Technical and economic investigation of raised bed planting (on high ridge) of irrigated wheat and conventional drills (Case study: Pars Abad county)

Introduction
Wheat is considered as a strategic plant in many countries including Iran. This crop has a special role in feeding and supplying energy to many people in world. In addition to economic aspects, the production of this crop is very important in term of food security. Due to the increase in global population and limited resources, serious efforts are being made to optimize agricultural processes and improve their productivity. In this regard, cultivation on high permanent ridges, known as “raised bed” planting, has been proposed as a new and efficient method in the production of various plants such as wheat. In many regions of the world including Iran, water is the most important limitation in agricultural productions. Raised bed cultivation method can improve water use efficiency. Therefore, in addition to the role of this method in improving yield per unit area, it is possible to produce more product with the available water resources. Also, in this method, preparation of seedbed and deep tillage is only needed in the first year to create ridges, and therefore energy consumption is also reduced in the following years. Regarding the effects of raised bed planting method, several studies have been conducted on different crops in some regions of the world, but due to the lack of consensus among these researches and the low generalizability of the results in the field of agriculture, it is necessary to conduct separate studies for each region and each crop. creates the need to conduct a separate study for each region and product. In the present study, the effect of raised bed planter in comparison with conventional grain drills was investigated on the quality of planting, water consumption, yield, costs, and economic profit of irrigated wheat cultivation.
Materials and methods
To investigate the performance of different planters in a rotation system based on irrigated wheat, an experiment was carried out in a randomized complete block design with three treatments and four replications in Moghan agro-industry, Pars Abad county, Ardabil province, Iran, in 2021-2022 crop year. The treatments included planting with raised bed planter (four rows on a 75 cm width ridge), a typical grain drill (three rows on a 60 cm width ridge), and a grain drill without furrower (seeding + furrowing). The measured traits included field capacity, seed breakage rate, germination percentage, seed distribution uniformity coefficient (horizontal and vertical), water use efficiency, number of spikes per unit area, number of seeds per spike, grain yield and harvest index. Partial budgeting method and final rate of return were used for economic evaluation, and comparison of means were done by LSD test. Excel and SPSS softwares were used for economic and statistical analysis.
Research findings
The results showed that raised bed planting had a significant effect on most of the yield components at 5% probability level, and on harvest index and grain yield at 1% probability level. The highest grain yield (8611.75 kg.ha^-1) was obtained using raised bed planter, which was 7% and 8% more than the second and third planting methods, respectively. The harvest index for these three methods was 47.54%, 42.62% and 41.26%, respectively. The results of the economic analysis showed that the application of raised bed planter was the most profitable. The net profit from these three cultivation methods was 87.85, 51.91 and 42.51 million rials per hectare, respectively. The final return rate of replacement of the raised bed planter compared to the conventional seed drill and the seed drill without furrower was also calculated 123.95% and 173.73%, respectively.
Conclusion
The use of raised bed planter resulted in a significant increase in net profit in the first year, but multi-year studies are needed for a more comprehensive investigation. The need for deeper tillage and the preparation of high ridges in the first year, as well as the high price and low field capacity of the planter, increased the costs of the seedbed preparation and planting operations, but the reduction in seed consumption to some extent moderates this increase in cost. In contrast, the increase in revenue resulting from a significant increase in crop yield was much greater than the cost changes. In addition to increasing the direct profit of farmers, saving water and energy in the raised bed cultivation method is another reason for the preference of this method over the conventional methods, because farmers do not pay the real cost of these two inputs. However, more studies are needed to remove the obstacles to the expansion of this cultivation method.