| Water shortage is the main limited factor for the vegetation restoration and agriculture development in Loess Highland which belongs to rainfed dryland agricultural area.One crop annual harvest cropping system“winter wheat-spring maize”rotation and conventional tillage?moldboard plowing?with harrowing are prevailing in this area.However,conventional tillage in crop rotation at fallow period intensify the evaporation of soil water,lead to serious soil erosion and low and unstable crop yield in this region.Conservation tillage including straw mulching with no tillage and subsoiling in fallow period,reduced soil distribution in arable layer,increased covering on soil surface and soil organic carbon content and promoted more precipitation store and less soil water consumption.These benefits lead to high crop yield,alleviate the soil water loss and ameliorate the quality of farmland.Conservation tillage has been an important measure to improve crop yield,conserve soil water and enhance soil properties in Loess Highland.However,long–term mono conservation tillage also brought some defects in field,such as compacted soil layer,unmanageable pests and weeds and unstable crop yield etc.And limited by the field conditions and long-term experiment cycle,the long-term observation on crop yield,soil water change and soil enhancement of conservation tillage were less in Loess Highland.Rotation tillage combined conventional tillage,no tillage and subsoiling in a rational sequence,can mitigate or avoid some defects in mono long-term tillage.And WinEPIC model can quantitatively simulate crop yield,soil water use characteristics and evolution law of soil nutrients for a long-period.Beginning in 2007,a long-term two-factor split-plot experiment?2007-2017?was established in Heyang County,Shaanxi Province,China.Three fertilization practices?balanced fertilization?BF?,low fertilization?LF?and conventional fertilization?CF??and nine tillage systems?no tillage?NT?,subsoiling?ST?,conventional tillage?CT?,no tillage with subsoiling rotation?NS?,subsoiling with conventional tillage rotation?SC?,conventional tillage with no tillage rotation?CN?,no tillage applied two years with subsoiling rotated in the third year?NNS?,rotated no tillage,conventional tillage and subsoiling each year?NCS?and conventional tillage applied two years with subsoiling rotated in the third year?CCS??were conducted to assess soil water preservation,crop production and soil enhancement under different rotation tillage patterns with fertilizations.This article combined the long-term field experiment?2007-2017?and WinEPIC model?1980-2016?to research the crop yield,soil moisture effects and soil property enhancement of winter wheat-spring maize field under different fertilization and tillage rotation treatments for a long-period.The main conclusions are as follows:1.The effect of crop yield increase,soil water preservation and soil property enhancement under different fertilizations in winter wheat-spring maize rotationDuring the experiment of 2007-2017,LF had better soil water conservation effect in fallow period,the average soil water storage was 420.4 mm.LF provided better soil water condition during wheat and maize growth season in winter wheat-spring maize rotation.But BF and CF improved the crop yield and WUE by increasing the water consumption during crop growth.With reduced N and P fertilizers and proper K fertilizer,BF produced high and stable yield,and had better economic profits.The average yield of wheat and maize,economic profit under balanced fertilization were 5077 kg ha-1,7057 kg ha-1 and 5611 yuan ha-1,respectively.With straw application,balanced fertilization enhanced the soil properties effectively.BF had higher content of soil aggregates,soil organic carbon and total N,and rational distribution of soil total and available nutrients?Total and available N,P,K?in soil arable layer.The optimal fertilization rate in Loess Plateau were N:150 kg hm-2,P2O5:120 kg hm-2,K2O:90 kg hm-2.2.The effect of crop yield increase,soil water preservation and soil property enhancement under different continuous conservation tillage system in winter wheat-spring maize rotationIn this experiment,NT had better soil water conservation effect in fallow period,the average soil water storage was 397.7 mm.NT provided better soil water condition during wheat and maize growth season in winter wheat-spring maize rotation.But ST and CT improved the crop yield and WUE by increasing the water consumption during crop growth season.As the high economic inputs in ST and CT and the unstable crop yield in conventional tillage,NT had a better economic profit,the average value was 5543 yuan ha-1.ST had higher content of soil aggregates,soil organic carbon and total N in this experiment.Soil nutrients in NT accumulated in soil surface and that were less in CT,but ST had a rational distribution of soil total and available nutrients?Total and available N,P,K?in soil arable layer.The optimal continuous conversation tillage system in Loess Plateau was ST.3.The effect of crop yield increase,soil water preservation and soil property enhancement under different two-year conservation tillage rotations in winter wheat-spring maize rotationIn fallow period,CN rotation had better soil water conservation effect in fallow period,the average soil water storage was 385.8 mm.CN and NS rotations provided better soil water condition during wheat and maize growth season in winter wheat-spring maize rotation.CN rotation improved the crop yield and WUE by increasing the water consumption during crop growth season.As the low economic inputs and stable crop yield in CN,it had a better economic profit of 6254 yuan ha-1.In this experiment,NS and SC rotations decreased the soil bulk density in soil surface?0-20 cm?efficiently.But CN rotation has a low soil bulk density in deep soil layer?20-60 cm?,and increased the soil porosity.In 0-10 cm soil layer,NS rotation had higher content of soil aggregates,but SC and CN