| Weibei dryland belongs to typical arid areas.Spring maize,as one of the main food crops in Weibei upland,is more widely cultivated than wheat,since the factor of price and yield.Firstly,main reasons for low and unstable grain yields in this area are low precipitation and great fluctuation of annual rainfall.Besides,single and unscientific regional farming methods make the regional farmland soil harden and increase soil compactness,thus causing unfavorable growth and germination soil environment,and hindering the crops to increase production.In order to improve the soil quality and soil environment,make crop grow ecologically and healthily,and reach the goal of increasing regional agricultural production and income,this study was carried out in Heyang County,which is the typical area of Weibei upland,from 2007 to 2014 with spring maize planted under single cropping system.Three different types of fertility,including flat,conventional fertilization and low fertilization,were applied as main treatments for balanced fertilization.Three farming methods(no tillage,subsoiling and tillage treatment),were applied in alternative combination.So that six kinds of sub-treatments were formed: subsoiling-no tillage(N-S)T,subsoiling-tillage(S-C)T,tillage-no tillage(C-N)T,no tillage-no tillage(N-N)T,subsoiling-subsoiling(S-S)T and tillage-tillage(C-C)T.Among them,tillage-tillage(C-C)T was regarded as the traditional method and control group.Through a seven-year continuous field positioning test,the effects of different fertility levels and tillage measures on soil bulk density,porosity,aggregate stability,water change,chemical shape,agronomic shape,physiological characteristics,yield components,harvest index,water use efficiency and economic benefit were studied.This study provides a scientific basis and technical support for the development of regional agriculture by providing scientific fertilization ratio and reasonable tillage measures to improve the soil quality and production performance in Weibei highland.1.Effects of different tillage methods on soil physical properties of spring maize continuous cropland.Compared with pre-experimental status and traditional measures,reasonable and scientific alternate farming measures are conducive to reduce soil bulk density,increase soil porosity,and improve soil permeability.In the 0-60 cm soil layer,the effect of “no-tillage and subsoiling” treatment on the improvement of bulk density and porosity was the best.With pre-trial and conventional tillage as comparison,the soil bulk density decreased by 3.8% and 8.6%,and the soil porosity increased by 3.3% and 7.8%."No tillage-subsoiling" treatment can better improve soil stability in 0 ~ 40 cm soil layer.The soil mechanical aggregate and the ratio of water-stable aggregate content can be increased by 11.4% and 5.2% in the layers beyond 0.25 mm.Compared with the conventional tillage,the soil structure breaking rate and other factors were significantly decreased in rotation tillage.The effects of “no tillage-subsoiling” and “subsoiling-subsoiling” treatments on reducing the fractal dimensions of aggregates were significant.2.Effects of different tillage methods on soil moisture of spring maize continuous cropland.The reasonable rotation combination of different tillage measures helps to improve water storage capacity of soil.In six tillage periods,the soil water content in early and late winter was the best under “no tillage-subtillage” and “no tillage – no tillage”.The soil water content in 0 ~ 200 cm soil layer was 7.0% and 5.5% higher than that in the conventional tillage(P <0.05)during the whole slack winter season.Soil water storage in 0 ~ 200 cm layer was the best under “no tillage-subtillage” treatments during late winter fallow.Which was followed by “no tillage-subtillage” treatment,and the third was "subsoiling-subsoiling".Compared with traditional tillage,the soil water storage under three treatments was increased by 6.0% ~ 8.7%(P <0.05).In seven years of trail planting,Soil moisture and water storage of spring maize during bell stage and tasselling period showed the optimum value under the treatment of "no tillage-subsoiling",which was followed by "no-tillage-no-tillage" treatment,and the third was "subsoiling-subsoiling" treatment.Consistent with the trend of fallow period,average soil water storage under three treatments was 5.9% ~ 7.7%(P <0.05)higher than that of traditional farming.3.Effects of different fertility levels and tillage patterns on soil nutrients in spring maize field.After the harvest of spring maize in seven planting trial years,soil nutrient content in 0 ~ 60 cm soil layer always showed the highest level in all types of treatments when balanced fertilization was applied.Conventional fertilization ranked secondarily,and low fertilization showed the worst level.In three fertilization modes,the