Brazilian Ultisol Research Articles

Characterization of mixtures of Brazilian Ultisol with urban pruning waste biochar at two different proportions

Characterization of mixtures of Brazilian Ultisol with urban pruning waste biochar at two different proportions

Phosphorus accumulation in a southern Brazilian Ultisol amended with pig manure for nine years

ABSTRACT: This study evaluated P pools after nine years of successive application of either pig slurry (PS) or deep pig litter (DL) in a no-till Ultisol from southern Brazil. The experiment was established in Dec 2002 with the treatments control, application of 90 and 180 kg N ha−1 N as PS and as DL. In Mar 2010, soil samples were taken at six layers up to 30 cm deep. Total organic and inorganic P were assessed by the ignition method, and P compounds classes were evaluated by 31P-NMR spectroscopy. Total soil P increased proportionally with the P amount applied via DL and PS. Only DL application increased soil organic P, mainly at the highest dose and in the uppermost soil layers. The application of high doses of manure to these soils under no-till to meet crop N demands significantly increased P accumulation at the soil surface, especially with DL. This, in turn, increases the risk of contamination of water bodies due to P transfer from soil to rivers via runoff. The ignition method overestimates organic P compared to P-NMR. The highest proportion of organic P estimated by the ignition and P-NMR methods, at surface layers in the control suggests that inorganic P is added to the plots treated, increasing inorganic P and decreasing organic P. Moreover, with no P additions to the control, inorganic soil P is removed by plants, causing an apparent increase in the organic P proportion.

Benefits of microbial fertilizer in interspecific interaction with textile sludges on cowpea in a Brazilian Ultisol and on wastes toxicity

Abstract The lack of knowledge of the effects of jean textile sludge on microbial communities, plant growth and nutrition in tropical soils represents an important problem for using organic wastes for sustainable agriculture. The microbial fertilizer is produced from P and K in rocks plus sulfur with Acidithiobacillus bacteria, mixed with organic matter inoculated with selected diazotrophic bacteria (Beijerinckia indica) and Cunninghamella elegans, a fungus that contains chitosan and that may be an alternative to conventional fertilizers. The microbial fertilizer was applied in three doses and was compared with conventional soluble fertilizers, and the interactions with various textile sludges were observed. A greenhouse experiment was conducted as a factorial scheme (4x3) in a randomized block design, with 4 replicates. Multivariate analysis was used to identify the effects of the treatments on the environment, especially with respect to heavy metals. The microbial fertilizer showed similar effects compared to the conventional soluble fertilizers. The jean textile sludge provides positive effects when applied to cowpeas growing in a Brazilian Ultisol. We conclude that the microbial fertilizer improves the plant characteristics and may be a viable alternative to conventional fertilizer. Associated with the jean textile sludges, the microbial fertilizer promotes great effectiveness in the plant characteristics and provides positive results for sustainable agriculture.

Response of horticultural crops to application of bioprotector and biological control of Ralstonia wilt in Brazilian Ultisol

Response of horticultural crops to application of bioprotector and biological control of Ralstonia wilt in Brazilian Ultisol

The non-recoverable phosphorus following sorption onto a Brazilian Ultisol

Phosphorus (P) immobilization in soil involves geochemical (e.g., sorption, precipitation, and diffusion) and microbiological (microbial uptake) processes. Using a Brazilian Ultisol, relative contributions of both processes to the total immobilization of applied P over 14 days were investigated. The P immobilized by microbes as interpreted by microbial suppression (achieved by mercury sterilization) was 17, 50, 54, and 56% (of the total immobilized P) on days 3, 7, 10, and 14 after fertilization, respectively. In the short-term (1 to 3 days), microbes played less of a role than did the physical effect of shaking the soil, but became the major factor by days 7 to 14. Geochemical process that might be considered short-term ageing caused only 13–16% of the total immobilization in the same time period above. Calculations supported the interpretation that measurable diffusion occurred across water films on the soil particles.

