Management alternatives for sandy soils to overcome edaphic limitations in irrigated okra cultivation

N.F. Rodrigues¹*, S.R.L. Tavares², F.C. Silva³, C.M. Hüther³ G.M. Corrêa⁴, J.R. Oliveira⁴, L.S. Hamacher³ and E.P. Clemente⁵

¹Federal Rural University of Rio de Janeiro, Posgraduate Program in Agronomy, Rodovia BR 465, Km 7, 23890-000, Seropédica, Brazil
²Brazilian Agricultural Research Corporation (Embrapa), Embrapa Soils, Rua Jardim Botânico, 1024 - Jardim Botânico, 22460-000 Rio de Janeiro, RJ, Brazil
³Federal Fluminense University, School of Engineering, Department of Agricultural and Environmental Engineering, Rua Passo da Pátria, 156 - São Domingos, 24210-240 Niterói, RJ, Brazil
⁴Federal Fluminense University, Postgraduate Program in Biosystems Engineering, Rua Passo da Pátria, 156 - São Domingos, 24210-240 Niterói, RJ, Brazil
⁵Brazilian Agricultural Research Corporation (Embrapa), Embrapa Maize and Sorghum, Rodovia MG 424, Km 45, 35701-970 Sete Lagoas, MG, Brazil
*Correspondence: rodriguesnataliafe@gmail.com

Abstract:

Sandy soils are often unsuitable for agriculture due to their poor physical and chemical properties. However, using conditioners can improve these parameters, making these soils viable for cultivation. This study evaluated Red-Yellow Argisol (Clay), Biochar, and Ceramic residues as soil conditioners for Planosol. The experiments were conducted in pots in a greenhouse and the experimental design was completely randomized with three treatments and five replications, compared to a control (100% P). Treatments included Clay (50% P + 570.6 t ha^-1 A), Biochar (50% P + 189.9 t ha^-1 B), and Ceramic (50% P + 459.9 t ha^-1 C). Okra (Abelmoschus esculentus L.) was used to assess the impact on development and productivity over 90 days from transplanting (DAT). Granulometry of conditioners, and the carbon, hydrogen, nitrogen, and ash content were analyzed. For constructed soils, granulometry, bulk density, particle density, and water retention capacity (CRA) were measured before planting. Chemical parameters, including Ca²⁺, Mg²⁺, K⁺, Na⁺, Al³⁺, H⁺, pH, and others, were measured at 0 and 90 DAT. Okra growth parameters, such as height, stem diameter, leaf number, leaf area, stomatal conductance, and chlorophyll a fluorescence dry biomass and leaf nutrient contents (N, P, K, Ca, Mg, Na) were assessed at 90 DAT. Results indicated that conditioners improved the physical and chemical properties of the Planosol and the physiological parameters of okra. Biochar increased phosphorus and potassium, while Clay enhanced nitrogen and sodium for okra cultivation.

Key words:

Abelmoschus esculentus L., horticulture, soil conditioners

Electrical field based detection of fruits and vegetables for robotized horticulture

V. Osadcuks* and A. PeckaV. Osadcuks* and A. Pecka

Latvia University of Agriculture, Faculty of Engineering, Department of Energetics, Cakstes blvd. 5, LV-3001 Jelgava, Latvia; *Correspondence: vtl@tvnet.lv

Abstract:

In this research authors study possibilities of using transmitting-type electric field based sensors for recognition of fruits and vegetables. The main idea is to detect distortions of electrical field between electrodes of sensors by measuring capacitance changes for these electrodes. Electrical field is strongly affected by relative permittivity of medium, which is several times larger for fruits and vegetables consisting mainly of water than for surrounding air, leaves and other low-mass non-conductive objects. This could help to develop electrical field sensing device with number of electrodes for detection of fruits or vegetables and determining their position thus serving as additional sensor in multi sensor system with optical camera or as stand alone device. The research covers both theoretical aspect of proposed approach and experimental evaluation of prototype device based on mixed signal controller MGC3130 originally intended for electrical field based gesture sensing periphery for consumer electronics. Main results show that in worst condition when an electrode is fully covered with a physical model of leaf 43% of signal value in comparison to sensor output without obstacle is still usable. Thus this type of sensors potentially can be an integral part of complex fruit or vegetable recognition system in robotized horticulture applications.

Key words: