| Weibei Highland is located in the southern part of Loess Plateau,which belongs to the semi-humid and drought-prone area.It is the main cultivation area for grain crops in Shaanxi Province,such as winter wheat and spring maize.It is called “the second granary in Shaanxi Province” and plays a key role in ensuring food security in China.The region with a low precipitation,deep groundwater level,and no irrigation conditions for field crops.It is a typical dryland farming area.Secondly,the cultivated soil in this area is loose,with less clay and low organic matter content(less than 1% in most areas),and even lower in some areas.At the same time,the drought and flood season in Weibei Highland is the main grain producing area.Longterm crop continuous cropping and high-intensity cultivation management lead to serious soil nutrient consumption,which has deteriorated soil physicochemical-and biologicalcharacteristics with the increase of continuous cropping years.Therefore,lack of water resources,and infertile soil,and low water-and fertilizer-use efficiency and outdated cultivation measures have become the key factors restricting the production and sustainable development of food crops in Weibei dryland.A study has been conducted to investigate the effects of different conservation tillage and optimized fertilization modes on winter wheat productivity and soil quality during September,2015 to June,2018 in Fuping Modern Agriculture Comprehensive Experimental Station in Weibei,Shaanxi Province,which aims to provide new ideas and solutions for innovative models of soil fertility restoration in dryland.The test included ten treatments: no fertilizer(CK),conventional cultivation(CC),straw mulching(SM),plastic film mulching(PM),bare furrow and ridge(BRF);plastic film-mulched ridge and straw-mulched furrow(MRF);green manuring(GM);potassium fertilizer input(KF);low manure input(M1);high manure input(M2).Soil water utilization and productivity of winter wheat under different treatments were measured,and the effects of different treatments on soil fertility factors were analyzed after 4 years.At the same time,the comprehensive effects of different treatment on soil fertility level were comprehensively evaluated by grey correlation analysis.The following results were obtained through a 4-year field trial:(1)Compared with CC,the soil water storage were greatly increased in 0-70 cm layer under MRF,and increased in 0-40 cm layer under PM,followed by SM(0-40 cm layer),and all of them improved soil conductivity in the same soil layers;however,soil water storage and conductivity were reduced in 130-150 cm soil layer.The temperature under MRF and PM substantially increased the surface temperature during the wheat growth period,i.e.,increased by 0.2-1.4 °C under MRF and 0.1-1.1 °C under PM),while straw mulching reduced the surface temperature(0.2-1.1 °C).Compared with CC,the yield and water use efficiency of winter wheat under MRF,PM and SM,respectively,i.e.,the yield under MRF was increased by 37.7%-59.8%,33.1%-44.3% and 17.2%-24.0%,and the water use efficiency was increased by 35.3%-45.8%,29.3%-35.9% and 18.0%-17.2%,respectively.Additionally,the yield and water use efficiency of winter wheat under M1 and M2 were increased with cultivation years.There was no obvious difference of soil water utilization or yield of winter wheat between the remaining treatment and CC.(2)The contents of soil organic carbon and available nutrient were significantly increased in 0-40 cm soil layer under MRF and SM,compared with CC,i.e.,by 6.3% and 5.2% with organic carbon,and by 40.2% and 23.4% with available nitrogen,and by 53.5% and 24.5% with available phosphorus,and by 23.1% and 18.9% with available potassium,respectively.Moreover,the MRF substantially increased the contents of total nitrogen,phosphorus and potassium in 0-20 cm layer,and increased the contents of available nitrogen,phosphorus and potassium in 40-60 cm soil layer.However,there was no obvious difference of organic carbon,total and available nitrogen,phosphorus and potassium in soil between the remaining treatment and CC.The nutrient uptake of winter wheat under MRF,PM and SM was increased compared with CC,and the order was arranged by MRF>PM>SM,while the difference of nutrient uptake between other treatments and CC was not significant(p>0.05).(3)The contents of active organic carbon(e.g.,light fraction organic carbon,readily oxidized carbon,particulate organic carbon and dissolved organic carbon)in 0-40 cm soil layer under MRF,SM and organic manure input(M1 and M2)were significantly higher than those under CC.The increases in active organic carbon under MRF were significantly higher than those under straw cover and organic manure input,and MRF obviously increasd the contents of active organic carbon in 40-60 cm soil detph.Additionally,the mineralizable carbon under MRF and SM was significantly higher(p<0.05)than that of CC,followed by organic manure input.Overall,the order of the storage of mineralizable carbon was arraged by MRF>SM>M1> M2>GM,whil PM significantly(p<0.05)reduced soil mineralizable carbon during this study.The changes of soil mineralizable carbon under rest treatments were consistent with CC.Additionally,the soil organic carbon structure under different conservation tillage and optimized fertilization was not affected,and the functional group in organic carbon was mainly composed of C-H,C-O and O-H.(4)Compared with CC,MRF,SM and M2 effectively improved the soil aggregate stability(particle size > 0.25 mm),mean weight diameter,and carbon distribution in water-stable aggregates,and the MRF held the maximum;however,the soil aggregate stability(particle size>0.25 mm)and the carbon distribution in water-stable aggregates were decreased under PM,compared with CC.Meanwhile,the microbial quantity,respiration intensity and enzyme activity in 0-40 cm soil layer were significantly increased under MRF,SM and M2,of which MRF significantly improved soil organisms in 40-60 cm soil depth.The stability of water-stable aggregates and their carbon distribution under M1 was lower than those under M2,and M1 merely increased the activity of urease and phosphatase activity in 0-40 cm soil depth.The soil aggregate stability,microbial biomass and their activity were not significantly different from those of CC.In general,the order of soil aggregate stability(particle size>0.25 mm)and microbial activity were shown as follow: MRF>SM>M2>M1>GM>PM,and their changes of the rest treatment was consistent with CC.(5)The comprehensive ranking of soil fertility level by grey correlation analysis method was MRF>SM>M2>M1>GM>PM>KF>BRF>CC>CK,i.e.,the optimal treatment during this study was MRF.Meanwhile,the soil fertility levels were ranked by cluster analysis.The system clustering map divided the experimental treatment into four levels: the first level was MRF and SM,and the second level was organic manure input and GM,and the third grade was PM,KF,BRF and CC,and the fourth level was CK..In a 4-year field experiment,we drawn the following conclusions: the cultivation of plastic film-mulched ridge and straw-mulched furrow can significantly improve soil moisture,temperature and conductivity,and increase winter wheat yield and water use efficiency in Weibei Dryland.Meanwhile,it also can effectively improve soil physical and chemical properties and biological characteristics,and ameliorate the deeper soil ecological environment.Therefore,the cultivation of plastic film-mulched ridge and straw-mulched furrow has significant effects on improving soil fertility and winter wheat productivity in Weibei dryland,whchi can be popularized and applied in local agricultural production. |
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