ORGANIC ANIONS AND PHOSPHORUS DESORPTION AND BIOAVAILABILITY IN A HUMID BRAZILIAN ULTISOL

Phosphorus (P) bioavailability is controlled by combined reactions of adsorption/precipitation and desorption/dissolution. Soil P has been fractionated; however, current P metrics do not necessarily measure discrete pools of bioavailable P based on mechanisms of soil inorganic P extraction by plants. Plants can desorb P by creating disequilibria between solid and solution phases (disequilibria desorption) and through the action of exuded organic anions on soil surfaces (ligand desorption). Both desorption mechanisms involve surface reactions of exchange and dissolution. These pools of P are potentially bioavailable pools because they react to plant mechanisms. However, these pools are not well documented. Our study had three objectives: (i) to measure ligand-desorbable P, (ii) to determine if we could separate ligand-exchangeable and ligand-dissolvable pools, and (iii) to investigate the fate of applied fertilizer P as it was incorporated into disequilibria-desorbable and ligand-desorbable pools. All studies used a tropical Brazilian Ultisol. Seven hours of interaction time and 500 μmol of anions g−1 soil were found optimum for the measurement of ligand-desorbable P. Our data suggested that ligand exchange and ligand dissolution could be operationally separable when anion concentrations were below 1 μmol g−1. In the short term, P fertilization preferentially put P in the disequilibria-desorbable pool over ligand-desorbable pool. Fractionation of soil bioavailable P must account for the mechanisms that plants and microorganisms have for extracting P from soils, which means they must go beyond the common P fractionation schemes commonly used today, which have their roots in soil pedology.

Influence of soil pH on inorganic phosphorus sorption and desorption in a humid brazilian Ultisol

Liming is a common practice to raise soil pH and increase phosphorus (P) bioavailability in tropical regions. However, reports on the effect of liming on P sorption and bioavailability are controversial. The process of phosphorus desorption is more important than P sorption for defining P bioavailability. However few studies on the relationship between soil pH and P desorption are available, and even fewer in the tropical soils. The effects of soil pH on P sorption and desorption in an Ultisol from Bahia, Brazil, were investigated in this study. Phosphorus sorption decreased by up to 21 and 34 % with pH increases from 4.7 to 5.9 and 7.0, respectively. Decreasing Langmuir K parameter and decreasing partition coefficients (Kd) with increasing pH supported this trend. Phosphorus desorption was positively affected by increased soil pH by both the total amount of P desorbed and the ratio of desorbed P to initially sorbed P. A decreased K parameter and increased Kd value, particularly at the highest pH value and highest P-addition level, endorsed this phenomenon. Liming the soil had the double effect of reducing P sorption (up to 4.5 kg ha-1 of remaining P in solution) and enhancing P desorption (up to 2.7 kg ha-1 of additionally released P into solution).

Evaluation of perennial herbaceous legumes with different phosphorus sources and levels in a Brazilian Ultisol

AbstractThis study was carried out under field conditions with the aim of evaluating the period of time necessary for soil cover, dry matter production and accumulation of nutrients by perennial herbaceous legumes with different phosphorus sources at different levels. Four legumes were evaluated: calopo (Calopogonium mucunoides Desv.), forage groundnut (Arachis pintoi Krap. & Greg.), siratro (Macroptilium atropurpureum (OC.) Urb.) and tropical kudzu (Pueraria phaseoloides (Roxb.) Benth.). Each of these species received different phosphorus (P) sources and levels: no phosphate fertilization; 44 and 88 kg of P ha−1 applied as rock phosphate; and 44 kg of P ha−1 as triple superphosphate. Calopo, siratro and tropical kudzu completely covered the soil surface 129 days before forage groundnut. Phosphate fertilization did not increase the dry matter production of any species. The legumes forage groundnut, siratro and tropical kudzu showed desirable characteristics that promote their use as cover crops, such as high dry matter production and shoot accumulation of nitrogen (N) and potassium (K). Forage groundnut had the highest proportion of N derived from the atmosphere at the end of the rainy season, while there were no significant differences between the legumes at the end of the dry season. There was an elevation of soil pH and calcium+magnesium (Ca+Mg) contents, associated with a reduction of aluminum (Al) content, in the surface soil layer (0–5 cm) for siratro in relation to groundnut and tropical kudzu. Tropical kudzu promoted higher soil organic C contents when compared to groundnut.