Prediction of soil nutrient content via pXRF spectrometry and its spatial variation in a highly variable tropical area

Precision Agriculture - Precision agriculture provides detailed information on the spatial variability of soil properties, including nutrient content, allowing for local-specific decision making....     

Semantic segmentation of citrus-orchard using deep neural networks and multispectral UAV-based imagery

Precision Agriculture - Accurately mapping farmlands is important for precision agriculture practices. Unmanned aerial vehicles (UAV) embedded with multispectral cameras are commonly used to map...     

Micronutrient Contents of a Revegetated Saprolite Exposed by Excavation of an Oxisol

Soils of the Brazilian Cerrado biome have been found to be deficient in copper (Cu) and zinc (Zn). In this area, an Oxisol was deeply excavated in 1962 during the construction of a hydroelectrical plant, and the exposed saprolite material was abandoned, without any reclamation measures. The abandoned land was a harsh environment for plant growth, and the secondary vegetation has not recovered. A field trial was established in 1992 to assess the effects of different grass species and lime amendments on soil reclamation at the degraded site. In 2011 soil samples were collected at three depths (0–10, 10–20, and 20–40 cm) from vegetated and bare plots over tilled saprolite, from an untreated area of the saprolite, and from an Oxisol under native forest, used as external reference. Nineteen years after the reclamation effort was begun, the organic carbon (OC) content of the restored saprolite still was much lower than that of the Oxisol under natural vegetation. The undisturbed Oxisol was deficient in extractable Cu (0.16–0.10 mg kg^?1) and Zn (0.10–0.02 mg kg^?1) and exhibited rather low concentrations of extractable iron (Fe; 5.24–1.47 mg kg^?1) and manganese (Mn; 3.21–0.77 mg kg^?1). However, the saprolite under reclamation showed even lower levels of these elements compared to the native forest soil. In the natural soil, OC, N, extractable Fe, Mn, and Cu showed stratification, but this was not the case for extractable Zn. Although the reclaimed saprolite still was far from predisturbance conditions, the revegetation treatments promoted recovery of OC, N, Fe, Mn, and Cu at the surface layers, which resulted in incipient stratification. Extractable Fe, Mn, and Cu were correlated to OC, whereas no association between Zn and OC was detected. Our results also suggest that reclamation of the excavated saprolite may be constrained by micronutrient deficiencies and mostly by the extremely low levels of Zn and Cu.     

Modelling soil salinity across a gilgai landscape by inversion of EM38 and EM31 data

The soil in arid and semi‐arid areas is often markedly saline, which can severely limit agricultural productivity. Increasingly, geophysical methods are being implemented to map the levels and areal extent of soil salinity. One of the most effective methods is electromagnetic (EM) induction with instruments designed to measure apparent soil electrical conductivity (EC_a). This study describes the generation of electromagnetic conductivity images (EMCIs) by inverting EC_a data obtained with the EM38 and EM31 devices along two closely‐spaced transects by the EM inversion approach in the EM4Soil package. The EM38 EC_a data are shown to be a more effective predictor of soil EC_e. Calibration equations based on calculated true electrical conductivity (σ) and measured electrical conductivity of a saturated soil‐paste extract (EC_e) provide reliable estimates of EC_a. The patterns of σ in a test of the method in soil developed over thick alluvium on a clay plain in central New South Wales, Australia, compare favourably with existing pedological mapping; the mounds and depressions of gilgai were strongly differentiated from the more sandy alluvial sediments that characterize prior stream channels. The overall approach is potentially useful for generating a single calibration equation that can be used to predict EC_e at various depths in the soil. Improvements in EMCI modelling can also be sought by joint inversion of EM with other geophysical datasets.     

Ecosystem restoration after bauxite mining: favorable indicators for Technosols construction and soil management using liming and subsoiling

New Forests - Although its economic importance, bauxite mining causes the loss of natural ecosystems. In this sense, the Technosols building from materials made or modified by man, such as mine...     

