Soil physical properties and crop response in direct seeding of spring barley as affected by wheat straw level

Abstract

The outcome of direct seeding is influenced by sowing technology and residue management, and by water disposal in semiarid conditions. Most studies regarding direct seeding include little information about the amount of residue at sowing time. This paper shows the results of a no-till seeding of barley (Hordeum vulgare L.) with different levels of wheat (Triticum aestivum L.) straw. Experiments were carried out from 2012 to 2015, and treatments consisted of three different wheat straw levels to represent three common scenarios depending on the way farmers manage straw. Bulk density and soil moisture content were measured at three different stages: germination, anthesis, and tillering. Measurements included sowing depth, emergence rate, yield, and harvest index. Soil moisture was related to residue level, with higher soil moisture in plots with higher amounts of straw, reaching a maximum increase of 39% in 2015 at the stage of tillering, when minimum water content was present. Similarly, the lower significant differences in soil water content between residue levels were found when soil had higher water content values. Emergence rate was affected by residue level in all years, and rates had a maximum variation in 2013 when they ranged between 31.7% in the highest level of residues and 81.8% in residue removed plots. Yield was affected by residue level, mainly in years 2013 and 2014 when the lowest production of grain took place, with a minimum of 35% decrease in plots with highest amount of straw. No effect on harvest index was observed in this experiment. A higher amount of residues positively affected soil water content, but it decreased plant emergence rate. Consequently, yield was negatively affected by the level of residue cover. Therefore, removing excessive crop residues in spring barley can be a good practice in rainfed conditions and warm Mediterranean climates.