Majallah-i Chughundar-i Qand (Sep 2013)
Determination of the number of working days of mechanized planting and semi-mechanized harvesting of sugar beet in Nahavand region
Abstract
A study was conducted to determine the appropriate number of working days in mechanized planting and semi-mechanized har-vesting of sugar beet in Nahavand city, Iran in 2010. The most important limiting factor for agricultural operations in agricultural calendar is the time of operation which is a function of soil moisture for some operations such as ploughing. To determine the number of working days, the parameters considered in this study included determination of the proper threshold for the most ef-fective limiting factor in mechanized planting and semi-mechanized harvesting of sugar beet, determination of the factors affect-ing the limiting factor and also to determine the probability of the number of days appropriate for mechanized planting and semi-mechanized harvesting of sugar beet. The allowed limit of soil moisture in clay-loam texture, for having the capability of running field operations was determined to be 14.5% of the weight. In this limit, soil has acceptability of 6.34 mm of water (rainfall) for sowing and 10.62 mm for harvesting at the depth of operation in each turn of rainfall or irrigation. Factors influencing the soil moisture changes are the amount and intensity of rainfall, soil drainage, moisture content percentage in air, evapotranspiration, soil surface runoff, the rate and intensity of solar radiation (day and night length), ambient temperature, the rate of crop cover, and the soil profile. At sowing and harvesting times, 19.3% and 7.5% of the rainfall is converted to runoff. Therefore, the maxi-mum allowable rainfall in a situation that doesn’t change the soil condition from the proper situation for mechanized sowing and harvesting operation is 7.6 and 11.41 mm, respectively, in each rainfall turn. For the drainage of excess moisture after rainfall, in sowing and harvesting operations, five and seven days are required, respectively. The number of working days for mechanized planting was estimated about 20 days, and for semi-mechanized harvesting was about 23 days with 99% confidence.
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