effective increasing range of organic carbon storage under each treatment were 1.4 ~ 2.8 t /,0.02 ~ 1.67 t / and 0.4 ~ 1.5 t /,respectively.For the whole effect of nutrients,the contents of total nitrogen,total potassium and total phosphorus under all treatment models of balanced fertilization increased by the range of 7.1% ~ 15.6%,2.1% ~ 23.9% and 5.9% ~ 20.8%,respectively.Among them,"no tillage-subsoiling" and "tillage-no tillage" were beneficial to increase the content of total nitrogen and total phosphorus."Subsoiling-tillage" and "no tillage-subsoiling" could promote the improvement of total K content in soil.For available nutrients,the contents of available N,available P and available K in the 0 ~ 60 cm soil layer under balanced fertilization showed the highest level in “ no tillage – subsoiling” treatments,which were 43.8,9.43 and 105.4 g / kg,respectively.And compared with traditional tillage,the other treatments had a positive effect on improving the available nutrient content of soils.4.Effects of different fertility levels and tillage on agronomic characters and physiological characteristics of spring maize field.In three fertilization levels,the agronomic traits and physiological characteristics of spring maize had the same trend,showing the best in balanced fertilization treatment.This was followed by conventional fertilization.Low-fat treatment had the worst performance.Compared with conventional tillage,balanced fertilization through seven planting trial years under six different tillage measures made the average plant height and dry matter accumulation of spring maize,during the main growth period,increase by 1.7% ~ 7.3% and 11.6% ~ 24.4%,respectively(P <0.05).When applying balanced fertilization,among those six tillage measures,the average plant height and dry matter accumulation were at the optimum value under “subsoiling-no tillage” treatment,which were 1.4%~8.1%、5.7%~25.0% and 6.2%~20.6%(P<0.05)higher than traditional measure.With the advancement of reproductive period,chlorophyll content in spring maize leaves increased during its main growth period.In comparison with the traditional tillage,the average chlorophyll content in other treatments increased by 2.1%~6.4%,and increased mostly by “no tillage-subsoiling” measurement.“No tillage-subsoiling” and “subsoiling-tillage” were conducive to the improvement of the average transpiration rate,photosynthetic rate,and stomatal conductance,which were 6.7%、8.9%,9.9%、15.3% and 0.5%、2.6% higher than that of traditional tillage.5.Effects of different fertility levels and tillage on crop production factors,aggregative indicator and economic benefit of spring maize field.In three types of fertilizer levels,crop production factors,aggregative indicator and economic benefit showed the same tendency,performing the best under balanced fertilization.Conventional fertilization came second,and low fat processing performed the worst.In comparison to conventional fertilization and low fat processing,the average spike number per unit area,average kernels number,and average 100-seed weight under balanced fertilization were increased by 4.3%,8.9%,9.0%,16.1%,5.2%,9.4% and19.8%,38.4%(P<0.05).The effects of integrated soil fertility level and different cultivating treatment on spring maize yields were studied by seven-year planting experiment.When balanced fertilization was applied,“no tillage-subsoiling” treatment could effectively improve the yield components of spring maize,having the best yield-increasing effect,which was followed by “subsoilingtillage” and “subsoiling-subsoiling” treatments.When using “no tillage-subsoiling” under balanced fertilization,output,harvest index,WUE and economic benefit were 9404.4 kg/hm2、45.1%、22.6 kg/ hm2 ?mm,and 8122.8 元/ hm2,which were at the maximum value,followed by “subsoiling-subsoiling” and “subsoiling-tillage”.This study showed that,compared with long-term single conventional tillage,reasonable cultivation measures in scientific rotation could effectively reduce the capacity of the soil,improve soil physical properties,improve soil nutrient,and meliorate soil environment.In the study of different soil fertility degree and different combination of cultivation measures,“no tillage-subsoiling” treatment under balanced fertilization was most effective to improve soil quality,productivity and water retention ability.Besides,agronomic characters and physiological traits of spring maize were improved obviously.This has provided a good foundation for increasing both production and income.“No tillage-subsoiling” treatment under balanced fertilization could be the optimal combination of tillage for Weibei dryland to increase the production and income.Apart from this,“subsoiling-tillage” and “subsoilingsubsoiling” under balanced fertilization could be the second choices. |
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