with 100%chemical fertilizer can increase the dry matter accumulation and nutrient accumulation in wheat maturity period.It can be concluded that in the northern foothills of Yinshan,the implementation of organic fertilizer replacement can not only gradually increase the content of soil organic matter,but also improve the soil by increasing the availability of nutrients in the critical growth period(tuber expansion stage)of potato,thus increasing and sTableilizing the yield of potato and wheat in the current season.Therefore,the alternative nutrient management techniques of potato-wheat rotation system in the northern foothills of Yinshan were as follows:in potato season,the application amount of organic fertilizer was 8 t/ha,nitrogen,phosphorus(P2O5),potassium(K2O)was 124 kg/ha,110kg/ha and 135kg/ha,respectively;In wheat season,the application amount of organic fertilizer was 5 t/ha,nitrogen,phosphorus(P2O5)and potassium(K2O)was 76 kg/ha,62kg/ha and 75kg/ha,respectively. |
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