Sustainable tillage methods for irrigated wheat production in different regions of Iran

Wheat (Triticum aestirum L.) is widely grown in Iran as a staple food with high nutritional value; so it is important that sustainable tillage systems are used in its production. Conventional tillage methods rely on excessive use of moldboard plows and disk harrows, and are known to cause several types of damage to soils and land in Iran. On the other hand, conservation tillage methods in recent years have demonstrated positive effects on energy consumption, time inputs, erosion control, soil properties, yields and productivity potential. The success of these methods however, varied with different regional conditions, and therefore these differences must be considered in the selection of tillage systems. The main purpose of this study was to identify and evaluate tillage methods for sustainable wheat crop production in Iran under different climatic and soil conditions. The effects of tillage methods on soil physical properties and crop productivity were studied in various parts of Iran (center, south, west and northeast) with average annual rainfall ranging from 230 to 480mm, and soil texture ranging from silty loam to clay loam. In local projects, tillage systems compared were conventional, minimum and no-tillage, chosen according to site-specific conditions. In a nation-wide project, conventional tillage was compared with reduced tillage. The results indicated that obviously the effects of tillage methods differed over the regions, but in practically all situations, reduced tillage methods (chisel plowing) showed promising results. No significant yield reductions were found when compared to the traditional tillage methods (moldboard plowing). The field capacity using a chisel plow increased from 0.50 to 0.75hah⁻¹. On the other hand, no-tillage methods did not produce favorable results, indicating that some degree of soil disturbance is necessary. Conservation tillage by chisel plowing can be recommended in most provinces of Iran but care must be taken that the sowing operation is done correctly.