Spray deposit uniformity of a 'dual' field sprayer assessed with a new optical device.

摘要

On modern field sprayers, pesticide distribution is manually controlled by valves or, more frequently on high-level machines, by computer-controlled electro-valves. To evaluate the operative improvements obtained by using a computerized sprayer, a "dual" machine was set up. The sprayer was fitted with two separate assemblies, manually and computer-controlled, including tanks, pumps, filters, and pressure/flow control devices. The system was tested on a flat, smooth track and in the field. The distribution uniformity was checked in both favorable and severe conditions, such as working on slopes, traveling at high speeds on rough soil surfaces, or when traversing dips and humps. In particular, the pesticide distribution tests in the field were carried out on slopes with different gradients. A solution of Tartrazine diluted in water was sprayed, evaluating its concentration on absorbent cellulose collectors attached to boxes placed on the ground. A new optical device was developed specifically for measuring Tartrazine concentration. The results showed that the computerized system was better able to control the flow rate because it compensated well enough for sudden and unpredictable variations in travel speed. On the contrary, the mechanical pressure control system displayed operational limitations under the same working conditions. It was only under extremely severe conditions (i.e., large gradient variations) that the boom controlled by the computer did not show a response time sufficient to correctly adjust the flow rate.