Design, construction and testing of an ascending micropenetrometer to measure soil crust resistance

摘要

The increasing world population is putting pressure on global food production.Agriculture must meet these growing demands by increasing crop yields. One phenomenonwhich prevents seedling emergence and damages crop yield is soil crusting. Understandingof soil crusting and the factors which influence it is fundamental to ensuring good cropproduction. An instrument which will test soil crust strength in a novel way, mimickingseedling growth, may lead to pre-emptive agricultural soil management which couldincrease crop production. This work details the process of design, construction and testingof an ascending penetrometer to measure soil crust strength. The full design process isdiscussed from concept generation and evaluation, using experimental methods and amulti-criteria decision making tool, through to final design configuration, specification,manufacture and testing.Traditionally, soil penetrometers measure soil strength by forcing a probe from the surfaceof the soil into the bulk soil below. To more accurately measure the direct impedance aseedling would experience a device should measure impedance from the bulk soil upwardsand into the soil crust, mimicking what a growing seedling would experience. Resultsprove that the manufactured ascending penetrometer with a force resolution of 0.01N anddisplacement resolution of 0.0004mm is capable of detecting differences in soil crusts. Atthese resolutions and accuracy to 0.1N and 0.1mm excellent repeatability was achieved.The machine is therefore a useful and realistic tool for quantitatively comparing soil crustsin soil. It is hoped that being able to compare soil crust strength will lead to improved soilmanagement techniques.