| No-tillage seeding system is one of the conservatives and sustainable agriculture,which has been continuously the axis of attention to many farmers,researchers and policymakers in R-W rotating system in China.Straw cover has many benefits(e.g.increased resistance to wind and water erosion),but also has several defects.The dense straw left on the soil surface after rice harvesting makes direct seeding of wheat difficult and non-uniform.Researchers indicated that,in direct seeding operation,failures of the furrow openers to drill through a large amount of straw resulted in the seed being placed either in the straw or on the soil surface,which leads to poor germination.Therefore,development of straw cutting tools could be of immense contribution to successful direct seeding operation in such conditions.Keeping all these facts in view,this research contains two parts of study,the first part was designed to develop a precise and easy-to-handle field method to estimate the percent of ground cover and develop more suitable plain disc coulters for cutting the straw under direct seeding system.The second part includes studying the performance of one of the vertical tillage plows that are used in conservative tillage to leave a consider amount of straw on the soil surface.The results are generalized as follows:1.The method to estimate the straw ground cover percent in fieldEstimation of crop straw left on the soil surface is one of the fundamental requirements in numerous agricultural practices,such as assessing the possibility of different tillage tools in conserve crop straw.There are many techniques for estimating straw covering the soil;however,most of them are not only strenuous and consume time but also affected by human errors.In this study,a method that can be used to measure the percentage of straw covers was developed using image processing techniques.The study included two different types of straw conditions,single flat straw(SFS)and standing with flat straw together(STWFS).In SFS,six different straw densities were considered(10006000 kg/ha)and a 1 x 1 m frame was used to control the straw density and pictures were captured.Straw was redistributed inside the frame six times and pictures were taken in each time;this process was repeated in All straw densities.In STWFS,a frame of 0.5 x 0.5 m was placed at three different points in the field,each point covering all the harvester's width and pictures were taken,this process was repeated in three different fields,each field harvested with a different harvester.The characteristics of the camera used to acquisition images were:Nikon D3200 digital camera(1920×1080 pixels).Image subtraction technique and Otsu's method were applied using imsubtract function in MATLAB R2019a.Straw coverage percentages against the weight of the straw per unit area were collected from the image-based technology.The mean relative percentage error(MRPE)was applied to measure of how accurate a prediction system is.The results of SFS show that there is a good correlation between the weight of straw and coverage area(R2=0.9838).The MRPE was 3.3%.Also,the percentage of the straw cover increased with the straw mass increasing,and it was almost 100%when the straw mass reached 6000 kg/ha.STWFS results showed that there is no significant difference(P>0.05)between the mass of standing and flat straw for the three harvesters,while there is a significant difference(P<0.05)between the ground cover percent.The coverage percentages were 69,89,and 71%when the straw masses were 6738,6755,and 6940 kg/ha respectively.The higher the coverage percentage indicate to higher uniformity of the straw distribution.It can be concluded that this technique is practical,easy and fast in determining the amount of straw on the soil surface in case of the soil surface is not completely covered.2.Plain disc coulter equipped with press-wheels for cutting straw under direct seeding system.To investigate the developed plain disc coulter on the straw cutting process under conditions of direct seeding system,a series of laboratory,soil bin and field experiments were carried out on the laboratory and experimental field of Nanjing Agricultural University.The purpose of this work is to study the effect of soil moisture contents(SMC),straw moisture contents(STMC),straw density(STD),operating depths(OD),Thickness of the knife blade(TKB),and press-wheels on the percentage of straw cut(PSC),amount of straw pushing into the soil(hair-pinning),horizontal and vertical forces requirement.To simulating disc coulter equipped with two press-wheels,cutting knives and a pair of clips for holding the straw on both sides of the knife(fixed-ends