| Lime concretion black soil,a kind of medium and low-yielding soil,has shallow topsoil.It is a new way to solve the problem of low yield on Lime concretion black soil by eliminating,using the current technology,the negative impacts of shallow topsoil.The field trail was conducted in Suixi Wupu farm in Huaibei to study the effects of different treatments on the improvement of soil fertility under the condition of shallow topsoil in 2012-2014.There were 2 kinds of topsoil thickness(15cm for thick topsoil,10 cm for shallow topsoil)in the experiment.8 treatments were designed as CK(thick topsoil,conventional tillage),CT(shallow topsoil,conventional tillage),NT(shallow topsoil,no tillage),DT(shallow topsoil,deep tillage),CTS(shallow topsoil,conventional tillage +straw),NTS(shallow topsoil,no tillage +straw),DTS shallow topsoil,deep tillage+straw)and CTF(shallow topsoil,conventional tillage+pig manure),with 3 replications and randomized block design in order to study their effect on crop yield,nutrient absorption and soil fertility.The main results are as follows:1)The shallow topsoil has negative impact on crop yield and different impacts on soil fertility.Compared to CK,CT got yield decreased by 3.07%,1.35%,12.01%,2.69%,except the 4th season.Especially,it had significant difference in the 3rd season.Shallow topsoil didn't have any significant effects on the soil physical and biological properties,but on the chemical properties: compared to the CK,soil total nitrogen content of CT was reduced by 1.06%-7.22%,having significant difference in the 4th season and soil readily available potassium got reduced by 8.13%-19.34%,having significant difference through all seasons.2)Only changing cultivation measures could not eliminate the negative effects of shallow topsoil obviously.In the aspect of production,in the maize seasons(the 1st,3rd,5th season),NT could partly weak the negative effects of reducing the topsoil,having a increase trend on yield,which wai better than DT,while it was not obvious in the wheat seasons(the 2nd,4th season).DT got significant reduction in the 3rd season due to inclement weather.In the aspect of soil fertilities,NT had certain effect on improving soil bulk density and readily available potassium content,but DT had no significant increase on both.Different cultivation measures and organic material input had good synergia on crop yield.Compared with CK,CTS and NTS got better yield in all 5 seasons.The increase rate of CTS was between 3.14% and 14.61%,and the same of NTS was between 0.98% and 13.53%.The 2 kind of increase were bothsignificant in the 4th and 5th season.DTS got increase production started from the 3rd season and the rate was between 7.22% and 8.39%,but not significant.CTF got significant increase of yield in the last season of maize(the rate was 10.06%)and both2 wheat seasons(the rates were 14.36% and 29.92% respectively).3)Different cultivation measures and organic material input could improve the physical properties of soil.Compared to CK,all the treatments had no significant differernce on soil bulk density and porosity.The treatments of straw mulching and pig manure had got significantly increasing on the soil water content,on which CTS and NTS did better.CTS and NTS also increased soil water storage significantly..Straw mulching and using pig manure could increase DMWD and WMWD value and increase content of >0.25 mm elastic-stable aggregate and >0.25 mm water stable aggregate in the mass.NTS,DTS and the CTF could decrease rate of structure deterioration and index of unstable aggregate significantly.4)Different cultivation measures and organic material input had different effects on soil nutrient and enzyme.Straw mulching treatment can basically eliminate the negative impact on total nitrogen content caused by shallow topsoil.However,using pig manure could significantly increase the soil total nitrogen content.In terms of increasing organic matter,straw mulching treatments got significant aftereffect;organic fertilizer treatment could remove the negative effect caused by the shallow topsoil and the synergia was rising along with the increasing length of test.In term of readily available potassium,straw mulching treatment could relieve the negative effects of reducing the topsoil in a certain extent,NTS and DTS treatment were better than CT;Organic fertilizer treatment can completely eliminate the negative effects of shallow topsoil,increasing significantly readily available potassium content.In item of enzyme,compared with CK straw mulching treatment could significantly increase the activity of soil urease,invertase and catalase except DTS.CTF had significantly increase in activity of invertase and catalase.5)Correlation analysis showed that organic matter,total nitrogen,readily available potassium,sucrose all had significantly positive correlations with yield.While all the physical properties of soil had no significant correclation with yield. |
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