Effect Of Mulching And Green Manures During Summer Fallow On Soil Water?Nutrition And Growth Of Winter Wheat

The deficiency of water resources is a problem that the whole world agriculture is dealing with.The dry land on the Loss Plateau of China is a typical rain-fed agricultural area.The deficiency of water and barren soil are the crucial factors limiting the agricultural production of this area.Developing dry land agriculture and improving the crop production of rain-fed area can relieve the shortage of water resources and guarantee food security.The experiments were carried out from the harvest of previous wheat to the sowing of next wheat(three months fallow).(1)To investigate the effect of plastic film mulching during summer fallow on soil water and the yield of wheat.(2)To investigate the effect of different tillage on soil moisture and soil microbial communities during the summer fallow.(3)To invesitgate the effect of planting green manures duing the summer fallow on the changing regulations of soil water,nutrition,enzyme activity and yield of wheat.Expecting these three experiments can provide theoretical and practical guidance.The deficiency of water resources is a problem that the whole world agriculture is dealing with.The dry land on the Loss Plateau of China is a typical rain-fed agricultural area.The deficiency of water and barren soil are the crucial factors limiting the agricultural production of this area.Developing dry land agriculture and improving the crop production of rain-fed area can relieve the shortage of water resources and guarantee food security.The experiments were carried out from the harvest of previous wheat to the sowing of next wheat(three months fallow).(1)To investigate the effect of plastic film mulching during summer fallow on the changing regulations of soil water and the wheat yield.(2)To investigate the effect of different tillage patterns on soil moisture and soil microbial communities during the summer fallow.(3)To investigate the effect of planting green manures during the summer fallow on soil water,nutrition,enzyme activity,yield of wheat and so on.Expecting these two experiments can provide theoretical and practical guidance.The soil samples were collected on 12th August,30th August and September 25th.The deep tillage or sub-soiling treatments in this year(L2,L3,L5,L6)could kept more rainfall than the no tillage treatments(L1,L4),especially the deep tillage-deep turning-deep tillage treatment(L5).On the three investigating dates,the bacterial community composition was investigated at the phylum level.L4(deep turning-deep turning-no tillage)and L5(deep tillage-deep turning-deep tillage)held higher proportion of Proteobacteria.L1(no tillage-no tillage-no tillage)and L4(deep turning-deep turning-no tillage)kept higher proportion of Actinobacteria.In the multiple comparison analysis,the bacterial community diversity in surface soil(0-20cm)is significantly higher than that in plough layer(20-40cm).All the rotation treatments had the highest abundance of bacterial communities in amino acid metabolism.The rotation treatments had the second highest bacterial community abundance in sugar metabolism.The bacterial community abundance ranked third in energy metabolism.On the three investigating dates,the fungal community composition was investigated at the phylum level.L4(deep turning-deep turning-no tillage)and L1(no tillage-no tillage-no tillage)had higher proportion of Ascomycota.L3(deep turning-deep turning-deep turning),L5(deep tillage-deep turning-deep tillage)and L6(deep tillage-deep tillage-deep tillage)kept higher proportion of Zygomvcota.L1(no tillage-no tillage-no tillage)held higher proportion of Basidiomycota.In the multiple comparison analysis,the richness of fungal communities on September 25th was significantly higher than the richness of August 12th and August 30th.The richness of fungal communities under L1(no tillage-no tillage-no tillage)and L4(deep turning-deep turning-no tillage)was significantly higher than that of L5(deep tillage-deep turning-deep tillage)and L6(deep tillage-deep tillage-deep tillage).In the bacterial and fungal community,the abundance indices(Chaol and ACE)and the diversity indices(Shannon and Simpson)had a significantly correlation(P<0.05).The soil water and fungal diversity index(Shannon)had a significantly correlation(P=0.0247<0.05).During the green manures seedling,flowering and maturing stage,the different green manure rotation treatments held the various proportion of phylum of bacterial and fungal community.There was a relatively high trend of Alpha indices of bacterial and fungal community under the green manure rotation treatments.But the Alpha indices of the green manure rotation treatments were not significantly higher than that under the bare filed treatment(L6).Regarding to the individual wheat agronomic traits of different growing stages,the bare field treatment(L6)almost obtained the better agronomic traits than other treatments.Regarding to the group dynamics of wheat growing stages,the bare field treatment(L6)held a relatively higher trend of wheat tiller number during flowering stage.During the over-wintering and reviving periods of wheat,green manure treatments generally reduced the dry matter above the ground by an average of 80%.Growing green manures during summer fallow did not improve the yield of winter wheat.The green manure treatments reduced the one thousand grain weight by 8.52%to 13.62%and reduced the yield by 9.04%to 42.07%.The cultivation of green manure increased the starch content and soluble sugar content of wheat grain.The green manure treatments did not improve the nitrogen rate,phosphorus rate and potassium rate of wheat leaves,straws,roots and grains during the growing stages.The green manures treatments significantly reduced the soil relative water content.The bare field treatment(L6)kept the highest soil relative water content before wheat sowing(also the maturing of green manure).And L6 also held the better soil water content until wheat maturing stage.Growing soy bean during summer fallow had an increased trend of 0-100cm soil available nitrogen and total nitrogen during the wheat growing stage.Growing rape seed during summer fallow kept an increased trend of 0-100cm soil available phosphorus and total phosphorus during the wheat growing stage.Growing green manures and turning the green manures into the soil did not improve the soil available potassium and organic matter.During the green manures growing stage,the largest rape seed sowing rate treatment had better phosphatase,sucrase,urease and protease activity than the bare field(L6)in the 0-100cm soil.During the over-wintering,jointing and flowering stages,the residues of rape seed were turned into soil treatment(R6)held significantly better phosphatase,sucrase,urease,protease and catalase activity than the bare field treatment(L6).During the wheat flowering stage,the urease activity of surface soil had significant positive correlation with grain yield.The organic matter of plough layer soil also had significant positive correlation with grain yield.In conclusion,planting and overturning green manures in summer fallow had a trend to increase soil nutrients and enzymes activity.But resulting from the significantly low soil water content before wheat sowing,the green manures treatment reduced one thousand grain weight and grain yield.