Physicochemical Characteristics And Technical Control Of Surface Soil Of Typical Wheat-Maize Field In Low Plain Of Hebei Province

At present,the main problems of cultivated land in Hebei Province are shallow farmland and high soil bulk density,which have become the main factors hindering the improvement of crop yield.How to improve the quality of cultivated land in order to improve crop yield has become an important problem to be solved urgently.Based on the field investigation of wheat-maize rotation farmland in Ningjin and Xinji counties of Hebei province,this paper clarifies the changes of soil physical and chemical properties and yield caused by the existing problems of plough layer soil,and designs the technical scheme of improvement and regulation.There are 5 treatment methods in the wheat season:100%recommended formula?CK?,80%recommended formula?DF?,80%recommended formu--la+20%bio-organic fertilizer substitute?DF+1?,80%recommended formula fertilizer+20%bio-organic fertilizer replacement+biochar?DF+2?and 80%recommended formula fertilizer+20%bio-organic fertilizer replacement+biochar+soil structure conditioner?DF+3?;Based on the wheat season,the later maize was studied by flat seeding?NN?and deep pine?SS?tillage methods,and the effects of different control techniques on soil physical and chemical properties and yield were determined.Based on the wheat season,the post-cultivated corn was studied by flat seeding?NN?and deep pine?SS?tillage methods,and the changes in soil physical and chemical properties and yield were identified,and techniques for improving the physical and chemical properties of cultivated soil and increasing crop yield were explored.The main research results are as follows:?1?Ningjin plough layer is between 12.50²2.00 cm,91.67%of farmland plough layer thickness is less than 20 cm,the plough layer is shallow;Xinji plough layer is17.00²7.50 cm,25.00%of farmland plough layer thickness is less than 20 cm,the majority of farmland plough layer thickness is more suitable for crop growth.The soil bulk density of the two counties was larger than 1.33 g/cm³.The soil aggregation structure was better,but the water stability was poor.The MWD values of dry sieve ranged from 4.19⁵.09 mm,that of wet sieve ranged from 0.39⁰.99 mm,and that of E_LT ranged from63.03⁷9.26%.From the point of view of soil nutrients,available potassium and available phosphorus can provide normal growth of crops.The content of soil organic matter and nitrate nitrogen is low,which is not enough for crop growth.?2?The thickness of tillage layer was positively correlated with the total yield of wheat and maize.The total yield of farmland with 0¹5 cm thickness and>15 cm thickness was between 16.09¹6.39 t/hm² and 16.96¹7.13 t/hm²,respectively.The total yield of farmland with 0²0 cm thickness and>20 cm thickness in Xinji was between16.19¹7.22 t/hm² and 16.82¹8.60 t/hm²,respectively.In Ningjin,the yield of subsoiling field with plough layer>15 cm was 1.00%higher than that of traditional field,and 4.51%higher than that of subsoiling field with plough layer 0¹5 cm;in Xinji,the yield of subsoiling field with plough layer>20 cm was 10.58%and 8.01%higher than that of traditional field and subsoiling field with plough layer 0²0 cm,respectively.Soil bulk density,organic matter,available potassium,aggregate content>0.25 mm in dry and wet sieves,MWD,GMD and D values were also significantly correlated with total yield.?3?Different control techniques are beneficial to increase the total yield of wheat and maize.Compared with CK?100%formula fertilizer?,the yield of winter wheat increased by 4.23%,7.04%and 10.33%in DF+1,DF+2 and DF+3 treatments respectively,and the overall performance was DF+3>DF+2>DF+1>CK>DF;the yield of summer maize increased by 0.29%⁴.25%in subsoiling cultivation compared with flat sowing cultivation.In terms of total yield,DF+3+SS treatment increased yield by 0.11%¹5.85%compared with other treatments,and subsoiling tillage increased yield by 0.17%³.35%compared with flat tillage.?4?The addition of bio-organic fertilizer,biochar and soil structure conditioner can improve the contents of soil organic matter,nitrate nitrogen,available potassium and available phosphorus.The overall trend of wheat growth period is DF+3>DF+2>DF+1>CK>DF.In maize season,tillage mode had no significant effect on soil organic matter and available potassium content.Nitrate nitrogen content showed a slightly higher trend in subsoiling tillage at grain filling stage and maturity stage than in flat sowing,and available phosphorus content in subsoiling tillage was significantly lower than that in flat sowing.Compared with CK treatment,the contents of soil organic matter,available potassium and available phosphorus increased by 28.20%,6.37%and 92.16%respectively in wheat maturity stage,and the contents of nitrate nitrogen and available potassium increased by42.50%and 8.20%respectively in DF+3+SS treatment in maize season.?5?Different control techniques can help to reduce soil bulk density,improve the aggregation effect of soil particles,and enhance the structural stability of soil aggregates.The improvement effect of DF+3 treatment was the most remarkable,and the soil bulk density of wheat treated with DF+3 was significantly lower than that of other treatments at maturity stage by 6.15%¹0.29%.Dry-screening MWD increased by 16.35%compared with CK treatment,and ELT decreased by 26.16%.At the maturity stage of maize,the bulk density of soil decreased by 0.72%².72%,the dry-screening MWD value DF+3+SS increased by 8.20%compared with DF+3+NN,and the ELT value decreased by 22.81%.?6?Substitution of bio-organic fertilizer and deep-loosening tillage are beneficial to increase soil microbial biomass carbon and nitrogen content.Bio-carbon application reduces soil microbial carbon content,but has no effect on soil microbial nitrogen.Soil structure conditioner application reduces soil microbial nitrogen content,and there is no significant change in soil microbial carbon content.In wheat season,soil microbial nitrogen in DF+1 and DF+2 treatments was significantly higher than that in other treatments,which was 26.99%and 19.03%higher than CK.In maize season,soil microbial carbon and nitrogen content in DF+3+SS was the highest,which was 40.34%and 72.40%higher than CK+NN.In conclusion,deep pine tillage can effectively improve the shallow topsoil and reduce soil bulk density.Bio-organic fertilizer,biochar and soil structure conditioner can effectively improve soil nutrients,reduce soil bulk density,improve soil aggregate structure,and improve soil fertility and water retention capacity.In the wheat season,biological organic fertilizer was used instead of 20%formula fertilizer and biochar and structure conditioner were applied.In the maize season,deep pine cultivation was a new field regulation technology worth popularizing.