Abernathy,GH. 1975. Tillage systems for cotton- a comparison in the U. S. western rigion. California Agricultural Experiment station. Bulletin No. 870. 27p.
2- Ahmed, MH. and Haffer, I. 1993. Comparison of five tillage systems for cotton production in Rahad Scheme. Sudan. Journal of AMA. 24, 17- 20.
3- Anon. 2002. Agricaltural statistical bulletin of Jehade- Agriculture ministry. Tehran. Iran. Crop year. (In: Farsi)
4- Balla, P. M., Ratislav. and Dana, K. 2000. The influence of varius soil tillage technologies on the energy balance of production process. The research institute of agrecology. Michalovce. 5p.
5- Bowers, G. 1986. Tillage energy requirements. Paper, ASAE. No. 86. 1524, 23p.
6- Eskandari, A. 2002. Comparison of different tillage methods on wheat yield after harvesting chickpea in dry land areas. J. of Agric. Eng. Res. 11(3): 57-73.
(In: Farsi)
7- Eskandari, A. and Hemmat, A. 2003. The effect of subsoiling on conservation of soil moisture and wheat yield in dry land. J. of Agric. Eng. Res. 14(4): 1-19. (In: Farsi)
8- Eshaghbeygi, A., Tabatabaeefar, A., Raofat, M. H. and Keyhani, A. 2002. Development and field evaluation of an oblique blade subsoiler and comparison of performance whit a conventional L- shape subsoiler. Agric. Sci. 12(3): 67-82.
(In: Farsi)
9- Johnson, J. R and Saunders, J. R. 2003. Cotton plant response to tillage systems. Annual Report 2002 of the north Mississippi research center. Information bulletin. 398, 122-124.
10- Johnson, J. R and Saunders, J. R. 2004. Tillage system for cotton. Annual Report 2003 of the north Mississippi research center. Information bulletin. 405, 152-154.
11- Jones, A. J. 1996. Subsoiling in Nebreska. NE. Coop. Ext. Serv. NebGuide
G96-258.
12- Jones, A. J., Dickey, E. C., Eisenhauer, D. D. and Wiese, R. A. 1987. Identification of soil compaction and its limitations to roots growth. NE. Coop. Ext. Serv. NebGuide G87- 331.
13- Jones, A. J., Grisso, R. D. and Shapiro, C. A. 1988. Soil compaction fact and fiction, common questions and their answers. NE. Coop. Ext. Serv. CC 342.
14- Khalilian, A. 1983. Soil strength and cotton yields from five tillage systems. Paper, ASAE. No. 83. 1023, 17p.
15- McCloskey, W., Husman, S. and Ottman, M. 2003. Conservation tillage benefits in a cotton- centered crop rotation system. On line http://wsare.Usu. Edu.
16- Musick, JA. 1985. An economic evaluation of selected cotton production practices, on a silt- loam soil in Mississippi. Proceeding of Beltwide cotton production. Research conference, New or Leans. 245-248.
17- Norozieh, SH., Tabatabeefar, A. and Ghorbani Nasrabad, GH. 2002. Effect of spiring subsoiling on soil compaction and cotton yield. Proceeding of the Second National Congress of Agricultural Eng. And Mechanization. (In: Farsi)
18- Randy, L. R., Reeves, D. W. and Grift, T. E. 2003. Effect of site- specific tillage on draft requirements and cotton yield. Beltwide cotton conferences. Nashville.
TN-January 6-10.
19- RNAM. 1995. Test codes & procedures for farm machinery. Published by UNIDO. PP7.
20- Rozbeh, M., Dehghanian, S. E., Boostanifar, M. and Hekmat, M. H. 2003. The effects of subsoiling and irrigation frequency based on crop water requirements on cotton yield in Darab. Final research report. (In: Farsi)
21- Rozbeh, M. 1999. Evaluation and comparison energy consumption for several tillage methods. M. Sc. Thesis. Chamran University. Ahvaz. Iran. (In: Farsi)
22- Shafii, A. 1992. Principles of farm machinery. Tehran university pub. Tehran. Iran. (In: Farsi)
23- Smith, D. W., Sims, B. G. and Oneill, D. H. 1994. Testing and evaluation of agricultural machinery and equipment. Published by FAO.
24- Solhjou, A. and Loghavi, M. 2000. Optimum moisture content for determination of cone index, whit cone penetrometer. J. of Agric. Eng. Res. 5(17): 43-50. (In: Farsi)
25- Solhjou, A. and Niazi, J. 2001. Effect of subsoiling on soil physical properties irrigated wheat yield. J. of Agric. Eng. Res. 2(7): 65-79. (In: Farsi)
26- Solhjou, A., Loghavi, M., Ahmadi, H. and Rozbeh, M. 2001. The effect of moisture content and plowing depth on soil polverisation and reduction of secondary tillage. Journal of Agricultural Engineering Research. 2(6): 1-13. (In: Farsi)
27- Walworth, J., Roth, R. Husman, S. and Wilson, P. 2002. Minimum tillage systems for cotton: Reduced energy, time and particulates. On line http://wsare. Usu.
Edu.
28- Zarif Neshat, S. 2003. Effect of land preparations in dry and wet planting on cumin yield. J. of Agric. Eng. Res. 4(16): 29-43. (In: Farsi)