straw)were fabricated and used during the laboratory experiment.TMS-PRO measuring instrument was used in the laboratory experiment.Five straw moisture contents(STMC)(10.11,18.9,34.29,46.83 and 54.80%),three different number of straw pieces(NSP)(1,2 and 3),five soil moisture contents(SMC)(16.17,19.28,22.26,26.18 and 30.16%)and three different Thickness of the knife blade(TKB)(1,1.5 and 2 mm)were considered during the experiment.In the soil-bin experiment,the plain disc coulter was equipped with two press-wheels to hold straw on both sides of the disc coulter during the cutting process.The performance of the disc coulter with and without press-wheels was evaluated on a wide range of SMC,from 16 to 32%;STD,from 3000 to 5000 kg/ha;OD,25 and 50 mm,at forward speed of carriage 2.5 km/h.Similar experiments were conducted on the field with two soil moisture contents(23.7 and 27.4%).The results obtained from the laboratory experiment show that the freeends straw was pushed into the soil(0%PSC)when the SMC was greater than or equal to 22.26%,or the STMC greater than or equal to 46.83%for all TKB and NSP.In the case of fixed-end straw,the PSC was 100%at all STMC,SMC,NSP,and TKB.The results also show that the cutting force for both(free and fixed-ends straw)increased with the increase of the STMC,NSP and TKB.Although the SMC had a considerable influence on the freeends straw cutting force requirement,it did not significantly affect(P>0.05)the force requirement to cut the fixed-ends straw.The effect of SMC on the fixed-ends straw was in the depth needed to cut the straw,the straw was cut at depths of 11.5,19,and 23 mm,when the SMC was 22.26,26.18,and 30.6%respectively.The soil-bin results showed that the PSC was 87-100%and 100%with press-wheels at 25 and 50mm OD,respectively,while it was 0-76%and 0-83%without press-wheels,these at soil moisture contents(32-16%)and straw densities(5000,4000 and 3000 kg/ha).In the field results,the PSC was 81-100%and 100%with press-wheels,while it was 0-37%and 0-51%without press-wheels at both moisture contents(27.4 and 23.7%)and all straw densities(5000,4000 and 3000 kg/ha).Both field and soil-bin results showed that with press-wheels,the hair-pinning was 0%,but without press-wheels,was increased with increasing SMC and/or SD and it reaches 100%when the soil moisture content was greater than or equal to 27.4%at all levels of straw density.Also,the results revealed that there are no significant differences(P>0.05)in horizontal and vertical forces.With exception of 50 mm depth when was used with press-wheels,the percentage of straw cut was decreasing with increase in soil moisture content and/or straw density.We concluded that,the plain disc coulter with press-wheels provided the highest PSC(100%)at 50 mm OD and expressed optimum performance compared with other conditions.3.Quantifying performance of chisel plow in heavy clay soilThe main objective of this study was to quantify the performance of chisel plow in heavy clay soil.The performance of chisel plow was evaluated by the change in the degree of field surface leveling(SL),mean weight diameter(MWD),ratio of unplowed area(UA),the remaining residues on the surface(RS),the percent of cutting weeds(CW),field capacity(FC),field efficiency(FE),draft force(DF)and slippage.Field experiments were carried out in the experimental field of Gezira University,and the laboratory experiments were conducted in the Faculty of Engineering,Khartoum University,Sudan.Traditional and factorial methods were used to carry out the field experiments.The data obtained were processed and evaluated by mathematical and statistical standard methods.The results revealed that MWD,UA,RS,CW,FC,FE,DF and slippage at working speed from 3.34 to 5.85 km/h at 20 cm depth were 22.96-19.35 mm,45%,36.25%,86.96%,0.59-1.0 ha/h,89%-86%,5.8-6.4 kN and 6%-9%respectively.However,for working speed from 3.34 to 5.75 km/h at a depth of 15 cm the outcome for MWD,UA,RS,CW and DF were 18.06 to 17.44 mm,33%,36.25%,86.96%and 4.5 to 5.6 kN respectively.The results also showed that the minimum value of specific draft at each working speed was at the critical depth(12.2 cm).The results also revealed that the quality of the chiseling process depended on the working speed and depth of cut.The aggregate size of the soil after chiseling decreased with increasing working speed.The draft force was more affected by the plowing depth than the forward speed.The chiseling process positively affected SL,in such that it decreased the unevenness of the soil surface.The average slippage of the chiseling process for this chisel plow under the conditions of the heavy clay soil was found to be 7.71%. |
PDF Full Text Request