| Weibei Highland is located in the north of Shaanxi Guanzhong Plain and in the south of north Shaanxi gully.The region is warm temperate arid areas,and the evaporation is about 1832 mm and the precipitation is about 536 mm,which mainly concentrated in July to September.Tillage measures have a huge impact on soil in the region.In the arid and semiarid regions,it is an important way for storing water and soil moisture conservation.Different tillage measures have different effects on soil,and thus have different effects on soil properties.Long-term one-crop farming has disadvantage effect on soil.The protective tillage,especially the combination of straw and cropland,has been paid more attention.In the view of this,the aim of the present study was to investigate the effect of different tillage measures and fertilization on soil physical and chemical properties and crop yield in Weibei Highland.An eight-year(2007-2015)field experiment in Weibei Highland black loessial soil with six tillage measures and 3 kinds of fertilization under wheat-maize rotation system and maize-maize rotation system was set up.The tillage measures were;no-tillage – subsoiling(NS),subsoiling – conventional tillage(SC),conventional tillage – no-tillage(CN),continuous no-tillage(NN)and continuous sbusoiling(SS),conventional tillage(CC).The fertilizationn were;balanced fertilization,low fat and conventional fertilization.The experiment provides a theoretical and technical support for reasonable tillage and topsoil structure in Loess Plateau and black loessial soil areas.The results were as follows:(1)Effects of different tillage measures on soil physical propertiesFrom different soil layers,compared with NN treatment and CC treatment,there was no significant difference in soil bulk density of rotary tillage in the 0-10 cm soil layer.The decrease of bulk density was mainly in the soil layer below 10 cm.The soil bulk density of the six treatments increased with the deepening of soil layer.There was no significant difference between different fertilization.From the 0-50 cm soil layer,compared with conventional tillage(CC),soil bulk density of NS treatment reduced by 4.7%~7.3%,CN treatment reduced by 2.0%~6.7%,SC treatment reduced by 2.7%~4.6%,SS treatment reduced by 3.4%~7.2% under the wheat-maize rotation system.And in the maize-maize rotation system,compared with conventional tillage(CC),soil bulk density of NS treatment reduced by 0.7%~4.0%,CN treatment reduced by 2.7%~4.6%,SC treatment reduced by 0.7%,SS treatment reduced by 1.3%~3.9%.Rotary tillage could deduce soil bulk density and play an important role in improving soil structure.NS treatment and CN treatment were better than SC treatment.SS treatment was also to be propitious to reduce soil bulk density.The effects of different tillage treatments on soil compaction and soil bulk density showed the same trend,and there was a certain correlation between soil compaction and soil bulk density,and they reached a very significant positive correlation.(2)Effects of different tillage and fertilization on soil nutrientsFrom different soil layers,compared with CC treatment,the nutrient contents of three kinds of rotary tillage and NN treatment and SS treatment were most obvious in 0-10 cm soil layer,while the increase of soil layer under 10 cm was not obvious.From 0-50 cm soil layer,the soil nutrient was higher under balanced fertilization than low fat and conventional fertilization.Under balanced fertilization,compared with CC treatment,CN treatment had the highest total nitrogen and available nitrogen,which was higher by 1.3%~8.0;NS treatment had the highest total phosphorus and available phosphorus,which was higher by 8.9%~9.2%;NN treatment had the highest total potassium and available potassium,which was higher by 5.0%~16.6% under wheat-maize rotation system.Under balanced fertilization,compared with CC treatment,CN treatment had the highest total nitrogen and available nitrogen,which was higher by 9.1%~24.0%;NS treatment had the highest total phosphorus and available phosphorus,which was higher by 8.9%~54.6%;NN treatment had the highest total potassium,which was higher by 7.5%;CN treatment had the highest available potassium,which was higher by 38.2% under maize-maize rotation system.Analysis of soil nutrients under two planting patterns,compared with CC treatment,3 kinds of rotary tillage could improve soil nutrient content,which combined with no-tillage and rotary tillage,CN treatment and NS treatment had better effects.(3)Effects of different tillage measures on soil organic carbon storageCompared with CC treatment,it could increase the soil organic carbon storage in the 0-35 cm by different reasonable rotary tillage.Under the wheat-maize rotation system,compared with SS treatment and CC treatment,the soil organic carbon storage of NS treatment increased by 5.9%~12.2%,SC treatment increased by 3.1%~9.3%,CN treatment increased by 12.2%~18.8%,and CN treatment increased the maximum.Under the maizemaize rotation system,the soil organic carbon storage of NS treatment and SC treatment and CN treatment were higher than single tillage.And compared with CC treatment,the soil organic carbon storage of NS treatment increased by 10.8%,SC treatment increased by 3.5%,CN treatment increased by 10.4%,and NS treatment increased the maximum.Tillage measures not only affected the soil organic carbon storage,but also affected the composition of organic carbon.Under the two planting patterns,compared with CC treatment,the rotary tillage which combined with no-tillage were better for increasing content of the total organic carbon,the particulate organic carbon,the easily oxidized organic carbon.Long term single tillage(SS treatment and CC treatment)were not conductive to the fixation and accumulation of organic carbon in soil.The increasing of the soil organic carbon storage was mainly controlled by the content of particulate organic carbon and easily oxidized organic carbon.The soil organic carbon storage was affected by planting patterns.The comparison between the same tillage,maize-maize rotation system was more conductive to soil organic carbon storage than wheat-maize rotation system.The rotary tillage which combined with notillage(CN treatment and NS treatment)had better detaining effect on soil organic carbon than other tillage measures.(4)Effects of different tillage measures on crop yieldUnder wheat-maize rotation system,winter wheat yield of 8 years of rotary tillage was higher than single tillage.CC treatment had the lowest yield.Compared with CC treatment,NS treatment and CN treatment were significantly higher than CC treatment,increased by 15.4% and 19.4%,respectively.The yield of maize between six treatments was NS>CN>SC>SS>NN>CC,and there was no significant difference among the treatments.Rotary tillage was more beneficial to increase crop yield,and the effect of rotary tillage which combined with no-tillage(CN treatment and NS treatment)were better.Under maize-maize rotation system,spring maize yield of eight years of rotation tillage was higher than single tillage.Compared with CC treatment,CN treatment significant increased yield by 29.7%.Rotary tillage was more beneficial to increase crop yield,and the effect of rotary tillage which combined with no-tillage(CN treatment and NS treatment)were better.In general,under different planting patterns,rotary tillage could reduce soil bulk density,improve soil physical properties.And rotary tillage could improve soil nutrient contents and effectively improve the soil organic carbon storage and crop yield.CN treatment and NS treatment were the better result,which are suitable for the cultivation of the region. |
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