Development of Tractor Operated Cotton Stalk Puller

The implement was designed and developed in a workshop held at the Agricultural Engineering Department, College of Agricultural Studies, Sudan University of Science and Technology between April2011 and June 2012. The implement was constructed from a series of disc blades mounted on a frame. The two discs arranged together with specific space and angles to adapt with cotton stalks pulling operation. The implement mounted on the tractor by three hitches linkage. The field performance test was done for the implementation in Gezira Scheme by measuring the tilt and rake angles parameters, operation speed, pulling operation cost for both systems; manual and mechanical and total cost to product the implement. The experimental design was split plot in a complete randomized block adopted with three replications. The results revealed that the best performance efficiency of the implement (94%) was found at both 30, 20 degrees of tilt angle and rake angle respectively. The suitable operating speed was found to be 2.8 km/h. When estimated, the total cost to achieve the cotton stalks removal per using two systems hand puller and designed implement found that 200,50 SDG required per feddans respectively. The current implement design can be manufactured in both industrial and semi-industrial factories and even small workshops due to design simplicity. Finally it was found that the total manufacturing cost of the implement was 3000 SDG (500$).


INTRODUCTION
Cotton is a versatile fiber crop, grown commercially in many countries throughout the world (Manian et al.,(1999). According to Patil et al (2007) the benefits from using the cotton stalks are ( general such as Renewable raw material to boards industries, Generation of Rural Employment, Many people will be involved on daily wages in collecting, cleaning and chipping cotton stalks, and Industry employs people in factories and transport, and Environmental Benefits.The international length of stem or branch of atypical upland variety exceeds 0.15 m (6 in) under the best of growing conditions, and is usually less than 0.07 m (3 inch) at the extreme. Destruction of old roots and stems is needed to combat plant diseases. Manual pulling of cotton stalks is difficult and time consuming for the manual power which could be devoted to some other productive work. Therefore, planning, and development are needed to develop equipments and methods to meet the requirements of stalks clearing. Cevdet (2009) explained that the chain type 1*Tel:+294912276054 E-mail:massagomi@yahoo.com. 2*Tel:+294122512063 E-mail:taiefg@hotmail.com. stalks chopper which is pulled by a tractor is used methods, cotton stalks and their roots were removed using deep tillage .The roots were therefore buried under the topsoil during forward movement of tractor by passing roots ,whereas the remains were mixed with the soil. The disadvantages of conventional method are therefore spending more money and time to perform deep tillage. El Zubeir (1966) tested a tool carrier single shank and a blade which had 80 cm cutting width and cut two rows at same time. Mahmoud (1968) in his development of stalk pulling machine utilized the idea of cutting roots by a u-shape cutting blade having 36 cm cutting width. Plus a pulling mechanism, which consists of two cylindrical rollers and none of these blades were really satisfactory to provide the first step of cutting the root and the removal of stalks.This research was therefore undertaken in order to overcome this problem. The study main objective is to design and construct equipment for pulling cotton stalks, and evaluate its performance.

Materials and Methods
The research contains two experiments: 1-Design and fabrication of the implement.

Design components and units working mechanism
The implement was designed and fabricated from series of disc blades mounted on a frame or main chassis, figure (3.1). Each two discs were placed in front of each other and were set at a tilt angle. Distance between discs at the nearest point to each other should be equal to maximum diameter of stalks (1.5-2cm). The disc blades used are conical and has outside surface flattened to a specific angle( figure 3.2). The rotary discs were well tangent to increase discs and soil movement ,and although discs were even driven when pulling, stalks from soil are continued.

Figure (3.2): Conical disc.
Discs are fixed on flanges and the flanges are connected to the mechanism by axles, so when the tractor pull the discs, the cotton stalks between two discs will exposed to the pulling forces .Hence, the cotton roots were been loosened and could easily be removed from the soil. The shank is tangent to horizontal beam of chassis. The frame is connected to the tractor by three points hitch, hence rake angles could be adjusted by screwing in or out.

