Experimental Research On The Cffect Of Straw Incorporation With Rotary Tillage

Straw reserves in China is huge but its utility is low.This situation is even worse in the South China where multiple crops are rotated to produce high amount of straw.The quick crop rotation led to the waste of crop straw in the field.Incorporation of straw into soil can not only solve the problem associated with the dense layer of straw cover in the soil surface,but also is a major management practice for the improvement of soil structure,soil fertility and an effective measure to the reduced fertilizer application.Straw incorporation is thus a beneficial way for saving the shift time window in conservation agriculture.The mainstream of straw management is thus to incorporate it into soil.In Jiangsu province,the primary tillage implement used for straw incorporation is rotary tiller.The paper thus investigated straw distribution in soil surface and the performance of straw incorporating with rotary tiller.Refined measurement and testing method were proposed to assess straw mixing status in the soil,with results to be used as practical and theoretical basis for straw incorporation with rotary tillers.The main achievements include:Experimental platform for rotary tilling was constructed,which is composed of mechanical lifting system,transverse and longitudinal transportation mechanism,traction system and braking system.The field trial test revealed that the constructed platform provided desirable control on a number of parameters.Both forward and up-cutting can be achieved on the rotary tiller.The rotary tiller can be tractioned in both direction and its draft,energy consumption can be monitored.The same measurement can be implemented on other tillage tools,including mouldboard plough or subsoilers.Repeated use proved the system stability and operational convenience.Measurement of mass-covering index relationship of straw layer on the soil surface proved that no relation exists between straw covering index and straw mass,proving that straw covering index is not a suitable parameter for straw cover assessment.In addition,both image processing and line interception methods were unable to measure the real condition of straw distribution in the field.New method was designed to measure post-harvest straw distribution on soil surface for harvester models as Xinjiang Gushen 4LZ-2.5,Xingguang 4LL-2.0D and Wode 4LZ-4.0G.The result showed that straw mass distribution and covering index can be used to evaluate straw covering condition after mechanical harvest.It was shown that different harvesters led to different straw conditions,which led to varied straw incorporating effects.Measuring and analyzing method for straw distribution in soil was proposed.A digitizer was constructed to measure straw distribution in soil,which illustrated that Pro-E modeling was able to visualize straw distribution status in the soil.Section of sampled space both longitudinally and vertically can quantify straw distribution in soil space,avoiding the disturbance introduced from soil sectioning directly.Soil space was divided into grids and statistical calculation was done in Matlab to acquire curve fitting,with inclination could be used to assess the distribution uniformity of straw in soil.Lower inclination stands for more uniformity of straw distribution in soil.The forward rotation and up-cutting of rotary tiller had different effect on straw distribution of straw in soil.Under the same working parameters,forward rotation led to more uniform straw distribution in soil than up-cutting.But the up-cutting resulted into a more uniform of straw distribution along the depth,also the soil-straw mixing status was improved which would be more desirable for straw decomposition.The longitudinal straw distribution in soil from up-cutting was worse than the forward rotation,which was due to the instability of the working condition and the soil piling ahead of the rotator.Overall performance of up-cutting for soil fragmentation,straw inclination and soil surface leveling was better than the forward rotation,but with its drawbacks of severe soil piling and straw inclination to the rotator.A major portion of straw was moved to the ahead and the two sides of the rotary tiller.Composite analysis revealed that forward rotation is superior than the up-cutting.However,straw density is a major concern when the correct selection of rotator tillers was to be made.Straw length was proved to have significant effect on straw incorporating performance.Comparison on the 5cm.12.5cm and 20cm straw length proved that longer straw length resulted into a better soil surface condition.But in view of the straw distribution uniformity in soil,the straw length was not correlated with the quality of straw distribution in soil.This indicated that the uniformity of straw distribution in soil can be achieved when proper length of straw is used,but not a shorter length.