Towards sustainable and regenerative territories: ecological restructuring of phosphorus retention and mobilization based on substance flow analysis (sfa) in Quirino Province

Phosphorus (P) is an essential and finite nutrient element that cannot be substituted by any other substance. To overcome limited supply of mineral Phosphate rocks (PR) deposits and to contribute to its sustainable management, a better knowledge on P flows is needed. In this study, a Substance Flow Analysis (SFA) for P was conducted for the Quirino Province. Different subsystems were investigated such as forestry, agriculture, anthropogenic consumption, organic wastes, and wastewater management. The researcher found that within the system under study, there is an excess total P inflow into the three (3) major river watersheds system in Quirino Province. The aim of the study was to analyze the flow of Phosphorus that enter, transform, pass through, and leave the territorial subsystems in order to create a knowledge bank that will aid in the transition of Quirino Province from linear to circular metabolism.

Phosphorus Dynamics in Sugarcane Fertilized With Filter Cake and Mineral Phosphate Sources

Organic residual material such as filter cake, combined with mineral phosphate fertilizers, may alter the soil phosphorus (P) bioavailability for sugarcane as a consequence of the competing effect in adsorption sites. This study aimed to quantify the changes in both the inorganic and organic soil P fractions as amended by phosphate fertilizer sources and filter cake and to link the P fractions to sugarcane response. An experiment was conducted in an Oxisol, in a randomized block design with factorial arrangement of 4 × 2, and three replications. Three P fertilizer sources (triple superphosphate, Araxá rock phosphate, and Bayóvar® reactive phosphate) plus a control (no P) were evaluated under both the presence and absence of filter cake. At the end of the second crop cycle, the following were measured: the cane yield, the tissue P content, and soil P fractions. All fertilizer sources were efficient in supplying P to sugarcane. Araxá rock phosphate generated a higher accumulation in moderately labile P, whereas the soluble triple superphosphate resulted in higher labile P. The filter cake, as a source of nutrients and organic matter, has an important contribution to maintain more available P for sugarcane absorption, especially when associated with triple superphosphate. The amount of P absorbed by sugarcane was correlated with the soil labile P (r = 0.58) and also with the inorganic P moderately labile (r = 0.42). Both fractions must be taken into account for a short- to medium-term availability of P for sugarcane in Oxisols.

Crc Regulates Succinate-Mediated Repression of Mineral Phosphate Solubilization in Acinetobacter sp. SK2 by Modulating Membrane Glucose Dehydrogenase

The plant growth-promoting Acinetobacter sp. SK2 isolated from Vigna radiata rhizosphere was characterized for mineral phosphate solubilization (MPS). To understand the contribution of the membrane glucose dehydrogenase (mGDH) and soluble glucose dehydrogenase (sGDH) in glucose oxidation and MPS, insertional inactivation of the corresponding genes was carried out. The disruption of mGDH encoding gene gdhA resulted in complete loss of mGDH activity, which confirmed its role in periplasmic glucose oxidation and gluconate-mediated MPS phenotype. The inactivation of sGDH encoding gene gdhB resulted in loss of sGDH activity, which did not alter the MPS or mGDH activity. Thus, it was also concluded that the sGDH was dispensable in gluconate-mediated MPS. Supplementation of succinate in glucose-containing medium suppressed the activity of mGDH (and sGDH) and therefore repressed the MPS phenotype. The catabolite repression control protein (Crc) of Pseudomonas was implicated in Acinetobacter sp. for a similar function in the presence of preferred and non-preferred carbon sources. To understand the regulatory linkage between Crc and genes for glucose oxidation, crc mutants were generated. The inactivation of crc resulted in increased activity of the mGDH in glucose + succinate-grown cells, indicating derepression. An increase in phosphate solubilization up to 44% in glucose + succinate-grown crc– compared with glucose-grown cells was recorded, which was significantly repressed in the wild-type strain under similar conditions. It is therefore proposed that in Acinetobacter sp. SK2, Crc is involved in the succinate-provoked repression of the MPS phenotype. The gene expression data indicated that Hfq may also have a regulating role in preferential utilization of carbon source by perhaps modulating Crc–Hfq functionality. V. radiata plants inoculated with the wild type improved both root and shoot length by 1.3 to 1.4-fold. However, crc– increased the root and shoot length by 1.6-fold, compared with the uninoculated controls. In mimicking the soil condition (in the presence of multiple carbon sources, e.g., succinate along with glucose), the crc– strain of Acinetobacter sp. SK2 performed better in supporting the growth of V. radiata in pot experiments.

Phosphate Organomineral Fertilizer Usage Compared to Mineral Phosphate in Corn Cultivation

Corn has great relevance for agribusiness as it is used in human and animal food, besides the energy matrix. The objective of this study was to assess the leaf content of macro and micronutrient, accumulation of primary macronutrients, production components and productivity with the application of pelleted organomineral fertilizer in different doses compared to mineral fertilization, in two soils of different textures in the corn crop. Two trials were conducted in the municipality of Uberlândia-MG-Brazil: one located near the highway BR 452 km 141, at the coordinate 18°55′26″S, 48°09′36″W, clay soil. The other at km 640 of BR 365, at coordinate 18°54′05″S, 48°25′20″W, sandy soil. A randomized block design with five replications was used, with five doses of organomineral fertilizer (40, 60, 80, 100 and 120% of the recommended dose of P2O5 for corn) and an additional with 100% of the recommendation of mineral P2O5, total of six treatments and 30 plots. The results showed that, with the exception of phosphorus leaf content, yield in the sandy texture and the number of grains per row in the clay texture, there was no difference between the doses of phosphate organomineral and did not differ from the mineral. Thus, phosphate organomineral is as efficient as mineral for phosphorus supply.