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Abstract
To study both physical and chemical characteristics of the soil along with yield in different alternatives under the conservation as well as conventional farming conditions of semi-tropical dryland, the present research was conducted in a randomized complete block design with a split-plot method for 4 years with 16 treatments. The experimental tests were carried out at Gachsaran Dryland Agricultural Research Station of the crop year of 2017-18 in four different replications. The main plot was tillage method at two levels of conservation (No-Till) and conventional (moldboard plow + disk harrow) and rotation subplots in 8 levels, including wheat - wheat (control), barley- barley (control), Forage - Wheat, Forage - Barley, Rapeseed - Wheat, rapeseed - Barley, Chickpea - Wheat and Chickpea - Barley in two adjacent phases. In this experimental study, the Karim wheat, the Khorram barley, the Telloe Vicia Sativa, the Adel chick pea, and the Canola Hyola 401 were used and these crops were placed in a 4-year periodic cycle. The results of the combined analysis of the studied factors demonstrated that the periodic options containing wheat and barley including forage, canola, and chickpeas had very favorable conditions compared to the option of continuous cultivation of wheat and continuous cultivation of barley. Therefore, their yield increase in wheat was 19.3%, 18.2% and 20.7%, respectively, and in barley was 18.2%, 18.6% and 10.2%. Likewise, the same, but not identical, trend was observed for plant biomass traits and harvest index. The highest amount of plant biomass in wheat treatments at the rate of 9352 kg.ha-1 was obtained from the forage periodic option. Reciprocally, the highest grain harvest index by 36.6% was obtained from the rapeseed-wheat periodic option. Furthermore, in the treatments containing barley crop, the highest values of plant biomass and harvest index were obtained from the periodic forage and rapeseed-barley options, respectively. In parallel with the obtained results, it was perceived that among different crops and according to their agronomic characteristics and production potential, the highest period of rotation (668 days), land use efficiency (45.8%) and the lowest Production efficiency (38.1 kg.ha-1.day-1) was obtained from the option of continuous cultivation of wheat. It is worth mentioning that the crop rotations of forage, rapeseed, and chickpeas with wheat and barley crops showed the significant desirable values in the aforementioned indices as well as other indices, i.e., production efficiency and economic productivity. Consequently, considering the higher productivity in economic and energy fields, it is recommended that wheat and barley crops not only should be placed in rotation with rapeseed under protective cultivation conditions (without tillage), but also should be utilized in the period of their rotation from chickpea crops and forage, simultaneously.
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