Effect of Tillage Systems and Different Crop Rotations on Yield and Yield Components of Wheat (Triticum aestivum L.)

Correct crop rotations selection and suitable tillage systems, and also considering the interaction of these two factors play an important role on the yield crops, especially wheat. Conservation tillage methods, considering the resource use efficiency in crop rotation (instead of efficiency of a single crop), are the focus of sustainable agriculture. The proper balance of nutrients in the soil, increase of soil organic carbon, prevention of erosion, prevention of soil compaction, improving soil structure, reducing weeds and increasing soil water holding capacity are the beneficial effects of the proper crop rotations and suitable tillage systems.
Material and A three year study (2011-2013) was carried out in the agricultural research station of Ardestan city located in 125 km North East of Isfahan (32º 50' N and 50º 34' E) using split plot, based on a randomized complete block design with three replications. Conventional tillage systems (moldboard plow), minimum tillage (a field cultivator) and no-tillage were the main plots and rotations of (Barley - corn - wheat), (Canola - sunflower - wheat), (Fallow - sugar beet - wheat), (Wheat - fallow - wheat), (Canola - fallow - wheat) and (Canola - corn - wheat) were the sub-plots. Comparison of the yield of wheat in different rotations was made in the last year rotation.
The results showed that wheat yield in conventional tillage and minimum tillage techniques was equal with 4531 and 4340 kg ha-1, respectively, being 33.8 and 28.1% more than the no-till method. In conventional tillage systems, yield of wheat in (barley - corn - wheat) and (canola - corn - wheat) rotations were equal to 4129 and 4118 kg ha-1. In the no tillage system, small canary grass (Phalaris spp) with 1485 kg ha-1dry weight significantly produced more dry matter than the other two systems. Among the rotations (Canola - sunflower - wheat) rotation, with 1.05 kg m-3 and 52.6 percent water productivity index and land use efficiency, respectively, was one of the best rotations.
Effect of tillage system depends on the type of crop rotation, soil type and climatic conditions. Successful adoption of no-tillage system (compared to conventional tillage) is more probable in cases where crops used in rotation with fast decomposed remnants (e.g. potatoes) improve soil conditions (e.g. sugar beet) or control weeds (e.g. sunflower).