Document Type : Research Paper
Abstract
High intensity evaporation from the soil surface due to low air humidity and poor soil structure and organic matter are constraints of agriculture in arid and semi-arid regions of Iran. Regionally, maintaining plant residue with tillage management is one method to improve these conditions. In this study, for a barley-corn rotation, four barley residue management methods for standing stubble (burning, burying, incorporating and leaving on the surface) were compared over four years at Isfahan Kabootar Abad Agricultural Research Station. The experiment was conducted using a randomized complete block design with six treatments and three replications. The tillage treatments for corn (second crop) were applied to the same plot every year and the plots were conventionally plowed every year for the first crop (barley). The first year results showed that no-tillage treatments reduced the yield due to insufficient contact of seed and soil which caused an inadequate number of seedlings per square meter. However, providing better seed-soil contact in subsequent years resulted in no significant difference in the yield of the no-tillage treatment with other treatments. There was also no significant difference in yield and other crop establishment parameters between the other treatments during the four years of the study. Incorporation, leaving the residue on the surface and burying to a depth of 25 cm resulted in 20%, 18%, 13% increases, respectively, in the average organic matter compared with burning after four years of testing. Results also showed that the earthworm population under the conventional method was significantly lower than for the no-till and reduced-till treatments. No significant difference in root dry weight to a depth of 60 cm was observed between treatments. After four years, the results of the study indicated that the forage corn production under no-tillage and reduced tillage had no adverse effect on biomass yield and can be an alternative method to the current tillage method. Therefore, an annual compilation system that combines conventional tillage for barley and reduced tillage for corn production (after barley) is an alternative to reduce soil moisture evaporation in summer, increase soil organic matter and improve soil structure (increase population of earthworms) instead of conventional tillage operations.
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