Effects Of Tillage In Summer Fallow On Soil Quality For Dryland Wheat Field

This experiment was carried out at the Wenxi Dryland Experiment base of Shanxi Agricultural University from 2016 to 2017 and based on the experiment from 2013 to 2016.Four types of free-range tillage treatments were set,named as no-tillage-no-tillage-no-tillage-no-tillage(4aNT),deep plow-deep plow-deep plow-subsoiling(3aPT-ST),deep plow-subsoiling-deep plow-subsoiling(4aPT/ST)and subsoiling-subsoiling-subsoiling-deep plow(3aST-PT).In order to study the effect of different tillage patterns on the soil quality of the dry wheat field in the Loess Plateau,the maximum productivity of the wheat field in dry land was realized.The main results are as follows:(1)The deep plow/subsoiling rotational tillage can significantly improve soil physical properties.The soil gravity water content under 4aPT/ST in 0-50 cm soil layers is higher than that of 4aNT,3aPT-ST,and 3aST-PT treatments by 91.92%-121.73%,53.92%-77.38%and 22.24%-37%.In addition,adoption of 4aNT will increase the compactness of the soil,while the deep plow/subsoiling rotational tillage can effectively reduce soil compaction.Both 3aPT-ST and 3aST-PT can reduce the soil bulk density to a certain extent,but the effect is not as good as deep plow/subsoiling rotational tillage.The total soil porosity and capillary porosity in deep plow/subsoiling rotational tillage in 0-50 cm soil layer were significantly higher than those in other three treatments.At the same time,compared with the other three treatments,the total porasity of 4aNT,3aPT-ST,and 3aST-PT treatments at maturity decreased,while the 4aPT/ST treatment increased by 1.00%-2.79%.The contents of water-stable aggregates(>0.25 mm)in 0-50 cm soil layer under deep plow/subsoiling rotational tillage were higher than those under 4aNT,3aPT-ST,and 3aST-PT treatments by 40.4%-45.5%,61.8%-98.0%,and 39.4%-106.1%,respectively.And the GMD and MWD under deep plow/subsoiling rotational tillage were significantly higher than other tillage treatments.(2)Deep plow/subsoiling rotational tillage during summer fallow period can significantly improve the soil chemical properties.Soil nitrate nitrogen content in 0-50 cm soil layer under 4aPT/ST was significantly higher than that under 4aNT,3aPT-ST and 3aST-PT treatments.No-tillage treatments in successive years reduced the soil accumulation nitrogen in the 0-50 cm soil layer in fallow stage and before sowing.While the content of organic matter,available phosphorus and alkali-hydrolyzed nitrogen in 0-50 cm soil layers under 4aPT/ST were higher than those other treatments.And deep plow/subsoiling rotational tillage reduce the soil pH.(3)The deep plow/subsoiling rotational tillage during summer fallow significantly improved the soil biological characteristics.The soil microbial biomass carbon,soil phosphatase activity and invertase activity in 0-50 cm soil layers under 4aPT/ST were significantly higher than those under 4aNT,3aPT-ST and 3aST-PT treatments.At maturity,soil catalase activity in 0-20 cm soil layers under 4aNT was significantly lower than that of 3aPT-ST,4aPT/ST and 3aST-PT,but there was no significant difference among 3aPT-ST,4aPT/ST and 3aST-PT treatment.However,the soil catalase activity in 20-40 cm soil layers had no significant difference among these four tillage treatments.The soil urease activity of 4aPT/ST treatment in 0-50 cm soil layers increased compared to the fallow stage,however,the soil urease activity of 4aNT treatment in 0-50 cm soil layers decreased compared to the fallow stage.While the soil urease activity of 3aPT-ST and 3aST-PT treatment in 30-50 cm soil layers increased compared to the fallow stage.(4)Using the soil quality index method,the soil score of 0-50 cm soil layers at maturity showed that the SQI of 4aNT treatment was the lowest.In the 0-20 cm soil layers,the SQI of 4aPT/ST and 3aST-PT treatments were the highest,and there was no significant difference between them.In 20-50 cm soil layers,the SQI values of 4aPT/ST treatment was the highest,followed by SQI(4aPT/ST)>SQI(3aST-PT)>SQI(3aPT-ST)>SQI(4aNT).All in all,adoption of deep plow/subsoiling rotational tillage during summer fallow period is beneficial to improving the soin quality of dryland winter wheat.And deep plow/subsoiling rotational tillage during summer fallow significantly increases the spike number and kernel number per spike of winter wheat,and yield under 4aPT/ST is significantly higher than that of 4aNT,3aPT-ST and 3aST-PT treatment by 90.79%,5.37%and 65.86%.Clearly,adoption of deep plow/subsoiling rotational tillage during summer fallow period is the most favorable model for improving the productivity of dryland winter wheat.