| In order to investigate the effects of tillage depth on soil physical properties,growth and yield of potato and wheat in rain-fed areas of southern Ningxia,the paper aimed at the problems of drought,intense evaporation and low water use efficiency in spring in southern Ningxia.In 2018-2020 different tillage depth(ploughing 15 cm(CK),ploughing 30 cm(C30),subsoiling 30 cm(S30),subsoiling 40 cm(S40),subsoiling 50 cm(S50))was set up to study on soil physical properties,potato and wheat growth and yield of different crops in arid regions of southern Ningxia for building the potato high-yield cultivation to provide theoretical reference and the main research results were as follows:(1)Different tillage depth significantly reduced the soil bulk density(0-60 cm)during crop harvest.Compared with CK,S30 treatment could significantly reduce soil bulk density in 0-20 cm layer by 8.55%,and C30 treatment had the lowest values in 20-40 cm and 40-60 cm layer,which were significantly decreased by 13.86%and 9.43%compared with CK,respectively.Soil bulk density in 0-20 cm layer under S30 treatment in wheat field was the lowest,which was significantly reduced by 5.33%compared with CK;soil bulk density in 20-40 cm and 40-60 cm layer under S40 treatment was the lowest,which was significantly reduced by 6.73%and 11.63%compared with CK,respectively.(2)Different tillage depth significantly increased the number of mechanical stability and water stability aggregates of>0.25mm soil in 0-60 cm layer of potato field and wheat field.The number of>0.25 mm mechanically stable aggregates in 0-20 cm layer of potato field was the highest in C30 treatment,and that in 20-40 cm and 40-60 cm layer was the highest in S50 treatment,which significantly increased by 14.80%,41.59%and 32.88%compared with CK,respectively.The amount of>0.25 mm mechanically stable soil aggregates in 0-20 cm layer of wheat field treated by S40 was the largest,which increased by 24.13%compared with CK.There was no significant difference between 20-40 cm layer and 40-60 cm layer treated by S30 was the largest,which increased by 30.79%compared with CK.The number of water stable aggregates in>0.25 mm soil of potato field was the highest under S30 treatment in 0-20 cm layer and 20-40 cm layer,and the highest under S50 treatment in 40-60 cm layer,but there were no significant differences among treatments.In the 0-20 cm and 20-40 cm layers of wheat field,the number of>0.25 mm soil water-stable aggregates in S40 treatment was the largest,which significantly increased by 54.63%and 25.45%compared with CK,respectively,while there was no significant difference between 40-60 cm layers.In both potato field and wheat field,the average WMD value(mean weight diameter)and average GMD value(geometric mean diameter)of soil mechanical stability and water stability aggregates in 0-20 cm layer under S40 treatment were larger,which were significantly increased by 29.38%and 15.98%in potato field compared with CK,respectively.The wheat field was significantly 80.13%and 51.71%,respectively.In 20-40 cm layer,S30 treatment was the largest in potato field,which significantly increased by 47.86%and 19.97%compared with CK,respectively.In wheat field,S40 treatment was the largest in DWMD value and DGMD value,which significantly increased by 3.25%compared with CK,and CK was the largest in WWMD value and WGMD value.In 40-60 cm layer,there was no significant difference among treatments.(3)Different tillage depth significantly improved soil compactness during crop growth period,and soil compactness under S50 treatment was lower.During the whole growth period of potato field,soil compactness of 0-40 cm layer under different treatments was S50<S40<S30<C30<CK in descending order.The average growth period of each treatment was significantly reduced by 17.38%,15.10%,15.05%and 12.85%compared with CK,respectively;The soil compactness of wheat field in the whole growth period was in order from small to large in the order of S50<C30<S40<S30<CK,The average values were significantly decreased by 7.35%,4.80%,4.76%and 4.55%compared with CK,respectively.(4)Under different tillage depths,soil water in 0-100 cm layer during crop growth period was significantly improved.During the whole growth period of potato field,the average soil water storage of C30 treatment was the highest,which was 13.71%higher than that of CK;During the whole growth period of wheat field,S40 treatment had the highest average soil water storage,followed by C30 treatment,which significantly increased by 21.32%and 20.15%compared with CK,respectively.The average soil water content of 0-100 cm layer was the highest under C30 treatment in both potato and wheat fields.At the early growth stage of potato(0-30 days after sowing),the soil water content in 0-100 cm layer of each treatment was higher than that in 0-40 cm layer,which was significantly increased by 7.23%in C30 treatment compared with CK.At the middle growth stage(30-90 days after sowing),the average soil water content in 0-100 cm layer of all treatments was the highest in CK,and there was no significant difference between CK and other treatments.At the later growth stage(90-150 days after sowing),the soil water content in 0-100 cm layer was higher in 0-60 cm layer,and C30 and S30 treatments significantly increased by 8.97%and 6.89%compared with CK,respectively.The average soil water content of 0-100 cm layer under S50 treatment was significantly increased by 7.43%compared with CK at the early growth stage(0-60 days after sowing).The average soil water content of 0-100 cm layer in C30 treatment was the highest in the middle and late growth period(60-120 days after sowing),which was significantly increased by 23.68%and 19.66%compared with CK,respectively.