Effects Of Different Conservation Tillages On Soil Quality In Farmland

In order to reveal the effect of conservation tillage on soil physic-chemical properties,biological characters and crop yield in Guangdong Province,the changes of soil moisture,nutrients,microbial biomass and nitrogen/phosphorus losses were studied in Tianyuan,Lianping and Duhu,Taishan under different tillage measures.Based on the former domestic and foreign researcheson conservation tillage technologies,field experiments were conducted to monitor the changes of soil p H,bulk density,nutrients（organic matter,nitrogen,available potassium,available phosphorus,total nitrogen,total phosphorus,nitrate nitrogen and ammonium nitrogen）,soil microorganisms（bacteria,fungi and actinomycetes）communities and nitrogen/phosphorus losses in deep soils（20-40cm,40-60cm,60-80cm,80-100cm）.The soil physic-chemical properties,biological characteristics,and soil yields were studied to explore the applying effect of co nservation tillage,and its effect on risk reducing of water pollution.The main results of this experiment are as follows:（1）Conservation tillage technology has been considered to be capable of conserving water and soil,and preventing runoff.Four type s of conservation tillage technology were employed in the current study,including no tillage-direct seeding（NTDS）,no tillage-transplanting seeding（NTTS）,minimum tillage-direct seeding（MTDS）,and minimum tillage-transplanting seeding（MTTS）.In Duhu town,soil sampling was performed 4 times during the year of 2016.Comparing with the conventional-tillage soil,it was found that the moisture content of the soil in Duhu were increased by 18.6%,1.7%,12.0%and 18.8%in the soil applied with N TDS,NTTS,MTDS,andMTTS,respectively in the dry land.The higher moisture content is probably due to straw returning to field（SRF）during the application of conservation tillage technology.While as for the paddy field,there seems no significant difference of moisture content between the conventional-tillage soil and conservation-tillage soil.Similar with the dry land in Duhu,the moisture content in the soil collected in Heyuan increased as high as 26.1%.As we know,the moisture content of soil largely depends on evaporation,utilization by plants and transpiration,as well as runoff volume.O ur results revealed that conservation tillage technology can play an important role in reducing evaporation and runoff volume,and conserving water.（2）In general,all the nutrient contents of the soils applied with various conservation tillage was higher than that in conventional-tillage soil.Comparing withconventional-tillage soil,the soil organic matter（SOM）,total nitrogen（TN）,total phosphorus（TP）and available nitrogen（AN）in conservation-tillage soil gradually increased with time prolonged.In Duhu,SOM,TN,TP,AN,and available potassium（AP）increased 13.83%、46.48%、8.81%、27.07%和2.63%,respectively.In Heyuan,SOM,TN,TP,AN,AP,NO₃^--N,NH₄⁺-N,and available potassium（AK）were increased by 3.90%、7.03%、53.92%、157.79%、13.95%、20.57%、12.24%,and43.66%.（3）As for the quantity of soil microorganisms（bacteria,fungi,and actinomyces）,there were no significant differencebetween the conventional-tillage soil and conservation-tillage soil.In Duhu,the quantity of bacteria,fungi,and actinomyces in conservation-tillage soil were decreased by 11.49%、12.76%and 3.94%,respectively,as compared with that in the conventional-tillage soil.However,in Heyuan,the quantity of bacteria,and fungi in conservation-tillage soil were increased by 15.81%和6.13%,and the quantity of actinomyces was decreased by 9.87%as compared with that in the conventional-tillage soil.（4）In Duhu,whenthe fertilizer input was reduced by 15%in conservation-tillage soil,the crop yields per mu was increased by 6.48%.In the meanwhile the production cost was substantially reduced.Based on the calculation,the average production cost per mu for conservation tillage was decreased by 41.96%with the net income increased by 434.24 yuan as compared with the conventional tillage.Thus,it can be seen that applying the conservation tillage technology can increase the economic efficiency,and isbelieved to be beneficial of saving agricultural resourceTo sum up,conservation tillage technology could provide both economic and ecologic advantages because of its effective water conservation,nutrient loss prevention,comparablead sorption capacity,shorter equilibrium time,non-invasive property,high crop yields,and low production costs.