Lucas H P Silva

Monitoring subsoil temperature ( T ) and relative humidity (RH) is crucial for optimizing agricultural productivity and ensuring sustainable farming practices. However, existing commercial data acquisition (DAQ) systems are often expensive and inaccessible to small-scale farmers. This study presents the development and real-world deployment of an affordable DAQ (A-DAQ) sensing system for monitoring subsoil T and RH. Designed with a modular approach, the A-DAQ system integrates three types of sensors: DS18B20 ( T only), HDC1080 ( T and RH), and DHT22 ( T and RH). The system incorporates low-cost components and custom circuitry to enhance the reliability of DAQ and prevent data loss. The A-DAQ was tested during controlled burns (CBs) in a sugarcane plantation to evaluate its performance in real-world conditions, with approximately 60 m of wiring demonstrating reliable long-distance data transmission. The DS18B20 and HDC1080 sensors provided consistent and accurate subsoil temperature measurements, with readings ranging from 23 °C to 29 °C before and after the CB, respectively. The HDC1080 performed reliably for RH measurements, capturing variations from nearly 100% (before the CB) to ∼0% (after the CB). In contrast, the DHT22 exhibited malfunctions, likely due to the subsoil’s high humidity conditions before the CB, which compromised its functionality. This study demonstrates that the A-DAQ system offers an affordable and scalable solution for subsoil monitoring, highlighting its potential to make precision agriculture technologies accessible to small-scale and family farming operations, ultimately supporting crop improvement.

The whitefly Bemisia tabaci is among the most important agricultural pests in the world and one of the world’s top 10 most invasive insect pests. Bemisia tabaci is associated with severe yield and quality losses, mainly due to the transmission of plant viruses, as in the case of common beans (Phaseolus vulgaris L.). Reducing insecticide applications is a research priority, e.g., developing innovative and clean tools such as electromagnetic waves. The present work aims to determine the effective parameters of laser to reduce the Bemisia tabaci population in common beans. Preliminary assays were conducted by manually irradiating continuous-wave laser beams with different wavelengths (444 nm, 527 nm, and 640 nm) and optical intensities directly on the insects. Among these, the most effective wavelength was 444 nm. Later, we repeated the experiments using a homemade automated system to control the exposure time (t₁ = 1 s, t₂ = 2 s, t₃ = 3 s and t₄ = 4 s) of whiteflies to the incident beam at different optical intensities (I₁ ≈ 10 Wcm⁻², I₂ ≈ 4 Wcm⁻², I₃ ≈ 2 Wcm⁻²). We have achieved 100% insect mortality by irradiating 454 nm laser wavelength on the 3rd instar nymphs of Bemisia tabaci, with the following parameters: I₁(t₁), I₂(t₃) and I₃(t₄). Moreover, the laser irradiation test did not affect plant yield and development, revealing that our preliminary results present a photonic technique that could control whiteflies without harming the plants’ development.