) Cotton stalks after pulling
Performance parameters:-Effective parameters for testing the puller are tilt and rake angles. Parameters test factors were selected in order to determine a range of chosen variable parameter while testing. The effect of their changing was recorded and evaluated. It was well documented that equipment performance parameters is a function of discs penetration depth rate, width of discs, length of stalks, the harvested amount of cotton stalk per hour , disc involvement area, and involvement area conditions. Construction of the equipment which should give these changes was designed. The blades of the equipment are somewhat smaller than those of standard disc plough (0.52m diameter). The minimum proper value of rake angle was found by using three levels of rake angles degrees; (15-20 -25). (Figures 3.6A, B).The maximum allowed rake angle was determined. Rake angle was determined so that engagement zone should remain under the soil while increasing of rake angle. Because of stalks pulling up function would ended in first half of engagement from primary engagement point to middle engagement point, hence the middle engagement point must remains under the soil. Accordingly, the maximum allowed rake angle was calculated. Through increasing discs penetration, the pressure on plates will increase and so will the engagement of discs with soil. Maximum proper penetration depth of discs was determined, which was found equal to effective root depth from 0.06 to 0.15 m. Range of allowed rake angle will be eliminated in each tilt angle. It was found that the result of increasing tilt angle, entrance width increased and pulling up height reduced, hence three levels of tilt angles were used(20 -25 -30) degrees, figure (3.7).Test and evaluation of implement performance was performed using a split plot design experiment with two factors ; Tilt and the Rake angles arranged in a completely randomized block design .The size of plots was equal to the implement width (1.80m) at length of 100.00 m. The distance between plots is 2.00 m. Three replications were used in length way. Each factor was therefore tested and evaluated. In each replication, operation speed was measured by monitoring a stopwatch. A comparison between the implement and the hand pulling was made. Also, the weight of the harvested amount of stalk per hour was determined using a balance.The time required by the implement to achieve the pulling operation was calculated and compared to the hand pulling method using a stopwatch. Also, the total fabrication cost of the implement was determined.

Results and Discussions
The experiment obtained data were analyzed using SPSS software. Analysis of variation (ANOVA) shown in table (4.1) revealed a significant variation of the tilt angle at the 0 .001 level of probability. Also, significant difference between some of the treatments and their interactions were recorded at the 0.05 level of probability.  Table (4.2) below shows that the maximum percentage of pulled stalks (94%) is related to third factor of tilt angle treatment (30degree) and is significantly different with others. As shown in the figure (4.1), the results showed that the pulled after Tilt 25degree increased and reached the maximum at Tilt 30 degree in agreement with the results of Mostofi (2008). Also, the results agreed with kepner et al., (1992), who stated that performance of 30 -32 degrees shows the best equipment performance. Therefore, the appropriate selection for the tilt angle is 30 degrees.  The levels of rake angle treatments in are shown in table (4.6), which reveals that there is no significant difference between selected angles. But, the maximum percentage of pulled stalks (89.1) is at 20 degree.

Figure (4.2) pulled stalks (%) -Rake angles
Interactions of tilt angles and rake angles are significant at the 0.01 level of probability and it's less than probability and that explain the maximum percentage of pulled stalks. In the level of tilt angle 30 degree selected with a rake angle 20 degree, it was found that the efficiency percentage of the pulled stalks was 94%.

Working speed , harvested amount of cotton stalks and Cost of the implement:-
The tractor speed was 2.80 km/hr and so the time required to pull out the stalks in one Hawasha is 3 to 4 hours while the hand pulling needs about 7 to 8 days. The harvested amount of cotton stalks per hour manually and by using the equipment was found to be 430kg and 5160kg, respectively. The fabrication cost of the implement is 3000 SDG (500$) and the cost required to pull out the stalks per faddan by the equipment is 50 SDG while the work using manual pulling needs 200 SDG.