Sustainable Tillage Methods in Irrigated Wheat Land for Different Regions of Iran

Several tillage methods were compared in different regions of Iran suchas: Isfahan(central), Shiraz (south west), Mashhad(North east) and Hamedan(west). InIsfahan (central), seven different tillage methods were compared during four years. InHamedan, four different tillage methods were studied for fall wheat within 3 years. InMashhad, four different tillage depths and four different moisture contents werecompared over 3 years. In Shiraz, seven different tillage methods on wheat yield werecompared in 4 years. A national study on possibility to use surface tillage in irrigated wheat land comparedto conventional method using moldboard plow was conducted in six different regions(Shiraz, Mashhad, Eastern Azarbayjan, Karaj, Golestan, and Khuzistan) for five years. Varied tillage methods have shown different yield but statistically was not significant.No till (direct drilling) and minimum tillage indicated significantly lower yield thereforecould not be recommended as a favorite system for wheat production. Chisel plowing(reduced tillage system) has shown promising performance and can be recommendeddue to higher field efficiency. Chisel plow (in spring) + disk + leveler in fall noted to be asubstitute for moldboard plows because of higher coefficient of harvest and fieldefficiency. In terms of deep tillage, subsoiling to the depth of 35 cm plus moldboard plow hadthe highest yield and the effective treatment for reducing CI by 12.8 % and increasingyield by 3.8 %. The moldboard plowing (conventional method) had the lowest yield. Dueto high cost, energy consumption and statistically no significant difference betweentreatments, subsoiling for wheat production would not be recommended. Maximum grain yield was obtained at 10 to 15 % moisture content and tillage depthof 10-15 cm (Mashhad). Optimum moisture content for tillage in Zarghan and Darabareas was 15 - 18 % and 13 -15 % respectively. However water irrigation methods mustbe study in detail in order to reduce water consumption. Shallow tillage noted as a good substitute for moldboard plowing because of lowerenergy consumptions and time saving. The suitable moisture content for surface tillage(disking) is about 10-15 %. The effect of year was significant on different regions due torainfall variation, temperature differences, and soil nutrition changes over the years. Itwas proved that for shallow tillage, crop residue is the main problem which planter mustbe modified with a sharp furrow opener. It is also recommended after each three years ofsurface tillage a moldboard plow or deep tillage operations can be used for weed control.