rotations had higher content of soil aggregates in 10-40 cm.SC rotation also had higher content of soil organic carbon and total N,and SC and CN rotations had rational distribution of soil total and available nutrients?Total and available N,P,K?in soil arable layer.The optimal two-year conservation tillage rotation in Loess Plateau was CN.4.The effect of crop yield increase,soil water preservation and soil property enhancement under different three-year conservation tillage rotations in winter wheat-spring maize rotationIn three-year conservation tillage rotations,NNS rotation had better soil water conservation effect in fallow period,the average soil water storage was 402.9 mm.NNS and NCS rotations provided better soil water condition during wheat and maize growth season in winter wheat-spring maize rotation.But CCS rotation improved the crop yield by increasing the water consumption during crop growth season.NCS and CCS rotation produced higher average wheat yield were 5169 kg ha-1 and 5168 kg ha-1,respectively.NNS had a higher WUE of wheat,the average value was 15.9 kg ha-1 mm-1.CCS rotation produced higher average maize yield were 7768 kg ha-1,NCS had a higher WUE of spring maize,the average value was 21.5 kg ha-1 mm-1.As the low economic input and stable crop yield in NCS rotation,it had a better economic profit of 6245 yuan ha-1.In this experiment,NCS rotation decreased the soil bulk density,increased soil porosity and aggregates efficiently.Tillage rotations enhanced the soil fertility in a certain extent,NCS and CCS rotations had higher soil organic carbon and total N,and NCS provided rational distribution of soil total and available nutrients?Total and available N,P,K?in soil arable layer.NCS rotation was the optimal three-year conservation tillage rotation in Loess Plateau.5.The effect of crop yield increase,soil water preservation and soil property enhancementunder different conservation tillage treatments in winter wheat-spring maize rotationIn this long-term experiment?2007-2017?,NCS rotation had better soil water conservation effect in fallow period,the average soil water storage was 393.7 mm.CN rotations provided better soil water condition during wheat and maize growth season in winter wheat-spring maize rotation.CN and NCS rotation improved the crop yield by increasing the water consumption during crop growth season.CN rotation produced higher average wheat yield and WUE,were 5221 kg ha-1 and 15.5 kg ha-1 mm-1,respectively.NCS rotation produced higher average maize yield and WUE,were 7597 kg ha-1 and 21.5 kg ha-1mm-1,respectively.As the high economic input in NCS rotation and low economic input in CN rotation,CN had a better economic profit of 6254 yuan ha-1.In this experiment,CN rotation decreased the soil bulk density,increased soil porosity.NCS rotation increased the aggregates efficiently.Tillage treatemnts enhanced the soil fertility in a certain extent,NCS and CN rotations had higher soil organic carbon and total N,and CN provided rational distribution of soil total and available nutrients?Total and available N,P,K?in soil arable layer.CN rotation was the optimal tillage system in Loess Plateau.6.The effect of crop yield increase,soil water preservation and soil property enhancement under different fertilizations with tillage rotations in winter wheat-spring maize rotationIn this long-term experiment?2007-2017?,LNT had better soil water conservation effect in fallow period,the average soil water storage was 403.2 mm.CCN had a higher water consumption during crop growth season,but there was no significant difference among different tillage with fertilization treatments.CCN produced higher wheat yield and WUE,the average values were 5440 kg ha-1 and 15.2 kg ha-1 mm-1,respectively.BCN produced higher maize yield and WUE,the average values were 7433 kg ha-1 and 21.1 kg ha-1 mm-1,respectively.As the high and stable crop yield in BCN,it had a better economic profit of 6254yuan ha-1.In this experiment,BCN increased the content of soil aggregates,enhanced the soil properties efficiently.Fertilization with tillage rotations enhanced the soil fertility in a certain extent,BCN had higher soil organic carbon and total N,and provided rational distribution of soil total and available nutrients?Total and available N,P,K?in soil arable layer,was the optimal three-year conservation tillage rotation sin Loess Plateau.7.The simulation effect of crop yield increase,soil water preservation and soil property enhancement under different fertilization with tillage rotations in winter wheat-spring maize rotationIn this long-term experiment?1980-2016?,LNT had better soil water conservation effect in fallow period,and provided better soil water condition during crop growth in winter wheat-spring maize rotation,the average available soil water storage was 290.1 mm.CCN had a higher water consumption of 397.8 mm during crop growth season,but there was no significant difference among different tillage with fertilization treatments.In this experiment,CCN produced higher crop yield,WUE and economic profit,the average values were 5.65 t ha-1,14.59 kg ha-1 mm-1 and 6878 yuan ha-1,respectively.Fertilization with tillage rotations enhanced the soil fertility in a certain extent.In this experiment,CCN had a higher soil organic carbon content of 8.47 kg m-3.In long term experiment,the available soil water in0-300 cm declined significantly as the experiment process.From 2007-2016,CCT had the highest soil water sonsumption,the average reduction of soil water was 20.4 mm in a winter wheat-spring maize rotaion.In this experiment,CCN had higher crop yield and better economic profit,but the soil water consumption was on a high level,especially in deep soil layer.This is not conductive to the resume of soil water.BF fertilization had a high crop yield and the soil water consumption was close to LF,especially BCN,was the optimal fertilization and tillage rotation system in Loess Plateau. |
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