Efficacy of 1,3-dichloropropene plus chloropicrin application methods in combination with pebulate and napropamide in tomato

Small-plot research and large-field validations were conducted to determine the effect of 1,3-dichloropropene (1,3-D)+chloropicrin (Pic) application methods in combination with the herbicides pebulate and napropamide on pest control in fresh market tomato (Lycopersicon esculentum Mill.). In both the small-plot trials and the large-validation fields, various treatments compared the efficacy of soil fumigants and herbicides based on methyl bromide, in-bed and broadcast applications of 1,3-D+Pic, pebulate, and napropamide. The results consistently indicated that either in-bed or broadcast applications of 1,3-D+Pic in combination with pebulate and napropamide are equally effective against the weed Cyperus spp., the nematodes Tylenchorhynchus spp., Belonolaimus longicaudatus, and Meloidogyne spp., and the soilborne disease Fusarium oxysporum f.sp. lycopersici in fresh market tomato. Therefore, broadcast 1,3-D+Pic application can reduce personnel exposure and poisoning risks, without losing pest control efficacy.     

The influence of dicyanodiamidine sulphate on the quality of some cereal crops

The influence of dicyanodiamidine sulphate (DDS) on the quality of some cereal crops was studied in several pot experiments. In each of the experiments DDS was compared with ammonium sulphate (AS) and mixtures of AS + DDS in several proportions. The experiments were carried out in several soils and the influence of soil characteristics were evident in the final results. The cereals studied were sorghum, wheat, rye, barley and fescue. Influence of different treatments was studied in relation to the composition either of whole plants, or of straw and grain separately.Application of DDS is especially important for protein content and quality of products. The utilization of this fertilizer is rather slow and continuous during the vegetative cycle of plants, and as a consequence protein synthesis is mainly increased specially in the grain. Protein quality in wheat may or may not be affected depending upon the exchange capacity of the soil. In cereals used for pasture and subjected to several cuts the influence of DDS is also important, decreasing differences in production and quality among the different cuts, particularly noticeable in the summer cuts. Mineral composition of plants is also affected by DDS.The conclusion that can be drawn is that DDS, in mixtures with AS, may be a very important tool in nitrogen fertilization mainly on light soils, long term crops and under conditions of heavy rains, circumstances where its more or less continuous utilization and resistance to leaching are important features to be considered in production and for the quality of the products.

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Zusammenfassung Der Einfluß von Dicyandiamidinsulfat (DDS) auf die Qualität einiger Cerealien wurde in mehreren Gefäßversuchen untersucht. In jedem dieser Versuche verglich man DDS mit Ammoniumsulfat (AS) und mit Mischungen von AS + DDS in verschiedenen Proportionen. Die Versuche wurden in mehreren Böden durchgeführt. In den Endergebnissen kam der Einfluß der charakteristischen Bodeneigenschaften gut heraus. Die im Versuch stehenden Cerealien waren Sorghum, Weizen, Roggen, Gerste und Wiesenschwingel (Festuca). Der Einfluß der verschiedenen Behandlungen konnte durch die chemische Zusammensetzung der ganzen Pflanze oder getrennt nach Stroh und Korn verfolgt werden.Die Verabfolgung von DDS ist insbesondere für den Eiweißgehalt und für die Qualität der Erzeugnisse bedeutsam. Die Ausnutzung dieses Düngers ist während der vegetativen Entwicklung ziemlich langsam und andauernd, infolgedessen ist die Eiweißsynthese speziell im Korn besonders erhöht. Eiweißqualität kann oder kann nicht im Weizen beeinflußt werden. Dies hängt von der Austauschkapazität des Bodens ab. In Cerealien für Weidezwecke fand man bei verschiedenen Schnitten ebenfalls einen bedeutenden Einfluß von DDS. Unterschiede in Menge und Qualität zwischen den verschiedenen Schnitten wurden vermindert, insbesondere beim Sommerschnitt. Auch die Mineralstoffzusammensetzung der Pflanzen konnte durch DDS beeinflußt werden.Zusammenfassend kann gesagt werden, daß sich DDS zur Stickstoffdüngung zusammen mit AS hauptsächlich auf leichten Böden sehr nützlich erweisen kann, ebenso bei Pflanzen mit langer Vegetationszeit und bei schweren Regenfällen, also bei Bedingungen, wo es mehr oder weniger auf laufende Nährstoff-Ausnutzung und auf Verhinderung der Nährstoffauswaschung ankommt. Dies sind wichtige Fakten für die Erzeugung und für die Qualität der Produkte.