(5)Different tillage depth had promoting effect on crop growth index during the growth stage.Under different tillage treatments,potato seedling emergence rate of S30 treatment was the highest,which was 14.14%higher than that of CK.The average plant height and stem diameter of S50 treatment were the best in the whole growth period,which were increased by 14.27%and 21.19%compared with CK,respectively.S30 treatment had the highest seedling emergence rate,average plant height and leaf area in the whole growth period,which were significantly increased by 37.30%,13.64%and 71.20%compared with CK,respectively.(6)Different tillage depth had promoting effect on photosynthetic physiological indexes of crops.Under different tillage treatments,the relative chlorophyll content(SPAD value)of potato leaves in the whole growth period was the highest under S40 treatment,followed by S50 treatment,which was significantly increased by 4.15%and 3.09%compared with CK,respectively.The maximum photochemical efficiency Fv/Fm value)of potato PSII under all tillage treatments was the highest in the whole growth period,with an average increase of 4.51%compared with CK,but the difference was not significant.The potential activity(Fv/F0 value)of potato PSII under S30 treatment was the highest in the whole growth period,with an average increase of 13.32%compared with CK.The average net photosynthetic rate(Pn)and instantaneous water use efficiency(WUEP)of potato were the highest under S30 treatment,which were increased by 20.41%and 5.92%on average compared with CK,respectively.The transpiration rate(Tr)of potato was the highest under S40 treatment.The average increase was 19.11%compared with CK.The SPAD value and Fv/Fm value of each tillage treatment in wheat field were the highest in S40 treatment,which were significantly increased by 4.15%and 4.44%compared with CK on average,respectively.The Fv/F0 value in S30 treatment was the highest in the whole growth period,which was significantly increased by 13.33%compared with CK on average.During the whole growth period,Cond,Pn and Tr values of S30 treatment were the highest,which were significantly increased by 14.66%,19.66%and 20.04%compared with CK,respectively.WUEp values of S50 and S40 treatment were higher,which were significantly increased by 8.32%and 4.76%compared with CK,respectively.(7)Different tillage depth could promote potato dry matter accumulation and wheat grain filling rate.The dry matter accumulation of shoot in C30 and S50 treatments was higher than that in CK,which increased by 32.65%and 32.35%,respectively.During the whole growth period,S40 treatment had the highest dry matter accumulation,which was significantly increased by 74.89%compared with CK on average.The grain filling rate of wheat in the whole growth period was the best with S40 treatment,which was 3 1.95%higher than CK on average.(8)Different tillage depth has significant effect on crop yield.The yield,net income and output/investment ratio of potato field S40 treatment were the highest,which significantly increased by 15.17%,18.91%and 8.45%compared with CK,respectively.Different tillage depth in wheat field could improve wheat yield composition and significantly increase wheat yield,and the wheat yield was significantly increased by 59.25%and 56.56%in S40 and S50 treatments compared with CK,respectively.The net income and the ratio of production to investment of wheat under S40 treatment were the highest,which were significantly increased by 88.22%and 43.48%compared with CK,respectively.The results showed that the maximum potato yield was 31666.70 kg/hm2 when the tillage depth was 45.66 cm.When the tillage depth was 41.80 cm,the maximum wheat yield was 5499.06 kg/hm2.(9)Principal component analysis showed that Fv/Fm value,the number of>0.25 mm soil mechanically stable aggregates and the underground dry matter accumulation were most closely related to potato yield,followed by soil water storage in 0-100 cm layer during growth period.For wheat,SPAD value,net photosynthetic rate,soil water content in 60 cm layer,40 cm layer,grain-filling rate,and the number of>0.25 mm soil mechanically stable aggregates were most closely related to yield,followed by soil water storage in 0-100 cm layer during growth period.In conclusion,different tillage depth can significantly affect the number of soil mechanically stable aggregates,improve soil water status,enhance photosynthetic characteristics of crops,and finally promote the formation of crop yield.In conclusion,different tillage depth could affect the soil structure of surface layer,thus increase the soil water storage effect,promote the growth of potato and wheat,and improve their yield,and the subsoiling 40 cm treatment had the best effect of increasing yield in both two years.Therefore,,tillage depth of 40 cm was more conducive to water conservation and storage on the basis of improving soil structure of surface layer,so as to obtain better yield increase effect for potato and wheat fields,and to provide theoretical support for rational cultivation in the arid region of southern Ningxia. |
PDF Full Text Request