Seedlings Emergence in Compacted Soil as Measured by a Pressure Transducer

Abstract

Research was conducted to obtain an instrument for a more precise method of measuring seedlings emergence, also to indicate the amount of pressure exerted by seedlings before emerging to the surface, hence the design and fabrication of a data logger capable of measuring and logging the pressure exerted by seedlings of maize (hypogeal) and okra (epigeal) in emergence study on compacted Egbeda soil series (Ultisol). The PIC18F4550 Microchip microcontroller unit serves as the heart of the data-logging system, while seedling emergence pressure was determined using MPX5050DP pressure sensor (0-5000 milibar). The date and time were monitored with DS1307 RTC (Real Time Clock) timer, 24LC512 a 512 kbit EEPROM was used as the storage unit and LCD LM016L was used as the display unit. The circuit was designed with Proteus ISIS. The software that interfaced the design with computer was designed with Microsoft Visual Studio using Visual Basic.NET. The experiment was conducted at the departments of Physics, Civil Engineering and Soil Science and Land Resources Management of Obafemi Awolowo University, Ile-Ife, Nigeria, between August, 2013 and June, 2014. The emergence experiment was conducted with soil treatments consisting of four levels of soil compaction (0, 5, 15, and 25 blows of a standard proctor rammer of 2.5 kg; light BS 1377, equivalent to 0, 39, 116 and 193 kJm-3 respectively), at 0.12 g/g moisture content, and replicated three times in a completely randomized design. The results showed that soil strength had significant (p = 0.05) effect on percent seedlings emergence and pressure exerted by seedlings, percent seedlings emergence was negatively correlated (p ≤ 0.05) with pressure exerted by seedlings. Positive correlation (p ≤ 0.05) was also observed between soil strength and pressure exerted by seedlings at emergence as measured by the pressure transducer. Therefore the pressure transducer provides an alternative method of measuring seedling emergence as against indirect method being used.