Document Type : Research Paper
Authors
Dryland Agricultural Research Institute (DARI), Agriculture Research, Education and Extension Organization (AREEO), Maragheh, Iran
Abstract
Introduction: Harvest loss is one of the main challenges in wheat production systems. More than 75% of harvest losses are related to the header loss which is influenced by various factors such as defective cutting blade and unsynchronized speed between the combine forward with reel speed and plant density. The low performance of wheat combine harvesters has always existed and yield losses during harvesting will result in less income for the farmers. Therefore, estimating the amount of harvest losses within different parts of the harvester and determining the factors affecting yield loss according to the actual situation of mechanized wheat harvesting is important for the effective reduction of harvest losses.
Methodology: The Present study was performed at the research station of Dryland Agricultural Research Institute (DARI) located at Maragheh during the 2020-2021 cropping season and 18 dryland winter wheat fields were assessed for estimating harvest loss. The soil tillage system was carried out as minimum tillage and sowing rate was 380 plant m-2. Harvest losses were measured separately for head losses, cleaning losses, and beating losses. John Deere 1055 and 955 combine harvesters were evaluated in this study. Seasonal services of the harvesters were performed before the experiment and its technical health was ensured. Each plot area was 120 m2 that the head losses and yield estimation were evaluated in half of the plot (60 m2) and the other half of the plot was devoted to the estimation of cleaning and beating losses. Also, to determine the effective factors in the rate of losses of different units, forward speed, linear speed of the Reel, spike density, crop yield, and grain moisture were measured at the harvest time.
Research findings: The results showed that the loss of cutting unit had the largest share of harvest loss with 89%. By implementing the correct settings of the cleaning and beating units and choosing the right harvest time, as well as choosing reel speed (RS) in accordance with the forward speed (FS), the head loss was reduced by 0.45% and the total loss was reduced by 0.51%. Head losses increased with a decreasing ratio of RS/FS (V2/V1) and the lowest head loss was obtained at a relative speed (V2/V1) of 1.6-1.8. By reducing the FS to 2 km/h and increasing the relative speed (V2/V1) to values greater than 2, as well as by reducing the relative speed to 1.36, head losses increased sharply. In other words, by adjusting the FS according to the spike density and stabilizing the relative speed (V2/V1) in the allowed limit (1.6-1.8), as well as making the correct adjustments of the winnowing and threshing system, the losses of the combine were reduced to less than 1%. To reduce the losses of the cutting unit, it is necessary to design and install the relative speed (V2/V1) stabilization system for grain harvesters.
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