Effects Of Different Tillage Models On Soil Physicochemical Properties And Winter Wheat Yield

Shallow tillage and compact structure have become one of the key factors limiting crop yield in the double cropping area of winter wheat and summer maize in China.To create a deep and loose soil environment and improve soil fertility through improving soil tillage mode is an important technical way to achieve sustainable high and stable grain yield in this region.The experiment was conducted in Dongping county Institute of agricultural sciences from October 2015 to June 2018 for three consecutive winter wheat growing seasons.The main winter wheat cultivar Shannong 20 was used as the test material.The experiment was designed as split plot.The main plot was 3-year rotary tillage（RS）,2-year deep plowing tillage（DS）,2-year rotary tillage followed by deep plowing tillage in the 3rd year（RS/DS）,and the secondary plot was nitrogen fertilizer level:125 kg·ha^-1（N125）,165 kg·ha^-1（N165）,225 kg·ha^-1（N225）,300 kg·ha^-1（N300）.The effects of Different Tillage Modes on soil physical and chemical properties and winter wheat yield were studied.The results provided theoretical and technical basis for improving soil quality and guaranteeing stable yield of Winter Wheat in this region.The main results are as follows:（1）Tillage patterns have significant effects on soil bulk density,porosity,stability of aggregates and mass ratio of macroaggregates in 0-30 cm soil layer,but have little effect on30-40 cm soil layer.Nitrogen fertilizer application can significantly affect soil bulk density,porosity and stability of aggregates in 0-10 cm soil layer,but has little effect on 10-40 cm soil layer.The interaction between the two methods has significant effects on soil bulk density,porosity and 30-40 cm soil layer.The stability of aggregates in cm soil layer and the mass ratio of large aggregates.RS significantly reduced the proportion of soil bulk density and aggregate mass in 0-10 cm soil layer;DS significantly reduced the proportion of soil bulk density in 10-20 cm and the proportion of soil mass and aggregate stability in 20-30 cm soil layer;RS/DS significantly improved the mass ratio and aggregate stability of 10-20 cm soil mass,and combined with 225kg·ha^-11 nitrogen application effectively reduced soil bulk density and increased aggregate stability.Different treatments have little effect on the physical properties of 30-40 cm soil layer.（2）The tillage mode significantly affected the nutrient content of 0-30 cm soil,but had no significant effect on 30-40 cm soil layer,while the effect of nitrogen fertilizer application and their interaction on the nutrient content of 0-40 cm soil reached significant level.Under RS,soil organic carbon and total nitrogen in 0-10 cm soil layer were significantly higher than those in DS and RS/DS,but the dominance gradually decreased with the increase of nitrogen application rate.DS and RS/DS significantly increased soil total nitrogen content in 10-20 cm soil layer and soil organic carbon,total nitrogen and total phosphorus content in 20-30 cm soil layer,but significantly decreased soil available phosphorus content in 0-40 cm soil layer,and increased.The fixed effect of phosphorus in 20-40 cm soil layer decreases with the increase of nitrogen application,and the content of organic carbon and total nitrogen in 0-40 cm soil increases gradually with the increase of nitrogen application,especially in DS and RS/DS.（3）Tillage pattern,nitrogen fertilizer application rate and their interaction have significant effects on soil carbon,nitrogen and phosphorus ratio characteristics.The carbon,nitrogen and phosphorus ratios of DS and RS/DS were consistent,but different from those of RS.With the increase of nitrogen application rate,the difference of C:N and P ratio among the three increased gradually.At the N225 level,soil N:P and C:P showed significant difference.The soil C:P of RS was higher than that of DS and RS/DS on the whole.（4）The correlation degree between physical properties of 0-10 cm soil layer and wheat yield was higher,while the correlation degree between chemical properties of 10-40 cm soil layer and wheat yield was higher.The C/N/P of soil was lower than that of wheat yield.Compared with RS,DS and RS/DS could significantly increase the number of grains per spike and 1000-grain weight of wheat,and the effect of RS/DS on 1000-grain weight of wheat was more significant.With the increase of nitrogen application,wheat yield showed a distinct upward trend.Under RS/DS at N300 level,wheat yield reached the maximum of this experiment.There was no significant difference in yield between N255 level and N300 level in RS/DS.The combination of RS/DS with N255 level has better economic benefits.