Open Access Short Research Article

Chemical and Physical Quality of the Entisol in a Natural Regeneration Area in the Semiarid Region of Paraiba

Cássio Ricardo Gonçalves da Costa, Vânia da Silva Fraga, George Rodrigues Lambais, Kilmer Oliveira Soares, Stella Ribeiro Prazeres Suddarth, Salomão de Sousa Medeiros

Journal of Experimental Agriculture International, Page 1-7
DOI: 10.9734/jeai/2019/v35i230202

The change in the use of the soil causes an imbalance in the ecosystems, altering the chemical and physical properties, which can make their natural recovery unviable. This study aimed to characterize chemically and physically an Entisol under the Caatinga area in a 30 years ecological succession stage in the Semiarid region of Paraiba. The experiment was carried out at the Experimental Station Professor Ignácio Salcêdo, belonging to the National Institute of Semiarid (INSA), located in the municipality of Campina Grande, in the state of Paraíba, soil samples were collected in the 0-10 cm layer, for the determination of pH levels (H2O), exchangeable acidity (Al3+) and potential acidity (H + Al), Ca2+, Mg2+, K+, P, Na+, CTC and SB, Total organic carbon (TOC) and organic matter (OM). In the physical analyses, texture, soil density, particle density, total porosity and aggregate stability were determined. The chemical characterization observed the presence of high levels of K+, Ca2+, Mg2+, CTC and SB, and low levels of Al3+ and Na+ with reduced OM and TOC contents in the 0-10 cm layer. As for physics, the textural classification was sandy loam soil, the soil density, soil porosity and aggregate stability showed values below the critical root growth index in sandy soils. The soil presented recovery characteristics of its chemical and physical quality. The description of the Entisol in the field in soil surveys contributes to a new database in order to predict a better way of use, and these results are references in studies of soil quality recovery in degraded areas in the Caatinga area.

Open Access Original Research Article

Influence of Hypsometry in the Occupation of Semiarid Areas

Jéssica S. A. Cunha, Ana Lícia P. Feliciano, Emanuel A. Silva, Luiz Carlos Marangon

Journal of Experimental Agriculture International, Page 1-9
DOI: 10.9734/jeai/2019/v35i230198

This research aims with the help of geotechnologies to map the different uses and coverage of the earth by analyzing its effects in relation to the altitudinal gradient in semiarid regions. In order to do so, RapidEye images were acquired in the year 2014, after the organization of the database the digital processing of the acquired scenes was carried out which were performed contrast technique, segmentation, identified eight classes of use and land cover and submitted to Maximum Likelihood classification. The relationship between forest cover and different uses indicates that the most representative class was Agriculture and Livestock, as a consequence of the local economy being based on subsistence culture and the Lowland environment is the most affected. In addition, it is verified that there is a lower degree of anthropization in the tops evidencing that in the Plateau environment persists a greater density of native vegetation. This research confirms the hypothesis that the process of fragmentation of the native vegetation of the semi-arid region changes in relation to the altitudinal gradient, since the higher the altitude, the lower the degree of isolation and, consequently, the high forest coverage.

Open Access Original Research Article

Efficacy of 2,4-D Choline as Influenced by Weed Size in the Texas High Plains

Misha R. Manuchehri, Peter A. Dotray, J. Wayne Keeling

Journal of Experimental Agriculture International, Page 1-8
DOI: 10.9734/jeai/2019/v35i230199

Aim: Postemergence timing trials based on weed size were conducted near Lubbock, TX to assess the effectiveness of 2,4-D choline + glyphosate on control of Palmer amaranth (Amaranthus palmeri S. Wats.), Russian-thistle (Salsola tragus L.), and kochia (Kochia scoparia L.) at three growth stages (3 to 5 cm, 10 to 15 cm, and 20 to 30 cm).

Study Design: All trials were arranged in a randomized complete block design with four replications.

Place and Duration of Study: Field experiments were conducted in 2013, 2014, and 2015 in Lubbock, TX at the Texas A&M AgriLife Research and Extension Center near Lubbock, TX.

Methodology: Herbicide treatments consisted of a single postemergence application of 2,4-D choline + glyphosate at two rates, 2,4-D choline + glyphosate at two rates + glufosinate, 2,4-D choline + glyphosate + S-metolachlor, 2,4-D choline + glyphosate + acetochlor, 2,4-D choline + glufosinate, glyphosate, or glufosinate.

Results: The greatest level of weed control for all three weed species was achieved at the 3 to 5 cm timing; however, weed size was most critical for Palmer amaranth and Russian-thistle compared to kochia. Averaged over all three years, Palmer amaranth control decreased from 93 to 74% when evaluated 21 days after treatment following applications that included 2,4-D choline when applied to plants 3 to 5 and 10 to 30 cm, respectively. For Russian-thistle, control decreased from 98 to 78% when evaluated 21 days after treatment following treatments that included 2,4-D choline when applied to plants 3 to 5 and 10 to 30 cm, respectively. For kochia, control decreased from 98 to 84% when evaluated 21 days after treatment following treatments that included 2,4-D choline when applied to plant 3 to 5 and 10 to 30 cm, respectively.

Open Access Original Research Article

Biomass Production and Nutritional Characterization of Eucalyptus benthamii in the Pampa Biome, Brazil

Claudiney do Couto Guimarães, Dione Richer Momolli, Huan Pablo de Souza, Mauro Valdir Schumacher, Aline Aparecida Ludvichak, Angélica Costa Malheiros

Journal of Experimental Agriculture International, Page 1-9
DOI: 10.9734/jeai/2019/v35i230201

The objective of this study was to evaluate the biomass production and to characterize a 7-year-old Eucalyptus benthamii stands in the Pampa-RS Biome. Initially, a sample inventory was performed for the dendrometric characterization of the stand. For the determination of biomass, nine trees were felled and fractionated in wood, bark, branch and leaves. Soil samples and plant tissues were collected and analyzed for nutritional characterization and determination of biological utilization coefficient (BUC). The average annual increment (AAI) with bark was 49.87 m3 ha-1. The biomass production was 192 Mg ha-1, distributed in wood (81.2%)> branches (11%)> bark (6,5%)> leaves (1,3%). The leaves component presented the highest nutrient concentration and the wood the highest amounts of nutrients allocated in the biomass, except for Ca and Mg, observed in the bark. The highest BUC was observed in the wood. Mg was the nutrient that provided the best efficiency with a yield of 6,014 kg of wood per kg of Mg used, followed by S, P, Ca, K and N.

Open Access Review Article

Optical Sensors for Precision Agriculture: An Outlook

Lucas de Arruda Viana, Deborah Campos Tomaz, Rodrigo Nogueira Martins, Jorge Tadeu Fim Rosas, Fernando Ferreira Lima dos Santos, Marcelo Fagundes Portes

Journal of Experimental Agriculture International, Page 1-9
DOI: 10.9734/jeai/2019/v35i230203

The growing human population added to the rural exodus has aggravated the pressure in the agricultural sector for greater production. Faced with this problem, research has developed optical sensors for more productive agriculture with the purpose of minimizing the effects of rural exodus, obtaining rapid information and promoting the rational use of natural resources. Optical sensors have a differential consisting of the ability to use the spectral signature of an attribute or part of it to gain information, often not obvious. This review provides recent advances in optical sensors as well as future challenges. The studies have shown the wide range of applicability of optical sensors in agriculture, from detection of weeds to identification of soil fertility, which favors management in different areas of agriculture. The main limitation to the use of optical sensors in agriculture in most parts of the world has been the cost of purchasing the devices, especially in poor countries. So one of the future challenges is the reduction of final prices paid by consumers.