DEVELOPING THE METERING UNIT OF THE PNEUMATIC SEEDERS

Abstract

Although, the planting operation was one of earliest farming operations to be mechanized after tillage mechanization, many planting machinery are not available in Egypt to suit most crop seeds, which require expensive and complicated operations after seeding and leads to low yields and high costs (El-Sahrigi -1985). In general, the planter must perform a number of functions to plant irregular seeds in rows or on beds. Metering of seeds is the major and the most critical function. In fact, different mechanism systems can perform this function. Meanwhile, many researchers (El-Shal - 1987), and (Srivastava - 1995), reported that using the mechanical metering mechanisms cause seed damage due to the friction forces between the mechanical parts and the seeds. On the other hand pneumatic metering mechanisms may deal gently with the seeds and no damage during planting can occurr.

The pneumatic planters have limited use in Egypt for many reasons. It has complicated designs, to be operated and maintained, and still not suitable for many seed types. The low pressure values resulting from the dusty air condition of the farms and the relatively high prices also limit their popularity.

Anyhow, the metering devices have to drag seeds from seed box. Then shift individual seed simultaneously a side and fmally push it into feed tubes or directly into the soil in a stream line flow. The proper seed flow characteristic should involve a uniform seed path, a steady pouring of seed mass and accurate seed dispensing. These characteristics are affected by planting uniformity, seed damage and feeding rates.