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Resumé L'influence du sulfate de dicyanodimidine (SDD) dans la qualité de quelques céreales a été étudiée dans des essais en pots. Le SDD a été comparé dans tout les cas avec le sulfate d'ammonium (SA) et avec des mélanges SA+SDD.Ces essais ont été conduits sur différents types de sols et on a vérifié l'influence des caractéristiques du sol dans la production et dans la qualité des produits. Les céreales qui ont été essayés sont le sorghum, le blé, le seigle, l'orge et la fétuque. L'influence des traitements a été étudiée soit sur la composition chimique de la plante intiére soit sur la composition de la tige et du grain en séparé. Le SDD influence notamment la teneur et la qualité des protéines. On vérifie que ce produit est utilisé par les plantes d'une façon lente et continuelle tout au ling de son cycle de végétation et, en conséquence la synthèse des proteínes du grain est assez béneficiée. Dans le cas du blé on a verifié que la qualité des proteínes est diminuée ou non selon la capacité d'échange du sol. Dans les céreales utilisés comme paturage l'influence du SDD est aussi importante, en diminuant les variations de production et de la qualité parmis les différents coupes, notamment en ce qui concerne la production d'Eté. La composition minérale est aussi modifiée par le SDD.On a conclus que le SDD, en mélange avec le SA, peût constituer un important instrument de la fertilization azotée, surtout dans des sols légers, avec une pluviosité importante et dans des cultures de longue permanence dans le sol, parce que dans ces cas l'utilization plus ou moins continuelle et graduelle du SDD et sa résistance au lessivage lui permêt de représenter un rôle important dans l'amélioration de la production et de la qualité des produits.

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Professor of Agricultural Chemistry. Deceased on 5th October 1975.     

Effects of propylene oxide doses on Cyperus and Belonolaimus control and nutrient absorption in tomato

Among the current methyl bromide alternatives under study, propylene oxide has shown potential to control soilborne diseases, nematodes, and weeds in polyethylene-mulched tomato (Lycopersicon esculentum Mill.). Therefore, field trials were conducted to determine the most effective propylene oxide doses against populations for the nematode Belonolaimus spp. and the weed Cyperus spp. and their effect on nutrient uptake. Propylene oxide doses were 0, 190, 380, 570, 760, and 950 L/ha. Data indicated that populations of Belonolaimus and Cyperus rapidly decreased with 570 L/ha of propylene oxide. Propylene oxide doses also affected foliar concentrations of phosphorus and potassium. There was a linear increase of phosphorus concentration as dose increased, whereas potassium concentration increased rapidly after 190 L/ha of propylene oxide. The highest tomato yields were obtained with application of 760 and 950 L/ha of propylene oxide.     

Heterofucans from the brown seaweed Canistrocarpus cervicornis with anticoagulant and antioxidant activities

Fucan is a term used to denominate a family of sulfated polysaccharides rich in sulfated l-fucose. We extracted six fucans from Canistrocarpus cervicornis by proteolytic digestion followed by sequential acetone precipitation. These heterofucans are composed mainly of fucose, glucuronic acid, galactose and sulfate. No polysaccharide was capable of prolonging prothrombin time (PT) at the concentration assayed. However, all polysaccharides prolonged activated partial thromboplastin time (aPTT). Four sulfated polysaccharides (CC-0.3/CC-0.5/CC-0.7/CC-1.0) doubled aPTT with only 0.1 mg/mL of plasma, only 1.25-fold less than Clexane, a commercial low molecular weight heparin. Heterofucans exhibited total antioxidant capacity, low hydroxyl radical scavenging activity, good superoxide radical scavenging efficiency (except CC-1.0), and excellent ferrous chelating ability (except CC-0.3). These results clearly indicate the beneficial effect of C. cervicornis polysaccharides as anticoagulants and antioxidants. Further purification steps and additional studies on structural features as well as in vivo experiments are needed to test the viability of their use as therapeutic agents.     

Biochemical Composition and Indigestible Oligosaccharides in Phaseolus vulgaris L. Seeds

Common beans have a high nutritional value, but contain galactooligosaccharides (GO), which cause flatulence and intestinal discomfort in humans. The biochemical composition of ten bean cultivars was determined to select those of high protein and low GO contents. The cultivars varied in carbohydrate (47.02–60.17%), GO (3.12 – 5.71%), protein (22.17–33.50%), lipid (1.13–1.81%), moisture (11.42–12.93%) and ash contents (4.08–5.61%). ‘Mexico 222’ presented the highest α-galactosidase activity. Protein and GO contents were positively correlated. ‘Perry Marrow’ combined high protein and low GO concentrations, indicating it can be used in improvement programs aiming at high-quality cultivars for human consumption.